Confused! Heat Recovery- yes or no?

muinteoir

Hi, we are starting building in the next few months and as we don't have much background knowledge about building matters but after lots of research we have finally decided to go with underfloor heating, very good insulation/ passive windows but now we are wondering whether or not to go with a heat recovery system.. I'm wondering would we need one with the underfloor to keep the rooms fresh but I am wondering about side effects like recycling air when people have colds/ flus etc. Also are they worth the money as opposed to opening a window?

Any advice would be greatly appreciated!

MicktheMan

You havent mentioned air tightness. Good airtightness is necessary for hr to work. What AT result are you aiming for?

MVHR has nothing to do with underfloor heating nor is there an issue with "side effects like recycling air".

These questions you ask show that maybe you should be getting an experienced professional on board sooner rather than later to advise.

Good luck with your build.

sydthebeat

muinteoir wrote: »

Hi, we are starting building in the next few months and as we don't have much background knowledge about building matters but after lots of research we have finally decided to go with underfloor heating, very good insulation/ passive windows but now we are wondering whether or not to go with a heat recovery system.. I'm wondering would we need one with the underfloor to keep the rooms fresh but I am wondering about side effects like recycling air when people have colds/ flus etc. Also are they worth the money as opposed to opening a window?

Any advice would be greatly appreciated!

a basic fundamental of MHRV is that there is NO recycling of air.

The stale warm exhausted air NEVER touches the fresh cold incoming air.
They pass each other through filter pipes, this is where the heat is transferred from the exhaust to the intake.

muinteoir

Yes you are prob dead right! We are quite out of our depths to be honest. I havent a clue about the air tightness. We are going with triple glazed passive allu clad windows & 100ml in the floor, 150ml cavity in the walls pumped with bead fill, 300ml in the roof & 50ml insulated slabs on the inside walls. I keep asking profs but everyone keeps advising me different things! The more I ask people, the more confused I seem to be! It was an experienced builder I spoke to at the weekend who was saying he wasnt sure about recycling air with germs etc. This builder has fitted loads of them but said to be honest he wasnt sure of the health issues. From my own research I can see that it appears to be healthier because of taking the hot moisture out of the air.

The reason I (btw I could be totally wrong!) thought it would go well with ufh is because if the temp is to be maintained in every room at a constant, my thinking was that if you open a window to let fresh air in, the air temp would drop and ufl would need to kick in2 raise the room temp & therefore you'd use more oil. I thought heat recovery by refreshing the air would stop this need to open a window as well as the other energy benefits. Am I completely wrong?

blast06

Curiosity.... when was your planning permission granted, i.e.: do you have to comply with part L 2011 ?
Rule of thumb with underfloor i heard on Friday .... bump your floor insulation by 33% so in you case perhaps a 125 mm floor insulation (your're not going to get a 133 mm board !!) ??
I'm going with a HRV in a self-build that is ongoing but i don't know what constitutes a good system versus a bad one .... i.e.: what i am getting by spending 6-7K versus 3-4K.

sydthebeat

muinteoir wrote: »

Yes you are prob dead right! We are quite out of our depths to be honest. I havent a clue about the air tightness. We are going with triple glazed passive allu clad windows & 100ml in the floor, 150ml cavity in the walls pumped with bead fill, 300ml in the roof & 50ml insulated slabs on the inside walls. I keep asking profs but everyone keeps advising me different things! The more I ask people, the more confused I seem to be! It was an experienced builder I spoke to at the weekend who was saying he wasnt sure about recycling air with germs etc. This builder has fitted loads of them but said to be honest he wasnt sure of the health issues. From my own research I can see that it appears to be healthier because of taking the hot moisture out of the air.

The reason I (btw I could be totally wrong!) thought it would go well with ufh is because if the temp is to be maintained in every room at a constant, my thinking was that if you open a window to let fresh air in, the air temp would drop and ufl would need to kick in2 raise the room temp & therefore you'd use more oil. I thought heat recovery by refreshing the air would stop this need to open a window as well as the other energy benefits. Am I completely wrong?

even under 2008 regs 100mm under the floor isnt enough.
You must reach a u value of 0.15 min when using underfloor heating UFH and typically thats in the region of 130-150mm of floor insulation.

You sound like you are not getting any professional input into the construction specification for the house, or if you are its inadequate.
You should have a preliminary BER assessment carried out on the plans by a competent person, and that assessment will tell you what you must include to meet minimum regulations.

your 'experienced' builder doesnt understand how a MHRV system works if he was talking about 'recycling air with germs'

everything in a new build is connected, you must take a holistic approach to the specification in order for it to work. Yes, in order for you UFH not to be working at maximum all the time, a MHRV system is required, so that you 'recover' most of the heat already provided to rooms.

I think you need to sit down with someone who specifies construction and understands fully the regulations and requirements required under current building reg law.

blast06

Hi Sydthebeat,

Would you be able to PM me please ? I tried sending you a message but i think i had a problem doing so.

Cheers.

muinteoir

sydthebeat wrote: »

even under 2008 regs 100mm under the floor isnt enough.
You must reach a u value of 0.15 min when using underfloor heating UFH and typically thats in the region of 130-150mm of floor insulation.

You sound like you are not getting any professional input into the construction specification for the house, or if you are its inadequate.
You should have a preliminary BER assessment carried out on the plans by a competent person, and that assessment will tell you what you must include to meet minimum regulations.

your 'experienced' builder doesnt understand how a MHRV system works if he was talking about 'recycling air with germs'

everything in a new build is connected, you must take a holistic approach to the specification in order for it to work. Yes, in order for you UFH not to be working at maximum all the time, a MHRV system is required, so that you 'recover' most of the heat already provided to rooms.

I think you need to sit down with someone who specifies construction and understands fully the regulations and requirements required under current building reg law.

You are dead right! I am trying to research things but I do need help. My other half is having problems in work so the building things are left to me & I just havent a clue really, Im more a girly girl so its all totally out of my comfort. Im definitely going to change my floor insulation & I think a heat recovery system would go well with the ufh. Thank u for ur advice! Its really greatly appreciated. Ive arranged to met architect tomorrow evening to go over things, hopefully he can help! As you pointed out I need help! Do you think are other insulation- 150ml cavity in the walls pumped with bead fill, 300ml in the roof & 50ml insulated slab on the inside of the outside walls is ok? Thank you SOOO much for your help.

sydthebeat

muinteoir wrote: »

You are dead right! I am trying to research things but I do need help. My other half is having problems in work so the building things are left to me & I just havent a clue really, Im more a girly girl so its all totally out of my comfort. Im definitely going to change my floor insulation & I think a heat recovery system would go well with the ufh. Thank u for ur advice! Its really greatly appreciated. Ive arranged to met architect tomorrow evening to go over things, hopefully he can help! As you pointed out I need help! Do you think are other insulation- 150ml cavity in the walls pumped with bead fill, 300ml in the roof & 50ml insulated slab on the inside of the outside walls is ok? Thank you SOOO much for your help.

if it was me, personally i would increase the cavity from 150 to 200 and not put the insulated slab on the inside. A basis rule of insulation is not to split it up, to have all your insulation in the one plane.

Not installing the insulated slab means you can deal with making the build air tight a lot easier than with an insulated slab. Also you gain the benefit of 'thermal mass' which helps regulate the temps inside by storing heat where its warm and releasing heat when the internal cools down.

there are some knock on effect of increasing to 200 mm, but nothing that cannot be detailed out correctly.

If you want a low running cost home, you need it to be air tight, well insulated first off. Then you can worry about how you heat it.

muinteoir

sydthebeat wrote: »

if it was me, personally i would increase the cavity from 150 to 200 and not put the insulated slab on the inside. A basis rule of insulation is not to split it up, to have all your insulation in the one plane.

Not installing the insulated slab means you can deal with making the build air tight a lot easier than with an insulated slab. Also you gain the benefit of 'thermal mass' which helps regulate the temps inside by storing heat where its warm and releasing heat when the internal cools down.

there are some knock on effect of increasing to 200 mm, but nothing that cannot be detailed out correctly.

If you want a low running cost home, you need it to be air tight, well insulated first off. Then you can worry about how you heat it.

Oh man I really havent a clue! I have been researching like crazy but listening to everything you know I am totally out of my depths. Thanks for all your advise. You've given me lots of info especially about insulation so I know the questions to ask the architect tomorrow. I knew all about the importance of insulation n good windowd but I didnt really understand the point is to make it as air tight as possible. Thank you.

I really appreciate it!

sydthebeat

muinteoir wrote: »

Oh man I really havent a clue! I have been researching like crazy but listening to everything you know I am totally out of my depths. Thanks for all your advise. You've given me lots of info especially about insulation so I know the questions to ask the architect tomorrow. I knew all about the importance of insulation n good windowd but I didnt really understand the point is to make it as air tight as possible. Thank you.

I really appreciate it!

like everything in life, different people will have different opinions.
Its my personal view that insulated slabs are not a good idea unless used in specific applications ie offices etc which have a short 'user' timespan.

builders will always have their own preference about what way to build, and most of the time their preference will be whatever makes life easier in themselves... cant blame them for that. Insulated slabs are easy to apply, quick to finish, and 'dry out' quicker allowing for a relatively shorter build time.. in theory. However, if you have ever been in a house where an air tightness test was carried out, you would be flabbergasted at how porous concrete blocks are.

good luck with the build, and you can always come on here to 'shoot the breeze'.. theres some very knowledgeable posters here who are generous with their advise.

muinteoir

sydthebeat wrote: »

like everything in life, different people will have different opinions.
Its my personal view that insulated slabs are not a good idea unless used in specific applications ie offices etc which have a short 'user' timespan.

builders will always have their own preference about what way to build, and most of the time their preference will be whatever makes life easier in themselves... cant blame them for that. Insulated slabs are easy to apply, quick to finish, and 'dry out' quicker allowing for a relatively shorter build time.. in theory. However, if you have ever been in a house where an air tightness test was carried out, you would be flabbergasted at how porous concrete blocks are.

good luck with the build, and you can always come on here to 'shoot the breeze'.. theres some very knowledgeable posters here who are generous with their advise.

Yeah thats actually exactly what I am finding. I know I don't know enough so I am asking for help from people with more experience but everyone is telling me different things and the more I ask the more confused I get. Builders as you said just say exactly what they are used to. People who are knowledgable tell you whatever they have in their own house is the best so you just get totally different answers from everyone! It was great to get advice from you, you obviously know what your talking about so I feel much better about meeting my architect tomorrow! It can be daunting meeting all these men with strong opinions when you just know that you dont know enough & you dont want to appear completely stupid & then be pushed into a bad decision.

In a few weeks when all these decisions are made Im sure it will be alot less stressful & more exciting! Thank you for being so helpful. And patient! I know my questions were prob quite silly ones! Thanks for being so nice.

sydthebeat

muinteoir wrote: »

In a few weeks when all these decisions are made Im sure it will be alot less stressful & more exciting! Thank you for being so helpful. And patient! I know my questions were prob quite silly ones! Thanks for being so nice.

there are no silly questions, only silly answers

at the end of the day, you will be engaging this architect for his / her professional experience and opinions. once he / she is able to explain why they hold such opinions, to your satisfaction, then theres not much more you can ask for.

KCross

muinteoir
Notwithstanding all the good advice you have received above I think the decision to put in HRV is a good one.
Whatever it costs you to heat the house you dont want to be opening windows to get fresh air in as that is money blowing out your window. HRV also filters the air it is letting in so I think it is healthier if you have any asthmatics in the house.
-
With HRV the house will always have a fresh air feel. Rooms wont be stuffy first thing in the morning when you get up.
So, HRV gets the thumbs up from me.
-
One thing you did mention above was that you were driving the UFH with oil. You need to be careful with that. How is the oil going to control the UFH? Oil is expensive and is more suited to high temp(65C) rad type systems. UFH is a low temp(35C) system. Be careful there and ensure that your plumber has thought that out. I think most people use geothermal with UFH nowadays but that is an added expense of course.

muinteoir

KCross wrote: »

muinteoir
Notwithstanding all the good advice you have received above I think the decision to put in HRV is a good one.
Whatever it costs you to heat the house you dont want to be opening windows to get fresh air in as that is money blowing out your window. HRV also filters the air it is letting in so I think it is healthier if you have any asthmatics in the house.
-
With HRV the house will always have a fresh air feel. Rooms wont be stuffy first thing in the morning when you get up.
So, HRV gets the thumbs up from me.
-
One thing you did mention above was that you were driving the UFH with oil. You need to be careful with that. How is the oil going to control the UFH? Oil is expensive and is more suited to high temp(65C) rad type systems. UFH is a low temp(35C) system. Be careful there and ensure that your plumber has thought that out. I think most people use geothermal with UFH nowadays but that is an added expense of course.

Thanks for the advice about the HRV. I think I will go with it. I'm going to a friends house tomorrow night who has HRV to learn more about it! Regarding the geothermal I have heard such different things about how long it takes to recoup the money & then I was researching parts need to be replaced after 15/20 years so I dont know! I suppose I need to do more research on it. I was hoping the ufh, good insulation & HRV would be enough...

KCross

UFH is great, I would recommend it over rads but I have seen posts of people complaining of costs to run it via oil and I have a friend who is running it off oil and it is very expensive(€2000+) but his house is probably not insulated to todays standards which is part of his issue.

Its not so much what you are using to heat the UFH but what is used for control. Geo systems use weather compensating controls and you have the ability to use tremperature set backs at various times of the day and use night saver electricity to boost the slab temperature at night for release during the day. With oil, once it calls for heat it is costing alot of money immediately due to oil price. Stats in each room are important.

You are correct on the initial outlay being high for geo and replacement parts(compressor being the big one) is not cheap but oil burners dont last forever either so no system is flawless or maintenance free.

I suppose if you get the insulation tip top and airtight, the cost of the oil might be low enough to not warrant opting for geo.

As stated by others here, a professional opinion based on your overall project is required to be fully sure.

muinteoir

KCross wrote: »

UFH is great, I would recommend it over rads but I have seen posts of people complaining of costs to run it via oil and I have a friend who is running it off oil and it is very expensive(€2000+) but his house is probably not insulated to todays standards which is part of his issue.

Its not so much what you are using to heat the UFH but what is used for control. Geo systems use weather compensating controls and you have the ability to use tremperature set backs at various times of the day and use night saver electricity to boost the slab temperature at night for release during the day. With oil, once it calls for heat it is costing alot of money immediately due to oil price. Stats in each room are important.

You are correct on the initial outlay being high for geo and replacement parts(compressor being the big one) is not cheap but oil burners dont last forever either so no system is flawless or maintenance free.

I suppose if you get the insulation tip top and airtight, the cost of the oil might be low enough to not warrant opting for geo.

As stated by others here, a professional opinion based on your overall project is required to be fully sure.

Yeah you are right. I have got loads of numbers of people with UFH from friends/builders who would have good insulation so I will ring them to find out their oil cost to see would geo be worth if for us. I think that will help make up my mind. Thanks for the tips!

YouWantWhat

This is an expensive way to heat your house. The capital costs can be anything from €20-€30k and then there's the ongoing running/electricity costs. I think in the boom, people got carried away with themselves and wanted something different, just to have it.

In my mind the simplest way to heat a house is firstly make the most of solar gain, when you have this heat you need to retain it in the house by having lots of insulation in the roof, walls and floor, and by making the house relatively airtight. For additional heat use a gas or oil fired boiler with rads on a zoned system, room thermostats and a good heating programmer. This is a cheap installation and the running costs will be low. This is what I've done in my house and a 1000 litre tank of oil normally lasts about 18 months.

I have my system installed and will be running for about 15 years, for the cost of just installing what you are proposing!!

blast06

It would be a serious Ferrari model of a system that would cost 20-30K. 15-17K ballpark should get you geothermal and UFH for say a 2.5 to 3K sq ft house.
And with ltest building regs, you would have to put up ~4-6K worth of solar panels if you did not go with geothermal.

YouWantWhat wrote: »

This is an expensive way to heat your house. The capital costs can be anything from €20-€30k and then there's the ongoing running/electricity costs. I think in the boom, people got carried away with themselves and wanted something different, just to have it.

In my mind the simplest way to heat a house is firstly make the most of solar gain, when you have this heat you need to retain it in the house by having lots of insulation in the roof, walls and floor, and by making the house relatively airtight. For additional heat use a gas or oil fired boiler with rads on a zoned system, room thermostats and a good heating programmer. This is a cheap installation and the running costs will be low. This is what I've done in my house and a 1000 litre tank of oil normally lasts about 18 months.

I have my system installed and will be running for about 15 years, for the cost of just installing what you are proposing!!

fclauson

Can I suggest you engage a professional to help you - either an Architect or an indepepndant energy advisor (someone who is not tied to any specific vendor) who can advise on the various aspects of your build

You are asking a lot of very good questions and you need the right answers - but you also need someone to help you formulate them into a wholistic approch.

remember the addage "to change on the plan is cheap - to change once built is not"

just do it

muinteoir wrote: »

Thanks for the advice about the HRV. I think I will go with it. I'm going to a friends house tomorrow night who has HRV to learn more about it! Regarding the geothermal I have heard such different things about how long it takes to recoup the money & then I was researching parts need to be replaced after 15/20 years so I dont know! I suppose I need to do more research on it. I was hoping the ufh, good insulation & HRV would be enough...

Muinteoir

Where are you with the spec of your build at this stage? I was going to post some comments on issues thus far but as they are now a month old it may be better if you tell us what your current thinking is.

Here's a bit of good bed time reading regardless of whether you aim for passive or not - the SEAI passive house guide. There's been a lot of knowledge gained on passive/ low energy build since this guide was issued in 2007. The principles however remain the same.

woodoo

YouWantWhat wrote: »

In my mind the simplest way to heat a house is firstly make the most of solar gain, when you have this heat you need to retain it in the house by having lots of insulation in the roof, walls and floor, and by making the house relatively airtight. For additional heat use a gas or oil fired boiler with rads on a zoned system, room thermostats and a good heating programmer. This is a cheap installation and the running costs will be low. This is what I've done in my house and a 1000 litre tank of oil normally lasts about 18 months.

I have my system installed and will be running for about 15 years, for the cost of just installing what you are proposing!!

What type of heat programmer and stats do you use.

fisherman5

I have only read a couple of the suggestions above but here is my advice from practical experience;

Heat recovery is a waste of time, this is coming from people who have it and builders who have installed on new builds, and even builders with it installed on their own new builds.

Air tightness is the way to go, recommended by 99% of people who have experience with it

Underfloor heating is expensive and slow to respond. A rad heats the air in your rooms, the underfloor heating heats the floor first and then the air from that. This means that if your house is cold and you want to heat it the underfloor heating will kick in, this will warm the floor and then your feet but there could be a long delay until the air in the room is warm.

Dry lining (insulated slab) is a personal choice but comparing it to an insulated cavity, the heat doesnt travel through a layer of block before it hits insulation, it stops it straight away and keeps the air in the room warm! And dont forget, you can always do both?

Heat rises, over spec the insultaion in your attic, it makes a massive difference!

And something which hasnt been mentioned in this thread so far... a solid fuel stove! Used correctly it burns very little, gives off fantastic heat... not just to one room, open the door and let it heat the house if you want, and has the option of a back boiler.
Nobody I know of has regretting putting in their stove!

Dont forget that your house is a living space, not a sealed capsule that nobody goes in and out of. Doors will be opened, as will windows to air out rooms or for other reasons. The idea is not to keep your house a constant temperature 24/7, it will cool down and heat up so you have to design it to do so the best way which suits you and the way you want to live.

imitation

fisherman5 wrote: »

I have only read a couple of the suggestions above but here is my advice from practical experience;

Heat recovery is a waste of time, this is coming from people who have it and builders who have installed on new builds, and even builders with it installed on their own new builds.
.

I disagree, I have been living in a house with HRV the past 18 months, my house is coming in at approx 2 ach air tightness wise. My HRV was offline for a few days after an alarm installer accidently cut one of the cables used to control it. The house only has 2 people in it on average, but the difference was noticeable immediately, mainly in the bathrooms as they were now missing there primary form of extraction, but I have no doubt in my mind that if there was a full family in the house condensation problems would occur in no time.

Once you aim for a certain threshold of airtightness it becomes a must, the alternatives is basically just a hole in the wall with variable levels of ventilation (ie none when you need it, and far too much on a howling winters night).

I agree with the other sentiments about solar gain, my house isn't 100% optimized for it (went for the view instead of the free heat, doh !), in similar homes facing due south there is great return on the heat.

I went with rads instead of UFH, I'm pretty glad I did, mainly because there is nobody around during the day, and the house is insulated enough to enough heat to be gotten from an hour or two an evening during the winter. I think UFH would struggle in this setup.

topcatcbr

fisherman5 wrote: »

I have only read a couple of the suggestions above but here is my advice from practical experience;

Heat recovery is a waste of time, this is coming from people who have it and builders who have installed on new builds, and even builders with it installed on their own new builds.

Air tightness is the way to go, recommended by 99% of people who have experience with it

Underfloor heating is expensive and slow to respond. A rad heats the air in your rooms, the underfloor heating heats the floor first and then the air from that. This means that if your house is cold and you want to heat it the underfloor heating will kick in, this will warm the floor and then your feet but there could be a long delay until the air in the room is warm.

Dry lining (insulated slab) is a personal choice but comparing it to an insulated cavity, the heat doesnt travel through a layer of block before it hits insulation, it stops it straight away and keeps the air in the room warm! And dont forget, you can always do both?

Heat rises, over spec the insultaion in your attic, it makes a massive difference!

And something which hasnt been mentioned in this thread so far... a solid fuel stove! Used correctly it burns very little, gives off fantastic heat... not just to one room, open the door and let it heat the house if you want, and has the option of a back boiler.
Nobody I know of has regretting putting in their stove!

Dont forget that your house is a living space, not a sealed capsule that nobody goes in and out of. Doors will be opened, as will windows to air out rooms or for other reasons. The idea is not to keep your house a constant temperature 24/7, it will cool down and heat up so you have to design it to do so the best way which suits you and the way you want to live.

I disagree. I agree with air tightness being fundamental but this makes little difference if you have to put holes in it for natural ventilation. The best way of ventilating is HRV.
I also disagree with internal insulation/dry lining. The thermal mass if internal block work provides a balance like heat bricks in a night saver rad.

Like timber frame homes they heat up quick but get cold quick also.

fclauson

fisherman5 wrote: »

I have only read a couple of the suggestions above but here is my advice from practical experience;

Heat recovery is a waste of time, this is coming from people who have it and builders who have installed on new builds, and even builders with it installed on their own new builds.

Air tightness is the way to go, recommended by 99% of people who have experience with it

So expalin to me how you get rid of the moisture from a house if you are air tight but have no ventalation - and comply with Part F ?

Underfloor heating is expensive and slow to respond. A rad heats the air in your rooms, the underfloor heating heats the floor first and then the air from that. This means that if your house is cold and you want to heat it the underfloor heating will kick in, this will warm the floor and then your feet but there could be a long delay until the air in the room is warm.

as some one who lives in a passive/A1 rated house then can I explain
the house sits at 20 degrees day and night - there is no heat it up or cool it down - its 4:30 am - its 3 degress outside - and I am sitting hear nice and warm - and I am only using 2 to 3 euro a day to keep warm

Dry lining (insulated slab) is a personal choice but comparing it to an insulated cavity, the heat doesnt travel through a layer of block before it hits insulation, it stops it straight away and keeps the air in the room warm! And dont forget, you can always do both?

my walls are also permenantly at 20 degrees (250mm full fill cavity) -and using both is dangerous - read the articals about where the dew point sits if you do this (especially as you ahve decided to have no HRV)

Heat rises, over spec the insultaion in your attic, it makes a massive difference!

our roof accounts for about 30% of where heat can leak out of the house (the walls and floors being the rest) - yes it needs insulating - but you also have to do the other surfaces as well

And something which hasnt been mentioned in this thread so far... a solid fuel stove! Used correctly it burns very little, gives off fantastic heat... not just to one room, open the door and let it heat the house if you want, and has the option of a back boiler.
Nobody I know of has regretting putting in their stove!

we have a stove - but how would you circulate the heat accross the whole house (we are a bungalow) if you are airtight

Dont forget that your house is a living space, not a sealed capsule that nobody goes in and out of. Doors will be opened, as will windows to air out rooms or for other reasons. The idea is not to keep your house a constant temperature 24/7, it will cool down and heat up so you have to design it to do so the best way which suits you and the way you want to live.

1100010110

fisherman5 wrote: »

The idea is not to keep your house a constant temperature 24/7

Erm, is that not exactly what the idea is?
And by having the themal mass exposed by not drylining assists in this.

How smelly would an airtight house without any ventilation be? :eek:

sydthebeat

fisherman5 wrote: »

..... The idea is not to keep your house a constant temperature 24/7, it will cool down and heat up so you have to design it to do so the best way which suits you and the way you want to live.

:eek::eek:

ermmmmm NO

the whole point of energy efficient homes is to have the house at a constant temperature and not to have any heat up / cool down fluctuations.

If you eliminate / reduce your heat losses as best as possible then these fluctuations wont happen.

obviously im not talking about a slight deliberate cooling of a few degrees at night..... im talking about undesigned heat loss

just do it

fisherman5 wrote: »

here is my advice from practical experience;

What is your practical experience? Builder? Living in an energy efficient home?

.

Glengormanjay

Guys I am no expert but the basic is that it’s taken us 30 years to understand that high levels of insulation are very important to ensuring that we live in warm, comfortable, healthy and energy efficient spaces. Please don't let it take another 30 years for us to work out that we need to add two more legs to that stool.

1, Envelope integrity = Some level of Air tightness
2, Air movement / control = ventilation (with maybe heat exchange for extra stability)

Personally I think that any of us who are building per latest regs and with expectation of building performance should strongly consider ventilation as an integral part of the build in order to protect the structure as well as ensuring living space comfort.

Two practical examples are
My brother a specialist in this whole area, imported a super insulated, airtight timber house from Canada about six years ago. During construction he discovered that a single ventilation connection piece was missing (€3 part in any builder’s providers). The result was that he didn't start his ventilation system until a couple of months after he moved in. He very quickly learnt that the house was stuffy, smells were persistent but worst of all mould started to grow in the corners of his ceilings and the edges of his beautiful wooded passive spec windows. The point was proven when he got around to buying that plastic collar and starting up his ventilation system all of the above problems disappeared rapidly.

Last year a friend of mine who is a chronic asthmatic, built a highly insulated timber framed, airtight house with a heat exchanged ventilation system. He got through the autumn, winter and this year’s very prevalent flu without getting sick once! Normally he would have suffered from several chest infections by now. Believe me when I say that his reduced medical cost will more than pay for his ventilation system cost this year alone.

It strikes me that; we should try to stick to the basics of keeping our home dry (condensation), warm and fresh. If we’re not careful we will swop the problem poor thermal performance for that of condensation and stale air resulting in internal structural rot and worse, poor health!

plunkettrebel

We built our 2000 sqf house in 2010, we decided to build the house with aerated concrete blocks with 150mm external insulation u value 0.15, 150mm floor insulation, 400mm attic insulation, triple glazed windows, air tight membrane and air tight tape around the doors and windows, HRV and 30 Solar panel tubes We installed a Panasonic 9KW air to water heat pump with an inverter in September 2012. I was a bit sceptical of installing the heat pump to be honest because of the cost to purchase and install the unit but man is it worth every penny, we are on night rate so I have the unit heating the house during the night. I asked our electrician to place install a meter with the unit when it was installed. From the 27th of September 2012 to today it has cost us €245 in electricity. We have an 8 week old baby so the house is at a constant temperature of 18oC in the upstairs and 19oC in the down stairs. I have a 15KW stove with a back boiler which we used this at the start to heat the underfloor but it had to be lighting from at least 12pm and lighting all day to heat only a small part of the underfloor then we swapped to an oil boiler to heat the underfloor but thankfully we changed over to the heat pump and never looked back. If I had to change one thing is I would put in a smaller stove and use the money saved on the heat pump because we have only lit it 3-4 times since we installed the heat pump.

JavaEE_IDE

plunkettrebel wrote: »

If I had to change one thing is I would put in a smaller stove and use the money saved on the heat pump because we have only lit it 3-4 times since we installed the heat pump.

I have read through the various threads on heating systems, etc and this is the one question that jumps out at me. If you have multiple modes of heating in place, do you need a fireplace/stove?

For instance, if you go down the underfloor route, with a well insulated and airtight house, mhrv, etc, is a traditional chimney and and stove redundant? Do people that have both find they ever use the stove/fireplace?

A secondary concern is the aesthetic importance of a traditional chimney and fireplace. Are many houses specified nowadays without one?

sydthebeat

JavaEE_IDE wrote: »

I have read through the various threads on heating systems, etc and this is the one question that jumps out at me. If you have multiple modes of heating in place, do you need a fireplace/stove?

For instance, if you go down the underfloor route, with a well insulated and airtight house, mhrv, etc, is a traditional chimney and and stove redundant? Do people that have both find they ever use the stove/fireplace?

A secondary concern is the aesthetic importance of a traditional chimney and fireplace. Are many houses specified nowadays without one?

a stove can be a helpful and economic means of helping to comply with Part L regs.

that being said, the output of the stove makes no difference

brophis

JavaEE_IDE wrote: »

I have read through the various threads on heating systems, etc and this is the one question that jumps out at me. If you have multiple modes of heating in place, do you need a fireplace/stove?

For instance, if you go down the underfloor route, with a well insulated and airtight house, mhrv, etc, is a traditional chimney and and stove redundant? Do people that have both find they ever use the stove/fireplace?

A secondary concern is the aesthetic importance of a traditional chimney and fireplace. Are many houses specified nowadays without one?

Went without a stove or any chimneys myself. Didn't see the need for it nor the want when the house is always warm. Went with ufh which I'd take over a stove any day. Personally I think the roofline looks better with no chimneys.

And if anyone asks, yes Santa can fit through the HRV ducts!!!

fclauson

[QUOTE=JavaEE_IDE;83868200... If you have multiple modes of heating in place, do you need a fireplace/stove?

...
Do people that have both find they ever use the stove/fireplace?

A secondary concern is the aesthetic importance of a traditional chimney and fireplace. Are many houses specified nowadays without one?[/QUOTE]

So we put in a inset stove with external air - in 5 months we have lit it probably 15 times - reasons
1 - after 3 or 4 murky days the house was a bit cold (no solar gain) - the weather compenstor on the HP only sort of works to help with this - the heat curve is set at 28 but this assumes some solar gain - with out it we probably need it at 30 or 31. The HP ideally should have an input not only what the outside airtemp is but also how much sun there has been

2 - you cannot sit around UFH and drink your wee dram

So you choice has to be balanced between the pleasure of having a real fire and the need for actual heat

just do it

fclauson wrote: »

1 - after 3 or 4 murky days the house was a bit cold (no solar gain) - the weather compenstor on the HP only sort of works to help with this - the heat curve is set at 28 but this assumes some solar gain - with out it we probably need it at 30 or 31. The HP ideally should have an input not only what the outside airtemp is but also how much sun there has been

Would an immersion switch be a more cost effective solution for the rarity it would be needed.

Glengormanjay

I think it’s one of those modern questions? Do you actually need to satisfy the hunter gatherer in you with a stone hearth, chimney breast and flickering flame? the answer is no but most people still elect to maintain the tradition and have the comfort/experience!

Similar question can be asked about the need for a bath tub in our modern lives, how often do you take a bath as opposed to a shower?

One point that is definitely worth focusing for this forum is the difference between an open chimney and a closed feed/system stove!

Personally, my stove (sealed system with external air supply) in a super insulated and airtight environment is way over sized and can only be used very infrequently with a small fire throttled back. But for my wife and kids it’s still an essential element of our home.

sas

Glengormanjay wrote: »

But for my wife and kids it’s still an essential element of our home.

I think this is the important part that people are missing. These are not office buildings, these are not a technical specification for archs\engineers etc. to play with. They are homes and people like what they like.

I will have a stove once budget allows, having gone through a winter without it I really missed it. I know of 2 other PH builders that didn't include them and have expressed some regret at that. Not because they are cold but because they miss having a fire to sit in front of.

The only question I have is boiler or non boiler. Which is a 3k question...

fclauson

just do it wrote: »

Would an immersion switch be a more cost effective solution for the rarity it would be needed.

The issue is the UFH - I have it set at a curve of 28 (28 degrees when out side its 0)

on week when there is sunshine this is fine - but on a week when its not then the house cools down a bit - some of this is emotional cooling and some of thsi is real (the temp gauge in the house hardly moves)

Glengormanjay

The only question I have is boiler or non boiler. Which is a 3k question...[/QUOTE]

Can I suggest that you definately don't need a boiler that is large enough to cost 3k ( not unless you are in the gods relevant to square footage). Its like putting a big block chevy engine into a Toyota Prius.
Or better again its like me fitting my 12kw stove in a super insulated house - LOL!

As above I also agree about the stove, technically we dont actually need them but a radiating flickering flame is essential to the comfort and well being of the home

JavaEE_IDE

Glengormanjay wrote: »

Personally, my stove (sealed system with external air supply) in a super insulated and airtight environment is way over sized and can only be used very infrequently with a small fire throttled back. But for my wife and kids it’s still an essential element of our home.

I completely agree with the point about a fireplace being a nice place to sit around. It is something that has been ingrained in the psyche down through the centuries, so much so that it is next to impossible to imagine a house without a fireplace/stove of some sort.

Originally, the purpose of the fire was to provide heat for comfort and cooking. People huddled around massive, open hearths and those at the far end of the room would be frozen. My understanding of modern part L compliant homes is that the thermal conditions in the space are relatively uniform. The need isn't there to 'pull over by the fire'.

Do you just end up with a very expensive ornament, taking up a large area of your sitting room?

Leading on from that, if a stove is non-negotiable, what is the best way to incorporate one into a part-L compliant home, with UFH, etc?

imitation

JavaEE_IDE wrote: »

I completely agree with the point about a fireplace being a nice place to sit around. It is something that has been ingrained in the psyche down through the centuries, so much so that it is next to impossible to imagine a house without a fireplace/stove of some sort.

Originally, the purpose of the fire was to provide heat for comfort and cooking. People huddled around massive, open hearths and those at the far end of the room would be frozen. My understanding of modern part L compliant homes is that the thermal conditions in the space are relatively uniform. The need isn't there to 'pull over by the fire'.

Do you just end up with a very expensive ornament, taking up a large area of your sitting room?

Leading on from that, if a stove is non-negotiable, what is the best way to incorporate one into a part-L compliant home, with UFH, etc?

I would recommend putting it somewhere central to get the most of it when you are using it. I think the stove is a good purchase for a few reasons

-Its free heat if you can get timber to burn easily, a part L house is efficient but it still needs to run heating, instead of paying to keep the house at 22C with constant heating you can keep it at 17-18C with much less + solar gain and still keep cosy by the fire.
-The effect is nice and some people enjoy the little rituals of chopping the timber, lighting the fire etc.
-The tin foil hat side is somewhat reassured by having a stove incase of power outage, gas outage, central heating failure, oil being robbed, economic ruination or Nuclear winter.

Glengormanjay

Persuming your house is highly insulated and airtight -
Make sure that it is sized correctly - couple of kilowatts non back boiler for high thermal performance house.
Make sure you can vent heat into other rooms (4 inch wall vents), also if stove is standalone use an "Eco Fan" very effective at heat distribution.
Make sure your stove has an external air supply. Place MHRV extraction points so that they encourage warm air circulation accross the greater area of the ground floor. Personally my warm air vents up through floor to the upstairs landing.

Again in a highly insulated and airtight house I personally would only use a back boiler with a suitably sized (oversized) thermal store. Your plumber should be technical expert on this.

JavaEE_IDE

imitation wrote: »

I would recommend putting it somewhere central to get the most of it when you are using it. I think the stove is a good purchase for a few reasons

-Its free heat if you can get timber to burn easily, a part L house is efficient but it still needs to run heating, instead of paying to keep the house at 22C with constant heating you can keep it at 17-18C with much less + solar gain and still keep cosy by the fire.

How does work though?

Suppose you have UFH and a heat pump of some sort, this isn't a system that you just switch on and off.

If you introduce a standalone stove to the mix, are you using the mhrv to circulate this heat and reduce the demand on the heat pump?

Or do you use some sort of buffer tank for the UFH and a boiler stove?

JavaEE_IDE

Glengormanjay wrote: »

Again in a highly insulated and airtight house I personally would only use a back boiler with a suitably sized (oversized) thermal store. Your plumber should be technical expert on this.

Thanks for all the information in your post. It is very helpful.

Focusing on one of the points, would you say a thermal store is a critical element of a modern house?

Glengormanjay

Its not so important for me becuase my stove doesn't have a back boiler and my main heating is gas (instant on off). Also I have rads instead of underfloor so my need to store hot water is probably less than yours. Although considering the length of time my eldest son spends in the shower singing maybe I should have beefed up my tank and solar panel specification - only joking!!!!

sas

Glengormanjay wrote: »

Can I suggest that you definately don't need a boiler that is large enough to cost 3k ( not unless you are in the gods relevant to square footage).

The price of stoves suitable for passive structures is much more related to their quality than their output.

Typical stoves (with boilers) suitable for my home fall in the 10kw range, 7kw to boiler and 3kw to room. I've seen none for less than €3500 and that would mean importing directly myself from Germany and doen't include ladomat or pump controller. Those will drive the package over the 4k mark. There would still be labour for installation along with no warranty because it isn't fitted by a certified installer. If I go with Irish agents I'm up around the 5k mark.

I can buy very attractive room sealed dry stoves for around the €2000 mark.

So I've to forget about the boiler or make my peace with the extra €3000 spend.

I'd imagine I'd be half way to an ASHP for that 3k so it's a difficult one for me.

Glengormanjay

Cheers Buddy I misunderstood your original post I thought you were buying a boiler for 3k as opposed to a stove with backboiler which will of course be more expensive.

Remember the earlier comments - make sure to size your stove correctly relevant to your house. Others I have spoken to say the same - the only negative with modern wood burning stoves is people try to match the same physical fire of their old fire place with that of their new ultra efficient stove - and as a result they're too good!

My brother once calculated it out for me - as a second heat source in a house of the thermal efficiency of mine 2.5kw of constant heat is more than enough. My stove is 12kw!!! Which would have been fantastic in my old house but not this one! Consider the fact that most people on this particular forum are moving towards the realms of passive type performance i.e zero heat input therefore we really don't need "big engined stoves" Talk to the supplier.

belcampprisoner

http://theforeigner.no/pages/columns/passive-houses-here-now-more-soon/

imitation

JavaEE_IDE wrote: »

How does work though?

Suppose you have UFH and a heat pump of some sort, this isn't a system that you just switch on and off.

If you introduce a standalone stove to the mix, are you using the mhrv to circulate this heat and reduce the demand on the heat pump?

Or do you use some sort of buffer tank for the UFH and a boiler stove?

I steered away from backboilers in the end after a few warnings about additional complexity in plumbing and potential issues. It might not have necessarily been fair, but by my logic it probably wasn't worth the complexity for the amount of times I light the stove in a year and the amount of heat that would actually be extracted.

MRHV won't circulate the heat from the fire in any noticeable amount I have found.

Glengormanjay

If your stove is stand alone (not intergrated into the wall) then seriously consider an "eco fan". Very effective at cirulating heat ( hotter the stove the better it works)
http://www.dhomekitchen.net/heat-powered-wood-burning-stove-fireplace-fan-eco-friendly-heating-nickel/

Cost between €100 - €150 on internet