Type of heating system

tobbslerone

Hi all
A relation of mine is building a house and cannot decide what heating system to put in or whether to use rads or underfloor heating.The house is 3200sq feet but will be weel insulated with 100mm insulation in a 150mm cavity and 50mm drywall board.The roof will have 150mm metac with 50mm insulated board.He has some access to bog but wants a system that is reasonable and would rather not depend on solid fuel.Any info is appreciated on your experience with different systems and installation and running costs or whether you would use underfloor or rads.
Thanks

Outkast_IRE

I would say tell your friend to get some professional advice.

I personally would never recommend putting in a 150mm cavity and then drylining the inside, it makes no sense to me.

Why wouldn't he just build a wider cavity and have all the insulation in one location that's a far better idea.

And again 150mm metac I assume in attic with drylining on the interior celings, wouldn't be my first choice, why not just increase the amount in the attic.

I think thinking about heating systems at this point is silly because there are some serious questions about the insulation that's being planned in my opinion.

Has he engaged professional advice ?

Will the build meet current regulations ?

tobbslerone

Yes that was the advice of the architect and engineer he employed and all regulations are being met.The insulation is decided on and most in place except the dryling so its just the heating that has to be decided on.Any advice regarding that?

allanpkr

the more insulation there is the better.whereever it is. back to your question. i would go for underfloor heating if cost is not an issue. underfloor heating runs at 20 degrees i think. make sure he has it zoned ,then he can turn off some areas. im not an expert but we did put this in many building renovations in uk. and i was surprised the amount of EVEN heat which it threw out.

Outkast_IRE

allanpkr wrote: »

the more insulation there is the better.whereever it is. back to your question. i would go for underfloor heating if cost is not an issue. underfloor heating runs at 20 degrees i think. make sure he has it zoned ,then he can turn off some areas. im not an expert but we did put this in many building renovations in uk. and i was surprised the amount of EVEN heat which it threw out.

No have to disagree its not just a case of throw insulation in anywhere you like the more the better, this is not the case, its nonsensical in a new build.

Its proven that its better to keep all your insulation in one layer where possible, be that external, in cavity or my least favourite interior. Hopefully an architect or similar will come on shortly to verify this stance.


Back to the original question, ok is it a bungalow or 2 stories if its 2 stories is the upper floor concrete or wood ?

Underfloor is great but needs to be sized correctly, needs to be well zoned with thermostats in each room controlling the zone.

Radiators often work out to be the cheaper option, but again need to be sized correctly in order to give you best value for money.

MicktheMan

tobbslerone wrote: »

Yes that was the advice of the architect and engineer he employed and all regulations are being met.The insulation is decided on and most in place except the dryling so its just the heating that has to be decided on.Any advice regarding that?

This detail should have all been worked out before a sod was turned!

Have the architect/engineer calculate the heat load. Then and only then can a sensible and educated decision be made on the heating and distribution system taking other elements such as structure, layout and budget into consideration.
Tell your friend too to do a proper job on airtightness and ventilation details if he/she wants a comfortable and healthy home.

allanpkr

of course all heating must be sized properly. but tell me why is internal insulation your least fav

Outkast_IRE

allanpkr wrote: »

of course all heating must be sized properly. but tell me why is internal insulation your least fav

Internal insulation to me in a new build is my least favourite because off the top of my head .

1. Out of External , Cavity and internal insulation , internal is the most likely to cause problems with interstitial condensation, leading to mould growth and a very unhealthy house to live in.

2. Internal insulation decreases the usable living space.

3. Internal insulation decreases the thermal mass of the building, with additional thermal mass its easier to maintain a given interior temperature when the heating is switched off, and its easier to store heat in that mass from sunshine in the winter if the house is designed properly.

4. Internal insulation also means less solid walls in the house so plenty of messing about if/when you decide to hang anything on the wall be it kitchen units or that brand new 50 inch TV you got to go in your new house


I understand that internal insulation has its place in retrofit/renovation situations but even then its my least favourite.

fclauson

tobbslerone wrote: »

Hi all
A relation of mine is building a house and cannot decide what heating system to put in or whether to use rads or underfloor heating.The house is 3200sq feet but will be weel insulated with 100mm insulation in a 150mm cavity and 50mm drywall board.The roof will have 150mm metac with 50mm insulated board.He has some access to bog but wants a system that is reasonable and would rather not depend on solid fuel.Any info is appreciated on your experience with different systems and installation and running costs or whether you would use underfloor or rads.
Thanks

I am confused - what was the provisional BER for the build - How is part L being met ?

and how are you going to "run in heating" without leaving a significant number of air gaps about the place

allanpkr

my you have been busy on google..lolol off top of your head.what about your own thoughts?:.

with todays modern built houses mould growth is less likely a problem if like old and new builds the ventilation is correct . whether interstatial or on internal living space.
heating a house so that first you heat the solid walls , then this will be released later . when. people are out most of day working they want to benefit from heat when its on and they are relaxing not why they are in bed.
most houses do not have major glass walls to obtain solar heat.
as for fixings with enough forethought you can build into internal insulation areas to fix to.

MicktheMan

Outkast_IRE wrote: »

Internal insulation to me in a new build is my least favourite because off the top of my head .

1. Out of External , Cavity and internal insulation , internal is the most likely to cause problems with interstitial condensation, leading to mould growth and a very unhealthy house to live in.

2. Internal insulation decreases the usable living space.

3. Internal insulation decreases the thermal mass of the building, with additional thermal mass its easier to maintain a given interior temperature when the heating is switched off, and its easier to store heat in that mass from sunshine in the winter if the house is designed properly.

4. Internal insulation also means less solid walls in the house so plenty of messing about if/when you decide to hang anything on the wall be it kitchen units or that brand new 50 inch TV you got to go in your new house


I understand that internal insulation has its place in retrofit/renovation situations but even then its my least favourite.

Not to mention the fact that very often the internal leaf block wall is left unplastered allowing significant air leakage and drafts in the house.

fclauson

allanpkr wrote: »

my you have been busy on google..lolol off top of your head.what about your own thoughts?:.

:eek:

with todays modern built houses mould growth is less likely a problem if like old and new builds the ventilation is correct . whether interstatial or on internal living space.

Yes if ventilation is correct but even our house had a mould issue under the kitchen sink- a leak,lead to very high localised humidity and the lack of air flow lead to mould on the ever so slightly cold wall. But most people are busy blocking up vents to save heat which is causing a condensation/mould problem

heating a house so that first you heat the solid walls , then this will be released later . when. people are out most of day working they want to benefit from heat when its on and they are relaxing not why they are in bed.

Saw tooth heating is a thing of the past (on in the morning then again in the evening) - a modern well insulated house sits at a constant temp

most houses do not have major glass walls to obtain solar heat.

It's a myth you need a lot if glass to get good solar gain - you just need correctly speced including u- value AND g value

allanpkr

stating itsa myth you need a lot of glass to get good solar gain,,,, is no way enough info correct specs and u value . would seem you mean to get a house down to passive house standard .then heating question would not come into equetion.
but most houses dont have great u values.
your comment on ventilation seems to agree with me , but at same time looks to find fault with my statement. strange!

my argument was about heating solid walls that let heat out at night. when people dont want it.
again i do know what the ideal situation hopefully will be in future builds. but that isnt the case mostly yet.

ad finally my comments were aimed at mick the mans comment on internal insulation, and although i love to read other comments, and welcome it, not one of your comments even though you tied them to my individual statements , although stating the obvious did NOT refute my comments..though you seem to think they did.

allanpkr

sorry i do apologize my comments were aimed at outkast ire

allanpkr

and one last point on internal insulation.
there is a type of concrete build walls, which has 50mm internal insulation ,also 85mm insulation inside concrete block this system has passive house certification . which as you know is the highest standard certification you could get

allanpkr

sorry before you state this would give you passive house cert. of course i was just stating how walls are built as to insulation. i wont go into the whole house build lol.

we all know good insulation - good ventilation- unless passive house standard, a good heating system= a comfortable home.
these are very obvious facts.

but ANY insulation is bettr than none. ventilation in todays d/glazed is a must. if you have a vent / system good maintenance is a must.
and internal insulation has no problems - and a lot of positives.
it finally comes down the home owners choice. but spurious arguments against are just misinformation.

Outkast_IRE

allanpkr wrote: »

my you have been busy on google..lolol off top of your head.what about your own thoughts?:.

with todays modern built houses mould growth is less likely a problem if like old and new builds the ventilation is correct . whether interstatial or on internal living space.
heating a house so that first you heat the solid walls , then this will be released later . when. people are out most of day working they want to benefit from heat when its on and they are relaxing not why they are in bed.
most houses do not have major glass walls to obtain solar heat.
as for fixings with enough forethought you can build into internal insulation areas to fix to.

Busy on google ? I doubt it, if you want to check my post history over the past 4 years you would find the I quite often give detailed responses on issues such as insulation , heating and plumbing etc, your not the first person to ask questions in this area.

Im a qualified plumber with additional certs in solar hot water heating, passive house systems, along with a 2 year cert in building services engineering not to mention the fact I am currently doing my level 7 degree in building services engineering , and will doing a level 8 degree in building energy systems next year.

What information and knowledge I can spout off the top of my head would be well worth heeding since its free advice.

Now to respond to the rest of your posts.
You mention todays modern builds are less likely to suffer interstitial condensation if the ventilation is correct .
Well there in lies the problem modern houses are being built with better airtightness than ever and if the ventilation is inadequate in any way your in trouble, because before air leakage would of hidden the problem, in a more airtight house this wont happen. The amount of modern homes built with inadequate ventilation is staggering, mostly due to a lack of regulation enforcement. If everything meets the regulations there probably wont be an issue but this doesn't always happen unfortunately.


Secondly your comment about heating the walls during the day so its released later isn't what thermal mass is all about, that's what solar gain is about and unless your house is designed to take advantage of it I don't even mention it. The thermal mass would help maintain the temperature through the night after you turn off your heating when heading to bed.

Everything is interlinked. I pose this problem to you a house such as you describe with low thermal mass (due to internal insulation) and air vents in each room for ventilation relies mostly on the air temperature to maintain comfortable temperatures in the home, when you switch the heating off at night, the ventilation from outside air will be able to relatively quickly lower that air temperature leading to occupants noticing the temperature drop and what is their response .......... Usually to close the air vents, and there in one move your modern relatively airtight home no longer has adequate ventilation.

The solution is MHRV where a heat exchanger can warm the incoming fresh air and ensure there is always adequate ventilation.


And finally you do not need major glass walls to benefit from solar gain, every correctly placed window and smart design choice will help with solar gain, most architects will design smart, placing small windows on north side and larger windows on south side.

tobbslerone

Well i do agree that it is better to put all the insulation in the cavity or insulate externally,i am not a fan of internal insulation either but that is whats going to be used in this house.The main question now is the heating system to use.He had a plumber out the weekend who recommended an air source heat pump.I would like to hear from anyone who has experience of these systems or has one in their house and if they would recommend it.

fclauson

I have an a/HP - love it - runs 24/7/365 - the heating part has not run since mid may - I augment this with PV ( and not solar thermal). - I use the grid as an inter seasonal store

It looks like my total heating and hot water bill will be covered by the by the PV. The year

Outkast_IRE

tobbslerone wrote: »

Well i do agree that it is better to put all the insulation in the cavity or insulate externally,i am not a fan of internal insulation either but that is whats going to be used in this house.The main question now is the heating system to use.He had a plumber out the weekend who recommended an air source heat pump.I would like to hear from anyone who has experience of these systems or has one in their house and if they would recommend it.

I like air source heat pumps under the following provisions.

1. The house is very well insulated(it sounds like the one you describe will be.)
2. The house has good airtightness( Drafty house will make the air source heatpump work hard)
3. The heat load in the house is very accurately determined by a professional.
4. Others may disagree but I have a fierce dislike of the Chinese crappy imported ones, there are some very good European brands that are dearer but imo a lot more reliable.

What fclauson describes, using Solar PV and heat pump is a good combination as long as your solar PV is sized and orientated correctly.

Also with air-water heatpumps personally I would be leaning towards an underfloor heating system, these generally work well at the lower temps the heatpump operates at. Once again under the provision the system is designed correctly , with as much control over zones as possible.

JD6910

my advise is to insulate and airtight the house. install a heat recovery ventilation system and a good stove. then put in a simple, tired and tested heating system (boiler with solar panels) to satisfied the small heat demand. one could always future proof the boiler room for a heat pump in years the come....

tobbslerone

Yea he is going for underfloor if he goes with the air source heat pump.It would be good to hear from others who have it installed too.Thanks to all for comments

JD6910

tobbslerone wrote: »

Yea he is going for underfloor if he goes with the air source heat pump.It would be good to hear from others who have it installed too.Thanks to all for comments

i would almost suggest alu rads because they can work off the traditional boiler system or air to water system in years to come. apparently underfloor and boilers are not a success....

Outkast_IRE

JD6910 wrote: »

i would almost suggest alu rads because they can work off the traditional boiler system or air to water system in years to come. apparently underfloor and boilers are not a success....

Underfloor and boilers work grand together, what I did notice in the past 10 years was a glut of celtic tiger one off houses with underfloor and a boiler in which.
A. The houses insulation and airtightness weren't up to scratch.
B. The underfloor loops weren't designed they were simply laid down by the plumber as best he could.
C. No buffer used (on-off cycling an issue)
D. Complete lack of controls in the system mainly very little proper zoning and lack of thermostats controlling zone.

Underfloor isn't a good solution for a home unless you have very good levels of insulation and airtightness.

BryanF

Outkast_IRE wrote: »

Underfloor and boilers work grand together, what I did notice in the past 10 years was a glut of celtic tiger one off houses with underfloor and a boiler in which.
A. The houses insulation and airtightness weren't up to scratch.
B. The underfloor loops weren't designed they were simply laid down by the plumber as best he could.
C. No buffer used (on-off cycling an issue)
D. Complete lack of controls in the system mainly very little proper zoning and lack of thermostats controlling zone.

Underfloor isn't a good solution for a home unless you have very good levels of insulation and airtightness.

+1

I've seen +3k a year heating in many homes. correcting insulation & air-tightness is a tough pill to swallow in a celtic finished interior in negative equity

allanpkr

you state the obvious about air tight houses, i dont need all the qualifications to understand about air tightness and ventilation thats why i stated mechanical ventilation systems must be maintained...i.e filters on these systems must be replaced or cleaned regular as mould can build up on filter and make house worse than it was originally.
and of course if you design a house today of course you would design it to highest specs you can afford.and there lies the rub. we would all like passive house standard houses but can we afford them,what about retro fits ect ect.
to say if someone closes vents then venti is back to normal is rather crass as i can say if you dont change filter problem of mech vent is worse. we cannot comment on worse case problems as it would argue both sides.
in my old cottage i have internal insulation in old part and in new extention cavity insul. we have heating on when needed and windows open on lock cause we are so warm with heating on low. at night when heating is off we are still warm and windows are open all night even in winter. i have a nerve problem that makes my skin very sensitive to cold . so i need heat . we do not have heating on during day and we are still warm .i dont have passive house .i also have no mould growth . again as i said orinally ventilation will always be the key to mould growth. then i got loads of discussion on my points of ventilation and growth, stating exactly what i said.

rockabaloo

allanpkr wrote: »

we have heating on when needed and windows open on lock cause we are so warm with heating on low.

Um, am I missing something here? If you're too warm why not just turn off the heating rather than trying to warm up your whole neighbourhood?

allanpkr

this is by a 5kw solid fuel stove which i have almost closed off but pushes out a lot of heat. stove needs air to breath and partner feels more cold than me, although i need it for nerve damage i dont need a massive rise. i accept your point .and just to further point on internal insul.that part of house is at least 5 degreeswarmer than other part of cottage without internal.

cunninstunt

Hi Guys,

New build at the planning stage, circa 2,300sqf bungalow and had planned to go with ufh. Due to house orientation and cost I had planned on going with a solar array and 1000 litre buffer tank with an oil burner as a secondary system. Is this a realistic option.

I understand that during winter months the performance of the solar will be reduced and this is obviously when you need performance most, my understanding was that ufh was a much lower temperature system requiring between 30/40 degrees. What temperatures can be expected from solar arrays during the winter months, my hope was that the oil burner would only be needed to top up a base level from the solar.

With ufh I understand that its efficiency is in maintaining a temperature within the heated area, I plan on a good level of insulation and air tightness with MHRV. My question is, given it takes time to heat the thermal mass using the ufh, will this require the oil burner to be on for long periods of time?

Having initial planned for solar, I am wondering if I would not be better off with an air source hp with secondary oil burner?

All help appreciated.

fclauson

cunninstunt wrote: »

Hi Guys,

New build at the planning stage, circa 2,300sqf bungalow and had planned to go with ufh. Due to house orientation and cost I had planned on going with a solar array and 1000 litre buffer tank with an oil burner as a secondary system. Is this a realistic option.

I understand that during winter months the performance of the solar will be reduced and this is obviously when you need performance most, my understanding was that ufh was a much lower temperature system requiring between 30/40 degrees. What temperatures can be expected from solar arrays during the winter months, my hope was that the oil burner would only be needed to top up a base level from the solar.

With ufh I understand that its efficiency is in maintaining a temperature within the heated area, I plan on a good level of insulation and air tightness with MHRV. My question is, given it takes time to heat the thermal mass using the ufh, will this require the oil burner to be on for long periods of time?

Having initial planned for solar, I am wondering if I would not be better off with an air source hp with secondary oil burner?

All help appreciated.

How are you achieving part l?
You need to rethink your strategy
Firstly a well insulated house does not saw tooth - cold- hot-cold so your comment about time and thermal mass go away - the build SHOULD stay at a constant temp
Given that then you need to look at how to met the demand on a cold day - solar thermal will not and a 1000tank plus solar array is expensive

What is your heat demand - have you modelled it?

I would suggest a HP and PV - my house has a zero running cost for heating &hot water given it has a 2/8kw HP and a 3.6pkw PV array

BarneyMc

fclauson wrote: »

I would suggest a HP and PV - my house has a zero running cost for heating &hot water given it has a 2/8kw HP and a 3.6pkw PV array

This is very interesting. Can I ask the following:
1. Are you saying the PV powers the HP when it's producing electricity, i.e. during daylight hours?
2. Do you use 'standard electricity' to power the HP after daylight hours?
3. Can you feed unused electricity back to the grid when you don't need it?
4. Can the electricity from the PV be used for any domestic use and not just for the HP?
5. Do you require south facing roof for the PV plates?

Thanks for any info!

fclauson

BarneyMc wrote: »

This is very interesting. Can I ask the following:
1. Are you saying the PV powers the HP when it's producing electricity, i.e. during daylight hours?
2. Do you use 'standard electricity' to power the HP after daylight hours?
3. Can you feed unused electricity back to the grid when you don't need it?
4. Can the electricity from the PV be used for any domestic use and not just for the HP?
5. Do you require south facing roof for the PV plates?

Thanks for any info!

The approach I have taken is to install enough PV to produce the amount of energy I need to heat and produce h/w for the year. In my case its around the 4200Kwh mark.

The PV is grid connected so any over production of electricity I ask the ESB (very nicely) to look after for me until I need it. They give me 9c/unit for every unit I push back onto the grid.

I then programm the HP to
a) run 11pm-6am when you can purchase electricity at 8c/ unit night rate
b) to run 10am -> 5pm during which time if its sunny then I can directly use the energy I am producing.

during 6am -> 10am and from 5pm -> 11pm the system coasts as there is enough thermal mass to not allow the building to drop in temp much less than 0.1 degree most of the time !!

this set up effectively allows me to use the ESB as an inter seasonal store. During the summer I store up energy and in winter I draw it back again. Even if I am away for two weeks on hols then the ESB will keep storing up that energy (solar thermal does not do this)

Now obviously if its not sunny during the day then I pay 18c/unit from the grid - and in the midsts of a very cold winter that might happen - the nice thing is that very cold winter days are often clear so you will get solar gain into the building
On average over a year I believe that my config will roughly give me zero running costs for the HP - and that is true for the next 15 or 20 years until some component needs replacing (pumps probably being the first item to fail)

Solar thermal cannot do this - it can only heat the xxx L store you have and that's its