Air to Water Heat Pump in Cottage Renovation

kerrytigin

I am renovating a 180yr old cottage.
We are re-roofing, digging up the floors, hacking off the cement render and re-doing inside with hemp & lime ( hemp for insulation properties ) and outside with lime, allowing the walls to breath as they are designed to.
Re-roofing and installing new upvc sash windows and doors ( potentially wooden doors unsure yet )
We will be insulating the floor and hopefully installing under floor heating throughout.
Also building an extension. Cottage is 1000 sqft and extension ( block built ) will be 580sq ft so a modest size house.
My head is wrecked from trying to figure out a heating system !!

I understand that a heat pump runs at it's "most" efficient with a modern air tight home.

I do feel that although we may not achieve an airtight home ( or want to ! ) that the system should still perform well given that it is a complete renovation with all of the new insulated sections - floor / roof / newly installed windows and the walls are 2ft thick.

I have had a plumber out to give us a quote and it is coming in around €20k for ATW with underfloor throughout and all the plumbing ( 3 bed 2 bathroom house )

He did not seem to see an issue with installing ATW in the house and we also received a quote for oil fired heating ( with rads which I am not keen on as wish to keep as much of the vernacular design of the house )

I would love to hear from those of you that know a lot more about this than me what you think ?
Thanks in advance.

roy rodgers

Personally I wouldn't install a heat pump into anyones house without knowing the air tightness of the house first.
Heat pumps are great but if they air tightness isnt up to standards the heat pump will become to expensive to run. It's a big investment to take a gamble on.
If oil is the next option maybe look at adding a buffer tank to the system and the underfloor heating could pull from that when rooms need it.
You could add a stove with a back boiler to also help to heat the buffer tank and hot water to keep the oil Bill's reduced.

MicktheMan

kerrytigin wrote: »

I do feel that although we may not achieve an airtight home ( or want to ! )

Why in god's name would you not want to?

kerrytigin

Since I have posted here I've had people with a very similar set up to what we plan ( as I have asked on other forums ) reply to say they are really happy with A2W heat pump. 2Ft thick hemp/lime plastered walls = large thermal mass - new heavily insulated roof, newly installed heavily insulated floor and new double glazed uPVC windows. The heat pumps are not exclusively for an airtight home right? Seems to work efficient for others I have asked that are using the system. Regardless of what system if you have a drafty house ( which I won't ) it is going to draw from the system.

kerrytigin

MicktheMan wrote: »

Why in god's name would you not want to?

Its a 180 cottage with stone walls that need to breath to emit any moisture.

Airtightness =
Condensation on Exterior Walls and Windows
Excessive Indoor Humidity
Poor Indoor Air Quality
Stale or Stuffy Air
The Development of Mold and Mildew

So for my type of house I will open my windows for my fresh air and my walls will be able to keep dry without mold forming as they will be breathable.

MicktheMan

kerrytigin wrote: »

Its a 180 cottage with stone walls that need to breath to emit any moisture.

Airtightness =
Condensation on Exterior Walls and Windows
Excessive Indoor Humidity
Poor Indoor Air Quality
Stale or Stuffy Air
The Development of Mold and Mildew

So for my type of house I will open my windows for my fresh air and my walls will be able to keep dry without mold forming as they will be breathable.

I'm fully versed in the requirements of 180 year old solid wall stone structures, thanks.

Good airtightness (including appropriate ventilation which wasn't mentioned as it is generally assumed to go hand in hand) = the opposite of what you said.

chooseusername

MicktheMan wrote: »

Why in god's name would you not want to?

He might want a fire or a particular type stove?

Wearb

There seems to be some confusion here that airtightness equals no ventilation. It just means no uncontrolled air gets in. You still design for needed ventilation.

kerrytigin

Thanks everyone for your replies. I'm a she btw

We are not going down the airtight route - I can of course see the benefits for people but as we stand it's not in our plans as something we want.

@MickTheMan please don't take offence I never suggested that you had no idea on the performance of a thick stone wall, I was just stating what ( little ) I know about how it should perform in the overall plan that I have.

The conclusion I have come to is that I am going to install UFH with an A2W heat pump. I think with the retrofit and the size of the house being a modest size i won't go broke, I think that it will work pretty efficiently.

Thanks again to you all for answering.

Calahonda52

kerrytigin wrote: »

Its a 180 cottage with stone walls that need to breath to emit any moisture.

Airtightness =
Condensation on Exterior Walls and Windows
Excessive Indoor Humidity
Poor Indoor Air Quality
Stale or Stuffy Air
The Development of Mold and Mildew

So for my type of house I will open my windows for my fresh air and my walls will be able to keep dry without mold forming as they will be breathable.

Given your username, I am tempted to say that this is straight out of the Healy-Rea anti-science playbook.

What you have penned above are five untruths, pure and simple.

What follows is not for your benefit as you have clearly decided on the above.
.
However to leave them unanswered is a disservice to the other people who come on here looking for best practice, as well as those of us who try to share our collective experiences for the benefit of society.

Airtightness IS NOT THE CAUSE OF

1. Condensation on Exterior Walls and Windows
2. Excessive Indoor Humidity
3. Poor Indoor Air Quality
4. Stale or Stuffy Air
5. The Development of Mold and Mildew

Airtightness is
https://en.wikipedia.org/wiki/Building_airtightness

Note the use of the words unintentional and uncontrolled.

It is critical because it is the air that retains the heat, so when the air leaves the house, so does your money spent on heating it.

1. Condensation on Exterior Walls and Windows
2. Excessive Indoor Humidity
3. Poor Indoor Air Quality
4. Stale or Stuffy Air
5. The Development of Mold and Mildew

Are caused by a failure to remove, in a timely fashion, moisture laden air that arises from occupants' breath, washing, drying clothes indoors, showers, cooking, etc and in this case maybe moisture from the walls, especially if they suffer from solar drive.

Opening the windows on their own, with no other ventilation, will not comply with the building regs.
The best solutions for this sort of property is some kind of managed ventilation system. My preference, especially with a full refurb like this, is MHVR, which allows the RH to be controlled and thus assist in managing in water content in the walls, they being moisture, (not air) breathable, with no VCL.

Air tightness and fabric breathability are two completely different things

kerrytigin

Calahonda52 wrote: »

Given your username, I am tempted to say that this is straight out of the Healy-Rea anti-science playbook.

What you have penned above are five untruths, pure and simple.

What follows is not for your benefit as you have clearly decided on the above.
.
However to leave them unanswered is a disservice to the other people who come on here looking for best practice, as well as those of us who try to share our collective experiences for the benefit of society.

Airtightness IS NOT THE CAUSE OF

1. Condensation on Exterior Walls and Windows
2. Excessive Indoor Humidity
3. Poor Indoor Air Quality
4. Stale or Stuffy Air
5. The Development of Mold and Mildew

Airtightness is
https://en.wikipedia.org/wiki/Building_airtightness

Note the use of the words unintentional and uncontrolled.

It is critical because it is the air that retains the heat, so when the air leaves the house, so does your money spent on heating it.

1. Condensation on Exterior Walls and Windows
2. Excessive Indoor Humidity
3. Poor Indoor Air Quality
4. Stale or Stuffy Air
5. The Development of Mold and Mildew

Are caused by a failure to remove, in a timely fashion, moisture laden air that arises from occupants' breath, washing, drying clothes indoors, showers, cooking, etc and in this case maybe moisture from the walls, especially if they suffer from solar drive.

Opening the windows on their own, with no other ventilation, will not comply with the building regs.
The best solutions for this sort of property is some kind of managed ventilation system. My preference, especially with a full refurb like this, is MHVR, which allows the RH to be controlled and thus assist in managing in water content in the walls, they being moisture, (not air) breathable, with no VCL.

Air tightness and fabric breathability are two completely different things

How incredibly boring and downright ignorant to say that "Given your username, I am tempted to say that this is straight out of the Healy-Rea anti-science playbook" Just because my username includes the word Kerry does not confirm I am either from Kerry or ( and even if I was ) would have any similarities or comparisons to the Healy Reas FFS !!!

I got that information from a quick Google search on air tightness, a subject I hands up know little about, a subject that got a brief mention in my OP because I'm aware the A2W heat system I was asking for advice on for my property works most efficient.

Here is the link to where I got the info from - just to show I did't pluck it out of the wonderful Kerry air.

https://www.althoffind.com/blog/advantages-vs.-disadvantages-of-airtight-buildings

How did these houses perform so well for the last 150 years without mechanical ventilation I wonder.......

HillFarmer

Kerrytigin, Seriously, I mean no disrespect at all, but I would not recommend you to install a heat pump without verifying air tightness.

You may perform an excellent renovation, but if the house is not sealed to a reasonable standard your electricity bill will be through the roof with a heat pump.

Just my two cents.

You need a very well insulated house for a heat pump to work efficiently imo.

kerrytigin

HillFarmer wrote: »

Kerrytigin, Seriously, I mean no disrespect at all, but I would not recommend you to install a heat pump without verifying air tightness.

You may perform an excellent renovation, but if the house is not sealed to a reasonable standard your electricity bill will be through the roof with a heat pump.

Just my two cents.

You need a very well insulated house for a heat pump to work efficiently imo.

Thank you, appreciate your reply. Yes we intend on heavily insulating both the roof and floor and also the lime/hemp walls from what I hear seem to offer very good heat retention ( once heated up ) I understand if we headed off for a week and left heating off then it would take days to heat up the place again. We won't have a completely airtight sealed home but it will be very very well insulated so I'm hoping given that....we will be warm and toasty!

Thanks again.

chooseusername

Quote;
"Just because my username includes the word Kerry does not confirm I am either from Kerry
or ( and even if I was ) would have any similarities or comparisons to the Healy Reas FFS !!!"

Kerrytigín,when you go to your local TD about your water connection they may well have a copy of this in front of them.(it's a small world)

Having done similar to you, two things I would do differently with the benefit of hindsight;
Sliding sash windows, I would not have them tilting for cleaning.
(can be mistaken for opening for ventilation)
It just means getting up on a ladder once or twice a year.
Solid wooden door facing sun and prevailing wind and rain,
would go for composite door.
We did not go down the heat pump or air tightness route as it
is a holiday home used for 6 months a year(except this year)
Edited to add;
Clodi added this facebook site you might find useful,
but there is some very good advice on here too(Calahonda and others know their stuff).



p.s. apologies for assuming you was a he!

kerrytigin

chooseusername wrote: »

Quote;
"Just because my username includes the word Kerry does not confirm I am either from Kerry
or ( and even if I was ) would have any similarities or comparisons to the Healy Reas FFS !!!"

Kerrytigín,when you go to your local TD about your water connection they may well have a copy of this in front of them.(it's a small world)

Having done similar to you, two things I would do differently with the benefit of hindsight;
Sliding sash windows, I would not have them tilting for cleaning.
(can be mistaken for opening for ventilation)
It just means getting up on a ladder once or twice a year.
Solid wooden door facing sun and prevailing wind and rain,
would go for composite door.
We did not go down the heat pump or air tightness route as it
is a holiday home used for 6 months a year(except this year)
Edited to add;
Clodi added this facebook site you might find useful,
but there is some very good advice on here too(Calahonda and others know their stuff).



p.s. apologies for assuming you was a he!

No issue with my local TD's here in Mayo seeing this post. I did not insult anyone and I am aware that anyone can look at a profile and see all my posts as you have done. Also it's easy to see that Calahonda certainly know about airtight homes. Much more than I do that's for sure.

Thanks for your input on windows and doors etc. shame you can't advise on A2W in a similar type building but it wouldn't be suited to a holiday home as you say. As mentioned outside of this thread I have had some using a similar system in a similar retrofit that are happy with it so fingers crossed I'll be just fine