Heat recovery system

teednab-el

Hi

Just wondering has anyone here put in air to water with UFH upstairs and downstairs and without a heat recovery system?

Thanks

selfbuild17

Plenty of people do it but it’s not recommended. Current building regulations mean that you will be putting a lot of money and effort into making the house well insulated and airtight. You also obviously also must have reasonable ventilation in the house so that it’s comfortable and safe. A heat recovery system provides continuous background ventilation without losing much heat/energy in the process. If you don’t install one (or DCV or equivalent) you will have to provide background ventilation with old fashioned room vents or homes in the wall. They are difficult to control, cause bypassing of your expensive insulation and airtightness measures and create unwanted draughts.

It’s the equivalent of buying an expensive luxury car and trying to save a few quid by excluding the AC as you can crack the window open instead

teednab-el

selfbuild17 wrote: »

Plenty of people do it but it’s not recommended. Current building regulations mean that you will be putting a lot of money and effort into making the house well insulated and airtight. You also obviously also must have reasonable ventilation in the house so that it’s comfortable and safe. A heat recovery system provides continuous background ventilation without losing much heat/energy in the process. If you don’t install one (or DCV or equivalent) you will have to provide background ventilation with old fashioned room vents or homes in the wall. They are difficult to control, cause bypassing of your expensive insulation and airtightness measures and create unwanted draughts.

It’s the equivalent of buying an expensive luxury car and trying to save a few quid by excluding the AC as you can crack the window open instead

If you can open windows is that sufficient or have vents in the house instead? You can't open the windows with heat recovery system i was told. I be against not being able open your windows in the house. Maybe im wrong in saying that?

893bet

teednab-el wrote: »

If you can open windows is that sufficient or have vents in the house instead? You can't open the windows with heat recovery system i was told. I be against not being able open your windows in the house. Maybe im wrong in saying that?

The difference is you don’t need to open windows when you have MVHR.

You can open then with MVHR but it defeats purpose.

teednab-el

893bet wrote: »

The difference is you don’t need to open windows when you have MVHR.

You can open then with MVHR but it defeats purpose.

Thats what i thought.

knipex

teednab-el wrote: »

You can't open the windows with heat recovery system i was told. I be against not being able open your windows in the house. Maybe im wrong in saying that?

Of course you can. Nothing physically stopping you opening your windows.

BUT

Why would you need to ? People open windows to let in fresh air or to let out moisture. A Heat recovery system will provide fresh air.

As I said you can open the windows all day if you wish, the heat recovery system will not care but you in winter you will be letting out all that heat and in summer you will be letting it in.

teednab-el

knipex wrote: »

Of course you can. Nothing physically stopping you opening your windows.

BUT

Why would you need to ? People open windows to let in fresh air or to let out moisture. A Heat recovery system will provide fresh air.

As I said you can open the windows all day if you wish, the heat recovery system will not care but you in winter you will be letting out all that heat and in summer you will be letting it in.

Does the heat recovery systen act like the a/c in a car? Am i correct in saying that?

Lumen

knipex wrote: »

Why would you need to ? People open windows to let in fresh air or to let out moisture.

I'm guessing you live in a city, right?

Nonoperational

It doesn't cool much. You can set a bypass mode but I still open the windows wide on summer nights. Certainly no reason not to get it in an A rated house.

teednab-el

Nonoperational wrote: »

It doesn't cool much. You can set a bypass mode but I still open the windows wide on summer nights. Certainly no reason not to get it in an A rated house.

Is it worth the 8000 euro or is it a gimmick? Im hearing mixed views about it.my builder told it wasn't worth the money. Then other people swear by it so i just dont know.

If the house gets too warm and you open windows with the HRV and its still warm. How do you control that then to cool the house? You say you dont lose heat with the HRV but if you really want to cool down the house we will say in very hot weather what do you do? The windows are open but the heat isnt reducing because of the HRV? Genuine question.

BryanF

teednab-el wrote: »

1. If you can open windows is that sufficient
2. or have vents in the house instead?
3. You can't open the windows with heat recovery system i was told.
4. I be against not being able open your windows in the house. 5. Maybe im wrong in saying that?

1. No. Refer to building regulations
2. Yes in each habitable room, with mech vents in all wet rooms - MHRV takes care of this.
3. Horse S...
4. Agreed. Required for fire safety.
5. Seek professional advice

teednab-el

BryanF wrote: »

1. No. Refer to building regulations
2. Yes in each habitable room, with mech vents in all wet rooms - MHRV takes care of this.
3. Horse S...
4. Agreed. Required for fire safety.
5. Seek professional advice

Do you need room allocated in house for HRV? Can it be installed before house reaches ground level. If I were to change my mind about it?

knipex

teednab-el wrote:

Does the heat recovery systen act like the a/c in a car? Am i correct in saying that?

No.

An AC system in your car cools air, recirculates air within the car or brings in fresh air.

A host recovery unit exhausts stale moist air and brings in fresh air. It uses the heat from the stale air to heat the fresh air being brought into the house..

So instead of paying to heat air and then dumping it out a window or a vent you can save money..

knipex

teednab-el wrote:

Is it worth the 8000 euro or is it a gimmick? Im hearing mixed views about it.my builder told it wasn't worth the money. Then other people swear by it so i just dont know.

teednab-el wrote:

If the house gets too warm and you open windows with the HRV and its still warm. How do you control that then to cool the house? You say you dont lose heat with the HRV but if you really want to cool down the house we will say in very hot weather what do you do? The windows are open but the heat isnt reducing because of the HRV? Genuine question.

teednab-el wrote:

Is it worth the 8000 euro or is it a gimmick? Im hearing mixed views about it.my builder told it wasn't worth the money. Then other people swear by it so i just dont know.

Cannot comment on price but HRV is not a gimmick. It will save you money and the air quality will be better.

teednab-el wrote:

If the house gets too warm and you open windows with the HRV and its still warm. How do you control that then to cool the house? You say you dont lose heat with the HRV but if you really want to cool down the house we will say in very hot weather what do you do? The windows are open but the heat isnt reducing because of the HRV? Genuine question.

The HRV will not cause the house to overheat. In hot weather the unit will be in bypass so no heat exchanger is utilized. Stake air out and fresh air in, no exchange of heat.. you can open the window if you want same as anyone else..

Having your house well insulated will not only keep your house warmer in winter but cooler in summer..

knipex

teednab-el wrote:

Do you need room allocated in house for HRV? Can it be installed before house reaches ground level. If I were to change my mind about it?

You dont need dedicated room. The units are not that big.

A HRV is installed at first fix stage, after the roof is on..

Irishphotodesk

Just to add, with a heat recovery unit, you will also have to change the filters every few months (think we do it twice a year).

I would say do it, not sure it was permitted in the BER assessment when we got house assessed, attic door insulation was one of the sticking points that annoyed me, the ladder is part of the attic door but doesn’t count as insulation...sore point with the BER assessment we had done, if my memory is correct there wasn’t a grant for it (heat recovery unit) at the time we got ours put in (possibly 10yrs ago).

Can’t really comment on if it’s great or not, don’t know any different, but my In-laws have gotten it done recently and plan to do it for their current build.... can recommend a company if you want (they have done the in-laws recent build and will be doing the current build, funnily enough, they are also the company we used about 10yrs ago)

runawaybishop

teednab-el wrote: »

Is it worth the 8000 euro or is it a gimmick? Im hearing mixed views about it.my builder told it wasn't worth the money. Then other people swear by it so i just dont know.

If the house gets too warm and you open windows with the HRV and its still warm. How do you control that then to cool the house? You say you dont lose heat with the HRV but if you really want to cool down the house we will say in very hot weather what do you do? The windows are open but the heat isnt reducing because of the HRV? Genuine question.

8000 sounds very pricey. It's a very simple job and a good unit is not expensive. Shop around.

The summer bypass will help cool the house down but you can't put in a mountain of insulation and no cooling and expect a house to be cool in the summer. You can just open a window if you want.

teednab-el

runawaybishop wrote: »

8000 sounds very pricey. It's a very simple job and a good unit is not expensive. Shop around.

The summer bypass will help cool the house down but you can't put in a mountain of insulation and no cooling and expect a house to be cool in the summer. You can just open a window if you want.

I am thinking of putting it in now listening to all the sound advice here.

The house is at subfloor stage at the moment. Can it be added at this stage or is it too late?

bee06

100% recommend HRV if building a well insulated, air tight house. No condensation, even straight after a shower in the bathroom, the air is alway fresh. You’re not losing heat in the winter by opening windows. We still open the windows in the summer if it’s hot.

BryanF

runawaybishop wrote: »

8000 sounds very pricey. It's a very simple job and a good unit is not expensive. Shop around.

The summer bypass will help cool the house down but you can't put in a mountain of insulation and no cooling and expect a house to be cool in the summer. You can just open a window if you want.

8k sound about right for unit plus ducting/ attenuators/ grill install

OP,
Let’s start at the beginning,
1. have you carried out a provisional BER assessment?
2. What technology is proposed to achieve renewable compliance?
3. What air-tightness factor is specified in your construction contract?
4. What heating system is currently proposed ?
5. What ventilation system is currently proposed?

Thanks
This is the second thread where you’ve stated you’re at sub-floor level. Thats kind of alarming with the questions being asking.

teednab-el

BryanF wrote: »

This is the second thread where you’ve stated you’re at sub-floor level. Thats kind of alarming with the questions being asking.

Eventhough you are knowledgeable at what you do and appreciate your advice i only asked the question. Might be alarming but i had a 2nd thought and was looking for advice. You have great knowledge on houses.

I didn't want to alarm you. Sorry if my questions are stupid. Just looking for friendly knowledge. It things cant be done that's fine but i said i would ask anyway. From hearing thoughts on here i would put it in now if i can or if it doesn't effect the design process. If it does then theres nothing i can do.

Do you reckon the HRV an be put in at the stage im at?

BryanF

Op please answer the questions I asked

Metric Tensor

OP - you need a ventilation system. Modern houses are built to such a high standard you can't rely on draughts to get rid of stale air and replace it with fresh air. The "heat recovery" part just makes sure that exhausting the stale air from your house isn't wasting all the money you spend on heat.

Openable windows are still mandatory for purge ventilation as they always have been. If you need to change the air in any room quickly in an uncontrolled manner you always opened windows and will still do so. For gradual background ventilation that used to be provided in a half arsed way by a hole in the wall of each room you now have a designed system to do it instead.

In the odd days in summer where the temperature is hotter outside than inside your ventilation system should have a "bypass" that prevents the temperature transfer part of the system. This is not present or poor on some cheaper units - so do your research.

Your builder is almost certainly not qualified to advise on the above. The person who designed/specified your dwelling air tightness and ventilation *might* be in a better position - hence the questions BryanF asked.

There's an increasing push in all elements of life to count everyone's opinion as equal. They are not. Just like you wouldn't let the guy at the pub prescribe you medication you shouldn't let him design your house either. Filter bullsh!t advice from qualified advice.

Calahonda52

teednab-el wrote: »

Will the answers to these questions determine if i should install the HRV or not for you? If so il provide the answers.

Another one for the ignore list

dellas1979

Hi OP,

I have a beam system (MVHR)/air to water pump/UFH. Am getting subfloor tomo/concrete poured (windows/roof/slabbing/first fix plumbing/elec done).

I chose to have this as the house is so airtight. Well, there wasnt really an option not to as on first airtightness test it was 1.4 air changes per hour. And that was before floor and slabbing was done. Passive house is 0.4 air changes per hour.

I have a BER assessor (and architect) who look into this for me and advise. The architect couldnt advise - was the BER assessor. As am not a builder, I do have times when I need the information broken down a bit more to enable me to understand. There is also a very good facebook forum to ask these questions (PM me if looking for info).

But anyways, basically, I have an airtight box on my hands. How do I get air into it and out of it (efficiently)?

Now, my house was designed with these internal vents (they are in the ceiling as ducting needs to be done up stairs and downstairs). And it needs to be planned out by a specialist - not the builder or you going "yep-put a vent in here". Usually, it extracts bad air from kitchen and bathrooms (as these rooms have most moisture) and converts it to heat, and fresh air pumped in around the rest of the house.

If you dont put it in such an airtight house, the house is at risk to moisture and damp and stale air.

Edit: I have to say/ask also, you have a mortgage I assume. So even if this is to save money, the bank have a certain amount (on your costings form) attributed to this system. I wonder then how would you get this money? i.e., architect/eng signs off the work/material to be paid to builder. I wonder how that could work out for you in this case. I guess you just dont drawn down the 8k for the unit.

Lumen

I found this article quite useful.

The PH+ guide to heat recovery ventilation
https://passivehouseplus.ie/magazine/guides/the-ph-guide-to-heat-recovery-ventilation

teednab-el

dellas1979 wrote: »

Hi OP,

I have a beam system (MVHR)/air to water pump/UFH. Am getting subfloor tomo/concrete poured (windows/roof/slabbing/first fix plumbing/elec done).

I chose to have this as the house is so airtight. Well, there wasnt really an option not to as on first airtightness test it was 1.4 air changes per hour. And that was before floor and slabbing was done. Passive house is 0.4 air changes per hour.

I have a BER assessor (and architect) who look into this for me and advise. The architect couldnt advise - was the BER assessor. As am not a builder, I do have times when I need the information broken down a bit more to enable me to understand. There is also a very good facebook forum to ask these questions (PM me if looking for info).

But anyways, basically, I have an airtight box on my hands. How do I get air into it and out of it (efficiently)?

Now, my house was designed with these internal vents (they are in the ceiling as ducting needs to be done up stairs and downstairs). And it needs to be planned out by a specialist - not the builder or you going "yep-put a vent in here". Usually, it extracts bad air from kitchen and bathrooms (as these rooms have most moisture) and converts it to heat, and fresh air pumped in around the rest of the house.

If you dont put it in such an airtight house, the house is at risk to moisture and damp and stale air.

Edit: I have to say/ask also, you have a mortgage I assume. So even if this is to save money, the bank have a certain amount (on your costings form) attributed to this system. I wonder then how would you get this money? i.e., architect/eng signs off the work/material to be paid to builder. I wonder how that could work out for you in this case. I guess you just dont drawn down the 8k for the unit.

Excellent thanks for that advice. Regards the 8k i will pay that from my savings. I can afford it. It was my builder who said day one that there was no need for the hrv. I didn't know enough about it at the time but on further research and advice i was thinking it should go into house due to current building regulations.

teednab-el

Lumen wrote: »

I found this article quite useful.

The PH+ guide to heat recovery ventilation
https://passivehouseplus.ie/magazine/guides/the-ph-guide-to-heat-recovery-ventilation

Cheers.

Il take a look at that.

teednab-el

Metric Tensor wrote: »

OP - you need a ventilation system. Modern houses are built to such a high standard you can't rely on draughts to get rid of stale air and replace it with fresh air. The "heat recovery" part just makes sure that exhausting the stale air from your house isn't wasting all the money you spend on heat.

Openable windows are still mandatory for purge ventilation as they always have been. If you need to change the air in any room quickly in an uncontrolled manner you always opened windows and will still do so. For gradual background ventilation that used to be provided in a half arsed way by a hole in the wall of each room you now have a designed system to do it instead.

In the odd days in summer where the temperature is hotter outside than inside your ventilation system should have a "bypass" that prevents the temperature transfer part of the system. This is not present or poor on some cheaper units - so do your research.

Your builder is almost certainly not qualified to advise on the above. The person who designed/specified your dwelling air tightness and ventilation *might* be in a better position - hence the questions BryanF asked.

There's an increasing push in all elements of life to count everyone's opinion as equal. They are not. Just like you wouldn't let the guy at the pub prescribe you medication you shouldn't let him design your house either. Filter bullsh!t advice from qualified advice.

Good advice. Il take a look into that.

dellas1979

teednab-el wrote: »

It was my builder who said day one that there was no need for the hrv.

It should definitely not be the builder who is giving you advice/influencing you.

He can give you an opinion, but you cannot take professional advice from a builder nor even us on this.

You need to engage a BER assessor.

I know the idea of saving a few quid during a build is like dangling a carrot infront of you/us. But if you want this build done correctly and for the right reasons (not just to save a few quid), you need to engage an assessor.

A report will cost you about e300.

Id prefer to live with ****ty furniture of whatever for a bit, rather than put the wrong systems into a house am building/have responsibility for.

BryanF

teednab-el wrote: »

Will the answers to these questions determine if i should install the HRV or not for you? If so il provide the answers.

Yes

teednab-el

BryanF wrote: »

Yes

Il get the info and report back.

runawaybishop

BryanF wrote: »

8k sound about right for unit plus ducting/ attenuators/ grill install.

2-2.5k for the unit and ducting, 5.5-6k for labour?

selfbuild17

€8k sounds like a lot. I’m seeing prices of about €6k for typical detached house at the moment

teednab-el

BryanF wrote: »

8k sound about right for unit plus ducting/ attenuators/ grill install

OP,
Let’s start at the beginning,
1. have you carried out a provisional BER assessment?
2. What technology is proposed to achieve renewable compliance?
3. What air-tightness factor is specified in your construction contract?
4. What heating system is currently proposed ?
5. What ventilation system is currently proposed?

1. No
2. air to water
3. Air tightness to first floor ceilings.
4. Underfloor heating downstairs and upstairs.
5. Vents on walls but subject to change.

knipex

teednab-el wrote: »

1. No
2. air to water
3. Air tightness to first floor ceilings.
4. Underfloor heating downstairs and upstairs.
5. Vents on walls but subject to change.

You really need to get advice and not from your builder.

1. Get a preliminary BER
2. OK
3. Air-tightness is measured in air-changes per hour. Have you set a required standard in your contract with the builder ? Will it be checked and certified before sign off or are you just planning on taking the builders word that its airtight ? (get it tested dotn take his word)
4. OK
5. This doesn't make sense.. How are you going to have an airtight house if its going to have holes (vents) in the walls ??? Are you going to have a fireplace ? A stove ??

brav

knipex wrote: »

You really need to get advice and not from your builder.

1. Get a preliminary BER
2. OK
3. Air-tightness is measured in air-changes per hour. Have you set a required standard in your contract with the builder ? Will it be checked and certified before sign off or are you just planning on taking the builders word that its airtight ? (get it tested dotn take his word)
4. OK
5. This doesn't make sense.. How are you going to have an airtight house if its going to have holes (vents) in the walls ??? Are you going to have a fireplace ? A stove ??

Yes and to add to this, if getting a stove and if at subfloor level already, then there should be a central air intake duct thing(very technical I know) piped in at this stage for the stove, as if air tight should be no vents like you mentioned, so stove breathes in through direct connection.

I find it strange to be this stage of a build and your architect not have engaged a BER assessment before picking what A2W system etc to use before going to tender and to builder

teednab-el

knipex wrote: »

You really need to get advice and not from your builder.

1. Get a preliminary BER
2. OK
3. Air-tightness is measured in air-changes per hour. Have you set a required standard in your contract with the builder ? Will it be checked and certified before sign off or are you just planning on taking the builders word that its airtight ? (get it tested dotn take his word)
4. OK
5. This doesn't make sense.. How are you going to have an airtight house if its going to have holes (vents) in the walls ??? Are you going to have a fireplace ? A stove ??

Stove in living room.

BryanF

teednab-el wrote: »

1. No
2. air to water
3. Air tightness to first floor ceilings.
4. Underfloor heating downstairs and upstairs.
5. Vents on walls but subject to change.

Strongly recommend you do the following

1. Seek independent advice and get a provisional BER assessment carried out - if this is part of your arch’s design (TGD L) then ask him why it hasn’t been carried out.
3. Sit with your arch and builder and ask the builder what the premium would be to achieve ‘better than 1ACH’ at this stage (can we assume some form of contract is in place? )
4. Perhaps ask the arch if the the extra cost of ‘3’ could be offset By going to other low temp rads upstairs instead of ufh
5. Negotiate design with arch and install / commissioning of hrv with builder

teednab-el

BryanF wrote: »

Strongly recommend you do the following

1. Seek independent advice and get a provisional BER assessment carried out - if this is part of your arch’s design (TGD L) then ask him why it hasn’t been carried out.
3. Sit with your arch and builder and ask the builder what the premium would be to achieve ‘better than 1ACH’ at this stage (can we assume some form of contract is in place? )
4. Perhaps ask the arch if the the extra cost of ‘3’ could be offset By going to other low temp rads upstairs instead of ufh
5. Negotiate design with arch and install / commissioning of hrv with builder

Thanks for the advice and feedback. I will look into all of the above.

runawaybishop

teednab-el wrote: »

Stove in living room.

Not much point spending money to be airtight and then having a stove that's open - look into getting a room sealed stove.

oppiuy

We decided to go with DCV. We visited a few House with the system installed and they were lovely and warm. Feedback was great and the houses were A3 rated. Also visited house with MHRV and again no issues and feedback was great. Cant remember the BER rating of those but they had been installed longer

knipex

teednab-el wrote:

Stove in living room.

If your house is airtight then you need to pipe in external air for the stove and you will need to purchase an appropriate stove to suit. This needs to be done before the floor goes down.

How did you spec your heat pump without a BER.

You really need to sit down with your architect. If you dont have one you need to get advice... even a preliminary BER will point you in the right direction.

rolling rock

Hi,

We've done retrofit insulation on a 1979 4 bed bungalow 200 sq m and am seeking advice on the best MHRV systems. Also, I'm looking for advice on reputable installers. Could anyone PM if you can help?

Thanks

teednab-el

knipex wrote: »

If your house is airtight then you need to pipe in external air for the stove and you will need to purchase an appropriate stove to suit. This needs to be done before the floor goes down.

Thats complete.

teednab-el

runawaybishop wrote: »

Not much point spending money to be airtight and then having a stove that's open - look into getting a room sealed stove.

Pipe in for that already.