HRV unit - How do you know if it's working?!

selfbuildache

We're finally in to our new house; airtight, triple glazing, excellent U values etc etc (with no small thanks to Board's advice over the build) - but I'm suspicious. We've just started lighting our stove and to my mind, the whole house should be (somewhat) the same temperature. But I don't notice the house heating up and some rooms stay colder than others. (There's no central heating and house is very open plan.)
Without trying to sound too simplistic - How do you actually know this machine is doing its job?? (The remote is telling me it's all working fine...)

sas

What build type is it?

If it's masonry you need to give the house a while to warm up. That's a commonly held view for masonry passive houses. They can be quite cold for the first year.

selfbuildache

Thanks. It's timber frame. Outer leaf is masonry - so would it still take as long to heat up?? (As a full masonry build.)

sas

selfbuildache wrote: »

Thanks. It's timber frame. Outer leaf is masonry - so would it still take as long to heat up?? (As a full masonry build.)

The outerleaf shouldn't be getting heated so my theory doesn't count mostly. The floor slab could still be warming up.

The TF should warm up quickly in my opinion. Are you concerned that your HRV isn't recovering heat?

How big is the house and how big is the stove?

tred

selfbuildache wrote: »

We're finally in to our new house; airtight, triple glazing, excellent U values etc etc (with no small thanks to Board's advice over the build) - but I'm suspicious. We've just started lighting our stove and to my mind, the whole house should be (somewhat) the same temperature. But I don't notice the house heating up and some rooms stay colder than others. (There's no central heating and house is very open plan.)
Without trying to sound too simplistic - How do you actually know this machine is doing its job?? (The remote is telling me it's all working fine...)

Are you expecting the HRV to heat the house by taking the heat from the room where the stove is???????
HRV from what I read main aim, is to retain the heat its picking up from the stale air being pushed out to the house, and then passing as much as it can of that heat the incoming air...but a HRV is no way a means of heating your house, its just a smart venitalation system....was this house built to a passive specification?

brophis

To follow on from what tred said, from my understanding the incoming air temp is never going to be warmer than the outgoing air temp and the extracted air is air from "wet" rooms, so if these rooms are not warm to begin with (i.e. not heated by stove or usage) then the air going to the other rooms will not be any warmer than the "wet" rooms without extra heat input or convection (?)

selfbuildache

sas wrote: »

How big is the house and how big is the stove?

House is 2000 square ft. Stove is 8kw.
I'm looking more at the stove since your post. Going back to the book there to see how to use it most efficiently / get the most heat out of it. At least I can SEE this working!

Tred: (&Brophis)
House is built to passive specifications (can't remember exact figures, def A1 BER and air (ex)?changes really low). I understand the HRV is not a heating system (that was drummed in from day one!) but from what I understood when researching, it IS meant to 'disperse' air evenly throughout the house (it's above 95% efficiency), so surely if one room is hotter than the others (e.g. where the stove is) the others should gradually heat up as a result?
We have one room which is more separated from the others and it remains significantly cooler than the others that are all open plan.

sas

selfbuildache wrote: »

House is 2000 square ft. Stove is 8kw.
I'm looking more at the stove since your post. Going back to the book there to see how to use it most efficiently / get the most heat out of it. At least I can SEE this working!

Tred: (&Brophis)
House is built to passive specifications (can't remember exact figures). I understand the HRV is not a heating system (that was drummed in from day one!) but from what I understood when researching, it IS meant to 'disperse' air evenly throughout the house (it's above 95% efficiency), so surely if one room is hotter than the others (e.g. where the stove is) the others should gradually heat up as a result?
We have one room which is more separated from the others and it remains significantly cooler than the others that are all open plan.

That was my understanding too incidently (HRV equalises heat) but in practise apparently it's not that cut and dry.

For those rooms that are cooler, did you leave space beneath your doors (or in some other manner) to allow the heat to be dispersed?

I'm being told to leave approx 20mm beneath each door clear for this. Not the most beautiful of features but I'll be doing something like that.

Are the cooler rooms on the north side?

Have you taken temperature measurements in all your rooms for comparison?

Are you burning the correct type of fuel in your stove e.g. if it's a timber stove are you burning properly seasoned timber? This can greatly affect the performance I'm told.

HRV has 95% efficient according to whom? That sounds very high!

tred

sas wrote: »

That was my understanding too incidently (HRV equalises heat) but in practise apparently it's not that cut and dry.

For those rooms that are cooler, did you leave space beneath your doors (or in some other manner) to allow the heat to be dispersed?

I'm being told to leave approx 20mm beneath each door clear for this. Not the most beautiful of features but I'll be doing something like that.

Are the cooler rooms on the north side?

Have you taken temperature measurements in all your rooms for comparison?

Are you burning the correct type of fuel in your stove e.g. if it's a timber stove are you burning properly seasoned timber? This can greatly affect the performance I'm told.

HRV has 95% efficient according to whom? That sounds very high!

I wonder SAS would an air vent above each door frame look better with a stainless stell vent cover..???. Just a thought. OP, i was scared someone had told ya, that the HRV was a room heater!.

sas

tred wrote: »

I wonder SAS would an air vent above each door frame look better with a stainless stell vent cover..???. Just a thought. OP, i was scared someone had told ya, that the HRV was a room heater!.

It's crossed my mind. Need to consider what I'm going to do a little more.

MicktheMan

OP,
you probably know this but one way to check if the heat exchanger is functioning is if the condensate drain has water dripping out of it. If it has then at least (some) heat exchange is happening.

Is all the ducting within the thermal envelope? If not then is the ducting insulated sufficiently.

Another thought. Have you had the ducting pressure tested for air leaks? Maybe something to ask the mvhr installer.

selfbuildache

SAS

For those rooms that are cooler, did you leave space beneath your doors (or in some other manner) to allow the heat to be dispersed?

At the moment there's only curtains as doors so there should be no prob with dispersal:D but even a curtain seems to keep out the heat. The doors are sitting there to be hung and no, there's no space underneath - that's a new one for me. Y'see I had thought the HRV would be doing that work.

Are the cooler rooms on the north side?

The one cooler room IS on the North side...

Haven't taken temperatures in rooms....

And the timber being burnt is leftovers from the site - we cut it all up and dried it out but it's everything and anything! There's a lot of it so will be using it all up but I hear you on the quality...

you probably know this but one way to check if the heat exchanger is functioning is if the condensate drain has water dripping out of it. If it has then at least (some) heat exchange is happening.

Is all the ducting within the thermal envelope? If not then is the ducting insulated sufficiently.

Another thought. Have you had the ducting pressure tested for air leaks? Maybe something to ask the mvhr installer.

I'll check the drain this eve - thanks!
The ducting is all within the envelope.
Air leaks?! At this early stage?? I'd kill him. (But will think on your advice!)

I guess I'm just disappointed with the house performance and the turn in the weather. I'll check on all advice. Thank you!

selfbuildache

sas wrote: »

HRV has 95% efficient according to whom? That sounds very high!

According to the SAP Appendix Q - As far as I remember that's what it got there. (It' a Vort Promoteo) Definitely over 90%..

sas

selfbuildache wrote: »

The doors are sitting there to be hung and no, there's no space underneath - that's a new one for me. Y'see I had thought the HRV would be doing that work.

This is my "idiots guide to HRV" understanding

You have a room that has a good tight door.
Your room is well sealed.
You have a HRV extract in that room.

In order to extract, it needs to be able to draw air. It won't be able to do this terribly well because the room is sealed.

When you have the gaps under the doors (or equivalent wall vent) the air supplied through the HRV in 1 part of the house, is drawn away in the room extracts.

This is very basic I appreciate but it made sense to me.

tred

sas wrote: »

This is my "idiots guide to HRV" understanding

You have a room that has a good tight door.
Your room is well sealed.
You have a HRV extract in that room.

In order to extract, it needs to be able to draw air. It won't be able to do this terribly well because the room is sealed.

When you have the gaps under the doors (or equivalent wall vent) the air supplied through the HRV in 1 part of the house, is drawn away in the room extracts.

This is very basic I appreciate but it made sense to me.

On the extracts, are they only really in the so called wet rooms , bathrooms, kitchen utility etc. Inputs then in the rest?

selfbuildache

In our house the extracts are in all 'wet' rooms (+kitchen + room with stove). Inputs in all other rooms.
So, my undertanding is that you shouldn't need a gap in any door as each room has whatever's appropriate.
So, for example, the 'colder' room I'm talking about has an input 'duct' there, so surely, simply put, if the house is warm enough in general, this room should be getting input from the HRV/the rest of the house, and getting warmed up!?
Our kitchen/dining/sitting room has 2 ducts - extract up near cooker etc and input down the other end....

creedp

selfbuildache wrote: »

In our house the extracts are in all 'wet' rooms (+kitchen + room with stove). Inputs in all other rooms.
So, my undertanding is that you shouldn't need a gap in any door as each room has whatever's appropriate.
So, for example, the 'colder' room I'm talking about has an input 'duct' there, so surely, simply put, if the house is warm enough in general, this room should be getting input from the HRV/the rest of the house, and getting warmed up!?
Our kitchen/dining/sitting room has 2 ducts - extract up near cooker etc and input down the other end....

There was a discussion recently on the dangers associated with negative pressure arising from having forced extraction ventilation in the same room as an open fire/stove. Was this taken into account when installing an MHRV extract vent in the room with the stove. Intuitively, its seems like a good idea to extract the excess heat produced by the stove and distribute it around the house but is there any risk that in doing so you could create negative pressure in that room thereby drawing smoke/CO from the stove into the room?

Carlow52

Looking for some self interest clarity here.
Out of interest I have just read the spec for the Vort Promoteo and it seems the intakes are from the kitchen and up to 8 wetrooms.

The opening THERMAL efficiency is 92% for kitchen plus 1 wet room down to 87%
This assumes rigid duct work.


I get the impression from the OP that the house is open plan so I am a bit puzzled by how the HRV will work in such a case.

In addition I presume the air intake for the stove is external and sealed.

What make is the stove?

In terms of getting 8kw from it read the manual for how often u need to stoke it, prolly every 45 mins and you also need to burn the fuel properly, good draft to burn fast at start so little smoke..
ps I agree with earlier poster, the ducting for cold room needs to be looked at, maybe stuffed/kinked/too small a bore etc

sas

selfbuildache wrote: »

So, my undertanding is that you shouldn't need a gap in any door as each room has whatever's appropriate.

Your missing my point I think. You can't extract a m3 of air from a room if that room is sealed because air needs to be able to move into that room to replace it. This is the negative pressure as described above.

If your doors are very tightly fitted, you could end up a situation where the HRV is trying to extract air at a faster rate than replacement air can be drawn into the room.

sas

tred wrote: »

On the extracts, are they only really in the so called wet rooms , bathrooms, kitchen utility etc. Inputs then in the rest?

I can only speak for what was done in our home.

Attic:
Gamesroom Supply

1st Floor:
4 Bedrooms Supply
3 Bathroom\Ensuite Extract
1 Walk in wardrobe Extract

Ground Floor:
Lounge Supply
Study Supply
Open plan kitchen\living\diner Supply & Filtered Extract
Utility Extract
Wc Extract

So it would appear to be the case but I'm a customer, not a supplier:)

selfbuildache

creedp wrote: »

There was a discussion recently on the dangers associated with negative pressure arising from having forced extraction ventilation in the same room as an open fire/stove. Was this taken into account when installing an MHRV extract vent in the room with the stove. Intuitively, its seems like a good idea to extract the excess heat produced by the stove and distribute it around the house but is there any risk that in doing so you could create negative pressure in that room thereby drawing smoke/CO from the stove into the room?

I confess, no, this is new, and worrying to me. Only thing is that the 'stove room' doesn't need to be 'doored' off from dining/kitchen so I guess I just make sure the doors aren't sealed or as previous poster wrote, maybe vents?

SAS

Your missing my point I think.

I think you were right, but between you and creed, I'm with you now, unfortunately:(

Carlow52

I get the impression from the OP that the house is open plan so I am a bit puzzled by how the HRV will work in such a case.

All open plan here for the moment as no doors hung yet. There WILL be one room separate downstairs + utility separate + maybe hallway.
My layman's understanding of the eventual idea is, as well as allowing the house to 'breathe' and take in fresh air, the HRV would disperse heat/ help keep all rooms a similar temperature.

Carlow52

In addition I presume the air intake for the stove is external and sealed.

What make is the stove?

In terms of getting 8kw from it read the manual for how often u need to stoke it, prolly every 45 mins and you also need to burn the fuel properly, good draft to burn fast at start so little smoke..
ps I agree with earlier poster, the ducting for cold room needs to be looked at, maybe stuffed/kinked/too small a bore etc

Air intake is indeed sealed.

Stove is Clearview. 'Pioneer', if I remember correctly.

And yes, I have JUST started reading the manual, after starting this thread, on how to use the thing properly/efficiently, so a lot of fault is with me, in terms of the stove, as I wasn't using it properly.:o

And I'll check out the ducting for the cold room. Thank you!

creedp

selfbuildache wrote: »

I confess, no, this is new, and worrying to me. Only thing is that the 'stove room' doesn't need to be 'doored' off from dining/kitchen so I guess I just make sure the doors aren't sealed or as previous poster wrote, maybe vents?

SAS
I think you were right, but between you and creed, I'm with you now, unfortunately:(

Carlow52
All open plan here for the moment as no doors hung yet. There WILL be one room separate downstairs + utility separate + maybe hallway.
My layman's understanding of the eventual idea is, as well as allowing the house to 'breathe' and take in fresh air, the HRV would disperse heat/ help keep all rooms a similar temperature.

Carlow52

Air intake is indeed sealed.

Stove is Clearview. 'Pioneer', if I remember correctly.

And yes, I have JUST started reading the manual, after starting this thread, on how to use the thing properly/efficiently, so a lot of fault is with me, in terms of the stove, as I wasn't using it properly.:o

And I'll check out the ducting for the cold room. Thank you!

I'm interested in your experience with the Clearview stove. I am looking at stoves and one on my list is the Clearview Vision 500 with an external air supply. How are you finding the stove? Any issues with smoke entering room especially when loading? Referring here to the operation of a stove in an airtight house with MHRV. I'd appreciate also a pm of where you sourced the stove as there doesn't seem to be too many suppliers in this country.

Thanks

sas

selfbuildache wrote: »

Stove is Clearview. 'Pioneer', if I remember correctly.

And yes, I have JUST started reading the manual, after starting this thread, on how to use the thing properly/efficiently, so a lot of fault is with me, in terms of the stove, as I wasn't using it properly.:o

Good for you. These stoves are a different beast to the ones from waterford. It's not just a gloried open fire. Working through the manual should really help.

What I've did was get some hardwood back in july. Currently drying in my shed. I won't be near it for use as fuel until Sept. next year.

In the interim I'm going to buy from one of the suppliers of kiln dried firewood.
I'll pm you on some sites I've come across, might help.

selfbuildache

creedp wrote: »

I'm interested in your experience with the Clearview stove. I am looking at stoves and one on my list is the Clearview Vision 500 with an external air supply. How are you finding the stove? Any issues with smoke entering room especially when loading? Referring here to the operation of a stove in an airtight house with MHRV. I'd appreciate also a pm of where you sourced the stove as there doesn't seem to be too many suppliers in this country.

Thanks

I've just looked up details and we too got the Vision 500 NOT the Pioneer which came 2nd.
I'll PM you the details of the shop. In Dublin. The guy there is a mine of information and really well informed. The price we got was best we could find in a limited market for this kind of stove, although I think Stanley were about to launch something similar (just not in time for us.) and this guy seemed to think they'd have something competitive.
I can't tell you how well the stove is working as I think I may be at fault, as per previous post, in terms of using it like our fire place from when I was a kid! So, there's been lots of smoke when starting up and I don't feel there's been a lot of heat - but again, I think I'm using it badly. Gotta study some more - or ring that guy in the shop again now that i think of it!

selfbuildache

sas wrote: »

Good for you. These stoves are a different beast to the ones from waterford. It's not just a gloried open fire. Working through the manual should really help.

What I've did was get some hardwood back in july. Currently drying in my shed. I won't be near it for use as fuel until Sept. next year.

In the interim I'm going to buy from one of the suppliers of kiln dried firewood.
I'll pm you on some sites I've come across, might help.

Thanks - another whole new world of information I need to get studying on obviously...

creedp

selfbuildache wrote: »

I've just looked up details and we too got the Vision 500 NOT the Pioneer which came 2nd.
I'll PM you the details of the shop. In Dublin. The guy there is a mine of information and really well informed. The price we got was best we could find in a limited market for this kind of stove, although I think Stanley were about to launch something similar (just not in time for us.) and this guy seemed to think they'd have something competitive.
I can't tell you how well the stove is working as I think I may be at fault, as per previous post, in terms of using it like our fire place from when I was a kid! So, there's been lots of smoke when starting up and I don't feel there's been a lot of heat - but again, I think I'm using it badly. Gotta study some more - or ring that guy in the shop again now that i think of it!

Great, thanks. Its gas isn't, there was a time which isn't that long ago when thinks just seemed a lot simpler ... progress ...

selfbuildache

The HRV that is. The remote has started showing that there is a blockage of the intake and the discharging motor so it's shut down altogether.

I guess at this point I get on to the HRV guy....

(Possible stupid question here - the ducting coming directly out of the machine at the inlet and outlet spigots is flexible - is that normal?? (we asked for rigid ducting - but maybe at the spigots it needs to be flexible??)

Troy McClure

I viewed a HRV in a house that was done in rigid ducting. We are thinking of getting same system. I wondered that also - Why was there flexi ducting for a couple of feet on either side of the unit.
Was told by the company that it's to counter vibrations and stop noise transfer from the unit it self. It can be avoided by hanging or suspending the unit instead. Was told it had little effect on performance as it is short.

selfbuildache

Thanks for that. In fairness, the HRV guy came out and fixed the problem quite quickly, just by adjusting speeds of the motor on the remote. I also quizzed him on some of the questions raised here and I'm somewhat more at ease with the system.
Troy - he also said the same thing about the ducting.

sas

Troy McClure wrote: »

I viewed a HRV in a house that was done in rigid ducting. We are thinking of getting same system. I wondered that also - Why was there flexi ducting for a couple of feet on either side of the unit.
Was told by the company that it's to counter vibrations and stop noise transfer from the unit it self. It can be avoided by hanging or suspending the unit instead. Was told it had little effect on performance as it is short.

In the manual for my HRV unit (one of the BIG german companys with several PHI certified units) it states that this should be done although it doesn't specify how much of it to use. It is to minimize sound transfer from the unit by vibration as I under it too.

I've just emailed my supplier seeking clarification. I'll post here again if anything of use comes back.