Air recovery system in new build

grazeaway · 22-08-2012 12:30PM #1

This has probably been talked to death here already. In the middle of a new build and we are looking at installing an air recovery system into the house.
How have people found these units?
What size ducting is usually needed?
Plan on putting the piping down through the internal stud work. I know a few companies that have smaller ducting to fit inside standard stud frames.
Is there any compaines i should avoid? and also comapies i sould ask for a quote from.
what kinda price range are we talking about for a 2300sqm house?

heavydawson · 22-08-2012 05:57PM

grazeaway wrote: »

This has probably been talked to death here already. In the middle of a new build and we are looking at installing an air recovery system into the house.
How have people found these units?
What size ducting is usually needed?
Plan on putting the piping down through the internal stud work. I know a few companies that have smaller ducting to fit inside standard stud frames.
Is there any compaines i should avoid? and also comapies i sould ask for a quote from.
what kinda price range are we talking about for a 2300sqm house?

Grazeaway, you'll need to plan the airtightness of your home before you even look into HRV. Have you decided on the air changes per hour you hope to achieve?
Also, as you've already started the build, have you left vents for ventilation in the walls and/or trickle vents in the windows?

Generally you're better off with rigid ducting, the size of which will be determined by who supplies your system

grazeaway · 22-08-2012 08:54PM

No I was hoping to agree the room charges when we are sizing the unit. Not putting in trickle vents into the windows. Not planning on a passive house just one that's very well insulated

air · 22-08-2012 09:04PM

Consider taking a look at demand controlled ventilation as an alternative, far lower install costs and achieves the same or better effect depending on who you listen to.

heavydawson · 22-08-2012 09:11PM

air wrote: »

Consider taking a look at demand controlled ventilation as an alternative, far lower install costs and achieves the same or better effect depending on who you listen to.

Yup, a fair point. All that said, you need to think about your plan for making the house airtight. Any ventilation system will depend on you putting the effort into the house airtightness beforehand.
I'm no expert, but you essentially need to start thinking downstairs about how every structural joint in the rooms can be sealed properly, and the attic needs to be dealt with as it's own entity. Do a little bit of research, and you'll understand why it's important. And not just for passive houses.
Read the TGD:
http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,27316,en.pdf

grazeaway · 22-08-2012 09:24PM

What's demand controlled ventilation?

Was planning on using the sealing tape to seal up around all the joints on the dry lining and around the doors and windows. House will be finished in stages

heavydawson · 22-08-2012 09:27PM

grazeaway wrote: »

What's demand controlled ventilation?

Was planning on using the sealing tape to seal up around all the joints on the dry lining and around the doors and windows. House will be finished in stages

http://constructireland.ie/Articles/Ventilation/How-do-demand-control-ventilation-and-HRV-compare.html

fclauson · 23-08-2012 06:31AM

To work out you air flows etc you need to read TGD Part F - its very clear what is required. Do not skip in it - as an airtight house you are getting non of the "benefits" a leaky house has for ventalaiton. Bathrooms & kitchens will require their full quotiant of airflow to ensure you get no condensation.

And remember in a passive house condensation gets concentrated. If you build a thermal bridge free building but have just one piece of the superstructure which fails on the FRSI test (see Part L for what this is ) then the conendensation will concentrate of that element which is cold.

You should always get a professional to help with this

BryanF · 23-08-2012 08:11PM

air wrote: »

achieves the same or better effect depending on who you listen to.

Can you point to any independent studies on new builds) Thanks ( not the aeroco one)

has anyone looked at the BER : DC v HRV

air · 23-08-2012 08:22PM

Hi Bryan,
Nope, I haven't put a lot of research into it tbh but the theory of operation appears sound to me.
I intend to retrofit it in my own house on the first floor for extraction in wet areas and control of room vents but just haven't gotten around to it yet.

I suspect there are probably plenty of French out there studies since that's where it the technology originated.
Here's one from 20 years back after a quick google, paywalled unfortunately though - http://www.tandfonline.com/doi/abs/10.1080/09593339209385162

Another Swedish one from 2004:
http://www.sciencedirect.com/science/article/pii/S0378778804001884

BryanF · 23-08-2012 08:53PM

The OP is building a new house - very different thing to retrofitting..

air · 23-08-2012 09:00PM

BryanF wrote: »

The OP is building a new house - very different thing to retrofitting..

Yes I realise that, but I see no indication that those studies deal with retrofitting exclusively.
I only mentioned retro as an aside to explain my own interest.

BryanF · 23-08-2012 09:45PM

air wrote: »

Yes I realise that, but I see no indication that those studies deal with retrofitting exclusively.
I only mentioned retro as an aside to explain my own interest.

Look, I'm pro DCV but in a new build, when you consider the lifespan payback and heat recovery bonus , the initial cost can be justified IMO. So unless the OP has a free plentiful source of timber to waste heat, HRV is going to be more efficient with lower running costs. With retrofit I would think DC is an easier option due to the air - tightness and thermal envolpe requirements. I'm looking at this option in a deep retro fit at the moment but any of my new builds will be HRV installs.

Villain · 23-08-2012 10:01PM

Interesting thread I had always hoped to put in HRV but it's just too expensive, I'm looking at DCV now and it's less than half the cost of HRV. If you have the capital I think based on my research HRV is the best option but DCV is more affordable and does a good job.

BryanF · 23-08-2012 10:44PM

Villain wrote: »

Interesting thread I had always hoped to put in HRV but it's just too expensive, I'm looking at DCV now and it's less than half the cost of HRV. If you have the capital I think based on my research HRV is the best option but DCV is more affordable and does a good job.

Any BER issues?

Villain · 24-08-2012 06:16AM

My house was above wall plate level by 2008 so doesn't affect me really but I believe you can set the rate to whatever is required.

air · 24-08-2012 07:00AM

I haven't done serious research into either system so am not in a position to recommend one or the other.
However with regard to running costs, DCV supposedly limits the level of "unnecessary" air changes by only ventillating occupied rooms.
The relative performance would then be largely decided by the occupancy level of the home, with higher occupancy favouring HRV. An objective comparison of the two systems for a particular home would be quite complex in this regard.

grazeaway · 24-08-2012 08:55PM

Got a budget price of about 5 and a half k for a HRV system, got to do a bit more fiddling around before I commit but will be doing some kind of system.

BryanF · 25-08-2012 11:17AM

air wrote: »

DCV supposedly limits the level of "unnecessary" air changes by only ventillating occupied rooms.
The relative performance would then be largely decided by the occupancy level of the home, with higher occupancy favouring HRV. An objective comparison of the two systems for a particular home would be quite complex in this regard.

? The building regs set the ventilation requirements, the internal RH may then increase the ventilation and occupant load is obviously a facto, BUT what has HRV and higher occupancy got to with anything? Min vent requirements are set, HRV recycles heat, occupancy effects both systems..

consider a comparison done using IES. Then compared with phpp and deap to discuss/ conclude along with cost comparision/ life cycle analysis to ISO standards.

air · 25-08-2012 04:09PM

I'm just going on the Aereco literature. As I read it, it implies that when a room is unoccupied that the vents will be shut so the level of air changes will be reduced.
When it's occupied the vents open and circulation is increased. If rooms are occupied a lot then there's going to be more air changes and so the lack of heat recovery becomes more of an issues as you're losing more hot air.
I don't have any knowledge as to how their vents sit in terms of minimum ventilation requirements - as I said above I haven't done a huge amount of research in the area.

stoneill · 26-08-2012 04:12AM

I'm in the middle of a new build and was interested in air recovery systems before we started.
I did a bit of research, read some of the trade mags, all seemed well and yep I was all go!
I was invited to see some houses that have they system installed and after that I changed my mind.

Why? - the smell. There was a distinct odour of dirty laundry in the three examples we went to visit, all installed during construction and none common to one installer or supplier.

Maybe it was just bad luck, but it made my decision for me.

heavydawson · 26-08-2012 12:18PM

stoneill wrote: »

I'm in the middle of a new build and was interested in air recovery systems before we started.
I did a bit of research, read some of the trade mags, all seemed well and yep I was all go!
I was invited to see some houses that have they system installed and after that I changed my mind.

Why? - the smell. There was a distinct odour of dirty laundry in the three examples we went to visit, all installed during construction and none common to one installer or supplier.

Maybe it was just bad luck, but it made my decision for me.

Hey Stoneill,
Just wondering:
1. How did you end up ventilating your own place after that experience?
2. Did the owners of the houses say anything about the smell to you?

grazeaway · 27-08-2012 08:12AM

stoneill wrote: »

I'm in the middle of a new build and was interested in air recovery systems before we started.
I did a bit of research, read some of the trade mags, all seemed well and yep I was all go!
I was invited to see some houses that have they system installed and after that I changed my mind.

Why? - the smell. There was a distinct odour of dirty laundry in the three examples we went to visit, all installed during construction and none common to one installer or supplier.

Maybe it was just bad luck, but it made my decision for me.

That sounds like a problem with the installation. The air should be drawn out of the bathroom, utility and kitchen area and into the livign rooma nd bedroom areas. If you are getting a smell from the laundry area either there is a leak int eh transfer system and outgogn air is gettign sucked into the incoming air, or the ducts are the wrong way around and the fresh air is beign blown into teh laundry area. also the system may not be balanced correctly and air is beign sucked out of the room under the door rathe rthan through the vent. also the people could be smelly or leave colthes drying in a living room or bedroom where the air will transfer back into the house rather then out.

ShiresV2 · 27-08-2012 09:22AM

grazeaway wrote: »

That sounds like a problem with the installation. The air should be drawn out of the bathroom, utility and kitchen area and into the livign rooma nd bedroom areas. If you are getting a smell from the laundry area either there is a leak int eh transfer system and outgogn air is gettign sucked into the incoming air, or the ducts are the wrong way around and the fresh air is beign blown into teh laundry area. also the system may not be balanced correctly and air is beign sucked out of the room under the door rathe rthan through the vent. also the people could be smelly or leave colthes drying in a living room or bedroom where the air will transfer back into the house rather then out.

I agree with this poster. I installed a HRV system in my house a few months ago and it is odourless. The only smell it has ever emitted is from duct mastic curing when first installed, and that disappeared very quickly.

The house is a whole lot fresher with it than without, especially in the mornings when waking up. Think about it.. There would be no market for it if it made houses permanently smelly.

Air recovery system in new build

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