Air Recovery/Ventilation System

C

carrotcake

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Hello, Can you help me? I am in the process of building a new home and thinking about going with Geothermal underfloor heating (for upstairs of house also). I have spoken to some people about it and they have all been very positive about it but they have it in only a year or so. I have been told I should speak to people who have it in a good few years to get their opinion so does anyone out there have an opinion on going with geothermal? Also, one of the people I spoke to said if he was installing geothermal underfloor heating again, he would definitely install an heat exchanger/ventilation unit? Can anyone advise me on this? I would really appreciate your opinion. I have given my house plans to three companies for a quote - one company has come back with price of 22K for the geothermal underfloor heating. (My house is 1937 sq. ft.). Many thanks. (ps. I live in the West - if anyone can recommend a company they used for Geothermal that they found good/reliable, that would be a help). Tks.
 
We are only in our house for 9 months, but our house would be a similar size to yours, 1800 sq. ft. We also installed the heat recovery ventilation unit with the geothermal (different companies though) and find it all very efficient. Our house is designed to catch the sun, and we invested heavily in windows & insulation, and judging from our bills, we estimate our esb bills for heating and general usage will come to about 1200 euro for year. That includes hot water, lights, everything. So far, we are delighted as the company we used for the geo-thermal heat pump has given very good after-care and customer service.
 
Hi pops,

Would you mind letting me know the name of the company you went with, I'd be glad to know.

many thanks

angela59
 
Thanks very much for your reply Pops - I am just wondering also what is the name of the companies you went to for both the Geothermal and Air Recovery Unit - maybe it's not possible to give those details on this site - I am not sure. It's great that you are so happy with your system anyways. Thanks again.
 
Hi, we were considering going with geothermal but between the few reviews of it not been all its cracked up to be, cost and the lack of info on it, we decided against it. We also thought of wood pellet but it is messy and expensive, pellets availability and price plus storage?? So, we got an engineer to look at our dormer 3,000sqft house and he came back with an air tight house with a heat recovery unit with solar panels. the key to this is insulation!! The ventilation system is very good with the help of the solar panels. If in winter, the house is a wee bit cooler we can put on our oil condensing boiler for a bit but all in all it is the most efficient house. This is the passive solar house and saves the most on esb etc. Think its 70% energy efficient. It works out around the same as the geothermal, we were quoted €21,500 plus vat for the whole system, grant for solar panels not deducted. There is a programme on next tuesday, I think called interior design?, 9th Oct, on RTE1 I think at 8.30 about passive solar houses and vent systems if you are curious?
 
Abbica, did you build a Timber Frame house? How did you get it "air tight" was it solely through the level of insulation you installed??
 
Hi Mickey, We are building a timber frame house and the design of the heating system was implemented by our architects before it was made, which means there can be no air vents, so basically no open fires. So in the sitting room we will have a multi-fuel stove which isn't punishment as this keeps 80% heat whereas open fires only give out 20% and in the good room, a log burning stove. The ventilation system will supply us with constant fresh air and replace the stale air with this fresh warm/cold air constantly, but I am sure the ventilation police won't knock on our doors if we open a window, just means that the ventilation system won't work as well, same as an air conditioning unit in a car, if you open the window, it loses its purpose. The insulation (kingspan) is just a bit thicker than usually used but not much different than any other house but good insulation also means no drafts, hence air tight. No heat loss!
 
Abbica said:
good insulation also means no drafts, hence air tight.
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No it doesn't. The weak points from an airtightness point of view in most building envelopes are around openings (windows\doors) which has nothing to do with insulation.

This requires special detailing and the use of airtight tapes\membranes etc.

Certain construction types are naturally more airtight than others (ICF and SIPs for example) but pretty much anything can be made airtight if the detailing is correct.

The reason timberframe walls tend to be airtight is because a vapour check membrance is used behind the plasterboard on the walls to prevent moisture damage to the timber frame. This also doubles as an airtightness membrane.
 
Abbica what company did you use and when you say in the winter you turn on your oil condensing boiler what is this connected to normal Rads?
 
The ventilation unit works with the oil condensing boiler so you don't need radiators. I am not technically competent to go into detail on this but basically, my understanding is that the vent unit pumps warm air back into the house and when it is cold you turn the oil condensing boiler on and it works with this to pump warmer air in when needed.
 
Abbica said:
The ventilation unit works with the oil condensing boiler so you don't need radiators. I am not technically competent to go into detail on this but basically, my understanding is that the vent unit pumps warm air back into the house and when it is cold you turn the oil condensing boiler on and it works with this to pump warmer air in when needed.
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First off I'm not trying to have a go at you. But this doesn't make sense to me either.

The only heating system I've ever come across that is used in the manner you've described (i.e. warm air added to the ventilation system when required) is an electrical heating element. In my experience Oil boilers (standard or condensing) heat water, not air. Which is why I'm curious as to how the HRV and boiler are being used in conjunction without radiators\UFH. I am open to correction on this.

Are you living in this house or is it under\pending construction?
 
Abbica that sound exactly like the system I am looking for, however I am also interested in knowing what kind of electrical heating element can be used instead of oil and what the costs of each compare like.

I don't see why you would need RAD's etc if you can introduce the warm air through the HRV system, although I'm sure people will tell me if this isn't possible.
 
It didn’t make sense to me first either but it works. Basically told us, through extensive research to use, Kar Units, HRV systems, Air handling units, evacuated solar hot water cylinder, ducts and this is left for us to enhance our system with a condensing boiler which can be used with oil, gas or wood pellets, so hence warm air goes through the HRV system. Our solar system would suffice as our hot water energy for most of the year and the boiler would only need to supplement the heat on bad days, but the boiler is also utilised for heating the air and therefore our home. We were told because it is airtight and well insulated, we will not have to turn on the condenser that often. We are getting our timberframe delivered at the end of the month.
If I say something that isn’t technically correct, I apologise, I am only after learning about this whole system as well and it is so new, well to me, I also was scratching my head. I told a few friends and they can’t fathom it at all. WHAT!! No radiators?? Madness.
 
what abbica is describing is the usual workings of a HVAC system.... these are more pertinent to large large industrial or commercial situations....

maybe theyre starting to produce them for domestic situations....
 
Was at the Self Build show recently and a guy there had a set up that was using the flue from a high efficiency stove redirected through a HRV heat exchanger to pre heat the incoming air. Looked like a plausible solution to what your looking for. I didn't get a chance to talk to the same guy as there was a large-ish crowd around him and there was a lot to see else-where. I thiink he was from a crowd in Wexford that deal in insulation solutions. I will have a look in the bag of brochures and see if I can come up with his contact. (May take time - very big bag!!!)
 
Just my tuppence worth on air recovery units. I know a building design engineer personally from one of the large TF companies who now also supply HRV's, solar panels etc. as a value add item. I considered investing in one of the KAR/HRV solutions when building my house recently, and was advised by the person promoting and designing the solution that it is not worthwhile. He reckoned that if its a choice in deciding between any of the renewable options to opt for solar.
 
I think there's a number of topics combined into one thread here :)

Heat recovery ventilation (HRV) is not a renewable technology although these units are often used in conjuction with new technologies and building methods as it is far easier to incorporate into a new build than to retrofit.

In essence, the units remove stale air from bathrooms etc., pass this air through an exchanger where residual heat from this air is transferred to the incoming fresh air, and then expel the fresh, slightly-warmed air into the living spaces of the house. The idea is that there is a constant flow of fresh air into the house and a percentage of the heat is kept within the house. Most systems come with bypass cores which can be used in summer which do not do any heat exchange and most have dust filters.

The system promises advantages in terms of energy efficiency, air quality, and vapour/moisture control at a cost of running the fans and taking meticulous care/detail into building detail around openings etc. - i.e. there isn't any point in having an open fireplace but on the flipside you don't need room trickle vents.

So, these units will, to some degree, distribute the warmed air from a point heat source around the house but they are not the same as forced air heating which was in vogue a few years ago - where electrically-heated air was expelled through grilles in the floor (with usually a cat lying on top of it) or air-conditioning.

So the use of these units is entirely independent of the heat source used - boiler, WPB, GSHP, whatever. They may, possibly, allow you to reduce use of central heating and use a point heat source only on those marginal days, particularly if additional insulation is specified.

SSE
 
Good info been posted here, I'm slowly learning.

What I am looking to achieve with my build is a good U value using an ICF build with extra insulation in the roof and make the house as air tight as possible.

Then I went to get away from oil and wood pellet burners as I believe the price of these products will double in about 10 - 15 years. So I want to use electricity for my heating which will be partly subsituted by Solar and maybe Wind technology although most people seem to think Wind is not a good investment at the minute.

So I will have no Rad's I will instead have a Heat Pump which will pump heat into the HRV system when the temp drops, this heat pump will work on electricity.

The water will be heated by Solar where possible and immersion when needed. I may also look at electric UFH for the bathrooms although budget will probably not strecth that far.

Opinions?
 
Tulach said:
Opinions?
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Of course :)

You don't expect electricity to double in price too in the next 5 - 10 years? Even though most of our electricity is generated via fossil fuel sources!

Build as close to passive spec. as money allows and it won't matter what you heat it with.
 
Oh I'm sure ESB will be increase in price too, although with all the ways we have to generate electricty through renewable sources like wind, sun and tidal etc I think we will have more control of the costs.

I think a HRV system is a very good idea even without using it for heating, but I don't think it will be viable for me unless I go ICF as trying to use block cavity and make the house air tight will be a lot of work.

Cheers
 
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