Hi from Pembrokeshire
 

Hi,

Joined Ecorenovator after reading a thread on Heat recovery systems.
I will difinatly be having a go at building one, I already have Correx sheeting in My Ebay.

Hope to be posting more in the near future.

Hi Mini23, welcome to these forums!

At this moment both Kostas and me are in the proces of building a HRV though neither are finished yet, so we have no results of how effective our builds are.
In the next few days I'll finish mine though and I'll have some more chat about my buildingexperiences. It took me longer than expected and I learned a few things about the materials I am working with.
So keep on reading, don't rush your project and when asking a question give us a few days to respond.

Thanks for the reply and i'll be very interested in seeing the results.

My plan is to build a unit in the loft, so there is no size restriction, I live in a bungalow, so easy distribution.
Also the main aim is to run the contura wood burner at maximum capacity, as wood is free to me.
Then distribute clean air throughout the rest of the house.

At the moment the 4m2 room must be 30 degrees with the door open, whilst the oil central heating is heating the bedrooms.

Welcome to the site!

Definitely check out this thread:
http://ecorenovator.org/forum/conser...exchanger.html

Welcome to the site mini23. I lurk alot but feel out of place as I am still learning.

If you work out how much energy you can shift using air (use specific heat capacity of air and heat loss from your target room to work out how much air you need to move at whatever temp differential you like), you'll probably find that an HRV is not how you want to move this air around - the flows involved are really high. For comparison to get enough fresh air for a person, work to a rough figure of 10 litres per second per person (== 21 cfm, == 36 cubic metres per hour).

Say a room which you want to heat has s heating requirement of 800 watts.

Air (approx 50% humidity at sea level) can carry approx 0.0013 joules of energy per cubic centimetre per degree Celsius of heat difference.

If your extract air is 30 degrees, and you manage to recover 80% of heat, and you want to heat your other room to 20 degrees.

Stick the following directly into google:

80% * 0.0013 ((joules per cubic centimetre) per degree kelvin) * 10 litres per second * 10 degrees kelvin

and it'll say 104 watts.

So you'll need to ventilate at about 8 times that rate (or enough for 8 people) to heat it up enough. And that's just for one room!

If on the other hand, you could take air at 70 degrees from near the stove, and move the same amount of air directly to the target room then you'll be transporting:

100% * 0.0013 ((joules per cubic centimetre) per degree kelvin) * 10 litres per second * (70 - 20) degrees kelvin

= 650 watts

... which is a bit more like it.

That's not to say that you shouldn't have an HRV too, it's just that for moving mass heat, you need to take the warmest air from near the stove, and put it directly somewhere else...

About the only houses which manage to use the heat recovery ventilation air to shift around enough heat to heat them are passive houses (i.e. those that reach the PassivHaus standard - which in the UK means approx 300mm of conventional mineral wool or glass fibre insulation all-round, and triple glazing), and even then it's a bit marginal - they can end up over-ventilating.

Hope this helps - it'd be a shame to spend ages building a big heat recovery ventilation system only to find it doesn't move enough air to do what you want!

Tim.