Heat recovery, single room vs all house

[fex10]

I've been pondering about these heat recovery systems which vent the room while not letting heat out. My bro had one and said it worked really well, and they claim 75% efficiency (is that even realistic?). It's a three bedroom 1930s suburban terraced house.

What I'm trying to figure out is whether to go for a full house system with a single machine that vents the entire house, or do I install in individual rooms individual units? The whole house systems claim 85% efficiency, but my concern is getting the ducting to each room. Even if the upstairs ducting is installed via the loft to distribute to the upstairs rooms, there are joists that cross the house in both directions that stop you getting from one end to the other. Do you know what I mean? Lets say the joists from front to rear, at the centre of the house there is a single joist that goes left to right, hence blocking my path. This joist sits on a structural wall, but still I would not want to cut a 100mm hole in it!

What about making a feature of the ducting? Like in commercial buildings where the ducting is suspended off the ceiling, not hidden at all.

 

[endecotp]

These systems are most appropriate in newer or upgraded buildings where there is very good draught proofing. The need for such a system, and its effectiveness, is less in older buildings. They are also more appropriate in climates where the outside temperature is very low during the winter e.g. Canada (beware of stats that assume an outside temperature of -5C!).

75% or above is certainly feasible for the fraction of heat transferred from outgoing to incoming air.

Is your house currently stuffy? Do you often have to open windows?

 

[fex10]

I wouldn't call the house stuffy, 1930s terraced house and each room has a vent in the bricks. I just thought this would be a good way to get fresh air without loosing heat. My girlfriend likes to have the heating on full blast AND the windows open, and my lodgers repeatedly leave windows open when there's no one in the house which invalidates the burglary insurance right away. I thought this could solve both problems.

 

[empip]

I posted this in 2005,

http://www.nuaire.co.uk/Product/Residential_Products/Positive_Input_Ventilation/Drimaster_2000
Can you match the filtration?

...The Drimaster provides whole home ventilation using the Positive Input Ventilation principle. Essentially the concept is to introduce fresh, filtered air into the dwelling at a continuous rate, encouraging movement of air from inside to outside...

This cured a friend's condensation problems in his bungalow when other procedures provided little benefit... (see the similarity to your proposal) I did ask him about the effects of introducing cooler air from his loft, he said it was 'no problem'. Perhaps the removal of major condensation problems overuled other considerations.

My older house has full length loft vents over fascia boards, can be quite a nippy space during winter... Suffers no condensation.

-0-

http://www.nuaire.co.uk/our-products/Residential/products?pt=1685

Friend related his experience of the equipment back in the late 80's or even earlier ! I have no experience of living with it - Seems to be based upon slightly pressurising the interior of a building with fresh, filtered air thus causing an outflow from the property. Friend's three bed bungalow has but one inlet servicing the whole house.
The company has been around through all the bad times, and still exists - Perhaps their kit really does work ??

-0-

 

[simond]

I put a Villavent system in my Victorian house when it was being gutted in 2004, 75% heat recovery Swedish system.

As mentioned above, in older UK stock it is unsuitable. We still use it for centralised extraction from bathrooms, kitchen, utility..... but I have disabled the fresh air input. Heating bills made a significant drop afterwards.

Should have known better as I'm a heating engineer, but bringing in such vast quantities of colder air into a poorly insulated non-sealed house can only lead to higher bills.

It just needs the figures being considered. Forget recovering 75%; think more like; If you change the air twice an hour and lose 25% of the heat each time, how does that feel?