Whole home vent system question

[SimonH2]

Think about it..... If a whole house system works simply by removing the damp air by constant replacement, then ANY method of achieving this should also work.... and in our case, using two extractor fans, it is working brilliantly.

Indeed. The difference is that a heat recovery system won't throw out all that nice warm air and replace it with cold air. That's the theory anyway.

I believe the specific heat capacity of dry air is about 1.23 kJ/m^3 K. 3600kJ per kWH, so for (say) a 10˚ difference between inside and outside temperatures, that's 0.0034 kWH per m^3. I don't know which fan you have, but a couple of them will easily shift 100m^3/Hr according to some of the spec on Vent Axia's website. So that's 0.34kWH/H, or around 8kWH/day of heat lost. Obviously it'll be less in summer, more in winter - but it'll add up over a year, it's not for nothing that building regs stipulate minimum standards for air tightness of new buildings.


Timely, as my letting agent is having to talk to my current tenants about how not to make the flat damp and grow mould None of my previous tenants had any problem.

 

[joepeddos44]

Have just moved in to a 2 bedroom bungalow which has an envirovent whole house ventilation system which was installed 6 years ago.
Reading the info the previous owner left the fan is powered by a brush less direct drive DC motor not sure if this makes it more economical to run than an ac fan.

 

[SimonH2]

... the fan is powered by a brush less direct drive DC motor not sure if this makes it more economical to run than an ac fan.

Not really - neither better nor worse - just different.

There's a description on Wikipedia, but in short, it's really just a small synchronous AC motor driven by some clever electronics. In this application, it makes speed control very easy as the electronics directly control the supply frequency and hence synchronous motor speed.