HRV

hiagain · 19-08-2014 4:29am #1

Hello there,

I am wondering is HRV is suitable for my house. It is around a 1100 sq ft, 1970's build. It has an air tight membrane and 9 inches of insulation under the floor boards. It will have an air-tight membrane and dry lining up the walls and cellulose in the attic, insulated pipes etc, triple glazing.

Should we get HRV? The system we have looked at is for a larger house, but I will look at more if it's something that we need to get. Any advice welcome

DeeJunFan · 19-08-2014 7:29am

Have you had a blower door test done?

If so what was the result?

If not; you should and then decide

hiagain · 19-08-2014 8:38am

No I haven't because all of this work hasn't been done yet. If I wait until after it has all been done then I won't be ripping things up again to do it!

DeeJunFan · 19-08-2014 8:48am

ok, so what is you target for air-tightness? i take it from the triple glazing you are getting new windows. You would need to know if you are getting trickle vents on them also.

If you targeted air-tightness is low enough for MHRV then i would say go for it. I'm not sure what the Irish building regs are for MHRV but i believe in NI they say under 3m3/hr most people would say go for less than 2 for it to be worthwhile.

hiagain · 02-09-2014 2:25am

I guess I don't have a target. I am just trying to get each individual jib done to the best level possible

MicktheMan · 02-09-2014 8:53am

hiagain wrote: »

I guess I don't have a target.

MV HR

The target / actual airtightness is important to know in order to decide on the HR bit, but you most probably will need the MV bit anyway.

RITwing · 02-09-2014 9:02am

Scant information available but from what we know here I think you should research DCV - deman controlled ventilation. In simple terms you have a centralised extarct only vent system together with hole in wall vents which will only open when the 02 levels fall. No heat recovery but heat loss due to over ventilation is reduced. The big advantage in your case is 1. less cost and 2. it is simpler to retro fit. MVHR and all its ductwork is space hungry.

RITwing · 02-09-2014 9:03am

oh .... and do all you can to get the air tightness up and test it after

MicktheMan · 02-09-2014 9:09am

RITwing wrote: »

together with hole in wall vents which will only open when the 02 levels fall.

Nothing to do with O2 levels. They open / close with rising / falling RH levels!

RITwing · 02-09-2014 9:28am

My bad - thanks

HRV

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