HRV queries

alfa_aficionado

beyondpassive wrote: »

An A3 house isn't an energy efficient house, its just a bog standard build with solar and geothermal eco-bling bolted on.

I'm still trying to get my head around the various categories but my (limited) uinderstanding is that A3 is the highest category that can be reached without worrying about the need to install a MHRV system - is this correct?

Would it not be far more effective to put the €30-35k into a passive specification and meet the substantially reduced space heating and winter hot water with a small 7kw air source heat pump combined the MHRV. Its much more prudent to spend money on preventing heat loss, than spending on a big heating system to compensate for heat loss through the cavity walls.

I agree that the best approach is to minimise heat loss first but given the orientation of our site (majority of glazing is facing east due to views etc) solar gain would be signficantly less than 50%. I don't think we could achieve passive status, although we are considering the fitment of triple glazing throughout. I'm also not sold on MHRVs - can anyone convince me? for example, what happens when ESB shut off the power for 8-12 hours at a time?

sinnerboy

The above post was moved from a thread about Heat Pumps .
Alfa - the forum works best if we keep a narrow focus within each thread

sinnerboy

HRV ( MVHR ) is used to conserve energy in 2 ways

1. The holes in wall vents , which can lead to excessive heat loss in cold weather are not required with HRV .
2. The heat in the air that you paid to generate within the building is not simply dumped it is used to pre warm the fresh incoming air

This holds true whatever BER grade of house . There are a lot of threads about HRV on the forum .

This is not bad starting point http://www.boards.ie/vbulletin/showthread.php?t=2055817629

MicktheMan

alfa_aficionado wrote: »

for example, what happens when ESB shut off the power for 8-12 hours at a time?

Open a few windows from time to time:)

imitation

alfa_aficionado wrote: »

I agree that the best approach is to minimise heat loss first but given the orientation of our site (majority of glazing is facing east due to views etc) solar gain would be signficantly less than 50%. I don't think we could achieve passive status, although we are considering the fitment of triple glazing throughout. I'm also not sold on MHRVs - can anyone convince me? for example, what happens when ESB shut off the power for 8-12 hours at a time?

The main advantage is the energy saving, it wasnt really enough to sell me on it either to be honest, but the additional benefits are very nice.

- Better control of humidity, from what I read it cuts it down quite alot.
- Quality of Air, there are various filters available for asthmatics.
- More control over ventilation, it will be at a nice constant level instead of having open windows on very still warm days, and from loosing heat in howling winds.

I know of somebody with a new house on an exposed site, and they rue the fact they didnt get HRV, as a very windy night can have a huge impact on the amount of heat required, he has window vents and there is no real control with them.

sunnysoutheast

The HRV, except maybe the structured cabling, is one thing we would absolutely definitely put in to any house we build in the future. Yes you have to clean out the filters but we find a huge difference in the indoor air quality in particular.

I don't think it can be justified in payback terms but we've found it makes a big difference in qualitative comfort, it also seems to be one item that several people have said they wished they had put in to their builds, particularly on windy sites.

SSE

JuniorB

... and the more air tight the house the better it will work.

alfa_aficionado

How does zoned heating work with MVHRs?

sunnysoutheast

alfa_aficionado wrote: »

How does zoned heating work with MVHRs?

We have zoned underfloor heating downstairs and rads with TRVs upstairs. No connection between the systems, but might be an idea to site UFH thermostats away from the downward air supply vents from the HRV.

SSE