DCV limitations?

Scobiwankenobi

Hi there,

I have been recently looking into the mechanical ventilation systems. I was aiming at the HRV but the builder told us that we may have to seal up the house further for the HRV to be effective enough to warrant putting it in.We are not aiming for a passive rating. The airtightness is currently 3m cubed.

I then switched focus to DRV which I thought would suit fine as airtightness is not a similar issue. Upon speaking to a supplier he reckons that the house is too big for DRV to work well. Its 3000 sq ft. Nothing fancy just a couple of large rooms!

Looking for advice!

BryanF

Who is checking compliance with building regulations? What was their recommendation?

What stage is the build at?

Scobiwankenobi

Build is on block work, nearly up to the first floor.

Engineer reckons there is enough ventilation naturally. BER is expected to be at A3 but as window spec is increased from the windows calculated for I am worried that that could be A2 . Also while I am happy with the window quality I am extremely anxious that there wont be mould or mildew or stale air in any spots in the house after having the opportunity to build. Worried that build up of moisture could cause this , thought the DCV would be perfect to prevent this?

JonathonS

You don't have to be building a passive house to justify MVHR. Your engineer is effectively saying that you will have a draughty house that will lose a lot of heat. Go for MVHR, you still have time to achieve the required airtightness.

If you are still determined to avoid MVHR there are some useful threads on DCV/PIV here https://www.boards.ie/vbulletin/showthread.php?t=2056790886

and https://www.boards.ie/vbulletin/showthread.php?t=2057610160&utm_source=notification&utm_medium=email&utm_campaign=digestthread

and https://www.boards.ie/vbulletin/showthread.php?t=2056793413

and finally https://www.boards.ie/vbulletin/showthread.php?t=2057682181&utm_source=notification&utm_medium=email&utm_campaign=digestthread

B-D-P--

Even at an old house, MVHR is worth it, It takes stale air out and replaces with fresh air.

I would disagree with builder and put it in, Sounds like a trade stuck in his ways.

CJhaughey

We have HRV fitted for the last 10 years, TBH I think it would be madness to be building a new house without out it, regardless of airtightness it makes for a very comfortable dry house with no damp problems.
Air exchange is essential in any house for the occupants as well as the house.

dathi

Looking for advice!
"but the builder told us that"
1,stop listening to your builder he wants to build your house as cheep as possible to make a profit .
"Engineer reckons there is enough ventilation naturally."
2, you need a new engineer as this one is not up to date with regs