So I don’t have a passive house but I do have a house with multiple bathrooms and not an extractor fan anywhere. Since moving in we’ve found condensation is a bit of a problem, guessing because the bathrooms not being vented anywhere. So rather than install traditional fans I’ve starting looking at heat recovery ventilation systems instead as a better solution for the house. My questions are:

We’ve a wood stove in the lounge that required a permanent air vent due to being above 5kw (installed behind the stove). If you have ventilation system does that mean you can block the vents up? Does it have to be in the room rather than elsewhere in the house (this could be the tricky bit)

We couldn’t fit the vents downstairs in the kitchen only the first floor. The bathrooms are upstairs. Is that an issue as long as we site one duct above the stair well?

Are they worth it??

So rather than install traditional fans I’ve starting looking at heat recovery ventilation systems instead as a better solution different solution for the house

We couldn’t fit the vents downstairs in the kitchen only the first floor.

whats stopping you from running ducts under the floor upstairs and dropping them into the roofs of the downstairs rooms ?

You may want to pop over to the Navitron forum as they’re particularly knowledgable on stuff like this.

I guess anything is feasible, just not sure how to get the duct from the roof space into the floor upstairs. Just box it in the corner of a room I suppose? It’s a new concept to me but just naively assumed running ducts would be much easier/cheaper on a new build rather than retrofit.

The lounge is also challenging as it’s on the side of the house with no floor above just a thin sloping roof that meets the rest of the building. I think the duct would have to come through the wall

are your upstairs walls brick or stud/plasterboard ?

bring it down the inside of the walls if theladder into the floor ?

run it along the floor – measure carefully….. pop a hole in the wall ofthe lounge from below upstairs floor level.

retrofitting one of these without it being an obtrusive mess is going to be hard work – but its very possible and if you work logically you could DIY mostof it without too much disruption – baby steps.

ideally the ducts need to be sited to allow complete air change in the whole building and circulate through all spaces.

We were a little limited in fitting ours, but I managed to drop a duct at the back of the barn, at the opposite end from the main kitchen extraction to create a tiny but sufficient pressure differential across the whole downstairs. Upstairs, the flexi ducting just drops onto each ceiling through a valve fitting.

one inlet and one outlet in the kitchen to clear cooking air.

MHRV unit on the wall behind those kitchen valves

with ducting going out to the roof above the utility room and also up the wall internally into the roof space where it links up to the ceiling valves (extract @ bathroom and inlet at each bedroom).

inlet/outlet on roof:

In the loft space.
The rolls of glass batts on the left get rolled over the duct to insulate and maintain air temp

typical ceiling inlet valve:
http://www.ebay.co.uk/itm/100mm-air-valve-steel-ducting-domestic-ventilation-extractor-fan-/171505893997?

It’s a new concept to me but just naively assumed running ducts would be much easier/cheaper on a new build rather than retrofit.

Very true, and it’s not a simple as putting multiple ducts in and air will move equally to all rooms, especially if the house is not a sealed unit to start with.

There are lots of constant flow, low consumption, fans with integrated heat exchangers available.

Like this, for example.

Link

BTW, these guys are very helpful http://www.cvcdirect.co.uk/

307e for the single-room extractor with heat recovery in your link, Neilwheel. That’s the first I’ve seen that isn’t complete overkill for our house. Thanks for posting.