Extractor fans

[ScottishGasMan]

Hey all, doing some work in my house, and having kitchen and utility room refitted.

House is 100+ years old, and currently has no extractor in either

I'm hoping to fit a whole house heat recovery unit to reduce the heat moved to outside when extractors are on,

But I can only get an internal path for duct work to kitchen not to utility room.

There both pretty small areas about 3mx2m or just over and both have fully sloping roofs so at one side its about 1.8m high and other 2.7m high.

If I don't fit a door between the two rooms would it generally be acceptable to just have the one extract point for the two rooms?

It will easily pull enough volume through, just there won't be a fresh air path into the utility

 

[stem]

With heat recovery systems there are two key aspects.

1. Balance. The volume of air going out of the building via the extract points must equal the air coming in, otherwise air will be forced in / out elsewhere, instead of passing through the heat exchanger and heat will be lost. The house should be well draft proofed to maintain the balance. Open windows, chimneys etc will also disrupt the balance.

2. There should also be a flow of air through the areas that you wish to ventilate, which means an unobstructed route from intake points to extract points, otherwise you end up with 'dead' areas that don't have an air flow passing through them (some minimal air transfer will take place by convection or movement of people, as it would in a room without any ventilation). If I understand correctly what you describe, the utility room will be such a 'dead area'.

Ideally the source of input and extraction should be in diagonally opposite corners of an area to maintain a flow of air through all of it, not just part of it. Although in practice, with existing buildings, it's not always possible.