heat recovery ventilators

[benpost]

in my 2 bed ground floor maisonette there are 2 heat recovery ventilators fitted. they are made by kair. they are rather unsightly with 2 boxes each at the top of the walls in the lounge and main bedroom with a boost cord hanging down. also there is the trunking for the power cables going up the wall.

my question is, does anybody have experience with these or similar units. to be honest they don't seem to make any difference whether on or off. the maisonette has had problems with damp (i'm pretty sure its cold wall condensation and nothing more).

also one of them stays permanently in boost mode which is quite loud, the humidity sensor doesn't seem to work. its definitely not manually set to boost.

i get the feeling the previous owner called in a specialist company and had a salesman call in and sell these units without properly checking the cause of the damp/mould on walls.

any views welcome as i'm pretty inexperienced with diy!

[dg]

Heat recovery units are next to useless in the UK climate, OK for Scandinavia, but no use here.

But they may be functioning as a positive pressure fan to combat mould and damp, and in this situation they do tend to work if used in conjunction with other vents to let the damp air out.

dg

[benpost]

I think that makes sense , i'm guessing they were sold to the previous owner without a lot of research / trial and error being done. I'm going to live without them on for a few months and see whether a mould problem develops again (once ive finished cleaning it all off, not easy on a stippled ceiling).

If the mould problem doesnt come back then I'll get rid of them. Only thing is i'll have 2 holes in the wall! Cant believe someone paid =A3300+ each for 2 of these things.

[tom.harrigan]

Why do they work in Scandinavia but not here?

T

[Andrew Gabriel]

They are very expensive items. On that basis I wouldn't fit them, but if they were already there, I probably wouldn't take them out!

[Andy Hall]

Because on average, the temperature difference from inside to outside is much greater for longer times during the year and more heat can be recovered. Like any other form of heat exchanger, the heat transferred is proportional to the temperature difference between its primary and secondary sides.

[geoff]

Different kind of snow ...

[benpost]

I think i will take them out, for a few reasons:

- they dont seem to work properly, one stays on boost mode which is noisy, the other will sit on trickle mode but doesnt seem to go to boost mode at all even with a boiling kettle under the sensor

- as the wall backs on to an alleyway you can hear any activity such as kids through the ventilator and it seems to echo the noise

- i dont think they were required in the first place i'm pretty sure i can solve the problem by reducing condensation in the first place and using the window latch position for airflow

- it will be nice to have a smooth plain wall without trunking up the wall and 2 boxes at the top

[benpost]

hi, when attempting to remove the heat recovery ventilators, i found they are secured with a tamperproof screw. ive contacted the manufacturer and been told i need to buy either a screwdriver:

a drill bit: wondered whether these can be bought anywhere else? thanks

[benpost]

any ideas anyone as im going to the diy shop tomorrow! hoping to find a screwdriver like this one there, hoping its a standard tamperproof type and not specific to that company.

[benpost]

please please please does anyone know if this screwdriver bit is standard or do i have to order it from the specialist site i've been given:

[benpost]

well now i have got the tool i removed one of the ventilators from the wall and there is plastic tubing about 15cm diameter going from inside to outside. removing this will expose the bricks and cavity. if i do this what would be the best way of filling in the holes from inside and outside??

[benpost]

haha looks like i'm talking to myself on this post :P