Lmiln25

There doesn’t appear to be to be much difference between the boosted and general trickle sound wise but haven’t properly tested. Yes, separately you can turn on the boost switch/bathroom light, but when boosting at the same time it trips the electric.

Didn't end up getting a sparky in, found the root of the issue myself. The switch for the boost in the kitchen was left on, meaning when the bathroom light was turned on both the kitchen and bathroom were boosting at the same time. Not sure if that's normal and if you cant have both on at the same time or due to faulty wiring? Either way, I am happy to sacrifice the boost to the kitchen for whole house ventilation. Thanks for your help.

Thanks again guys, I expect to be beaten on the technical side but not on colour! Not sure how I got that wrong, but I did. I think I’m just going to do the sensible thing here let my pride take a hit and get a professional in. As you say, death is permanent.

Hi thanks all for the answers, I really appreciate it even thought it’s out my depths I think I have got my head slightly round it. I opened up the junction box next to the unit and found this (pic below). This should’ve been the first thing I done which I now realise… sorry. The unit is getting its power elsewhere. The brown cable at the bottom is coming from the light switch in for the bathroom. I’m assuming this is the boost function and is what is tripping the electrics and blowing the fuse (fuse box above this junction as shown on picture). I feel confident that this is the case and am hoping you far more informed people are going to tell me otherwise? If this is the case, could I terminate the brown cable coming up through the bottom of the junction next to the unit? (Boost cable). Hope I make some sense, thanks.

Hi Dave, Thanks for your reply. RCD trips, fuse blows every time it trips. It’s the bathroom light. Remove and terminate one of the cables circled in below pic? thanks 👍

Hi all, I have moved into a house that has a MVHR unit. Said MVHR unit doesn’t look like it has ever ran. Forgive me if I’m not using the correct terminology but I believe it is spurred of the bathroom light switch (pictured below). Every time I get the MVHR running (change 3A fuse) then turn the bathroom light on, upstairs electrics trip. I wonder if it’s as there is a boost function in that bathroom? A possible solution I had come to was to remove the boost function. If anyone has had a similar situation or could advise I would be extremely grateful. Thanks!