WWilts Posted January 27, 2023 Share Posted January 27, 2023 (edited) Vent Axia extractor bathroom fan stays on. Transformer box for 12V installed in loft. PIR switch connected to the fan. Intended to be on background trickle extraction, plus boost with pull cord (or boost when humidity is high) Builder says his electrician considers the unit faulty because "there is no switched live output from the loft". It was installed months ago, and this was mentioned only now after the electrician tried to set things right but failed. Builder wants me to supply another unit and to charge me for the installation of the replacement unit. Vent Axia faq say the humidistat needs to be set to maximum (90% humidity) so that it is not triggered by relatively low levels of humidity. Help! All Latin & Greek to me. I would be comfortable sending a unit back if it was found to be faulty at the start. But months later .... Qu: Is it faulty installation or faulty unit? Is there a straightforward fix if it is an error in installation? Edited January 27, 2023 by WWilts added second image Link to comment Share on other sites More sharing options...
Marvin Posted January 27, 2023 Share Posted January 27, 2023 (edited) 17 minutes ago, WWilts said: Vent Axia faq say the humidistat needs to be set to maximum (90% humidity) so that it is not triggered by relatively low levels of humidity. Hi @WWilts Crap! If the thing will only operate at 90% RH why have something you can adjust???? However if you turn the humidity dial up clockwise, gently, to the limit and it turns off then the humidity level that the fan turns on at has been set too low. Don't forget it has a delayed stop so may run on for 50 mins! (turn all the way anticlockwise for the least delayed off. I usually set fans between 40 and 60% relative humidity as this is considered the most appropriate for a home. This may or may not change things.... Edited January 27, 2023 by Marvin 1 Link to comment Share on other sites More sharing options...
ProDave Posted January 27, 2023 Share Posted January 27, 2023 WHICH diagram is it wired to, Fig 18 or Fig 19? 1 Link to comment Share on other sites More sharing options...
WWilts Posted January 27, 2023 Author Share Posted January 27, 2023 11 minutes ago, ProDave said: WHICH diagram is it wired to, Fig 18 or Fig 19? Have asked the sparky to clarify which diagram. PS When we go into the bathroom, a PIR switches the ceiling light on and sets the fan off at relatively low speed (with pull cord toggle in position 1). After a few mins the fan goes automatically to high speed even if the ceiling light goes off. Then stays on high speed. Only by switching off the isolator switch can it be stopped. Link to comment Share on other sites More sharing options...
WWilts Posted January 27, 2023 Author Share Posted January 27, 2023 (edited) 33 minutes ago, ProDave said: WHICH diagram is it wired to, Fig 18 or Fig 19? 19 SELV supply unit is in the loft Edited January 27, 2023 by WWilts Link to comment Share on other sites More sharing options...
Mr Punter Posted January 27, 2023 Share Posted January 27, 2023 I think it may be wired wrong. It needs a permanent live to keep the trickle going plus a switched live which is triggered by the PIR. 2 Link to comment Share on other sites More sharing options...
ProDave Posted January 27, 2023 Share Posted January 27, 2023 2 hours ago, WWilts said: Builder says his electrician considers the unit faulty because "there is no switched live output from the loft". If it IS wired to Fig 19 then the LS is the Live Switched from the loft unit to the fan (being pedantic is is actually switched 24V but does the same thing) So if the fan stays on forever it has to be humidity. Turn the humidity adjust pot fully clockwise to start with. and the timer pot fully anti clockwise so working out what is happening takes less time. 2 Link to comment Share on other sites More sharing options...
WWilts Posted January 27, 2023 Author Share Posted January 27, 2023 (edited) 3 hours ago, ProDave said: If it IS wired to Fig 19 then the LS is the Live Switched from the loft unit to the fan (being pedantic is is actually switched 24V but does the same thing) Initially the wiring seemed to be as shown in Fig 18 (no light, pull cord on fan, but no isolator switch) Then instead of the separate light switch an isolator switch was installed, plus a PIR that when triggered also switched the fan on. Depending on the fan pull cord toggle position, the fan starts at either slow extract (for few mins, then goes to max extract rate) or max extract rate from the very start. Thereafter stays on, until the isolator switch is turned off. The wiring from the loft SELV supply to bathroom fan was installed on the ceiling beams that are now under 400mm high loft insulation. Electrician asked to be let in after hours and (peculiarly) to be left alone in the new build house yesterday. Came well after 6 pm. Thereafter builder announced that the unit was faulty because in the electrician's words there is no switched live output from the loft. Builder also stated, peculiarly, that electrician came over to look at the fan and along with the fan manufactures support team went through all the possible reasons why it wasn't working properly and together they concluded that the fan was faulty and needs replacing. However, when I rang the manufacturer's Tech Support Team they said they close at 4:30 pm and nobody from their team spoke to any tradespeople yesterday. Seems that there may NOT be a switched live output from the loft, but only because the electrician initially wired according to Fig 18, that too apparently hardwired without an isolator switch. Some months later tried to wire according to Fig 19, but the wiring from loft to fan was buried under 400mm loft insulation. What to do, if that is the case? Builder seems to be trying to shift the burden of remedial work to me, perhaps assuming I don't know anyone who understands these things. Edited January 27, 2023 by WWilts Link to comment Share on other sites More sharing options...
WWilts Posted January 28, 2023 Author Share Posted January 28, 2023 Will this solution work? If so, can propose to builder as a mitigating measure acceptable to us. Link to comment Share on other sites More sharing options...
Marvin Posted January 28, 2023 Share Posted January 28, 2023 If the existing wire is under fluffy in the loft, it is accessible. I did this last week for a client. I assume the fan is in the wall, so cable down wall. The only problem, based on your information, is how tricky it is to install the new cable up the wall. The way to install a new cable behind a tiles wall.... If you live on the isle of wight, I will come over and do it for you free. 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now