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Humidistat controlled fans

whjohnson
Fitted a 100mm SELV Xpelair Silavent fan a month or two ago. Client says it is running all the time. I said I think it is designed to do so but am now not so sure.

I thought initially that the fan would sit there awaiting a rise in hunidity before kicking in and doing its thing until the levels returned to below the humidistat trigger threshold, then I looked again and it seems that the fan runs all the time on a slow speed until a higher humidity level triggers the sensor and then the fan speeds up.

She's annoyed with the noise of the fan running all the time and is switching it off at the isolator until needed.

So, just how are these things supposed to actually work?
  • 0
    Yes it probably is working as intended, but I think you can open it up to alter the jumpers so it behaves differently.
  • 0
    Yes, there is a set of jumpers which have to be preset - can't recall exactly what they do but will take another look. There is also a sensor adjustment on the humidistat side. Should this be turned up or down the lessen the likelehood of the fan running constantly? Any ideas?

    Am now led to understand that fitting humidistat controlled fans in the UK is not necessarily a good idea, since they don't appear to work very well.
  • 0
    Indeed we've had issues with humidistat controlled fans (greenwood CV2 GIP) NOT kicking on in the presence of huge humidity.... more than a few times. Greenwood could not explain this even with a returned fan?
  • 0
    Am now led to understand that fitting humidistat controlled fans in the UK is not necessarily a good idea

    Humidistats can work perfectly well in the UK - I used to have one in my old bathroom and it kicked in most reliably every time I had a shower (that was a stand-alone humidistat I think from RS - rather than anything built into a fan). In my 'new' house the ventilation system runs at a low level constantly but the main fan unit has a humidistat built in so to boost the speed - and again that seems to work perfectly well.


       - Andy.
  • 0
    AJJewsbury:

    In my 'new' house the ventilation system runs at a low level constantly but the main fan unit has a humidistat built in so to boost the speed 


       - Andy.




    I had a chat with an EPC assessor who came to a flat to do a new EPC taking account of the upgrades I made earlier this year to the lighting, space and water heating.


    The EPC guy says you can gain points on a SAP for constant ventilation, but lose around ten points on the EPC. 

     


  • 0
    Over ten years ago I fitted a humidistat controlled fan in a shower room and ended up cutting the wiring in it to make it a manually operated fan, since then I have never suggested fitting one to a customer and only fit them if the customer supplies the fan and controller.


    Fans that run constantly have a place in some schemes, but most home owners and tenants don’t like them.
  • 0
    AJJewsbury:
    Am now led to understand that fitting humidistat controlled fans in the UK is not necessarily a good idea

    Humidistats can work perfectly well in the UK - I used to have one in my old bathroom and it kicked in most reliably every time I had a shower (that was a stand-alone humidistat I think from RS - rather than anything built into a fan). In my 'new' house the ventilation system runs at a low level constantly but the main fan unit has a humidistat built in so to boost the speed - and again that seems to work perfectly well.


       - Andy.


    I have a Vent Axia100mm "through the wall" fan, with humidistat switching from trickle to boost, and like Andy's mine works fine.


    regards,

    burn


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