Mains fan with SELV humidity sensor

[mottlefeeder]

My bathroom needs more air changes per hour than an SELV fan can provide, and I want to use a humidity controller since we dry clothes over the bath when not showering in it. What I want to do is to use a humidity sensor on the wall above the bath, and a loft-mounted in-duct mains-powered fan.

SELV humidity sensors are readily available, as are mains powered fans. Common sense suggests that there should not be a problem in using an SELV transducer-switched SELV supply to control a relay (in the loft) that controls the fan.

I cannot find anyone who makes an interface from SELV to mains, and although I am competent to make one, I am not sure what hoops I would have to jump through to get a local electrician to certify that the system complies with the codes.

Can anyone help, with a supplier's name, or guidance on how to proceed.

 

[stem]

Try these people, they might be able to help you. They make humidity sensors for refrigeration equipment that require SELV for control switching mains voltages.

www.vigevano.net/tecnologic/emagentb.html

 

[BJS_Spark]

Try here SELV fans with optional humidity controller built in??
http://www.vent-axia.com/sharing/condensation-selv.asp

 

[mottlefeeder]

Stem, - Thanks, I have e-mailed them for info.

BJS_Spark - SELV fans do not shift enough air - it has to be mains.

An alternative option might be to use an SELV fan for clothes drying with SELV humidity control, and a separately switched mains fan for showering duties. That would mean fitting two fans in parallel in the loft ducting - but it might be easier than trying to get an electrician to certify something he/she has never seen before. Any thoughts on that?

 

[stem]

If you can obtain a proprietary packaged item to do the interfacing then it will have to conform to certain standards such as ISO, BS, CE or the like and be marked as such before it can be sold. The responsibility for safety of the product is down to the manufacturer in a similar manner for example as an electric shower. storage heater or fan etc., The installation of the appliance is the installers responsibility.

However, if it's something you've put together I imagine you might have a problem.

 

[mottlefeeder]

If you can obtain a proprietary packaged item to do the interfacing then it will have to conform to certain standards such as ISO, BS, CE or the like and be marked as such before it can be sold. The responsibility for safety of the product is down to the manufacturer in a similar manner for example as an electric shower. storage heater or fan etc., The installation of the appliance is the installers responsibility.

However, if it's something you've put together I imagine you might have a problem.

That suggests that if I take responsibility as the manufacturer, the installer can simply identify it as a black box which has passed his/her insulation tests. That could be in interesting discussion.

BTW I checked your link's UK distibuter, and they agreed with the design concept, but were unable to help with a ready-built module.

 

[fantronix]

As far as I am aware there aren't any fans bigger than 4" with SELV motors.

I would scrap the whole idea of 12v motors. Go for a fan (min IPx4) and wire with an RCD, this way you get the fan you want and comply with new 17th Edition IEE wiring regs.

 

[holmslaw]

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