reversing a thermostat

[Phillcbr400]

Is it possible to reverse the switching on a normal 230v AC thermostat, the spec is for an extraction fan to kick in when the heat builds up. I know that I could use a relay to reverse the normally open and closed sequence but something out of the box would be better.
Thanks
Phill

 

[Marvo]

If the thermostat has a changeover contact then you can configure it to be either make or break on temperature rise by swapping between the NO and NC contact for your switched live out.

 

[Phillcbr400]

Cheers marvo, I knew there must be something on the market with the option to reverse the switching. Have you got any recommendations? This doesn't need to be pretty or fancy just functional.

 

[Geordie Spark]

Most normal / standard central heating room thermostats have 3 terminals: Common, N/C and N/O

Have a look at Danfoss, Honeywell, Sunvic .......... the list is endless - just make sure that whatever you decide on has those three terminals.

 

[Marvo]

You'll need to give more details, you say it's an extraction fan, what kilowatt rating is it, is it commercial or domestic or industrial? Do you need it to be customer adjustable or preset. How and where do you want to mount the thermostat? Do you need an adjustable differential (hysteresis)?

 

[Geordie Spark]

You'll need to give more details, you say it's an extraction fan, what kilowatt rating is it, is it commercial or domestic or industrial? Do you need it to be customer adjustable or preset. How and where do you want to mount the thermostat? Do you need an adjustable differential (hysteresis)?

Hey you!!! ............... stop showing off !!

 

[guest119]

Aye, and make sure the 3rd terminal is not a neutral.
It should say.......changeover on the box or,..... spdt.(single pole double throw).
Use the common for the supply and eg L1 for cooling and L2 for heating. (or 2 stats with a normal one set for heating and a changeover one for cooling)

Boydy

 

[pennywise]

Sunvic ones are built like tanks!

 

[Marvo]

Hey you!!! ............... stop showing off !!

:smartass: :tongue3:

I forgot to ask if he needs humidity sensing as well

 

[Geordie Spark]

Sunvic ones are built like tanks!

I know!! ........... They last forever.

 

[Phillcbr400]

Cheers lads i have managed to find what I want through plumbers merchants instead of our normal supplier,
Marvo this is for my own house, fan is a massive 17watt, thermostat mounted on surface back box.
The purpose is to ventilate a cupboard kitted out with pc gear. So the thermostat will be set at 25.c I doubt it will be on much anyway so hysteresis shouldn't really be a massive problem.
Thanks

 

[Geordie Spark]

Cheers lads i have managed to find what I want through plumbers merchants instead of our normal supplier,
Marvo this is for my own house, fan is a massive 17watt, thermostat mounted on surface back box.
The purpose is to ventilate a cupboard kitted out with pc gear. So the thermostat will be set at 25.c I doubt it will be on much anyway so hysteresis shouldn't really be a massive problem.
Thanks

Aye .... right !! :gettree::sifone:

 

[Marvo]

Oooh, 17watts is quite a load.

Maybe one of these would work for your hydroponics....I mean computer cooling. Simple, cheap and it's got a SPDT switch contact.

 

[Phillcbr400]

That will do the trick, cheers marvo, got to love the angry reviews on diy sites

 

[Marvo]

I didn't see the review, for some reason their buggy website logged me in under someone else's name so I got out of there as soon as possible. I wouldn't worry about it though, it should handle every single one of the seventeen watts of power without too much problem.