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Gas heater thermostat replacement

Posted: 29 Apr 2015, 11:50
by jameshear
I think my gas heater thermostat has gone pop (its never worked since I bought the van) - and I need a new one. Its in a Holdsworth conversion, and I am hot sure of the make of heater (its a box under the van), but the thermostat doesn't click on anymore. I'd like to source a replacement, can anyone recommend where?

Re: Gas heater thermostat replacement

Posted: 29 Apr 2015, 13:16
by lloydy
What sort of stat is it? like this?
http://www.propexheatsource.co.uk/heate ... thermostat" onclick="window.open(this.href);return false;

Any household room stat will work as long as it has volt free contacts. Like the honeywell one
http://www.amazon.co.uk/Honeywell-T6360 ... B003CYTG60" onclick="window.open(this.href);return false;

or a digital one (I'd probably get this one)
https://www.plumbnation.co.uk/site/hone ... hermostat/" onclick="window.open(this.href);return false;

Re: Gas heater thermostat replacement

Posted: 29 Apr 2015, 17:40
by nicq
lloydy wrote:What sort of stat is it? like this?
http://www.propexheatsource.co.uk/heate ... thermostat" onclick="window.open(this.href);return false;

Any household room stat will work as long as it has volt free contacts. Like the honeywell one
http://www.amazon.co.uk/Honeywell-T6360 ... B003CYTG60" onclick="window.open(this.href);return false;

or a digital one (I'd probably get this one)
https://www.plumbnation.co.uk/site/hone ... hermostat/" onclick="window.open(this.href);return false;

The proper stats run the fan after the burner stops, a standard stat won't.
There are 2 propex stats according to the model of heater.

Re: Gas heater thermostat replacement

Posted: 29 Apr 2015, 17:46
by lloydy
i linked those last two as i know people have used them with a propex. I fitted the 1st one when i had a propex (old one broke) i was quite underwhelmed by it to be honest. Massive hot/cold cycles, i reckon it would drop 4-5c before it kicked back in. As for the fan over-run, does that not come from the pcb inside the propex itself? pretty sure my propex had a permanent 12v supply, then a switched live from the stat? long time ago though, so could be remembering wrong..

Re: Gas heater thermostat replacement

Posted: 29 Apr 2015, 18:14
by nicq
Mine is in the stat, it has a chip in which I think is a timer.
No doubt oldybutgoody will confirm that.

Re: Gas heater thermostat replacement

Posted: 29 Apr 2015, 18:35
by Oldiebut goodie
Stats can usually be adjusted if mechanical ones to cut down the lag. See this https://club8090.co.uk/forum/viewtopic.p ... t#p7867444
As far as I know the run on is governed by the pcb on the Propex. ( I have a remembrance that this can be adjusted also via a trimmer pot on the pcb)

Re: Gas heater thermostat replacement

Posted: 30 Apr 2015, 07:54
by ghost123uk
The "hysteresis" (delay between too cold to too hot) can be adjusted by a trimmer pot inside the standard Propex stat unit. I now have mine to a perfectly acceptable setting.

The cool down cycle is controlled by a sensor inside the main Propex heater unit (as it measures it's temp to a point cool enough to turn the fan off). Early units had a temp sensor that could turn the unit on to it's cool down cycle on a hot summers day :shock: . They later changed it to a 50 degree C item.

An after market stat (like that Honeywell one linked to above) could be a perfectly acceptable solution.

Propex are VERY good folk to deal with by the way (and they might be able to sell you a "real" one).

Re: Gas heater thermostat replacement

Posted: 30 Apr 2015, 08:09
by jameshear
Hi guys,

Thanks for all your comments so far. Here is a what it currently looks like:

Image

I'm not sure if that's a Propex or not, but I do notice it has an "on/off" switch which I assume is required. Also - stupid question, wouldn't the switch need to be 12v?

Thanks in advance