There are two temperature sensing "pockets" on my 300L Worcester-Bosch Greenstore unvented cylinder. The installer fitted the CS92 tank stat sensor in the top one (which is about 1/3 down from the top) and the W-B temperature limiting stat in the bottom one (about 1/3 up from the bottom. I haven't challenged the installer yet but I can't believe that this is correct because the tank stat is only controlling the temperature of the top 1/3 of the water ... or have I got an unknown unknown?
Evohome DHW temperature sensing with CS92
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Originally posted by DorrisMancer View PostThere are two temperature sensing "pockets" on my 300L Worcester-Bosch Greenstore unvented cylinder. The installer fitted the CS92 tank stat sensor in the top one (which is about 1/3 down from the top) and the W-B temperature limiting stat in the bottom one (about 1/3 up from the bottom. I haven't challenged the installer yet but I can't believe that this is correct because the tank stat is only controlling the temperature of the top 1/3 of the water ... or have I got an unknown unknown?
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A bit late to reply to this as I have just had a new install with same cylinder - from the Worcester manual, page 10;
I have a similar issue - but my electrician stuck CS92 to bottom sensor pocket and did not connect the high limiter sensor at all. So I'm now restrospectively fitting.
I'm wondering - did you manage to put both sensors into the same pocket at the bottom ?
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Originally posted by ojock View PostA bit late to reply to this as I have just had a new install with same cylinder - from the Worcester manual, page 10;
I have a similar issue - but my electrician stuck CS92 to bottom sensor pocket and did not connect the high limiter sensor at all. So I'm now restrospectively fitting.
I'm wondering - did you manage to put both sensors into the same pocket at the bottom ?
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You can buy tiny 10k NTC thermistors which are much easier to fit into the pocket.
I use one of these: https://www.ebay.co.uk/itm/122775246996
It's about the same size as a match head, and works perfectly with the CS92.
P.Last edited by paulockenden; 12 July 2018, 09:48 AM.
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Originally posted by ojock View PostThanks all for replies.
The top pocket suggestion sounds easiest, but I heard the reading might be out and limiter could set off too soon?
Although I'm guessing there's probably not much in it.
On the other hand the top pocket should be OK for a safety cutout that is not normally triggered, as the top pocket will always give the highest temperature reading of the two locations.
If the system starts heating well beyond the desired temperature convection in the cylinder during the heating will cause the temperature at the top of the cylinder to be as hot as the temperature further down thus still triggering the safety cutout. (Water coming out the draw off pipe at the top can't be any hotter than what the top sensor is detecting anyway)
So - CS92 always in the bottom pocket and safety cutout/limit sensor in the top pocket if it won't fit in the bottom pocket.Last edited by DBMandrake; 14 July 2018, 08:21 AM.
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Originally posted by mtmcgavock View PostI usually manage to get both sensors in the pocket. The easiest way is usually removing the front of your dual stat and threading it through the centre when the two probes go and thread the wire through the wire hole. Sometimes you can be lucky and the stat have two sections for two wires to come through.
thumbnail.jpgLast edited by ojock; 31 July 2018, 07:51 AM.
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