Cylinder Stat problem !

[steved101]

Hi

I was about to fit a frost stat and now have a problem with my cylinder stat!

for some reason it is not heating up the water in the cylinder. the programmer is on and the heating works fine as normal.

i was presuming the cylinder stat was stuck and not claling for heat. but am a little confused now after reading the honewelluk.com wiring guide website.

it said - assume the cylinder stat is faulty only is terminal c (common) is not live when calling for hot water. - now i have used a multi meter before and can do so again, BUT I thought that the Common (C) terminal would be live and the number 1 (CALL) terminal, which is also in the same terminal block as the orange from the 3 port and the s/live from the pump and boiler, would NOT be live (thus the stat sticking in the closed/satisfied position) - can anyone please clarify this so I guarantee my cylinder stat is faulty, before buying and fitting a new one?

Thanks in advance all.

 

[seco services]

check if the stat has power going into it from the programmer.
then check if their is power on the wire in the same connection as the orange.

 

[steved101]

seco - thats what i understand and how to do it, but the website said do not expect a faulty cylinder stat unless the common (C) terminal/from the programmer is not live when hot water is being called for. which doesn'tmake sense does it? if the common (C) terminal was not live when HW was being called for then i would suspect a faulty programmer!?? i have done what you suggested and what i already knew, and there was no power to it - so the stat IS stuck and not calling. new stat time....!

 

[swbjackson]

Which plan have you got? You are quoting from the fault finding for an S plan.

Mike

 

[steved101]

no i hae a Y PLAN system - thats why i am quoting what i am - the common termianl is powered from the prog. and then the call termianl is powered when the hot water is calling from heat.



sorry i am and i got it wrong - i was looking at an s plan!!! so sorry. the c termianl should be common for both plans anyway IMO!!!!!!!! the wire to the motor (brown wire) in a S PLAN is the C wire for some reason with an s plan !!

 

[swbjackson]

You want page fourteen

Cylinder Stat
First of all, make sure you have wired to the correct
terminals.
Terminal C (common) is the Left Hand terminal.
Terminal 1 is the Middle terminal.
Terminal 2 is the Right Hand terminal.
Suspect the cylinder thermostat is faulty only if
Terminal 1 does not become live when calling for
Hot Water, or Terminal 2 does not become live
when satisfied. (Make sure that Terminal C is live in
both cases). While checking, disconnect Terminals 1
and 2 to prevent false readings due to backfeed.

 

[seco services]

and there was no power to it - so the stat IS stuck and not calling. new stat time....!

if theirs no power to the stat then the programmers at fault.

 

[steved101]

sorry all i got it wrong - my fault i was looking at the wrong page!!! my apologies.

what is all this about removing wires to prevent backread signals though-never heard of that before?!

 

[seco services]

thought it was reading strange for a y plan.

 

[steved101]

can you please explain the need for removing wires 1 and 2 to avoid backread signals, as stated by swbjackson abve, is poss please?

 

[swbjackson]

what is all this about removing wires to prevent backread signals though-never heard of that before?!

If there's a call for heating at the time you are testing terminal 1 will be live even when the stat is satisfied. If there's fault with the programmer terminal 2 could be live.

 

[steved101]

why would the heating make the cylinder stat live?

 

[seco services]

cause the orange from the mot valve is in the same connector as the call for heat from term 1 of the cylinder stat

 

[swbjackson]

The boiler is fired by terminal 1 from the room stat or the orange wire from the 3 port which is live when the 3 port moves to the heating only position and actuates the end switch. These two are connected in the wring centre.

 

[steved101]

of course, yep the htg would make the orange wire live if the HTG was on ONLY on its own - thus the grey would also be live. - so if i just had HTG OFF at the programmer would I still get a chance of a backread signal ?