CH problem and fault finding

[PeteHeaton]

Hi Guys,

I'm not a plumber so I hope I'm ok posting here for some advice. I've got a fairly common set up that is unvented indirectly heated. This comprises:
-Worcester Greenstar Ri boiler
-Drayton Lifestyle LP522 controller
-Centercyl HE 120 cyclinder
-Sunvic Digital room thermostat
-Siemens 3PMP-V22 mid way valve
This was all newly installed last year but has never worked 100%.


The problem is that although the CH and HW initially come on together on the timer after a while (say an hour) the CH cools down. At this stage the room thermostat will still have the little flame icon saying it is calling for CH but nothing is happening.

I've done a bit of fault finding:

-If the CH and HW have been on in the evening (cyclinder is full of hot water and room thermostat is calling) switching between CH and HW timed and on makes no difference: CH remains cold.

-If the cyclinder thermostat is turned down and the CH switched to timed or on the CH remains cold.

-If the CH is on timed or on and the HW is turned off (either at the off setting or via the timer) the CH heating kicks in immediately.

What signal is sent out or cancelled when the HW is turned off which enables the CH to come on?

I had thought that perhaps the mid way valve was sticking but I have replaced both the mechanical and electrical sides.

Any suggestions on what to try or where the fault may lie? Am I looking at an electrical fault?

Thanks in advance. Pete

 

[wnjswozo]

electrical fault somewhere on the controls/stat

 

[weeman]

maybe on the satisfied on the cylinder stat

 

[ecowarm]

you probably have a wiring problem, I would start from scratch and re-wire

Eco

 

[Puddle]

maybe you do not have a satisfied connection on cylinder thermostat as said or cabling not connected,does sound like electrical fault

 

[PeteHeaton]

If there was no satisfied signal from the cyclinder thermostat would I get very hot water as the boiler is continually heating the HW with no off signal. I ask as that isn't the case.

 

[Stuthewarrior]

change the tank stat

 

[PeteHeaton]

Thanks for all your replies. As the cyclinder thermostat wasn't replaced I'll change that over this weekend and see what happens.