Call for hot water not activating boiler.

[warrenanderson]

Hi,

Our hot water system is not working. I've a Potterton suprima 40 boiler, Drayton LP522 programme unit, 2 x Apcom WH9 thermostats on the hot water tank and a drayton actuator. I recently replaced the pcb on the boiler has i had the common lock out problem. This cured that issue, the new issue i have is that the thermostat is calling for heat but not activating the boiler. I've checked the stat and it's working perfectly. Am i correct in assuming that the call for heat first activates the actuator which in turn calls the programmer to fire up the boiler and allow it to open the HW valve inside the boiler?. I've also replaced the program unit & the wall plate for it.

Any help would be greatly appreciated.....

 

[gas4you]

Not quite. The drayton valve when open, sends the 230V current to the boiler to fire up, no hot water valve in the boiler.

Boiler does not know whether it is heating HW or CH.

Change the Drayton actuator

 

[Agile]

The motor valve contains a switch which puts a live on the orange wire when its open. That is connected to the boiler to give the call for heat.

Either the motor is failing to open the valve or the switch is not being actuated and will require a new valve head if they are available.

Tony

 

[warrenanderson]

thanks... i had a feeling it was the actuator but couldn't figure out how to test it. It works ok with the CH though would that be right enough?.

Also, may seem a real silly question, but the system doesn't need the CH on to run the HW does is?. they should both work independently?.

 

[gas4you]

heating and HW should be totally independant

 

[warrenanderson]

Thanks Dave,

Would the actuator be faulty considering it works ok with the CH?.

Cheers

 

[Agile]

I have told you that its faulty!

Some primitive systems are unable to run CH without HW.

Tony

 

[warrenanderson]

New Actuator fitted..but still nothing... thermostat is clicking but no call is being generated... any more ideas??

 

[gas4you]

Just re-reading your post, why have you 2 cylinder thermostats? Is this some fancy system that the top stat just boosts the hw cylinder for a short while if you run out of hw during the day?

Not one of these systems that have the heating controls and alarm system all wired together via a main wiring centre is it?

 

[warrenanderson]

Hi Dave,

The bottom thermostat is linked to the Electric Immersion heater, the top one is linked to the Boiler system. I'm looking at the wiring diagrams to see how i can test for call at the boiler side. I've almost replaced half the system.. perhaps should have just called a sparky..