Help -CH but no HW- boiler thermostat or programmer wiring?

[AndyE]

Any ideas about the following problem:

We have a gravity-fed HW system and pumped CH, with a Glow-worm conventional boiler (model 60B).

When we had the kitchen redone we replaced the old electromechanical controller with a Lifestyle 522 programmer.

Now we only get hot water if the heating is on - not ideal at the moment

There are no cylinder or room thermostats, in addition the pump is probably buried inside some false panelling which has been tiled over (not by us!)

When we turn on the HW at the programmer, the boiler fires up for about 30 seconds then goes off. It sporadically restarts every 20 mins or so but then goes back off.

With CH and HW turned on then the boiler stays on constantly.

Investigating with the multimeter shows that the programmer is supplying the boiler correctly, and that the boiler thermostat is receiving power and operating the gas supply properly when first fired, but for some reason is shutting the gas off when HW is on, but not when CH is on.

The controller appears to be wired correctly, but as I can't get to the pump it's difficult to verify this.

Any thoughts?





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[breezer]

since it used to work before? and you have changed the controller it would indicate that the controller is wired wrong.

Why not get to the pump now before you HAVE to get to the pump

 

[ChrisR]

Too hot to think this one through but: check on the back of the programmer for a small switch marked something like 10/16 or gravity/pumped.
It should be in the 10 or Gravity position.

Do you have a motorised valve? (Brass bodied thing with a metal or plastic box on top about 5 inches long.)

 

[AndyE]

Thank you both for the suggestions/comments.

Checked the wiring for the controller and that's as it should be, it's also on the 'gravity' setting.

There are no signs of a motorised valve anywhere, nor any wiring for one.


Trying to apply some logic here, if the system functions correctly with CH&HW on, but the thermostat is cutting the gas with HW only on, then perhaps the thermostat is reading either incorrectly or from the wrong place.

One thought that strikes me is that when the kitchen was redone the installers must have removed the boiler cover to have done some of the work, I wonder if they moved/damaged the boiler thermostat 'probe' in some way?

 

[COG]

From what you have said the only diff between ch and dhw is the pump is on with ch, so may be your kitchen fitters disturbed your pipework and you have a plane old airlock?.when the pump is on it will keep the primary temp down giving a steady flow to your circs, check they have,nt moved the flow and return to the cyl even by a fraction. Did they move a rad?