Thermal store system boiler pump carries on running

[mcaw]

I have an Albion thermal store system, with 2 pumps ( boiler and ch ). This was in house when we bought it.
I have been using it with the hw and ch switching on twice a day, but was advised that it was better with a thermal store to have the HW on all day, keeping the thermal store at optimal temp. This is now how I run it.

The problem I have is that the boiler pump keeps running after the store is up to temp. So the water is being circulated around the boiler system, but the boiler isn't firing. I think this could be for a couple of reasons.

Problem with boiler overrun keeping pump running for longer than it should.

Or could it be that the tank stat is duff, so it thinks the water isn't at temp, and keeps the pump and boiler running. The boiler however doesn't fire because the water is at temp.

Can anybody confirm my reasoning, and maybe help with any other possible causes.

Thanks Martin

 

[Gray0689]

This is ment to happen when thermal store gets to hot it turns pump on to dump heat in to rads there will be a stat on somewhere controlling this or a pipe stat on the return

 

[mcaw]

The CH pump isn't running, so it's not sending anything through the rads.
The cylinder stat controls the thermal store temp, are you saying this is not working, this was one of my assumptions.

 

[Gray0689]

Then sounds like faulty stat on cylinder
Sounds like it's running on boiler stat boiler will not fire but pump will still run

 

[stevetheplumber]

ive got a gledhill thermal store which i aquired and fitted to my existing system boiler gledhils said it couldnt be done and would only recomend i changed to a normal boiler with no built in pump
im assuming from your description you now have three pumps in the sytem?
my solution was to disconnect all the wiring on the thermal store and remove the gledill pump that conects to boiler i then used the cyl stat to control the boiler
at first it took a while to get hot water on cold mornings so i set hw to come on 15 mins before heating and we get no problems now
unfortunatly in these over regulated days wher we can only do what it says in the rules and regs any adaptation is only something you can do for your self

 

[mcaw]

Sorry also forgot to mention, the pump keeps running without the boiler firing for hours. In fact it never shuts off as far as I can tell. This can't be normal

 

[Gray0689]

Sorry also forgot to mention, the pump keeps running without the boiler firing for hours. In fact it never shuts off as far as I can tell. This can't be normal

No it's not you need someone to take a look at it I'm afraid

 

[mcaw]

No I only have 2 pumps.
The HW pump is controlled by the Cyl stat, and also the overrun stat in the boiler.
The CH pump is controlled by the room stat.
As the HW pump seems to run constantly I assume the overrun isn't switching off, or the cycl stat is not switching off.
SO I think the cyl stat should be the first port of call. Time to get the multimeter out.

 

[RoryD]

Please try to keep it simple and we can help you mate.

 

[buckley plumb]

what make of boiler is it. all i can think is if its a system boiler the pump over run will keep the pump going even if the store has reached temp as the boiler is trying to dump the heat in the boiler by the pump over run but is pumping the hot water from the store to the boiler so the temp sensor in the boiler is thinking the boiler is still hot.some boilers allow the pump over run time to be changed in the engineers mode

ant

 

[mcaw]

Okay it's definately the tank thermostat. It's only switching HW pump off at around 30deg no matter how hot the cylinder is, so seems to be stuck at this temp. Manually turning stat down to 30 switches off the pump,and system behaves as it should when at nominal temp.
The problem I have is it's a pocket thermostat and I cant release the brass screw that holds it once it's pushed into the pocket, so I can't get pull the thermostat out of the pocket to replace it. I don't want to knacker it, so any tips on releasing a brass screw in a brass fitting ?

 

[Gray0689]

Drill it out

 

[buckley plumb]

just looked back to begining of posts and its not a system boiler so would agree with the others its the cyl stat . pull wires off stat to see if pump stops

ant