heating problem pump???

[unluckymichael]

Can someone please help x before i blow a gasket ) . When i turn my central heating on it runs for appx 10 minutes, then turns off without the rad's getting warm at all. On watching the pump upstairs, I have noticed that the pump stops working after appx 8 minutes then the boiler stops working. If i try to restart it, it dosent start straight away, but if i leave it about 15 minutes then restart it, the boiler lights but the pump dosent start so the boiler shuts off after appx 5 minutes. I have replaced the thermister and the PCB, but its still the same. I have tried calling plumbers in my area but they cannot come for a few weeks and i am freezing my feet off here!

PLEASE HELP

 

[crockett]

Sounds like a possible airlock in your primary somewhere. Have you done any work involving a drain down in recent days ?

 

[unluckymichael]

No, ive not done any drain work, But the heater was last used in march.
Thanks for your fast reply though

 

[jackecole]

is your system opne vented? and do you also have a hot water cylinder?

 

[crockett]

You may still have air in your system though. Have you a bleed valve near your pump ? If so, open it up to see whether any air comes out. Also, the bleed screw in the pump ( if a grundfos, the chrome slotted screw ) could be given a go as well.

 

[unluckymichael]

Thanks for both of your help, a plumber over the phone has just told me to put a circuit tester on the pump and turn the heating on, which i did, the pump ran for appx 5 minutes then stopped, but i was still getting power at the pump, yet it wasnt working. Does this confirm the pump is broken?

Thanks again for your replies

 

[Gasburner]

Sounds like it's the pump failing to me, I have seen this a couple of times (both Grundfos 15/60 models) were the pump stops after running for a few minutes then after it cools down it starts again, check to see if the power is still supplied to the pump when it stops.

 

[unluckymichael]

When the pump stops, there still is power there.

 

[crockett]

When the pump runs, does it run smoothly, or is it grinding or making any noises ?

 

[unluckymichael]

The pump runs smoothly

 

[crockett]

Doesn't seem like a pump issue, although I may be wrong always hard to diagnose by description

 

[namsag]

Simple if system is full of water and the pump stops and you are still getting 240v at it and its not running then it needs a new pump

 

[jackecole]

how would the OP know if the pump had 240 volts going to it for sure - the terminal block also has L from the boiler in it which could be giving a false reading?..

 

[seco services]

how would it give a false reading ?
if theirs live at the pump and it fails to turn.

 

[jackecole]

i mean if the OP takes the reading with the boiler live also in the terminal. as the pump will give a live reading but may not be actually live at all.