Central heating bangs.

[Givemeaclue]

Hope someone can help here,

I have a apollo 50B boiler, the problem i have is after approximately 30 - 60 minutes the central heating pipe's bang like crazy as if somebody is hammering the floor upstairs, now im pretty sure this is due to steam from the boiler as everytime it happens the pump has shut off.

I have fitted a new pump and this hasn't solved the problem, the pump continues to run when the heating is knocked off so i am assuming the pump overrun stat is ok.

Has anybody ever come accross this problem before? is it likely to be the overheat cut off device on the boiler that shuts of the pump hense causing the stationary water in the boiler heat exchanger to boil?

or would one of the hi/lo thermostats on the feed pipes cause the pump to stop?

after approximately 30 seconds the pump fires back up and all is back to normal unitil it happens again.

Any idea's solutions would be great , Thanks.

 

[kevplumb]

is the pump wired to the boiler

 

[Givemeaclue]

Im not sure kevplumb the pump, 3 way diverter valve and hot DHW stat are all wired to a central junction box in the airing cupboard i assume that it must be linked to the timer/controller and the boiler?

Any more idea's

 

[D_Hailsham]

is the pump wired to the boiler

I hope so! The boiler has pump overrun.

The overrun thermostat may be knackered.

 

[heatingman]

does it only do it on high setting, or low as well.

 

[kevplumb]

is the pump wired to the boiler

I hope so! The boiler has pump overrun.

The overrun thermostat may be knackered.

which was why i asked

 

[namsag]

If your saying pump stops and loses power.
Common fault with apollos .
Manufacturers part number 402S088 pump over run stat

 

[Givemeaclue]

Brilliant thanks for the replys,

I'll get a new overrun stat fitted and let you know if it solves it.

Thanks

 

[Givemeaclue]

does it only do it on high setting, or low as well.

seems to do it on both setting, but when on High the radiators get so hot you cannot touch them, and the noise made i can only explain as a child going pew pew pew as if playing with toy guns ( if you can get what i mean)