pump problem

[wilo2]

Hi
i have a thorn emi apollo 30 boiler about 18 years old.

Been having problems with banging noises, i have had a new valve, thermostat sensor, thermocouple in the boiler, also over the last year i have had a new cylinder, pump.

The problem iam having happens as follows......When the boiler switches on and fires up everything seems ok, then after about 4-5 mins the bioer starts to bang and make noises for about 5 secs before calming down and running as usual.

i have noticed that just before the noise happens there is a surge and the pump swithes off then the banging occurs. Sometimes the banging knocks out the pilot light sometimes it is ok.
after the banging noise the pump works as usual.

has anybody got any ideas of what can be happening and what i can do to put right.

Many Thanks

 

[EliteHeat]

Sounds like you may have a distinct lack of water in your system. Check that the F&E tank has water in it & the valve is working OK. If that's OK, try turning off the water and draining the system, if the F&E tank does not empty then you have a blocked cold feed - loads on here about that.

 

[bab]

You need to check the power supply to the pump to see if is stopping due to air or loss of voltage. The pump should have a supply all the time the boiler is firing & also when it shuts down for an over run. try running the pump on the next lower speed to rule out it sucking in air.

 

[wilo2]

thanks for that...could i t be the pump overun stat?

 

[bab]

The pump over run is to clear latent heat after the boiler has been shut down & if this happens soon after start up when the boiler is firing then the boiler should put power to the pump. If not its a fault with the boiler control unit .

 

[wilo2]

Thanks for that bab....

Have you got any ideas on what might be causing problem?

any help would be great

 

[ChrisR]

there is a surge

WHat do you mean by that?

and the pump swithes off

How do you know?

Are you sure of the order, surge(Air??), pump stops, boiler bangs.

COuld it be that the pump going off causes a noise which you're causing surge??

Thinking here: Usually a pump overrun stat supplies the pump from the common terminal of a changeover switch.
When the boiler is cool, power from the Switched Live input to the boiler goes through the POS to the pump.
When the boiler is hot enough, the POS switches Permanent Live to the pump.
If the contacts in the switch aren't clean, the pump stops while the contact is made. And the boiler bangs and overheats pdq.

 

[wilo2]

hi chris

sorry you could be right, i think the surge is happening beacuse of the pump being off.

what is my next step...sorry for seeming totaly thick about the subject, just trying to sort the problem out

 

[ChrisR]

Change the overrun stat!