Potterton Prima 60F Boiler banging!

[dazzystar]

Hi All,

I won't bother telling you the whole story but get straight to the point.

My boiler makes a series of loud bangs which I think are coming from the combustion chamber and after a few of these bangs cuts out.

Strange thing is that the boiler was on for about an hour then started this behavior, I let it cool down for about an hour and reset it but within a few minutes the bangs were back.

Any clues?

Cheers
Daz

 

[Razor900]

How hot is your pump, can you hear it working?

 

[dazzystar]

How hot is your pump, can you hear it working?

Didn't have time to go upstairs before the boiler banged again and cut out. It's almost as if someone turned the gas down and it was trying to ignite what was there. I could see the boiler casing move slightly as well!

The gas valve was replaced about a year ago if that helps.

 

[Agile]

We don't give gas/combustion advice here.

The obvious solution is to check what you can like the pump and isolation valves and any header tank.

Depending on the type of banging its usually a lack of water causing it to overheat.

Tony

 

[dazzystar]

We don't give gas/combustion advice here.

The obvious solution is to check what you can like the pump and isolation valves and any header tank.

Depending on the type of banging its usually a lack of water causing it to overheat.

Tony

Cheers Tony,

From your reply I guess you've ruled out a gas valve issue. The plumber who replaced my 2 x two zone valves did shut off some valves when draining the system, etc. Is there a chance they didn't turn on one of them enough?

He made mention that the balancing valve from the hot water tank was almost fully open and adjusted it.

 

[dazzystar]

This is probably quite important:

The boiler has been off for an hour yet I've just been upstairs and the pump is running and boiling hot!

Both zone valves are closed!

 

[Agile]

Something odd there.

In most old circuits the pump and boiler are powered by microswitches on the motor valves.

Modern boilers control the pump to provide over run after boiler use. Where is your pump connected to?

Tony

 

[dazzystar]

Something odd there.

In most old circuits the pump and boiler are powered by microswitches on the motor valves.

Modern boilers control the pump to provide over run after boiler use. Where is your pump connected to?

Tony

Pump connected to the boiler. Pump located upstairs with all the other bits including the junction box and programmer (which I've turned off to turn off the pump!)

 

[Agile]

You need to monitor the voltage applied to the pump.

Either its losing the voltage or the pump is sticking and not turning.

Have you bled water from the pump screw?

That's assuming this banging is due to lack of flow.

Tony

 

[dazzystar]

Hi Tony,

Can you advise a suitable contact number for you as I think I need to book you!

Cheers
Daz

 

[steve32]

Hi Tony,

Can you advise a suitable contact number for you as I think I need to book you!

Cheers
Daz

Click on his name and contact details may be in his profile

 

[McCombi]

Plumber has maybe closed bypass when replacing the 2 2 port valves.

If the pump is wired to the boiler and bouler set for fully pumped, the system needs a bypass before the 2 port valves, or the heat will have nowhere to go to when pump overrun is active after a boiler demand.

 

[McCombi]

Also worth noting that the pump is controlled by a pump over run thermostat in the boiler, it senses the temperature in the boiler, if system is still too hot and pump over run is on, turning off the programmer shouldn't turn pump off, it sounds like the boiler isn't wired correctly, and possibly doesn't have a permanent live and is working off a switched live instead.

 

[dazzystar]

The boiler stat is at 0 and I turned on the power to the programmer and the pump started to run. No changes to the boilers wiring has been made at all.

Any idea as to what can cause the pump to be on all the time? The bypass valve is fully open by the way.

Cheers

 

[McCombi]

The boiler stat is at 0 and I turned on the power to the programmer and the pump started to run. No changes to the boilers wiring has been made at all.

Any idea as to what can cause the pump to be on all the time? The bypass valve is fully open by the way.

Cheers

The pump should run if pump over run thermostat senses 80degrees or more.

May be worth checking that it is wired correctly though.
In wiring centre inside boiler, below control kn
Should have the pump connected to pump terminals
A permanent live connected to L
And switched lives from the 2 ports connected to swl
And also the neutrals and earth as designated terminals