I have problems with my vented c/h system making banging noises in the boiler and pumping over into the f/e tank.

The system is about 12 years old with TRVs on all but 2 rads. The Myson Orion Fanfare boiler was moved and extra rads added just over a year ago.

About 20 mins or so after it first comes on in the morning there is a rumbling/banging/rattling noise in the boiler for a few seconds and the system pumps over. Often it is then fine for the rest of the day, but sometimes it will repeat it later on. Occassionally it has done it repeatedly for 5-10 mins! At the point the rumbling/banging starts the sound of the water going round the rads dies down for a second and then surges (causing the pumping over) before going back to its normal speed.

I initially thought it was the pump as it was noisy and did jam once so I changed that, however it has not solved the problem. It's 3 speed and is currently set on 2. I tried turning it down to 1 (as is often suggested to stop pumping over) but this made it worse.  Unfortunately, running it on speed 2 makes the water circulating round the rads quite noisy!

I also had problems the other day with the f/e tank overflowing and pulling in fresh water at the same time so I've temporarily got the cold feed to the tank turned off. What level of water should there be in the tank? Mine was about 2/3 full with the end of the overflow dipping down below the surface, although there was no leak from the cold feed. With the cold feed off and rads bled, the level is remaining at just below halfway but I obviously need to set a level and get the supply turned back on.
I realise the pumping over is not good for the system and needs fixing as it will be causing corrosion, so what are the likely causes? Searching various forums etc. suggestions seem to be:

• faulty pump? - well it's been replaced and I've checked the electrics to make sure its not cutting out
• pump too fast? - it's worse when turned down
• bad design? - it used to be ok!
• f/e tank level too high? - it's still happening with the level reduced and again it used to be ok!
• a blockage? - possible, but all rads get hot (very hot!) so I think this is unlikely
• faulty boiler thermostat? - I currently think this may be the most likely cause (especially with the very hot rads?) Is there a simple check/test I can do to confirm this before calling out a Corgi to fix it, bearing in mind the fault is intermittent?

Thanks in advance for any help/advice……..

Thanks for the reply but I recently changed the pump and this didn't fix the problem.

One suggestion has been to drain it all down and refill in case there is an air lock in there somewhere. Is that likely and would draining/refilling be worthwhile?

Thanks.....

you say the boiler was moved, has the pump been moved too?  did the problem begin straight after the boiler was moved?

There are 2 motorised valves (HW & CH) which control the pump and I did manage to confirm that there was still a supply (simply with a voltage tester screwdriver) when the banging occurred and also it didn't sound like the pump was stopping! I'll try and check again, but with it being an intermittent problem it of course hasn't gone wrong today!!!

The boiler was moved over a year ago but the pump was not. There was the odd bang after the move but this was put down to air in the system and it seemed to settle down until recently. The move was done by pro's so I can only assume it was all done correctly!!

Today we turned the boiler thermostat right down to 1 and the rads are still too hot to touch so surely the boiler stat must be faulty. Do you agree? And would this cause the symptoms described?

Thanks again to you all for the help............

Turn the stat up, does the boiler come on  ???, trn the stat down does it go off  ???

Probably ok then.

You have two motorized valves how are they connected and where, also do you have an auto by-pass valve and where is it in relation to the pump.

scruff

Not sure where Scruff is today - This bypass he mentioned is to allow the pump to circulate water when both valves are shut and the pump over run is operating. So you would normally find a 15mm pipe connected to the flow pipe leaving the pump (before it gets to the valves) and connecting to the boiler return pipe it will also have a valve of some sort either auto or manual to regulate the amount of water that can pass along the bypass.

David.
______

Ah - Alive & well in the smoke I see

There is no by-pass as there were no TRVs originally. There are however still a couple of rads without TRVs.

So anyway, surely red hot rads with the boiler stat on 1 suggests the stat is faulty doesn't it? If so, how much roughly?

Incidentally what would you suggest is the lifespan for a Myson Orion Fanfare boiler?

Thanks....

What model number orion fanfare is it  ???

Oggy wrote;

"What level of water should there be in the tank? Mine was about 2/3 full with the end of the overflow dipping down below the surface"

Do you think that having the overflow pipe dipping into the water in the tank may cause a problem? As the heating cools water will be drawn up the overflow pipe and may be causing some sort of air lock which clears when the heating gets up to a certain temperature?

Just a thought  ???

Keith

Thanks BTK,

Ah well, would have been a good idea if I hadn't got my overflow mixed up with the expansion pipe

Thanks for the help guys, I'll investigate further soon.....