Serious banging and cool radiators.

ddahaa · 30 Jan 2005

Hi everyone, I hope someone can help me.

We had a leak in the summer from a ruptured joint in a pipe feeding the radiators in the living room, and since then neither of these radiators has heated up very well, though one more than the other. I\\\'ve got hot water at the input valve, drained the radiator and have water flowing back into the radiator from the exit valve, so no apparant blockages.

Over the last 2 days, the boiler has started banging madly (Pump is mounted on top of it), water is very hot, so I replaced the temp sensor thing on the hot water tank, but to no effect. It\\\'s as if the boiler is boiling the water so the pump is then trying to push bubbles around. Banging stops as soon as boiler stops heating.

Have I got a blockage causing all my problems. Any idea on what to do next? When I drained the radiator previously, the water was very black.

Thanks for any help that anyone can offer!!

Plumber Will · 30 Jan 2005

What boiler do you have?...Have you bled the system? Go to search on this forum and type bleed..bled.

ddahaa · 30 Jan 2005

Forgot to say, Boiler is a Myson Apollo 40B (just checked) radiators have been bled, and also bleed valve at input to hot water tank has been done. It's strange that this banging just started in the last 2 days.

All the other radiators are really hot. The boiler also has a thermostat switch on the front panel for low/high. Just tried switching it to low and it seems to have stopped the banging. Pump is just running without the boiler firing up, which is what it seemed to need as the water is already red hot.

Thanks for the quick reply. Do you think I should try and flush the whole system out, and where do I start?

Plumber Will · 30 Jan 2005

Is it only one radiator the fails to get heat to it?

ddahaa · 30 Jan 2005

Downstairs has 3 radiators, one is red hot, one gets warm after a bit, other gets a very small amount of heat after a while. Upstairs has 4 radiators, all red hot. Radiator problem has been there for a while, but banging only started on friday. Radiators and hot water appear to be hotter since the banging started.

Really appreciate the quick replies and help.

ddahaa · 30 Jan 2005

House is approx 12/13 years old, so thats how long everything has been in I think.

Plumber Will · 30 Jan 2005

feel the pipes to the radiadtors that are not heating correctly... if one pipe is hot (that is the flow..inlet) and the other is cold... (return..outlet) then I would suspect that they are bloked with sludge..drain down and refill several times use a flushing inhibitor on the last flush.

ddahaa · 30 Jan 2005

Do you think sludge might be causing my banging problems too? How do I get the flushing inhibitor into the system? Any you would recommend?

I bet you can't tell I'm a complete novice at this!! Is it possible to buy something to screw ontl the drain valve's with some flexi pipe so I can get it straight outside without getting leaks/stains on the carpets?

PEDANTICVINDICTIVEMAN · 31 Jan 2005

Hi stat needs replaceing plus the pump and the boiler and the toilet and the bath and the roof and the garden and the wife and the goverment, should all be ok then.

kevplumb · 31 Jan 2005

ddahaa said:
Do you think sludge might be causing my banging problems too? How do I get the flushing inhibitor into the system? Any you would recommend?

I bet you can't tell I'm a complete novice at this!! Is it possible to buy something to screw ontl the drain valve's with some flexi pipe so I can get it straight outside without getting leaks/stains on the carpets?

yes its called a hose

dont know about the garden ped

ddahaa · 31 Jan 2005

I'm really confused now!!

After setting the boiler thermostat to low last night, didn't get any more banging. Today, both living room radiators warmed up!!! Still not as good as the other ones, but a lot better than they have been.

But now, the hot water pressure has seriously dropped?!! Don't know why, but took ages to run a bath. Any ideas?

kevplumb · 31 Jan 2005

try bleeding the pump

ddahaa · 31 Jan 2005

Looked at the pump yesterday, appears to have a screw on both the front and the back, which are the only ones I can see that would bleed it. Slackened one yesterday and water oozed out. Does this sound right? I can take a pic and post it or email it if it would help.

Thanks again for the help.

kevplumb · 31 Jan 2005

feel free thats why its there

ddahaa · 31 Jan 2005

So should I just slacken these screws off a bit with the pump off to see if any air comes out? Or should I take a pic first?

It isn't banging anymore. And does the pump affect hot water pressure too? I thought that was just from the cold water pressure going into the hot water tank? Or am I completely lost!!

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Serious banging and cool radiators.

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