Hi. Having waved goodbye to the engineer who has spent all day power flushing my system - 2 hours later it is banging alarmingly and the overflow is pouring out (same symptoms before he came). Should I call him back with a few choice words or is there something else wrong? Boiler is a Potterton Netaheat 10-16, gas system with 10 rads (all recently serviced with british gas) Previous noise was definitely coming from boiler kettling (downstairs). The noise now seems to be coming from the cold water feeder pipe (upstairs in airing cupboard). Any suggestions?
noisy central heating - just flushed
- Thread starter linjo
- Start date
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Check the header tank has water in it.
If so, a few possibilities. Could be an air lock but that sounds a bit unlikely.
Is the pump working? ie any rads getting hot?
Most likely though is that there was/is hard scale in the pipes which doesn't flush out. usually its at the junction between the feed pipe and the circuit. Only way to find out & fix it is cut pipes to have a look.
Do you know what chemical the guy used? He may well have avoided using the most fierce because of the age of the system.
He's done his powerflush - did he guarantee it would cure the problem? I never do, but would expect to get the system right after whatever extra work is necessary - all chargeable.
If so, a few possibilities. Could be an air lock but that sounds a bit unlikely.
Is the pump working? ie any rads getting hot?
Most likely though is that there was/is hard scale in the pipes which doesn't flush out. usually its at the junction between the feed pipe and the circuit. Only way to find out & fix it is cut pipes to have a look.
Do you know what chemical the guy used? He may well have avoided using the most fierce because of the age of the system.
He's done his powerflush - did he guarantee it would cure the problem? I never do, but would expect to get the system right after whatever extra work is necessary - all chargeable.
Thanks for prompt and informative reply.
tried heating again this morning - worked fine for about an hour and then started banging loudly again with boiling water pouring from overflow.
Pump is working, rads hot (very!).
There is water in the header tank - although probably a bit less than before!
Chemical used was Kamco FX2. The guy had to cut out part of the section of feed pipe and manually unblock it before he could flush the system, so maybe that's the cause of the problem.
It sounds (rather depressingly) like I'm going to have to get him back for another look - perhaps it would have been cheaper to have installed a new system
tried heating again this morning - worked fine for about an hour and then started banging loudly again with boiling water pouring from overflow.
Pump is working, rads hot (very!).
There is water in the header tank - although probably a bit less than before!
Chemical used was Kamco FX2. The guy had to cut out part of the section of feed pipe and manually unblock it before he could flush the system, so maybe that's the cause of the problem.
It sounds (rather depressingly) like I'm going to have to get him back for another look - perhaps it would have been cheaper to have installed a new system
The FX2 is an acid flushing chemical, so no problems here. If he mechanically removed the blockage, that was good too.
Sorry to be unsettling, but you have an old system which has been cleaned, it will never be a new system. It sounds for the moment as if the job was reasonable so far. If the boiler is severly scaled, it may need cleaning seperately, and it could be a boiler fault as well. Kamco also do System Hush which you could add and it may help.
What happens if you turn the boiler temperature down?
Sorry to be unsettling, but you have an old system which has been cleaned, it will never be a new system. It sounds for the moment as if the job was reasonable so far. If the boiler is severly scaled, it may need cleaning seperately, and it could be a boiler fault as well. Kamco also do System Hush which you could add and it may help.
What happens if you turn the boiler temperature down?
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Agreed . The fact that the boiler goes for an hour bedfore there's aproblem is a bit odd - certainly not a straightforward blockage.
When you say "overflow" do you mean that water is peeing into the garden , or that the boiler is boiling and spurting water out of the vent pipe back into the header tank?
Sounding a bit like it was the boiler stat causing the immediate trauma, with sludge as a chronic condition. Money not wasted though - it would have needed cleaning sooner rather than later.
When you say "overflow" do you mean that water is peeing into the garden , or that the boiler is boiling and spurting water out of the vent pipe back into the header tank?
Sounding a bit like it was the boiler stat causing the immediate trauma, with sludge as a chronic condition. Money not wasted though - it would have needed cleaning sooner rather than later.
Have tried turning boiler temperature down, doesn't make any difference.
Only the radiator closest to the pump is working now (others all cold) so there's obviously a(nother) blockage somewhere. Have tried bleeding this radiator, nothing comes out (neither air nor water).
Boiler has recently been serviced (October) and seems to be working okay.
Banging noise is definitely coming from pipes somewhere between pump and tanks in loft. Within 5-10 mins of system being switched on, lots of banging and clonking and boiling water pouring into tank in loft, which then overflows. Ho hum...
Is it terminal or can it be saved?
Only the radiator closest to the pump is working now (others all cold) so there's obviously a(nother) blockage somewhere. Have tried bleeding this radiator, nothing comes out (neither air nor water).
Boiler has recently been serviced (October) and seems to be working okay.
Banging noise is definitely coming from pipes somewhere between pump and tanks in loft. Within 5-10 mins of system being switched on, lots of banging and clonking and boiling water pouring into tank in loft, which then overflows. Ho hum...
Is it terminal or can it be saved?
Hi. Very impessed with such helpful replies - thanks.
My plumbing skills are zero (sorry, it's a girl thing) so I have no idea how to tell whether the pump is working or not.
This morning the system worked fine for an hour before boiling over. Now it's a matter of minutes and no heat from rads (apart from the one mentioned before).
Boiler stat set to minimum (usually set to 3).
Am feeling more resigned by the minute to getting the engineer back..
My plumbing skills are zero (sorry, it's a girl thing) so I have no idea how to tell whether the pump is working or not.
This morning the system worked fine for an hour before boiling over. Now it's a matter of minutes and no heat from rads (apart from the one mentioned before).
Boiler stat set to minimum (usually set to 3).
Am feeling more resigned by the minute to getting the engineer back..
Yes you should call the guy. The pump: you can usually tell if it's on by feeling for a slight vibration, and it usually has a 1/2/3 speed switch to try. If nowt then unscrew the big screw in the middle (dribbles a bit) and shove something like screwdriver in. Kinda rattles about. It IS possible that a spinning pump is nonetheless not pumping! How much were you charged for the work so far?
Cost is not too bad if he had to do pipe cutting and clearing.
As ChrisR says, it looks like you have got two problems. One is that the boiler thermostat is not working. The boiler should stop at around 50 deg C with the stat on minimum. The other is either material blocking the pipe, or less likely, an air lock.
Are the valves on each side of the pump fully open?
Hey! stop that! you have already outperformed quite a few people who take money for claiming they can do this sort of diagnosis, keep it up.
As ChrisR says, it looks like you have got two problems. One is that the boiler thermostat is not working. The boiler should stop at around 50 deg C with the stat on minimum. The other is either material blocking the pipe, or less likely, an air lock.
Are the valves on each side of the pump fully open?
Hey! stop that! you have already outperformed quite a few people who take money for claiming they can do this sort of diagnosis, keep it up.
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