central heating help...
Discussion
My boiler has been playing up a bit recently so I had it serviced and the engineer said the pressure was very low, hence I was getting the low pressure cutoff on a daily basis. When he tried to repressure the system it was very slow and he almost wondered if there was a pipe blockage somewhere.
After the service teh system continued to cut out with poor pressure. Engineer comes back out with a more experienced guy. They look at the system again and run the hot water shows traces of an oil like substance, which the senios engineer suggests my matrix is breaking up and its new boiler time :(
Rather coincidentally, that evening a neighbour visits and asks if I am suffering low water pressure. It becomes apparent all the houses in the area have been for a few weeks and the water board were called to investigate. They have subsequently come out and the pressure is back to normal. However, the water pressure light still comes on the boiler every time the central heating goes off and a demand is made for hot water. Does the boiler need re-pressurising now that usual pressure has been returned to the external system? or is the boiler fubarbed? If so, would this have anything to do with the fact its been supplied with very low pressure water for a prolonged period? I am a bit miffed that my boiler seems f**ked in that its showing low pressure all the time after the water supply has been low pressure to all local houses for the last month or so....
After the service teh system continued to cut out with poor pressure. Engineer comes back out with a more experienced guy. They look at the system again and run the hot water shows traces of an oil like substance, which the senios engineer suggests my matrix is breaking up and its new boiler time :(
Rather coincidentally, that evening a neighbour visits and asks if I am suffering low water pressure. It becomes apparent all the houses in the area have been for a few weeks and the water board were called to investigate. They have subsequently come out and the pressure is back to normal. However, the water pressure light still comes on the boiler every time the central heating goes off and a demand is made for hot water. Does the boiler need re-pressurising now that usual pressure has been returned to the external system? or is the boiler fubarbed? If so, would this have anything to do with the fact its been supplied with very low pressure water for a prolonged period? I am a bit miffed that my boiler seems f**ked in that its showing low pressure all the time after the water supply has been low pressure to all local houses for the last month or so....
If you have a pressurised combi system it sounds like the expansion vessel is knackered and/or needs recharging. Or you have a leak elsewhere in the system.
The expansion vessel is like a large bladder which inflates and deflates to compensate the pressure in the central heating system. On the other side of the bladder is compressed air pressure so it does not inflate too much. It sounds as if the bladder has leaked or the air has leaked out of the vessel.
Recharging can be done using a bike pump or car footpump. Look in you boiler's manual for the location and recommended pressure.
If its a leak look out for water.I t could be the heat exchanger leaking which could mean new boiler time. What make and model is it?
>> Edited by batbuilder92 on Friday 28th October 14:04
The expansion vessel is like a large bladder which inflates and deflates to compensate the pressure in the central heating system. On the other side of the bladder is compressed air pressure so it does not inflate too much. It sounds as if the bladder has leaked or the air has leaked out of the vessel.
Recharging can be done using a bike pump or car footpump. Look in you boiler's manual for the location and recommended pressure.
If its a leak look out for water.I t could be the heat exchanger leaking which could mean new boiler time. What make and model is it?
>> Edited by batbuilder92 on Friday 28th October 14:04
batbuilder92 said:
If you have a pressurised combi system it sounds like the expansion vessel is knackered and/or needs recharging.
What he said! My combi was losing pressure every time it switched off. I posted on here about a year ago, but only just got it sorted! It's a Potterton boiler, so in the end I used their own engineers - £200, but this includes warranty on any boiler problems for 12 months, so not a bad deal considering I'd already spent over £100 on another engineer who rubbed his chin and replaced various parts at great expense! Potterton diagnosed the problem as knackered expansion vessel in a couple of minutes, and fitted the new one in about 20 minutes. Good luck!
If the pressure gauge on the boiler is showing less than 1 Bar cold it should be refilled using the filling loop which is a braided stainless steel hose with a valve at each end. Open the valve from the mains cold pipe (15mm) and you should hear the water filling the system. Stop at about 1 Bar cold.
If, as mentioned above, the pressure vessel is ruptured internally then there will be no air to compress when the water expands and water will discharge down the 3 Bar safety valve on the boiler to the outside world.
If the system regularly loses pressure have a good look around all visible pipework for signs of leakage. If none visible then suspect heat exchanger or, of course, the posibility of safety valve discharge. Any of the multitude of internal leak sealers are worth a go before considering a replacement boiler which will be EXPENSIVE.
If, as mentioned above, the pressure vessel is ruptured internally then there will be no air to compress when the water expands and water will discharge down the 3 Bar safety valve on the boiler to the outside world.
If the system regularly loses pressure have a good look around all visible pipework for signs of leakage. If none visible then suspect heat exchanger or, of course, the posibility of safety valve discharge. Any of the multitude of internal leak sealers are worth a go before considering a replacement boiler which will be EXPENSIVE.
As a related point, certainly in London it seems different parts of the system (i.e. different areas of town) have different water pressures and this contributes to leaks. So in order to reduce the leaking, they are reducing EVERYONE's water pressure to the same level. Which could be rather annoying to those of us relying on mains pressure for the shower.
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