Another boiler problem
Discussion
Any help gratefully received!
We have a 5 year old combi boiler that is playing up and would like some advice. It's okay when it is on DHW only but when calling for heat it randomly decides to either provide the heat or trip on low pressure. In fact the only way we can keep the heatibg working is by "cracking" the filling loop needle valve so the loop pressure is maintained. The boiler is mounted internally on an outside wall, outside there is a pipe that is very similar to an overflow, this "overflow" constantly has water flowing from it when the heating is turned on but is completely dry when we call for DHW only. Obviously we need a heating professional to come and have a look but a heads up from the resident Plumbers / heating technicians or engineers as to what the problem may be would be a great help.
Thanks in advance.
We have a 5 year old combi boiler that is playing up and would like some advice. It's okay when it is on DHW only but when calling for heat it randomly decides to either provide the heat or trip on low pressure. In fact the only way we can keep the heatibg working is by "cracking" the filling loop needle valve so the loop pressure is maintained. The boiler is mounted internally on an outside wall, outside there is a pipe that is very similar to an overflow, this "overflow" constantly has water flowing from it when the heating is turned on but is completely dry when we call for DHW only. Obviously we need a heating professional to come and have a look but a heads up from the resident Plumbers / heating technicians or engineers as to what the problem may be would be a great help.
Thanks in advance.
Thanks guys
But I cannot help thinking the reason for the overflow is I have the filling loop valve cracked open and the system is overpressuring. My main worry is the loss of pressure in the heating loop when I have the filling loop valve closed. Does anyone know how I can check if it is somthing in my boiler that is causing my pressure loss or if it is the radiator pipework? is there a simple check?
thanks
But I cannot help thinking the reason for the overflow is I have the filling loop valve cracked open and the system is overpressuring. My main worry is the loss of pressure in the heating loop when I have the filling loop valve closed. Does anyone know how I can check if it is somthing in my boiler that is causing my pressure loss or if it is the radiator pipework? is there a simple check?
thanks
The thing that is leaking is the Pressure Relief Valve, they "blow off" at 3 bar. Put the heating on and watch the pressure gauge on your boiler, if it starts rising, chances are you need a new expansion vessel.
If you can access your expansion vessel, you should see a schrader valve, similar to a car tyre valve on the top of it. Press the pin in and you should get gas out of it, if any water comes out, it needs replacing.
If you can access your expansion vessel, you should see a schrader valve, similar to a car tyre valve on the top of it. Press the pin in and you should get gas out of it, if any water comes out, it needs replacing.
Thanks Ricky
I do have gas from the schreder valve. it's the loss of pressure in the heating loop that is my problem. the PRV releiving is (I think) a result of my atempt to keep the heating going, thus cracking the filling loop valve open and pressurising the system to mains water pressure (3ish Bar. I think the PRV relieves at about 2.6 Bar)
When My heating trips the boiler says 0.5 Bar. I then open the filling loop to re-pressurise the systen to the recomended 1bar, the heating will come on for a cycle (during which time the pressure will rise to about 1.8Bar) then once the heating turns off the pressure in the loop will eventually drop to about 0.6, once it reaches 0.5 the boiler will trip and lock out. I need to know where to find the leak in the system. None of the radiators or pipes have a visible leak or "staining" but I really don't want to start to rip up the floor boards unless I have to.
Thanks guys
I do have gas from the schreder valve. it's the loss of pressure in the heating loop that is my problem. the PRV releiving is (I think) a result of my atempt to keep the heating going, thus cracking the filling loop valve open and pressurising the system to mains water pressure (3ish Bar. I think the PRV relieves at about 2.6 Bar)
When My heating trips the boiler says 0.5 Bar. I then open the filling loop to re-pressurise the systen to the recomended 1bar, the heating will come on for a cycle (during which time the pressure will rise to about 1.8Bar) then once the heating turns off the pressure in the loop will eventually drop to about 0.6, once it reaches 0.5 the boiler will trip and lock out. I need to know where to find the leak in the system. None of the radiators or pipes have a visible leak or "staining" but I really don't want to start to rip up the floor boards unless I have to.
Thanks guys
Ricky_M said:
Depends on what boiler and how handy you are with a spanner, some are easy and some are a bloody nightmare!
ferroli optima 701...got the manual off their site, and it looks straightforward...except for the control panel that#s in the way and I can't see how it's attached..although I've yet to look properly.cheers though.
mik.ross said:
Yep pretty sure it is sealing. Put some fairy liquid on it and it's not blowing bubbles.
Thanks
Just to point out that you may have misuderstood (apols if not..ETA although reading back, I think I have) : the PRV is NOT the schraeder valve on the exp vessel, it's an internal water valve and if it's shot/not closing you'll see dripping out of the overflow pipe outside.Thanks
ETA to clarify, I dn't understand the reference to fairy liquid on the PRV
Edited by DrTre on Friday 9th October 21:06
The pressure relief valve is on the over flow pipe that runs outside. Sometimes they do not re-seat once they have opened, try activating it manually a few times to re-seat it, it may have got some debris stuck in the valve seat.
Re the problem of the system over pressurising. As said before it could be the pressure vessel, often a big red tank at the back of the boiler. I had this issue, it turned out to be a blocked tube that leads to the vessel, it was full of debris/crap. Once I cleaned out the tube, all was good.
Re the problem of the system over pressurising. As said before it could be the pressure vessel, often a big red tank at the back of the boiler. I had this issue, it turned out to be a blocked tube that leads to the vessel, it was full of debris/crap. Once I cleaned out the tube, all was good.
Thanks for all your help people.
The boiler man was round earlier and has diagnosed a "weak" NRV. The system was venting at 1.5Bar therefore lossing pressure when the CH is on, he's back tomorrow (early
) with a new NRV spring. Must say a trully profesional service from BG.
Well done Robinhood, in true PH style the second post on a help topic is usually correct!
The boiler man was round earlier and has diagnosed a "weak" NRV. The system was venting at 1.5Bar therefore lossing pressure when the CH is on, he's back tomorrow (early
) with a new NRV spring. Must say a trully profesional service from BG.Well done Robinhood, in true PH style the second post on a help topic is usually correct!
Edited by mik.ross on Saturday 10th October 20:19
mik.ross said:
Thanks for all your help people.
The boiler man was round earlier and has diagnosed a "weak" NRV. The system was venting at 1.5Bar therefore lossing pressure when the CH is on, he's back tomorrow (early ) with a new NRV spring. Must say a trully profesional service from BG.
Well done Robinhood, in true PH style the second post on a help topic is usually correct!
I would bet that the BG man had the part on his van,but rather than fix your problem and having to miss his next appointment he bumped you to the next day.;)The boiler man was round earlier and has diagnosed a "weak" NRV. The system was venting at 1.5Bar therefore lossing pressure when the CH is on, he's back tomorrow (early
) with a new NRV spring. Must say a trully profesional service from BG.Well done Robinhood, in true PH style the second post on a help topic is usually correct!
Edited by mik.ross on Saturday 10th October 20:19
More to the point; Why has the prv failed? Is the charge in the expansion vessel low? If he just changes the prv without investigating the reason for failure he will become a frequent visitor.
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