Hi there,

I hope you can help me with a bit of advice please, my father in law has a combi potterton boiler, which is continuously ejecting hot water out of the overflow to the outside of the house. British Gas came to look yesterday, spent 5 minutes there and told him he needs a new boiler.

Whilst I dont doubt this may be true, is this diagnosis sound without even removing the casing to check anything?. My inlaws are both 80, and I cant help but think they see an easy target here.

A little advice as to possible causes for the water ejection would be helpful please.

Many thanks

Phil.

Just google the problem eg http://www.diynot.com/forums/plumbing/pressure-valve.312525/

Or http://www.google.co.uk/url?sa=t&source=web&cd=8&ved=0CDsQFjAH&url=http%3A%2F%2Fuk.answers.yahoo.com%2Fquestion%2Findex%3Fqid%3D20090408051030AAFxdeE&ei=GCnhT6GXHM2s8QPh4OWVDw&usg=AFQjCNEsT2zt8yUW_zCNcXiiKovfc0uA-Q

Without seeing the boiler and watching what is is doing getting up to temperature it can't say exactly what is wrong, but it sounds like the PRV needs changing or the vessel. PRV is around £15 and the vessel around £60 depends on the model of the boiler.

Thanks for the replies, boiler is a Potterton Performa 24 if that helps. British Gas keep saying that they need new boiler but nobody will give a price. They keep wanting to send round different people presumably for the hard sell.

Thanks for the replies, boiler is a Potterton Performa 24 if that helps. British Gas keep saying that they need new boiler but nobody will give a price. They keep wanting to send round different people presumably for the hard sell.

British gas will always say it needs a new boiler. My Brother in law visited some one who had been told the same by British Gas. A £5 component, a fuse and a new seal where some water had seeped onto a circuit board cured the fault.

I am a heating engineer with 14 years experience and I can say the the Potterton Performa (same boiler as a Baxi 80e) is a good boiler and was sold up until only a couple of years ago. Parts are readily available and it is perfectly repairable.

If water is CONTINUOUSLY disharging outside then either the filling loop is passing (mains pressure water into your central heating circuit), the plate heat exchanged is passing (mains water into your central heating circuit) or the pressure relief valve is passing (but the discharge would stop when the pressure droppedand start again when pressure is added to the system),

If the water is ONLY discharging when the heating is on then the expansion vessel is the likely culprit or possible a blockage i the pipework connecting the expansion vessel to the boiler, but these 99 times out of 100 just need recharging to solve the issue.

Even in the worst case scenario that the plate heat ex, filling loop, expansion vessel AND prv were needing to be replaced you shoul have change from £240.00 much cheaper than a new boiler.

Feel free to question me, if you can give some more details perhaps I can advise your further.

British Gas take the p!ss!

We've has this "need a new boiler" garbage from them on a few

occasions. You're much better off getting a learned chap like the one above in

when it goes wrong rather than use their service plan. They offered to charge us £11

a month but if something went wrong with the (Baxi) boiler they couldn't fix it.

I said what's the 11 quid for then? Jog on!

Great advise I'm sure from OCScene. I would rather believe him than British Gas. Recently they stung some neighbours of ours who are in their 80's and 90's for some extensive work including a new boiler. Funny, but there old boiler was just 5 years old and had not even stopped working. The engineer from BG said it needed renewing when he called for a routinge service! So, after 3 days work, a new boiler and lifting over £5,000 from them, British Gas had fitted a new boiler. Unfortunately, I came onto the scene too late to properly look into it but I'm certain there was nothing wrong with the old boiler in the first place. Most boilers will go for at least 10 years or more. Makes me a bit cross to say the least.

I would suspect the CH expansion vessel as it has a diaphram inside which perish, there should be a tyre type valve on the side of it press the pin inside it and see if water or air comes out, air is good water is bad, thats what was wrong on mine (not a potterton) cheers - Stuart

hi Phil

if one of your in laws are in receipt of any kind of benefits from the government then they will entitled to a grant for a new boiler completely free have a look below. some time the grant from warm front does not cover the full cost if you ask them they will give you the phone number of the local council who will give a top-up grant no mater what happen it wont cost your in laws any money

• 
  Heating and insulation improvements from the Warm Front scheme ...
  

Any boiler can be fixed, obviously without seeing it its impossible to diagnose. To me its sounds as though the quick fill has been left open maybe or is letting by, as has been said before if the prv has given up or the diaphram in the vessle then the pressure would have dropped and the water from the relief valve would have come to a stop, so if its constantly running and the quick fill is closed and not passing then there is a supply of wtaer getting into the system somewhere. I personally would rule out the heat exchanger, but the diverter valves diaphram could be away meaning mains water is getting into the heating circuit, over pressurising it above 3bar therefore the safety is blowing off to avoid anything popping off. I would call a local gas engineer to come and have a look and tell him a few of the things you have heard on here so he thinks you have an idea and wont try and put the arm in.

Check out the gas safe register website for a list of registered engineers.

Just realised you had said hot water, if its only happening when the heating is on the the expansion vessle maybe needs recharged to take the expansion again. Though if this is the case it shouldnt take long for your pressure gauge to read zero and the likes of your upstairs rads not heating and no more water should be ejected then.

I would suspect the CH expansion vessel as it has a diaphram inside which perish, there should be a tyre type valve on the side of it press the pin inside it and see if water or air comes out, air is good water is bad, thats what was wrong on mine (not a potterton) cheers - Stuart

Not strictly true, if water comes out its very often just condensation/moisture and nothing a re-charge will not cure. The diapragms can perrish but If I had a pound for everytime an expansion vessell was replaced un-nessarily as the re-charge procedure was not carried out correctly and component itself blamed , then id be on the Ferrari forum and not the Skoda one!!

Any boiler can be fixed, obviously without seeing it its impossible to diagnose. To me its sounds as though the quick fill has been left open maybe or is letting by, as has been said before if the prv has given up or the diaphram in the vessle then the pressure would have dropped and the water from the relief valve would have come to a stop, so if its constantly running and the quick fill is closed and not passing then there is a supply of wtaer getting into the system somewhere. I personally would rule out the heat exchanger, but the diverter valves diaphram could be away meaning mains water is getting into the heating circuit, over pressurising it above 3bar therefore the safety is blowing off to avoid anything popping off. I would call a local gas engineer to come and have a look and tell him a few of the things you have heard on here so he thinks you have an idea and wont try and put the arm in.

Check out the gas safe register website for a list of registered engineers.

It cannot be the divertor valves as they Incorporate and air break (the 2mm holes on a Giannoni but all divertors have an air break as its water regs) The diapragm on a divertor perishing cannot cause it to pass mains to heating as you have mains cold water either side of the diapragm as its the different pressures which causes the mechanical movement. If your thinking of the stuffing box on the spindle passing then the valve would just leak out of the air break as its designed to do.

Thank you all so much for the replies, checked the pressure gauge on the boiler last night, stable at 2 bar. Apparently after I left, a BG engineer arrived (they are on service plan), and shut off the water supply to the boiler. When the water comes out of the outlet, it is at a rate of about a pint a minute.

I think I am going to have to take control of this soon as it is obviously heading for a train crash.