sandspider Posted May 30, 2018 Report Share Posted May 30, 2018 Hi all Wonder if anyone might have any suggestions? We had a new oil boiler fitted last year. Install seemed to go OK and everything works. However, there's been a drip of water from an overflow pipe outside the house which has got heavier and heavier, and is now like running a tap slowly. The system pressure also seems to increase quite a lot, it was 3.5 bar yesterday! Had the boiler installer back a couple of times (not his pipework to be fair, he only replaced the boiler) and he replaced an expansion vessel, but still the drip continued. System pressured stopped increasing for a while, but is now rising again. And if I release the pressure from the expansion vessel water comes gushing out of two tundishes. Apparently one of these tundished pipes is backfilling, as the drip from the overlow is quicker than the drip through the tundish. The plumber was talking about replacing a second expansion vessel, but now says the fault is probably with the coil in the hot water cylinder itself. Pain, as it's got to be drained down to test. I'm not totally sure he knows what the problem is, and is replacing parts to see! Based on the fairly incomprehensible text above, is it possible for anyone to have a guess at what the problem might be? I don't want to get another plumber if it can be avoided, and I think our hot water tank pipework is quite a mess, so it may not be obvious. But we can't just keep replacing parts until something finally fixes it! Thanks. Just to add, plumber turned the cold water supply off and the boiler on, and the system pressure is stil rising. CH pump is making quite a bit of noise too... Quote Link to comment Share on other sites More sharing options...
Eyefor Posted May 30, 2018 Report Share Posted May 30, 2018 Is it still within the warranty? I would reject that boiler as not fit for purpose - it shouldn't be your issue to find a solution to the issues, it should be the installer. I'd advise them in writing as such, and if you (hopefully) paid by credit card I'd advise them and put them on notice that you may be making a section 75 claim. Hope you get it sorted. Quote Link to comment Share on other sites More sharing options...
aga man Posted May 30, 2018 Report Share Posted May 30, 2018 Sounds like the problem is with the unvented cylinder and not the boiler from your description. You need a plumber with knowledge and certification of unvented cylinders if that is the system you have. Quote Link to comment Share on other sites More sharing options...
sandspider Posted May 30, 2018 Author Report Share Posted May 30, 2018 Thanks chaps. It does seem to be a pipework / cylinder problem rather than the boiler, and it is still under warranty. Installer is doing his best to sort it, even though it's not his problem as such. I think I'll suggest getting a second opinion, he might be relieved. Not sure if it's vented or not tbh, I can't see any vents on it! Quote Link to comment Share on other sites More sharing options...
JohnfromUK Posted May 30, 2018 Report Share Posted May 30, 2018 My first unvented cylinder (Worcester Bosch) failed on first filling/heating. Real pain for my plumber to change as access to where it is located is very restricted, and once it had water in it, it was really hard to prevent it getting everywhere (located in a low loft above a single storey part of the house). Quote Link to comment Share on other sites More sharing options...
TIGHTCHOKE Posted May 30, 2018 Report Share Posted May 30, 2018 43 minutes ago, sandspider said: Thanks chaps. It does seem to be a pipework / cylinder problem rather than the boiler, and it is still under warranty. Installer is doing his best to sort it, even though it's not his problem as such. I think I'll suggest getting a second opinion, he might be relieved. Not sure if it's vented or not tbh, I can't see any vents on it! If it is un-vented there will be an expansion chamber within the circuit. Quote Link to comment Share on other sites More sharing options...
Rob525 Posted May 30, 2018 Report Share Posted May 30, 2018 Get him to isolate the coil to the cylinder. If the system was istalled by someone who knew what he was doing (although not very neatly as you say) There should be some gate valves / pump isolators etc. This way only the coil would have to be drained and watch for a flow of water or drips over the next 5mins. Providing there are isolaters the whole test should take 15mins and confirm weather the coil is the suspect. As for expansion vessels a simple tyre gauge on the vessels would indicate if it was to blame. Hope that helps Quote Link to comment Share on other sites More sharing options...
sandspider Posted May 30, 2018 Author Report Share Posted May 30, 2018 3 hours ago, TIGHTCHOKE said: If it is un-vented there will be an expansion chamber within the circuit. Right. It's probably unvented then because there are two expansion vessels on top. 28 minutes ago, Rob525 said: Get him to isolate the coil to the cylinder. If the system was istalled by someone who knew what he was doing (although not very neatly as you say) There should be some gate valves / pump isolators etc. This way only the coil would have to be drained and watch for a flow of water or drips over the next 5mins. Providing there are isolaters the whole test should take 15mins and confirm weather the coil is the suspect. As for expansion vessels a simple tyre gauge on the vessels would indicate if it was to blame. Hope that helps Thanks Rob, that's useful. Apparently there are no isolators however, so the lot has to be drained. I'll have some isolators put in if the whole lot does have to come out. One expansion vessel had failed and filled up with water and was replaced previously. The other seems to be OK. To be fair, the water cylinder and most of the install is now 15 or so years old, so not a bad innings... Quote Link to comment Share on other sites More sharing options...
Winston72 Posted May 30, 2018 Report Share Posted May 30, 2018 4 hours ago, Eyefor said: Is it still within the warranty? I would reject that boiler as not fit for purpose - it shouldn't be your issue to find a solution to the issues, it should be the installer. I'd advise them in writing as such, and if you (hopefully) paid by credit card I'd advise them and put them on notice that you may be making a section 75 claim. Hope you get it sorted. when you get a new battery fitted on a car it doesn't cover the exhaust breaking Quote Link to comment Share on other sites More sharing options...
Velocette Posted May 30, 2018 Report Share Posted May 30, 2018 Got any more helpful comments ? Quote Link to comment Share on other sites More sharing options...
vampire Posted May 30, 2018 Report Share Posted May 30, 2018 You could test the expansion vessel,press down on valve and if water comes out its failed and prv may have debris in it ? Quote Link to comment Share on other sites More sharing options...
Guest Posted May 30, 2018 Report Share Posted May 30, 2018 What make of boiler is it .mine broke the other month and Worcester Bosch came out and repaired . can you not get who made yours to come and look at .i had my boiler coupled to the old system which should not make any difference afterthe boiler all that’s left is pipes and radiators which don’t cause much trouble Quote Link to comment Share on other sites More sharing options...
JohnfromUK Posted May 30, 2018 Report Share Posted May 30, 2018 7 minutes ago, Swinton said: afterthe boiler all that’s left is pipes and radiators which don’t cause much trouble Not necessarily so; in a non vented hot water system, the 'outer' of the cylinder is at full mains water pressure. The inner coil is at boiler pressure - which will be lower. Hence al leak from the outer to the coil will cause a rise in pressure at the boiler. Quote Link to comment Share on other sites More sharing options...
Winston72 Posted May 30, 2018 Report Share Posted May 30, 2018 swinton thats ok with a combi, if its got a storage system , its not a combi and the components such as pump pressure vessel divert er valve etc are seperate it could be anything from a blockage to the expansion vessel to a mixer shower passing, boiler manufacturers are not interested in anything other than the box with the flames in it Quote Link to comment Share on other sites More sharing options...
shootthepigeon Posted May 30, 2018 Report Share Posted May 30, 2018 If the system pressure is still rising when the mains is isolated, I would presume an expansion vessel fault. Have you physically disconnected the filling loop? This could be fed from a seperate water supply and passing, forcing the pressure up?? If it is a fault with the coil, could you not isolate the mains feed and release all the pressure on the hot taps, a leak on the coil should release pressure from the c/h system? Backfilling the taps if you get where I'm coming from? Quote Link to comment Share on other sites More sharing options...
sandspider Posted May 31, 2018 Author Report Share Posted May 31, 2018 18 hours ago, vampire said: You could test the expansion vessel,press down on valve and if water comes out its failed and prv may have debris in it ? I think the plumber has done this, and one expansion vessel was replaced. Though we do seem to have a second one. What I find strange is that the drip from the outside overflow seems to be faster than the drip from the expansion vessel inside... 18 hours ago, JohnfromUK said: Not necessarily so; in a non vented hot water system, the 'outer' of the cylinder is at full mains water pressure. The inner coil is at boiler pressure - which will be lower. Hence al leak from the outer to the coil will cause a rise in pressure at the boiler. I think this is (probably) the problem, as I understand it. 17 hours ago, shootthepigeon said: If the system pressure is still rising when the mains is isolated, I would presume an expansion vessel fault. Have you physically disconnected the filling loop? This could be fed from a seperate water supply and passing, forcing the pressure up?? If it is a fault with the coil, could you not isolate the mains feed and release all the pressure on the hot taps, a leak on the coil should release pressure from the c/h system? Backfilling the taps if you get where I'm coming from? Filling loop has been disconnected. I understand the cold mains feed to the boiler was also disconnected, and the pressure still rose - but probably because the heating and hot water were turned on. Once boiler was off, if the cold feed was turned back on (filling loop still disconnected) the pressure rose again, even higher than when the boiler was on. To a max of about 3.5 bar which seems to be the max pressure of our cold mains water... Your second paragraph does makes sense, thanks! I will pass that on to the plumber (though I suspect he's thought of this - in fact he was opening the hot taps just a smidge with the mains feed turned off, and that did reduce system pressure again). Perhaps that confirms a fault with the coil? Thanks for all the suggestions people, turns out I don't know much about boiler systems and plumbing! One thing I did notice when the CH was turned on was that the radiators didn't actually get hot, and that the CH pump was making an odd noise - presumably due to air in the system after pressure and water was released from the expansion vessel? Plumber has no problem with my getting a second opinion, so I might do that... Quote Link to comment Share on other sites More sharing options...
vampire Posted May 31, 2018 Report Share Posted May 31, 2018 I would get him to test the expansion vessel again,have had exact same problem on a customers boiler and replaced vessel and prv . Quote Link to comment Share on other sites More sharing options...
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