huffhuff Posted April 1, 2013 Report Share Posted April 1, 2013 Hi guys and gals, We have a combi boiler that keeps dropping pressure. There is no real pattern, it can be fine for weeks on end and then just drops all of a sudden. Or like this weekend, it has dropped pressure every day. I simply refill using the manual tap and it gets going again. Sometimes it's going as low as 0. Other times just enough to conk out and activate the warning LED. Also, the overflow at the rear drips intermittently but not all the time. I have tried bleeding the rads, and they all seem ok. Where should I be looking next? Or is it a case of calling somebody? Ta very muchly in advance, Ben Quote Link to comment Share on other sites More sharing options...
shooternick Posted April 1, 2013 Report Share Posted April 1, 2013 Replace pressure vessel at back of boiler Quote Link to comment Share on other sites More sharing options...
huffhuff Posted April 1, 2013 Author Report Share Posted April 1, 2013 Replace pressure vessel at back of boiler Is that something I can do i I'm pretty handy with a hammer and chisel? Quote Link to comment Share on other sites More sharing options...
LondonLuke Posted April 1, 2013 Report Share Posted April 1, 2013 (edited) PRV is stuck slightly open I've seen it where you can actually blow all the pressure through it to clean them which will reset them. Equally it can make them worse. Probably best replaced Edit - assuming the overflow at the back isn't an unconnected condensate pipe (appreciate unlikely) Edited April 1, 2013 by LondonLuke Quote Link to comment Share on other sites More sharing options...
al4x Posted April 1, 2013 Report Share Posted April 1, 2013 Or you have a slight leak Quote Link to comment Share on other sites More sharing options...
huffhuff Posted April 1, 2013 Author Report Share Posted April 1, 2013 Or you have a slight leak That was my first thought. But, I can't see anything obvious. I'll have a proper look today and have a good feel of the pipes I can access. Quote Link to comment Share on other sites More sharing options...
goodo123 Posted April 1, 2013 Report Share Posted April 1, 2013 Don't know much about combi boilers but the prv idea sounds logical,maybe shut system down and open top up and manually open prv? Clean the v/v seat of any junk what might be holding it open... Have seen prv's weeping on thermal oil, hot water, cold water, steam and comp. Air Quote Link to comment Share on other sites More sharing options...
dazsl Posted April 1, 2013 Report Share Posted April 1, 2013 Could be expansion tank Pressure release valve A leak Never do work on a boiler or let anyone else who is not gas safe Quote Link to comment Share on other sites More sharing options...
kent Posted April 1, 2013 Report Share Posted April 1, 2013 Could be expansion tank Pressure release valve A leak Never do work on a boiler or let anyone else who is not gas safe If its a gas boiler the OP doesn't say Quote Link to comment Share on other sites More sharing options...
kent Posted April 1, 2013 Report Share Posted April 1, 2013 As people have already stated, but your not on a private water supply or one that can vary in its reliability are you? is the boiler outdoors or in? Quote Link to comment Share on other sites More sharing options...
B725 Posted April 1, 2013 Report Share Posted April 1, 2013 First thing to check is the air pressure in the expansion vessel (big red thing)you can only do this when there is no pressure in the system,it should be ! bar if it is lower then use a foot pump to increase the pressure.If this pressue drop on the vessel keeps happening then you need to change the vessel.Another cause could be a leaking rad valve but it will not be obvious as the water evaporates as it gets warm.The PRV only tend to pass if the pressure increases to 3 bar. Quote Link to comment Share on other sites More sharing options...
Twistedsanity Posted April 1, 2013 Report Share Posted April 1, 2013 Could be expansion tank Pressure release valve A leak Never do work on a boiler or let anyone else who is not gas safe This is a very common misconception, in order to work on a boiler the gas regs state you must be a competant person, in order to charge money to work on a boiler you need to be gas safe registered , check out the gas regs if you dont believe me , the first paragraph states that anyone needs to be a "competant" person, the rest of the regs are concerned only with employer and employee responsibilites only, i spent fifteen years doing commercial and industrial gas Quote Link to comment Share on other sites More sharing options...
Del T Posted April 1, 2013 Report Share Posted April 1, 2013 Simple things first. Fill to one bar cold.Put heating on and watch tge gauge to see if its going up a lot.Get the system hot then run the hot water and again watch the gauge.With a large demand on the hot water the gauge will raise rapidly if the pressure vessel is faulty ,if it gets over 3bar the prv will open and drop the system pressure. It's sometimes easier to put a new pressure vessel on the return pipe next to the boiler instead of removing boiler from the wall. Quote Link to comment Share on other sites More sharing options...
Del T Posted April 1, 2013 Report Share Posted April 1, 2013 This is a very common misconception, in order to work on a boiler the gas regs state you must be a competant person, in order to charge money to work on a boiler you need to be gas safe registered , check out the gas regs if you dont believe me , the first paragraph states that anyone needs to be a "competant" person, the rest of the regs are concerned only with employer and employee responsibilites only, i spent fifteen years doing commercial and industrial gas To be deemend competent though you have to do the training and pass the courses.! Del T ,18yrs corgi/gas safe regd. Quote Link to comment Share on other sites More sharing options...
huffhuff Posted April 1, 2013 Author Report Share Posted April 1, 2013 (edited) Sorry guys, it's gassed indoors. The make/model is Heat Line Compact It sounds like a lot of jiggery pokery for me so might just get in a man that can. Cheers Edited April 1, 2013 by huffhuff Quote Link to comment Share on other sites More sharing options...
Twistedsanity Posted April 1, 2013 Report Share Posted April 1, 2013 To be deemend competent though you have to do the training and pass the courses.! Del T ,18yrs corgi/gas safe regd. i have done the training and courses, whilst i agree entirely that you should have passed the courses and dont the training to be deemed competant there is no legal definition that requires it Quote Link to comment Share on other sites More sharing options...
al4x Posted April 1, 2013 Report Share Posted April 1, 2013 Sorry guys, it's gassed indoors. The make/model is Heat Line Compact It sounds like a lot of jiggery pokery for me so might just get in a man that can. Cheers If you need a decent one pm me as had one recommended from someone on here and he is spot on, fitted the system here and just straight up Quote Link to comment Share on other sites More sharing options...
Twistedsanity Posted April 1, 2013 Report Share Posted April 1, 2013 phone the mnufacturer and ask for them to send an engineer out , plumbers are not boiler engineers ! Quote Link to comment Share on other sites More sharing options...
vampire Posted April 1, 2013 Report Share Posted April 1, 2013 If you insert an allen key into the valve on the pressure vessel and water comes out,the bladder is split and the vessel needs replacing and its quite common to replace the prv at the same time.It is often easier to add another vessel of equal capacity fitted outside of the boiler,rather than trying to get the old one out. When you pressure up the boiler,it must be switched off and fill slowly or you will be adding air to the system,dont forget to bleed air at the boiler and the pump as well as the rads,start with rad nearest to the boiler. Quote Link to comment Share on other sites More sharing options...
Asa Bear Posted April 1, 2013 Report Share Posted April 1, 2013 Change the prv then save your pennies to replace the boiler next time it goes wrong & don't get a B&Q special next time. Quote Link to comment Share on other sites More sharing options...
dazsl Posted April 1, 2013 Report Share Posted April 1, 2013 As per competent person it means anyone qualified to do the work the HSE only recognise gas safe registered persons as competent have a play something goes wrong you won't have a leg to stand on regs are there for a reason not for gas fitters to make money Quote Link to comment Share on other sites More sharing options...
LondonLuke Posted April 1, 2013 Report Share Posted April 1, 2013 That said its completely legal for anyone not gas safe to fit a boiler in their own home. Only becoming an issue when you come to sell. Quote Link to comment Share on other sites More sharing options...
oldway Posted April 1, 2013 Report Share Posted April 1, 2013 hi there i've had 2 combi's doing just the same thing, i found that it was the braided pipe that connects pressure vessel to the aqua block was blocked just becarefull when you've drained down the boiler as if that pipe is blocked the water that is left in the pressure vessel is under pressure so make sure you got plenty of towels . just clean out the pipe and put back together being carefull not to nip the rubber washer , martin Quote Link to comment Share on other sites More sharing options...
Asa Bear Posted April 1, 2013 Report Share Posted April 1, 2013 As per competent person it means anyone qualified to do the work the HSE only recognise gas safe registered persons as competent have a play something goes wrong you won't have a leg to stand on regs are there for a reason not for gas fitters to make money If something goes wrong you won't have a leg to stand on wether you're GSR or not. Quote Link to comment Share on other sites More sharing options...
dazsl Posted April 1, 2013 Report Share Posted April 1, 2013 (edited) That said its completely legal for anyone not gas safe to fit a boiler in their own home. Only becoming an issue when you come to sell. it is illegal to put your own boiler in or try and repair your own gas appliances you would not be a competent person therefore making it illegal If something goes wrong you won't have a leg to stand on wether you're GSR or not. must agree logo brain not working 100% Edited April 1, 2013 by dazsl Quote Link to comment Share on other sites More sharing options...
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