To use my Gas Central Heating I have to top up the system to 2 bar. (any less and the pipes bang and the pressure needle jumps around) The boiler fires up and the radiators heat up as they should. The pressure gauge on the boiler touches the red when the system is fully warmed up and then gradually drops until it hits the red at the other end of the dial when the pipes and boiler bang and the error message is shown. This process takes about 12 hrs. I am aware that there must be a leak on the system but there are no signs on walls or ceilings as to where it may be. I was wondering if I was to call out an engineer would he have any way of finding the leak using metres or something or would he want to start tearing up floorboards etc.which sounds horrific. My thoughts are just to top up the system when I want to use it and continue in this way unless any signs of the location of the leak occur. Any thoughts? Thank you in advance.
Any problems like banging, kettling with hot water at the taps. What boiler have you got & how old is it. If it was leaking under the floorboards, there would be signs in rooms below, damp patches, or water coming through the ceiling. Ground floor also signs wet floor,carpet,etc. Heat exchanger might be leaking,blocked.
Hi It may be your expansion vessel is full of water, and the water may be going out the safety pipe work outside. That'd give the symptoms you describe, Regards Peter
Hi Trudy. Summat amiss If your pressure goes up to the red - 3 bar - when the system heats up, that suggests a 'faulty' expansion vessel. By faulty, it may chust need re-charging with air. Do you know how to check the pressure/condition of your exp vessel? Is this something you would be prepared to try? Mind you, even with a faulty exp vessel, your system shouldn't be banging away - but that's possibly a different issue. The good news is, you might not actually have a leak in the conventional sense - it may chust be that the safety valve is opening at 3 bar and dumping the excess pressure when your system is hot, and then the pressure will fall (due to that loss of water) when it cools down again. Anyhoo, one thing at a time - need to check the exp vessel. I don't know if I can face writing about this malarkey again, and there are a few posts on it already on here - I'll see if I can find one...
Thanks to everyone for the advice and help. My boiler is a Baxi Megaflow Condensing boiler, it is approximately 7 years old. There are no signs whatsoever of leaking inside the house (no stains to carpet, ceiling etc.,) I have noticed there are occasional drips from the vent on the outside wall. I'm not sure if this changes anything but yesterday I topped up the system to 2 bar, didn't use the heating at all and today the pressure has dropped to 1½. Would this mean that aside from any possible issue with the expansion vessel that there still must be a leak in the pipework somewhere? With regard to the expansion vessel, is this something that I can check myself and am more than willing to attempt it (you may have noticed I have very limited knowledge of such things ) I am a girl on my own, I could call on my brother who is ok at DIY but knows as much as me about boilers but again we are more than willing to give anything a try. Thanks again to everyone for your time and trying to help me.
Yes. If your system drops from 2 bar to 1.5 bar without it being turned on, then that means there's a leak. "I have noticed there are occasional drips from the vent on the outside wall" Can you explain what this 'vent' is? What size of pipe, what's it made from (plastic or copper) and where does it go or point in to?
Hi again If you brother is a bit handy, there is a way to prove it's the expansion issue..... First, best not to play with the boiler, Choose a radiator that's easy to access, isolate the rad, undo the Knut between the valve and rad, this will allow you to drain water from the rad. You may have to open the air vent to allow the water out, into a bowl that is... When you have let about 4 litres out, re tighten the knut and close the air vent. Now OPEN the rad valves, but NO BOT BLEED the rad The rad now will act as an expansion vessel, and the system pressure will stabilise when hot and cold. Regards Peter
Hi Baxi megaflow? Do you have a hot water cylinder? Is your boiler at a high point like upstairs? What is the fault code?
Thank you for your reply. It's a large plastic pipe which leads from the top of the boiler through the external wall to the outside. When the boiler is on it is the pipe which belches out steam. I think the drips I have mentioned may just come for the water vapour. If it helps I can take a photograph of the pipe tomorrow and upload it for you (its too dark now to take a photo). Thank you again.
Thank you for trying to help me. The house is 3 storey, the hot water cylinder is located on the first floor and the boiler is on the ground floor. Regarding the fault code, I'm sorry I can't remember what it was. I always try to turn the heating off before the pressure gets too low as I always think the banging pipes are going to cause more damage. When the code appears again I'll make a note of it. Thank you again.
I believe the pipe we're talking about is the flue pipe. Hope this helps, but can provide exterior photos if needed. Thank you.
Thank you for your reply Peter. I will show this post to my brother and I will see if he is up to it (fingers crossed!) Thank you for trying to help me.
If you can leave the boiler switched off for a good part of the day, then there's another test you (or your bro) can do too. Underneath the boiler where the pipes all connect, you will need to identify the boiler 'flow' and 'return' - they'll both be 22mm copper pipes. Where they connect to the boiler you should find isolating valves which are brass-bodied fittings with a largish screw slot in them. These slots will currently be aligned with the pipes, and to turn them offski you need to turn them thro' 90o - they might only turn one way. Ok, once you've identified these two valves, what you need to do is first check the boiler pressure (ideally with it cold) and top it up to 1.5bar (ish) if needed. Then turn the power supply to the boiler offski - it must NOT come on. Give both of these valves a quarter turn, and leave it for a good few hours - for as long as you can during the day (or overnight if you prefer). Ok, once the time is up, open these valves again and then turn on the power supply. Check the pressure now and compare it with the original. These valves will completely isolate the boiler's system water with everything outside it - pipes, radiators, hot cylinder heating. So, if the pressure remains constant during this test, you can assume that any leak is not within the boiler. If the pressure drops as soon as you open these valves, then you can assume that there's been a leak in the radiator/hot cylinder circuit.
Thank you so much for your reply and instructions. I've been in touch with my brother but he is not able to do it until Monday. I'll post the results then. Thank you again.
Hello again, Just had a quick look and the 2 flow pipes you described appear not to have the 'screw heads' but instead they are fitted with a black plastic tap on each. I presume that by turning these taps as you described will have the same result? Must sign off now for the night, but I appreciate all your help. Hopefully I will make some progress on Monday, thank you.
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