Constant Loss of Pressure Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Gasman]

Hi, I have an ongoing problem. It has been going on for about 2 months now. I keep losing pressure in my central heating system. I have an Ideal combi boiler which was fiited June 2007. I have had 6 eginners visits in the last 2 months. They have looked ofr leaks and seem to find small ones fix them and go away. But the problem is still there. The last 2 visits I have had leak sealant put into my system but the problem persists. I have to refill the boiler 3 times a day. It goes from 1.5 bar to 0.2 bar withing hours. The amount of watter I am putting back into the system I would definetly would have seen a leak if my system was leaking. I can't hear any strange noises from the boiler or anything coming out from the overflow pipe outside. One of the enginners have stripped the boiler but couldn't find any leaks in the boiler. I have rang ideal today and they have advised to take the filling loop of and close both pipes. I have done that and I will see what hapeens in the mean tiem can anybody help. I also have anohter enginneer coming out on Monday.

[htg engineer]

For the amount of water you're losing leak sealer wont work.

It could be a few things, a leak under the floor downstairs (if there's any pipes there. As if it was upstairs you would have noticed by now.

Does the water discharge via the pressure relief valve ? maybe the PRV is passing

Does the pressure rise ? could be the expansion vessel or the plaste heat-exchanger - again the pressure would rise and discharge via PRV.

Any decent engineer would have checked all of the above.

So my bet is - and i've had a few boiler where this has happened (if it is a condensing boiler) the secondary heat-ex is split the water will be lost via the condensate discharge pipework.

Check the condensate pipework for excessive water discharge - quite difficult to diagnose as there will be water discharging if the boiler is on. Try with the boiler off - any running water ?

Hope this helps

[Gasman]

Thank you for your reply.

I will put all this to the egineer who comes on Monday. I live in modern house and the floor downstairs is concrete. I don't think I have any pipe work in the floors downstairs. Most of the water is lost when the boiler is being used central heating or hot water. The ideal boiler also pre-heats the water so it does come on its own every now and again. It is a condensing boiler.

Only odd thing is that even after bleeding all my radiators and topping the boiler up. When the boiler first starts its sounds like its dragging air around. This sounds dissapears after a minute but sound is always there when I use hot water even if the boiler is topped up. Where abouts do I find the PRV?

Thanks for all your help.

[htg engineer]

The pressure relief should discharge outside normally via a 15mm copper pipe. It'll be near the flue and condensate pipe.

[Gasman]

Hi,
The engineer came today and has isolated the boiler and switched it off. He switched it off and pressure hasn't gone down. He has also switched the power off. If the pressure stays stable does this mean there is a leak on my system and not the boiler. I thought the boiler would have to be running to determine weather there is a fault.