Ideal Boxer C28 boiler losing pressure

[jon2003]

Before I rip up the floor boards, I just want to check I have considered all leak possibilities. There are no evident water leaks in or around the boiler. The same can be said for all radiators and exposed pipe work. There are no visible water traces on the ceilings. I therefore conclude I have a water leak on a pipe under the ground floor. I live in a semi-detached house by the way. But is this a reasonable analysis/elimination?

Could the pressure loss be caused by something else? For example, a faulty expansion vessel? What about the pre-charge pressure of the vessel, could that be an issue if low?

Just to give some perspective the pressure drops from 1bar to 0.5bar in less than 5mins. The pressure seems to hold at 0.5bar. Also, when the CH is switched on the pressure increases to 3bar. Does this seem a little high? Could any of this be related to the pressure drop? Any advice would be highly appreciated. Thanks for reading.

 

[kvsalamander]

Have you checked your pressure relief valve outside to make sure its not passing and dripping?

 

[kvsalamander]

Just read the last part of your post about heating going up 2.5bar. That is too much. it would be worth checking the pressure in the expansion vessel. If its not that then it would be worth contacting a gas fitter.

regards

 

[jon2003]

Thanks Ken for the prompt replies. Yes, I have checked the pressure relief valve, and the drain outlet outside. There are no traces of water. Also, I do not believe there is any flow problem (by checking the heat transfer on the CH flow). Perhaps the pressure increase is a separate/unrelated issue to the suspected leak. I just thought I would mention it in case relevant. Should I check the air pressure on the expansion vessel? Could it cause such a problem if low? I did press the valve and there was no water discharge from the valve (which is good). Thanks again for your reply.

 

[kvsalamander]

yes defiantly check the expansion vessel and see what pressure is in there, if you pressed the pin you should have had a puff of air come come out. Get a gauge and pump and hopefully thats all it is. Make sure you turn electrics off. Dont want to say too much more or ill get shouted at from the powers that be lol

 

[Agile]

You need to repesssurise the EXV in a special way, see FAQ.

Put a bag or bottle over the pressure release valve vent and you will probably find that it is leaking at some times!

Tony

 

[jon2003]

I finally got the expansion vessel re-pressured to 1bar, which incidentally was previously reading 0.2bar. I can now say when the system is cold the heating loop holds at 1bar. However, I still have the problem of too much pressure when I switch the heating on. After 5mins or so the pressure increases from 1bar to 2.5bar (and counting), before I manually shut off the heating. If I let the system go cold the pressure of the heating circuit returns to 1bar again - so no pressure is lost.

I guess the next thing to try would be to drain the system again, and re-check the pressure on the expansion vessel? Is this a worthwhile exercise? Any thoughts if this could still be an expansion vessel problem? It would seem a little suspect there was only 0.2bar before the re-charge. should I bite the bullet, and have a new expansion vessel fitted (which will be a couple of hundred pounds)?

I believe the flow is OK, all the radiators get warm in a reasonable time. I have also bled the radiators. Please let me know your thoughts. Thanks in advance.

 

[jon2003]

Maybe I should create an air lock in an unused radiator by draining it, and then introducing it to the heating circuit. That would work like an expansion chamber - right?

 

[Idealman]

I would say that the pipe connected to the expansion vessel is blocked poss at connection end on pipe work inside boiler casing this will cause boiler to over pressure because no expansion from vessel,have you checked for leaks inside casing of boiler only need slight leaking joint to cause pressure loss?

 

[Idealman]

Ref to your question if you drain a rad down this will give you an expansion gap for now and will do the same job as expansion vessel short term ,if pressure ok after you try this will say poss blocked pipe to expansion vessel,let me know how u get on,

 

[jon2003]

Thanks for the responses Idealman. Good call with the metal hose connected to the EV. I had not considered that. I will check it, and post back. I know when a plumber worked on this boiler in the past, the EV was left dangling out of the boiler by its hose. Thus there is every chance there could be a kink or blockage in the pipe.

I will also try the idea of creating a makeshift expansion gap.

The question I am pondering is if an EV does not leak water when pressing the valve, and it does not lose its charge pressure over time, does this mean the EV is in working order?

BTW, there is now no pressure loss, which is how this post started out. I am now just seeing too much pressure when the heating is on.

Thanks!

 

[Idealman]

Yes ok no pressure loss now,just over pressure I would say it sounds that hose is blocked like I say drain down boiler check hose both ends and pipe work in boiler for blockage were expansion pipe connects to,

 

[SortedPlumbing]

Hope your a competant person ie gas safe registered. As the expansion vessel on this boiler requires a combustion casing to be removed.

 

[Agile]

Are you sure you followed the FAQ procedure?

If you repressurise with ANY pressure in the heating system it just will not work!

Tony

 

[jon2003]

Hi Tony, I did not drain the full system if that is what you mean; I just drained the boiler, and then pressurised the EV to 1bar. I then opened the drain valve again, checked the EV pressure, and repeated as necessary, until I had a constant of 1bar.

The only doubt I have is the accuracy of the pressure gauge on the pump I was using. Out of curiosity would an over inflated EV cause the heating system to over pressure? Should an EV have water inside it when the system is cold? Should an EV have water inside it when the system is hot?

Thanks!