Glowworm 30ci pressure loss

[marev]

About 3 weeks ago our 30ci combi started losing pressure overnight (whilst not in use). The pressure would drop from the standard 1.0 down to 0.6 and shutdown the boiler with the red LED flashing. I had to top up the pressure every morning. However the pressure loss has now got progressively worse to the point where i have to top it up every 2 hours.

I have checked the whole system for leaks and there are definately none. There is also no water loss from the overflow.

An engineer called yesterday and confirmed there are no leaks, and he is stumped as to the reason for the pressure loss. He called Glowworm and were stumped as well.

Could the pressure relief valve be the cause even though there is no water being dumped out of the overflow?

Has anyone got any suggestions.

 

[Gasman1015]

No, not the prv if not leaking outside.
Expansion vessel requires replacing/checking.

 

[corgiman]

wouldnt say the expansion vessel needs replacing as the boiler isnt on overnight, no heat= no expansion

probably got a leak somewhere on system, and a biggun too

 

[Gasman1015]

Determine whether its a system leak or boiler by isolating flow and return
valves below boiler, while the boiler is off, leave for two hours.

 

[marev]

Determine whether its a system leak or boiler by isolating flow and return
valves below boiler, while the boiler is off, leave for two hours.

So to confirm that would be the following 3 isolating valves as detailed in the manual: "heating flow" the "cold water in" and the "heating return".

By the way, having previously mentioned there was no water being dumped by the prv, it has now suddenly started dumping water every time we use the heating and the pressure drops to 0.3.

 

[andsam]

Prv requires replacing. Also expansion vessel may need repressurising or the flexible hose to it needs cleaning. I would also clean the seating on the pressure sensor. I would not attempt to repair these faults unless you are an experienced corgi fella as removing the exp/vessel hose is a nightmare at the best of times.

 

[corgiman]

how do you make that out when it has been said that no water is coming out of the prv????????

 

[andsam]

Determine whether its a system leak or boiler by isolating flow and return
valves below boiler, while the boiler is off, leave for two hours.

So to confirm that would be the following 3 isolating valves as detailed in the manual: "heating flow" the "cold water in" and the "heating return".

By the way, having previously mentioned there was no water being dumped by the prv, it has now suddenly started dumping water every time we use the heating and the pressure drops to 0.3.

Sorry corgiman what did you say?

 

[marev]

An update:

Did as suggested by gasman1015. I topped the pressure back up to 1.0 and then shut off the main flow, heating flow and heating return valves. Checked it 3 hours later and the pressure had dropped to 0.5 so i presume that rules out a system leak and confirms a problem within the boiler.

Re-opened the valves and put pressure back up to 1.0.

Still had the problem with prv dumping water so the engineer fitted a new one yesterday. Turned on the heating and within 5 minutes the new prv also started dumping water. So obviously that wasn't the cause.

Engineer is coming back to fit a new heat exchanger but i think its more a process of elimination because he said the current exchanger looks fine with no visible rust or holes.

Before he fits the exchanger is there anything i, as a competent DIY'er, can safely check or clean.

Just to add, the pressure now sometimes drops down to zero.

 

[andsam]

I have given you the solution on a previous thread. Who has suggested the ht/ex is at fault ? Also if its a process of elimination why is he changing one of the most expensive part on your boiler first ?

I can tell you now if he fits the main ht/ex the fault will persist and you will be approx £200 down.

And if he continues on this course he will change the plate to plate next and I am pretty sure this will not solve it either.

 

[marev]

I can tell you now if he fits the main ht/ex the fault will persist and you will be approx £200 down.

Fortunately i have breakdown cover so any repairs are free, (apart from the monthly direct debit of course). They can keep chucking as much money as they like at it as long as it gets fixed.

The way its going it will be cheaper for them to replace the whole boiler because it is only 18 months old and is still under guarantee.

Thanks for the earlier suggestions, sorry i missed your post.

 

[andsam]

Dont be too sure. If its under warranty from the manu/fac and they find it is sludge causing the problem ( which it may be ) they may cover it on this occasion but they will suggest it is powerflushed before they replace any more parts.

 

[gasgeezer]

you say the engineer replaced the prv did he check the exp. vess. pressure as mentioned previousely.if not get him to check it also the exp. tube if blocked will give the same symptoms i suspect one of these is the problem.

 

[marev]

if not get him to check it also the exp. tube if blocked will give the same symptoms i suspect one of these is the problem.

Is it safe for a DIY'er to check the pressure and pump up if required using a pressure gauge foot pump. Or is it best left to the pros?

 

[marev]

They replaced the heat exchanger yesterday and surprise,surprise within 5 mins the prv still continued to dump water. So thats £200 they wasted on the heat ex. (doesn't cost me anything)

I then suggested they should check the exp vessel and in particular the pipe leading to it. They are coming back at the weekend to investigate further and hopefully will follow my (your) expansion related suggestions.

I'll let you know the outcome.