Losing pressure in Central Heating system - going crazy!

ThisIsWeird

More exciting!
A thought, I wonder how much water leaking from a cracked exchanger will simply be turned into steam and shoved out the flue?! I'd always assumed that it would end up in the condensate, but a boiler turned up high so only partially condensing is as likely to evaporate the leak, and dispose of it out t'flue.
So, good call checking the flue gas too - that had not occured to me

cheme7676

ThisIsWeird said:

More exciting!
A thought, I wonder how much water leaking from a cracked exchanger will simply be turned into steam and shoved out the flue?! I'd always assumed that it would end up in the condensate, but a boiler turned up high so only partially condensing is as likely to evaporate the leak, and dispose of it out t'flue.
So, good call checking the flue gas too - that had not occured to me

Hold on to your seat, it just got more exciting!!

Right, so I put the green food dye (120ml A LOT i know) into a radiator like 30 mins ago. Kept CH off (it hasnt been on since 16:30). I wasn’t expecting the dye to disperse that quickly.

in any case, after the dye was put in, I started using some hot water to get things going (left boiler unisolated). I then checked condensate trap and I noticed the slightest shade of discoloured water, but inconclusive, it could be the dirt that accumulates from combustion etc right?

So I take trap off, wipe a bit with some tissue around the outlet, and I’m almost certain of a tint of green.

With the HX hot due to useage of water, I isolated, then noticed that the pressure is rapidly decaying close to zero, takes about 5 mins from 1 bar to near zero.

I’ll keep using hot water for a few hours to keep the HX hot and the crack open, il write back here my findings and how that water colour develops. Il need to keep allowing CH water into the boiler by deisolating every 5 mins to keep the green dye entering

If it turns out to be the HX, despite me needing to fork out a huge amount, it’ll give me huge piece of mind. Il also be swapping out all old rads and putting stainless steel in all wet rooms. New valves on EVERY rad too. We aren’t taking any prisoners.

cheme7676

Also an issue I’m facing, boiler isolated at 0.4 bar, and even when only using DHW was rising fast towards 2.5 bar+ so I quickly deisolated. Seems like I’m unable to do that test.

not that it should matter with the dye in the system, given I can see green in the condensate anyway. If anything keeping it deisolated will allow the dye into the boiler and prove the result

cheme7676

Final update: Viessmann Vitodens 050 35kW ordered. Also brand new radiators with new valves ordered for entire house. Gas safe engineer expected to come within the next couple of weeks to install everything. Thanks all for your help

ThisIsWeird

Phew!

It does all suggest a failed MainX.

The isolated boiler shooting up in pressure suggests a non-functioning EV - that shouldn't happen.

And the very obvious drop in pressure from 1 bar to zero on the isolated boiler might just be due to the boiler cooling and the small amount of stored water inside contracting, espec with the faulty EV, but it's sooo dramatic a fall, that it does also imply the MainX.

Anyhoo, new boiler on the way! Chances are, by far I think, that the boiler was the culprit.

Donaldducking

Did this work? I also have a c35 ideal boiler, pressure all over the place dropping pressure while heating on, no visable leaks had BG out three times once for just the service ,they recharged ev then pressure dropped over night, then changed ev and pr valve and dropped over 6 days, no visable signs of leak anywhere.  It is doing my head in.  Why such random drops, currently dropping at night. Pressure 2.6 when hot and dropping below 0.5 Cold. 

cheme7676

Donaldducking said:

Did this work? I also have a c35 ideal boiler, pressure all over the place dropping pressure while heating on, no visable leaks had BG out three times once for just the service ,they recharged ev then pressure dropped over night, then changed ev and pr valve and dropped over 6 days, no visable signs of leak anywhere.  It is doing my head in.  Why such random drops, currently dropping at night. Pressure 2.6 when hot and dropping below 0.5 Cold. 

Sorry to hear you're having problems. It did work for me yes.

It's a bit unconventional, but I put food colouring into my system which told me within minutes that my boilers HX was faulty. Due to the nature of the crack, that was the only way I could find it.

If you've tried everything, there's no harm in putting some green colouring in and then monitoring the colour of your condensate trap. If the water in there starts turning green, that's your smoking gun that it's time to purchase a new boiler

ThisIsWeird

cheme7676 said:

Donaldducking said:

Did this work? I also have a c35 ideal boiler, pressure all over the place dropping pressure while heating on, no visable leaks had BG out three times once for just the service ,they recharged ev then pressure dropped over night, then changed ev and pr valve and dropped over 6 days, no visable signs of leak anywhere.  It is doing my head in.  Why such random drops, currently dropping at night. Pressure 2.6 when hot and dropping below 0.5 Cold. 

Sorry to hear you're having problems. It did work for me yes.

It's a bit unconventional, but I put food colouring into my system which told me within minutes that my boilers HX was faulty. Due to the nature of the crack, that was the only way I could find it.

If you've tried everything, there's no harm in putting some green colouring in and then monitoring the colour of your condensate trap. If the water in there starts turning green, that's your smoking gun that it's time to purchase a new boiler

Nice. I've heard of that as a suggestion, but never with an actual result!
Also heard of adding perfume, and sniffing everywhere.