Warmflow condensing boiler water pressure loss.

[JimH]

Hello everyone, I'm new to the forum... and would appreciate a little help?
I have a water pressure leak in my boiler warmflow "90 HE pumped". It is just over a year old.
I changed out the expansion vessel - pin hole leak in the bladder... the system held pressure for 2 days (2.5 bar) 25 deg C. Everything was fine until I lowered the temperature to 22 deg C, and the water pressure started dropping again?
I checked the pressure in the new expansion vessel - solid 1 bar (so it's working fine).
If the pressure is above 2.5 bar the water loss is very slow (25 deg C) - if below 25 deg C the pressure drops quite fast???
Before I start ripping up floorboards or replacing the vessel at the heat exchanger... can anyone suggest what might be wrong?
Thanks
JimH

 

[RTPS]

Try the PRV or the expansion vessel hose?

 

[JimH]

Thanks for the help... I'll check it out.

 

[rod A]

hi, Jim just checking facts 1 is the vessel at 1 bar checked with a tyre gauge when cold? 2 is the system pressure between 1 to 1.5 bar when cold , 3 volume of water in system i.e how many radiators , these are factors with this type problem. regards Rod

 

[JimH]

hi, Jim just checking facts 1 is the vessel at 1 bar checked with a tyre gauge when cold? 2 is the system pressure between 1 to 1.5 bar when cold , 3 volume of water in system i.e how many radiators , these are factors with this type problem. regards Rod

Hi Rod
There are 16 radiators of various sizes (9 downstairs, 7 upstairs).
When I checked earlier the pressure was 1.2 bar approx. (hot)
There is no leak at the PRV or at the cables
Jim

 

[Renewable M]

sorry to be daft if you've already checked this:

you know the pressure hot is higher than cold dont you? 1.2 bar hot could easily only be .3 to.6 when cold.

just ruling things out.

 

[JimH]

sorry to be daft if you've already checked this:

you know the pressure hot is higher than cold dont you? 1.2 bar hot could easily only be .3 to.6 when cold.

just ruling things out.

No problem, it was my fault.
I dumped the water from the system and took the pressure earlier tonight... It was 1.2 bar.
I forgot to add that the system also provides the hot water... the tank is in the loft... it always bothered me that the pressure inside the tank is 3.5 bar... the hot water from the boiler goes through a coil and returns via a common return pipe connected to the radiator return... I don't know if this is normal??
Even while losing pressure all the radiators are hot along with the hot water from the tank
Jim

 

[peteh20]

these boilers have a problem with the pipe from the primary to the secondary heat exchanger at the back of the boiler. the water dries out on the heat exchanger

 

[JimH]

these boilers have a problem with the pipe from the primary to the secondary heat exchanger at the back of the boiler. the water dries out on the heat exchanger

Hello peteh20, that sounds exactly right... I have excessive steam coming out of the flue long after the boiler has stopped & suspected a leak in the boiler piping or joints... I had done a system pressure test yesterday for over 4 hr, no pressure loss (2.5 bar)?
Sounds like there might not be a fix?
Jim

 

[peteh20]

the boiler comes with a 5 years warrenty talk to telford they will send out one of there engineers to confirm the leak i'll guess its on one of the welds with the baffle hangers if excessive vapour from flue good luck

 

[JimH]

the boiler comes with a 5 years warrenty talk to telford they will send out one of there engineers to confirm the leak i'll guess its on one of the welds with the baffle hangers if excessive vapour from flue good luck

Many thanks peteh20