Air Problem in Open Vented System after Boiler Change

[ThePook]

Looks like you piped this yourself, and the GSR installer was happy to sign this off?

No, not at all. They installed to existing system. Old pipework is not great.


Air separator was installed by the GSR, after air problems started, and.because the original flow went downhill from the boiler to the vent. At that stage there was no cold feed to it. Can see the old cold feed and vent pipes cut off at the top right, but as I say, they both run compromised routes.

Only pipework changes I have made were after the air problems became apparent. I found that the (existing) vent had air traps in it so ran a new vent in 22mm uphill all the way, moving the tank to suit it's entry into the loft above a wardrobe. I ran a 15mm in alongside, so I could try separate feed/vent to see if that alleviated the problems. They take an odd route through garage as is the only way to ensure constant rise and avoid crossing joists.

The reason that the new cold feed and vent have compressions to connect to the air separator is so that I could avoid the need to fully drain down, and flush the newly soldered pipework offline before finally connecting. I simply isolated at the filter and the pump to keep the system full while I did this.

Hope this helps understand.

 

[Riley]

I think people have asked as in the normal circumstance the responsibility should be with the installers to sort it

 

[ThePook]

I think people have asked as in the normal circumstance the responsibility should be with the installers to sort it

Agreed, and understand your point.

Unfortunately, I am really not keen on the solution of sealing the system.

Thanks again all for your suggestions.

 

[Harvest Fields]

Sometimes sealing is the only option.

 

[Riley]

Agreed

 

[king of pipes]

I had a similar installation where pipe work was 30 years old buried in screed floors I upgraded the system fitted a Worcester heat only system boiler so sealed it ,also added a sealed system kit and extra expansion vessel but added a pressure reducing valve to the filling loop so I could keep the system at a low pressure thus being sealed, air is pushed out when filling and venting but does not go above 0.5 of a bar expansion is taken up in the expansion vessels and when at 65- 70 degrees c does not rise above .75 of a bar this could work for you as a last resort but I think you need to rule out any leaks on the system first. Kop

 

[ThePook]

I had a similar installation where pipe work was 30 years old buried in screed floors I upgraded the system fitted a Worcester heat only system boiler so sealed it ,also added a sealed system kit and extra expansion vessel but added a pressure reducing valve to the filling loop so I could keep the system at a low pressure thus being sealed, air is pushed out when filling and venting but does not go above 0.5 of a bar expansion is taken up in the expansion vessels and when at 65- 70 degrees c does not rise above .75 of a bar this could work for you as a last resort but I think you need to rule out any leaks on the system first. Kop

Thanks, that's a good suggestion to include an extra expansion vessel to minimise pressure increase as it heats up. If I do have to seal, I will make sure a larger one is fitted.

I completely agree that there is something else fundamentally wrong, which needs fixing itself before sealing up. That's basically where I am at, and do plan to seal in future, but only after a repipe.

I guess the part I struggle to understand is how/why sealed with 0.5bar at expansion vessel connection (presumably near boiler/pump) would make the system behave significantly differently to how it is now with approx. 0.45bar static head at the pump?

Water level in expansion tank had risen approx 6mm this morning, but system was slightly warm. Will keep an eye on it and check again at the same time and temperature.

 

[gmartine]

I guess the part I struggle to understand is how/why sealed with 0.5bar at expansion vessel connection (presumably near boiler/pump) would make the system behave significantly differently to how it is now with approx. 0.45bar static head at the pump?

No air ingress, lesser corrosion, increased efficiency and far easier to remove trapped air without the need to turn on the system.

What makes you think your pipework (which has survived for decades) won't be able to take the relatively small increase in pressure from a sealed system?

 

[gmartine]

Oh and you have a manual vent on the return, I'd probably replace that with a bottle vent which would at least prevent any trapped air from being recirculated.

 

[fixitflav]

Sorry, don't understand that, is it something I said?

Neither do I. Can't rule anything out at this stage, as the politicians say!