Drained CH/HW system aftert refiling air clog in HW tank.

[tomton]

Hi,

System: standard open vented "S" plan ("C" plan till this afternoon), boiler and HW tank on the ground floor.

I have installed second zone valve which controls water flow from boiler to HW tank. To do it I had to drain CH and HW loop, now after refiling it looks like there is air clog on HW tank loop and I can't get rid of it, I have had bleed all radiators but I don't know how to bleed HW loop.

I don't have Auto Bypass Valve instead of it someone put normal valve which when open just directs all hot water back to boiler. I tried to shut it completely but after couple of secs I heard weird noise which I think was water bubbling in F&E tank but I'm not sure.

Any suggestions and ideas are welcome...

 

[twgas]

I take it you never put an air bleed on high point at cylinder

can you post a pic of your pipework

 

[tomton]

we bought this house last year and I know this installation is a mess, last winter HW was overheating because there was no valve to cut it of when it reached desired temperature.
we are planning on putting new combi probably next year but for now we have to use what we've got.

I take it you never put an air bleed on high point at cylinder

it doesn't look like its there :/

thanks

 

[ChrisR]

The lower of the two gate valves could be stuck shut. DOes it feel like it turns and operates properly?
Are you sure the new 2 port is opening?

 

[tomton]

yes I'm sure it works, at first i suspected faulty actuator so I've swapped them in CH/HW mode and CH was working fine but no heat on HW loop, I've also tried to open it manually with actuator removed but still no luck.

water goes through new valve when CH and AutoBypassValve are shut but its very slow and I'm afraid of those noises I described in my first post. I know that pressure is building up but i don't know where.

thanks

question: if the boiler is switched off (doesn't fire up) will water still go through it?

 

[buck51]

It looks to me like there is a drain cock on the lower connection to the cylinder try pulling water off from here, With zone valve and gate valve
closed one at a time

 

[tomton]

I've tried what buck51 suggested and it turned that valve on return pipe (just above "HW loop out" on the image) was stuck at 1/4 turn open with about 3.5 left to be fully open so water was just dripping, I had to use wrench and some force to open it, funny enough I don't remember touching this valve so it might have been in this position since we moved in... anyway everything is working now as it should

thank you all for your time and advice...

 

[Softus]

I've tried what buck51 suggested and it turned that valve on return pipe (just above "HW loop out" on the image) was stuck at 1/4 turn open...

The possibility of a closed valve was ChrisR's suggestion, actually.

 

[tomton]

The possibility of a closed valve was ChrisR's suggestion, actually.

you're right, sorry ChrisR

thank you all again...