Automatic Bypass Valve Query

[Tigermad]

I had an automatic bypass valve fitted to my unvented system yesterday and it was left at 0.4. Goes from 0.1-0.5. Anyhow I thought I would set it today according to the instructions. So I closed it off completely to th 0.5 mark and then turned all the trvs on. I then began turning it until the pipe started to get warm. Problem is the abv is in the airing cupboard and it is fitted to the pipes marked flow and return. The flow pipe is hot but the return pipe remains stone cold. Even after leaving the heating on for 10 minutes. So turning the valve makes no difference. Am I doing something wrong? Why is the return pipe stone cold?
I just tried turning the heating off and the pipe from the ABV got red hot even though the ABV is turned off

Ignore the non copper pipes. These are from the old system and are redundant.

 

[John.g]

Perhaps, but you did say that the return is cool in comparison to the flow, try again after say 20 minutes, and let us know the result.

 

[Tigermad]

Perhaps, but you did say that the return is cool in comparison to the flow, try again after say 20 minutes, and let us know the result.

Thanks. So do I have to turn all rads fully on our can i just do it to 1 to make the boiler fire up and stay on? Bit of a pain having to keep going round them all

 

[Tigermad]

Hi. Another question. This isn't my cylinder but I have one of the little white cylinders too. But mine is at floor level. What is it?

 

[John.g]

Just 1 will do, just make sure the boiler is firing, thats all, or if you go to the boiler now and feel the Flow (top) pipe it should be quite hot, once it is just open up the AAV and both sides of it should get very hot as well in a very short time.

The "white cylinder" is a expansion vessel.

 

[Tigermad]

Just 1 will do, just make sure the boiler is firing, thats all, or if you go to the boiler now and feel the Flow (top) pipe it should be quite hot, once it is just open up the AAV and both sides of it should get very hot as well in a very short time.

The "white cylinder" is a expansion vessel.

Thanks. Just ran it with 1 on for literally a few seconds and it got red hot straight away. Wonder why it didn't do that earlier.

 

[John.g]

Both sides of the AAV got red hot??

OK' it looks as if it did, now can you set the AAV (temporarily) to index setting of 0.2 with boiler on, then stop the boiler and see if you are still getting that whooshing sound from the rad.

 

[Tigermad]

Both sides of the AAV got red hot??

OK' it looks as if it did, now can you set the AAV (temporarily) to index setting of 0.2 with boiler on, then stop the boiler and see if you are still getting that whooshing sound from the rad.

Thanks. Yes red hot. It only makes the crackling sound now and again. I can't make it do it so will have to test over a few days. Just for info when the boiler fired up the water loudly gushed around all the pipework for about 30 seconds or so.

 

[JTplumbingservices]

Hi. Sorry for the late replies I did not get notifications. The boiler is downstairs under the stairs directly below the airing cupboard. The pump is in the boiler I don't have one seperatesl as far as I know

From what I’m gathering from your info the flow is on the right hand of the pic and the zone valve is on the return. If this is the case then B has to go to the boiler for it to work the way it’s been piped.

 

[John.g]

Thanks. Yes red hot. It only makes the crackling sound now and again. I can't make it do it so will have to test over a few days. Just for info when the boiler fired up the water loudly gushed around all the pipework for about 30 seconds or so.

Gushing sound; sounds like air in the system.

 

[Tigermad]

From what I’m gathering from your info the flow is on the right hand of the pic and the zone valve is on the return. If this is the case then B has to go to the boiler for it to work the way it’s been piped.

Yes that's correct.

 

[Tigermad]

Gushing sound; sounds like air in the system.

There's nothing coming out of the rads when I bleed apart the from the towel rail that needs bleeding every week or so because the toprails don't get as warm. Lots of air comes out when I do that which is strange for a sealed system. Been doing it for over a year.

 

[JTplumbingservices]

There's nothing coming out of the rads when I bleed apart the from the towel rail that needs bleeding every week or so because the toprails don't get as warm. Lots of air comes out when I do that which is strange for a sealed system. Been doing it for over a year.

If the towel rail constantly needs bleeding and nothing else does then it could be an issue with the towel rail which is quite common

 

[John.g]

Is there a AAV (automatic air vent) or a number of them in your system, if there is just check if the little cap on the air nozzle(s) on top of the AAV is open or shut, some prefer just to open these occasionally just to check for any air once all the air has been expelled after a drain down/refill of the system.

What pump/model have you got and what setting is it on?.

 

[Tigermad]

Is there a AAV (automatic air vent) or a number of them in your system, if there is just check if the little cap on the air nozzle(s) on top of the AAV is open or shut, some prefer just to open these occasionally just to check for any air once all the air has been expelled after a drain down/refill of the system.

What pump/model have you got and what setting is it on?.

Hi. No aavs on system. The only pump I have is inside the boiler as far as I know. Is that right for an unvented system?

 

[John.g]

That's correct (gas boiler) and you can't access it (not GSR) , post #57 above suggests that it could be a issue with the towel rail.

I meant to ask you this before, why did you decide to fit a ABV??, was it because the boiler manufacturers require it or some other reason.