Honeywell 2 port zone valve question

[Johntheo5]

So, does it only happen when the "last" zone valve closes, whichever one it is, CH or HW?.

 

[Mister Banks]

No, it only happens when the heating zone valve closes and it appears to make a difference depending on how many TRV’s are closed/open.

 

[Mister Banks]

The other strange thing is that the thud changes in volume and changes location!

 

[Johntheo5]

Going back to the ABV again, if the CH is on only (no HW) and even if some TRVs are throttled down or closed is there still no bypassing through the ABV?

 

[Mister Banks]

Going back to the ABV again, if the CH is on only (no HW) and even if some TRVs are throttled down or closed is there still no bypassing through the ABV?

No, the pipe exiting the ABV is cold until it activates. The pipework from boiler/pump is about 4.5m of 32mm copper reducing to 28mm into the ABV and zone valves.

 

[Johntheo5]

With the CH only on can you adjust the ABV very very slowly until it just starts bypassing then shut off the CH.

 

[Mister Banks]

With the CH only on can you adjust the ABV very very slowly until it just starts bypassing then shut off the CH.

I can do that later this afternoon, what results should I be looking for?

 

[Johntheo5]

No more knocking!!. Of course one might expect the HW valve to cause the same problems when it closes, maybe something peculiar to the CH 2 port?.

 

[Mister Banks]

No more knocking!!. Of course one might expect the HW valve to cause the same problems when it closes, maybe something peculiar to the CH 2 port?.

The knocking mainly happens in the evening and not every time the valve closes so a bit of a experimentation and patience will be needed on my part.

 

[ianmcd]

the Drayton system starts and stops the pump

The drayton does not stop or start the pump the zone valves do

 

[Mister Banks]

The drayton does not stop or start the pump the zone valves do

That’s kind of what I meant, in a round about way without getting into the technicalities. I’m pretty clued up on how my heating works

 

[Mister Banks]

With the CH only on can you adjust the ABV very very slowly until it just starts bypassing then shut off the CH.

I can turn the ABV all the way down to 0 and nothing happens. The pipe coming from the ABV stays cold. The pipe going to the ABV is hot. I have left the ABV setting on 2.

 

[Johntheo5]

Something has come adrift there I'd say, think I say something somewhere about recalibrating them.

 

[Mister Banks]

Something has come adrift there I'd say, think I say something somewhere about recalibrating them.



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I wondered if turning the ABV down and the valve not opening was not right. The ABV does operate when the zone valves are closed but presumably it needs a lot of pressure to do so.

 

[Mottie]

I’m investigating an issue where randomly when my CH thermostat stops calling for heat the boiler and pump (it’s a system boiler) turns off and I hear a pipe knocking with a single thud somewhere in the ceiling. This happens whilst the pump is still in overrun and doesn’t happen all the time. My question is, can I manually latch the CH zone valve open without damaging the motor in the valve head. I want to check if it’s the zone valve closing that causes the thud.

Thanks

I had the same with mine a few years ago. It turned out to be the auto bypass valve opening. Adjusting it cured the problem. Happened every night about 15 minutes after going to bed. I ended up finding it by holding my hand on the ABV and as soon as the heating or hot water reached demand or the system switched off, bang! As it opened.