Loud clunk from motorised valve

[jo23483]

When either of the 2 port motorised valves closes, I get a loud clunk. A Honeywell automatic bypass valve was fitted a year or so back to replace a gate valve bypass. I'm happy its in the correct position & orientation, Its set to 0.2 bar. I don't believe we had this clunk last year.

I suspect the automatic bypass valve has failed?

I note when I adjust it via the knurled knob, I feel no resistance, Only when it turned to up to around 0.5 bar I now feel slight resistance. It this normal. I was expecting a little spring push back, not a loose nut. I've no means to tell if there is any flow through the valve. As it's a complete drain job to replace, I'm looking for confidence that the diagnose is reasonable.
Any would be comments appreciated

Jo

 

[Deleted member 120897]

Sounds like it could be motorised valve failure.

 

[John.g]

Are you sure that the M.valves are orientated correctly despite no clunking last year??.

 

[jo23483]

Are you sure that the M.valves are orientated correctly despite no clunking last year??.

yes, pump, and all 3 valves are correctly orientated. The fact that I can get the clunk by turning off either MV (manually by the spindle) was pointing me to the bypass valve? Also how does a normal BP V feel when adjusted - turns with absolutely no resistance , sort of sloppy or firm with some resistance, say against a spring etc?

 

[John.g]

I havn't got a ABV but would expect resistance to increase as you are increasing the index setting. I would certainly expect it (if working normally) to be passing quite alot at the 0.2, 2M setting, is the pipe on either side of the ABV very hot, if so just screw it in to 0.5, see if the pipes cool off and then reduce the setting gradually until it just starts passing, if so, then can set up correct index later.
Have you a external circ pump?, if so post the mode/setting. If a gas boiler with a internal pump, post the make/model of boiler and whether a combi boiler.

 

[jo23483]

I havn't got a ABV but would expect resistance to increase as you are increasing the index setting. I would certainly expect it (if working normally) to be passing quite alot at the 0.2, 2M setting, is the pipe on either side of the ABV very hot, if so just screw it in to 0.5, see if the pipes cool off and then reduce the setting gradually until it just starts passing, if so, then can set up correct index later.
Have you a external circ pump?, if so post the mode/setting. If a gas boiler with a internal pump, post the make/model of boiler and whether a combi boiler.

Its an ext. pump: Grundfos UPS 15-60 130, on setting 2. Boiler: Worcester Greenstar 24Ri. I'll try the temp test & report.

 

[jo23483]

and its hot on both sides, I think I can feel the vibration of the flow through it.

 

[jo23483]

I previously stated the Drayton motorised valves ZA5 are the correct way round. I'm now not so sure. The brass body has no A, B marking. The actuator housing has a slide with A B on it. Water is flowing in the direction of the side A to B. The power cable is on the water entry side. i.e. water is flowing down wards in the image attached - is this correct?

 

[jo23483]

Sorry for the dribble info. I found the A & B marking on the MV, Water is flowing into Port B. So they are in fact the wrong way round and have been so for at least 15 years. I will reverse. Question; Will they have been damaged by this? and am I better to replace them?

 

[John.g]

If they are shutting off the flow as installed, I would just reverse them.

Sorry for the dribble info. I found the A & B marking on the MV, Water is flowing into Port B. So they are in fact the wrong way round and have been so for at least 15 years. I will reverse. Question; Will they have been damaged by this? and am I better to replace them?

Increase the setting to max, index 0.5/0.6, if passing at this setting, then ABV knackered.

and its hot on both sides, I think I can feel the vibration of the flow through it.