Noisy 3 Way Port Valve?

[wbjimmy1]

It’s‘ probably a coincidence but ever since I had an auto bypass fitted (which required some pipework alterations in my airing cupboard), I’ve been getting a vibration noise when my programmer instructs my Honeywell 3 way port valve to switch from Heating only to Heating and Hot water. My plumber replaced the auto bypass valve but it has made no difference. So I believe it’s either coming from water turbulence within the altered pipe work or, the 3 way port valve itself.
The vibration starts almost immediately the programmer calls for hot water ( in addition to Heating) but lasts only a couple of minutes. I can stop the noise by moving the lever on the 3 way valve to the “ manual” setting but it comes back when I “unhook” it and it returns to “ Auto”.
I’ve replaced the motor but that made no difference. Before I call back my plumber do you think I might get away with just replacing the valve head or do you think the whole unit needs replacing and/or pipework altered?

 

[ianmcd]

post pics of your mid position valve and by-pass and show as much of the pipework between them as possible might be something silly

 

[wbjimmy1]

Here are some pics from the airing cupboard.

 

[ianmcd]

The auto by-pass is fitted wrong, why did you think you needed one with a Y plan anyway ?

 

[wbjimmy1]

My plumber recommended it when he replaced my cylinder a couple of years ago. I wasn’t wholly convinced at the time but I’ve used him for a lot of other work so I trusted his judgement. You will see from the pics that it has isolating gate valves on either side. If I close them to disable the bypass is it likely to help or do I need to get it refitted/ removed? In the meantime can I just keep the 3 way valve on manual to stop the noise?- I don’t really want to get a plumber in during the current lockdown if I can avoid it.

 

[wbjimmy1]

P.s. He also fitted TRVs to all my rads.

 

[ianmcd]

The joint I have marked needs to be on the pipe coming up to the middle of the mid position valve , will be marked AB on the body of the valve

 

[MeldrewsMate]

The auto by-pass is fitted wrong, why did you think you needed one with a Y plan anyway ?

IMO that comfiguration is quite acceptable, the ABV will operate when on Heating only, once the TRVs start to gag down.

OP, try repeating the test with the heating thermostat turned high. Does it still vibrate when switching from CH only to CH & HW?
Does its vibration pattern change if you alter the setting of the gate valve (on the cylinder outlet, low down, just after that ghastly 4-elbow chicane)?

On rare occasions (very rare) I have seen the Honeywell rubber ball within the wet part of the valve come loose on its actuator, and this may cause your vibration, but it's best not to jump to conclusions before the evidence is presented!
Replacement parts for this are quite cheap, but involve an element of draining down to fit.
Did you replace the 'motor' with a genuine Synchron motor/gearbox unit? There are some cheap and nasty alternatives about....no surprise when the genuine article costs about £30!!

 

[wbjimmy1]

Thanks Meldrewsmate. I’ll try retesting as you suggest and report outcome. I can’t recall the make of the replacement Synchron motor ( I didn’t replace the whole head) but I do have a spare genuine Honeywell 3 way valve (complete unit) if I need to replace it or just the detachable head.

 

[wbjimmy1]

OK this is what happens. Programmer set at HW off, CH on, Room thermo not calling for heat and No tension on 3 way valve.
When the programmer switches on the HW, the 3 way valve is tensioned and the vibration starts. The vibration can be stopped if I turn up the room thermo and it calls for heat or I release the tension on the 3 way valve and set to manual.
Also The vibration noise changes if I turn the lower gate valve from the cylinder ( as you suggested ) and disappears if I close it fully.

 

[wbjimmy1]

Following my earlier text is anyone able to suggest the most likely cause of my CH noise problem or what other tests I can do to narrow down the possible culprit?

 

[wbjimmy1]

Is anyone able to provide a response to my earlier post which has gone unanswered since Feb?

 

[oldbuffer]

Check to see if the isolating valves for the auto bypass have directional arrows on them. For most it doesn't matter which way round they are, but there are exceptions. The valves are on opposite ways round in terms of the flow of water through them. Its a possible cause of vibration, but fairly unlikely.

 

[ianmcd]

Open the black handled valve above the connection for the ABV, and slacken the air bleed point above it until water comes out, it might just be trapped air, do it with the system switched off

 

[wbjimmy1]

Thanks “oldbuffer” and “Ianmcd”. The ABV alignment is OK and I’ve bled the valve. No change. Because the noise disappears when I turn up the room thermostat or close the lower gate valve from the cylinder I’m beginning to think it is either (a) a faulty gate valve (b) a sticking ball in the 3way port valve, or (c) turbulence in the pipework (which was altered when the ABV was retrofitted). Can you think of anything else or any way of ruling out any of these potential causes?