Central Heating 3 Way Honeywell Valve Head getting hot

[cycletech]

Hi All,
I replaced a 3 way valve (V4073) as rads where getting hot when just HW on, that part is now fine. But after CH switches off, from room stat or from programmer/timer, there is a faint buzz coming from the valve head and after a short time the head becomes very HOT!
(If HW is still being called for then its fine)
If I switch the heating off from the mains, I hear the valve return to rest, so I switch mains back on and the buzzing stops and the head cools down.
Has anyone had this fault or knows how I can test?
The A & B ports are the right way round and I have checked wiring. This fault may have been there before and what caused the original problem, there has also been a ticking noise coming from the valve, more noticeable after only HW used. The system is gravity feed and is HW priority

Untitled

• cycletech
• 16 Nov 2014
• 1

Thanks Martin

 

[jackthom]

The head shouldn't get so hot when it's being held in the heating only position, it should only be consuming a few watts (around 6W allegedly).

http://www.diyfaq.org.uk/plumbing/controls/midpositionvalve.htm


Your drawing is slightly hard to follow but looks like the sundial y plan so I'd double check the wiring using the diagram in the guide below. Was the V4073 new ?

http://www.honeywelluk.com/Documents/Reference-Guide/pdf/940.pdf

 

[cycletech]

Hi Jackthom

Thank you for your reply

The head only gets very hot after heating is stopped calling and no HW called. Yes the valve was new and has been replace by a plumber and he replaced again as he thought was faulty!

The wiring is the same as link to Honeywell diagram, apart from room stat having no Neutral!
But I will check wiring again....
What I have found, but not sure if a fault, after I switch off CH and no call for HW, with the fault/buzz, I am getting a low voltage of 3.6v at terminals 4,5 & 8. 240v at term 6 & 7. Now if I turn up HW stat and then back down term 4,5,& 8 are now less than 1v.

If a currant of 3.6volts is a problem, I will disconnect each wire when in the fault position. I have already done this with room stat.


After reading the link you sent:

"In the central heating and hot water "both off" state, the system wiring results in grey being live. If the valve happens to be in the A+B or A port open position, SW1 will have been operated, the motor will be fed with AC, and the valve will wind to open port A and stay there (although the orange boiler output will not be live). This is a fly in the ointment for this valve configuration: the motor can be left consuming power and wearing out its hot windings unnecessarily (the spec says the valve consumes 6W). This will not happen in the summer though, when heating is never selected: SW1 will be at rest, and the valve will sit un-energised with port B open"


This sounds like the system is wired and working correct but there is a disadvantage, that the system when HW only turns off with no call for HW the motor will get hot and increase wear????
Is there a way round this?

I have set HW to 24hr and thinking that the HW will be called for and move valve and stop motor from staying hot for to long!![/i]

 

[jackthom]

Yes it only takes a call for hot water by itself to get the valve to return to it's rest position where there will no longer be power on the motor.

I'm surprised your actuator gets as hot as you describe but it's true that the motor is stalled, with the full 230V across it, when the valve is in the fully open heating-only position.

 

[cycletech]

Yes gets very hot, even more when heating/ hot water running!