Central heating V4073 valve

8 Dec 2006
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United Kingdom
Hi All
Does anybody have a circuit showing the INNER wiring of the Honeywell V4073 Mid posn valve. I recently replaced the burnt out synchron motor in my system a couple of days ago and the replacement motor burnt out the next day. Further investigation shows that there is 240 volts applied to the motor which has run right up to the stop ( the heating only position) with heating calling and hot water satisfied. In this situation , 240 volts is supplied from hot water switch ' on' at the timeswitch through the cyl stat 'off' switch and on to the grey wire of the mid pos'n valve. This continues through a 'transferred' microswitch which is only 'not transferred' when the valve is in the 'hot water only' position. And Hey Presto , it is directly applied to the synchron motor at the full 240 volts. A further new motor is now fitted and feels very hot !!! The Honeywell descriptive leaflet gives no internal wiring detail but says " 240 volts on the grey wire via ' hot water satisfied' holds the valve at the last port selected"
I note that this voltage stays there even when the room stat periodically says that heating is satisfied. I have searched the internet for detail of the internal wiring diagram without success. I am trying to establish whether Honeywell expect the synchron motor to survive this stalled condition and whether my original motor died of old age , and my first replacement was a suspect new one. Rgds David C
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Yes the motor is expected to sit there stalled half its life :rolleyes:
Yes some of the new ones last five minutes :rolleyes: :rolleyes:
Thank you for your Reply Chris R

!5 years ago I retired from IBM as a computer engineer. We had a specialist called Tony Lenton who you could ring any time day or night and he would get you out of the SH*T
I called him this morning and asked if he had any 'call outs' lately . He straight away sugested I go to :-

If you go there the common of SW1 is the bottom terminal and the common of SW2 is at the top.

The circuit seems to conirm my fear and your reply.
Rgds David Cruikshank
Link not working , but I think I've seen it before. You'll also find a drawing on this forum if you dig.
Neither of them is quite correct in the detail!
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A bit of the link was missing for some reason
Last bit should have been

Rgds again
David C

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