ATTN: Roger Mills (or any other CH/HW gurus)

[For Q2 M8]

Hi Roger, I don't have your email address but I could do with some more help.

Not sure if you remember my earlier posting:

I've ripped the house apart sorting this out, found several problems but no huge ones...

But the cabling and plumbing (radiators connected to the HW return > flow - HW tank to boiler ???) seems very different from the pdf I have > from the Honeywell site, didn't have much time - I'll check it again > tonight.

Ignore my earlier remark about the rads, the plumbing is fine, it crossed beneath the only floorboard I couldn't lift :(

So, the rads downstairs were cold in the middle so I drained the system and flushed them out with a hosepipe and a lots of waving the rad around in the garden. The donkey that did the plumbing put my drain tap at shoulder height (above boiler) so when I drained it I only drained the upsatirs and had to do the downstairs from the pipe I disconnected from a downstairs rad ! Might have to adapt this in the near future...

I've got a room stat from screwfix so I can control the CH better (once I've fitted it), but I still get scalding HW when the system is switched to CH only. I took the valve head apart, with no power, the valve returned by spring to the position I assume is port B open. switched power on - the valve remained at same position. switched to HW only - the valve remained at same position. switched to CH and HW - the valve moved very slightly (about 10deg of rotation ?) - should be point AB switched to CH only - the valve remained where it was !!! should go to point A !

I did these test with the CH cold and the HW warm and played with the tank stat to get the correct HW ON /OFF level that I required to test it, all the signals to the valve operate as expected i.e. the room stat and the tank stat are both switching over OK.

**** heres where I need help ****

So it seems the valve is not travelling to position B. Hence my HW is scalding and the stat tries to shutoff the HW but the valve isn't blocking port B to give port A only, but where is the fault ?

Is it the head unit (that I can replace) ? Is it the actual valve, can I strip it and clean it ?

Do you get the entire head assembly (microswitches & motor) as

40003916 ? My valve is marked "Head replacement 40003916-003 It looks like it's the whole thing: what is this, is this the innards of the valve ? "272742A CARD Replacement ball and ?O' ring kit for V4043, V4044 and V4073 valves."

I've ordered some stuff from screwfix, but I don't want to use it until I know what the problem is and if I will have to drain the system again...

16307 CENTRAL HEATING SLUDGE REMOVER 1 LTR 13162 CENTRAL HEATING INHIBITOR 1 LITRE 1

Many thanks for your time and effort, Sam.

email addr is OK if you want to reply direct: for_q2 [e-mail]

P.S and Merry Christmas whilst I'm at it ;)

[Christian McArdle]

Remove the head from the valve. Now try turning the valve position with pliers. If this is easily achieved, then the head is the problem. If it is stuck, then you may need a new valve. It may be possible to replace just part of the head, but this requires time to diagnose which part is wrong. You can get replacement switches and synchron motors easily enough.

I have no idea if you can service the valve portion. However, at 30-40 quid for the entire thing, I wouldn't bother.

Christian.

[Andy Hall]

Some manufacturers have the paddle or ball assembly as a spare part, but needless to say the merchants never seem to have them......

.andy

To email, substitute .nospam with .gl

[Test]

Christian, I did try to turn the spindle with pliers but it was rock solid. But when I reassembled it and watched the motor turn the spindle it seemed to turn to position AB OK, so I figured that it was meant to be stiff and it was a strong motor.

However, I'm not sure about it now. I thought a Honeywell v4073 was more like £70 than £30 ? £30 for the replacement head ?

Sam.

[Christian McArdle]

Well, actually looking at the figures, I wasn't thinking genuine Honeywell.

You can get (from Screwfix inc. VAT : Horstmann 3 port = 35.99 Danfoss 3 port = 44.99

It seems the Honeywell is a touch over 60 quid, though, from discounted heating. Myself, I prefer S plan and 2 port valves, anyway, as I like to subzone.

Christian.

[Andy Hall]

Given this situation, you may well have knackered the gearing assembly in the head.

It would be far preferable to replace the whole thing and be done with it.

The Honeywell V4073 lists for around £70 but you should be able to get it discounted down to around £55.

Discounted Heating have them for £62 inc. or other good makes for a few pounds less.

.andy

To email, substitute .nospam with .gl

[Ed Sirett]

70 at Homebase, 40 at plumbers merchant, 30 for the head only.

[Test]

Hi Andy, It was the spindle into the valve that I tried to turn, not the motor that drives it...

Should I try the sludge remover and hope it clears the blockage ? Sam.