Wiring on 3 port valve.

I have just fitted a new 3 port mid position valve to my y plan central heating system. Now the valve doesn't move to switch the heating, it only works on water. I'm sure I connected the wires as before and even replacing the old valve doesn't rectify it. I am at a loss here. If I move the lever from auto to manual then the heating comes on and the pump starts.

Reply to
barrowfordred
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Did you check the operation of the timer and/or wall thermostat? It may be you have swapped a good 3-port valve for another 8-(.

Reply to
Ed Sirett

Which make of valve was it? colour code varies slightly, but it's eas to get right if you have the wiring diagram with the new valve

-- Paul Barker

Reply to
Paul Barker

Thanks for the replies. The old valve was a Honeywell V4073 the new one is a Horstmann Z32 from screwfix. The wiring colours are identical, I swapped them on a one to one basis. The new and old valve will not power up. They stay in the sprung position. I have noticed that the white wire (to room thermostat) is always showing current, even when it shouldn't. Trying to get a decent electrician to look at it is like doing the lottery.

Reply to
barrowfordred

Further to this - I have checked the operation of each wire and it is wired correctly. The valve is brand new. Even with current to the blue (neutral) wire nothing happens. When I operate the lever it fires up but then shuts itself off as it returns to the spring position. Strike me the valve is faulty, although how both of them are faulty is beyond me. The old on was replaced because the valve operating stem was sticking.

Reply to
barrowfordred

barrowfordred was thinking very hard :

I would be inclined to double check that the two manufacturers models are both absolutely compatible and that the wiring colours used are identical (or you know how to translate them).

If you mean the actuator... They most often stick such that the return spring is fully wound up. Joggling the actuator is usually enough free them and cause them to return under the springs force.

The actual valve stem (the brass bit) should turn quite smoothly and freely. You should almost be able to turn it with just your bare fingers.

Reply to
Harry Bloomfield

The old spindle was very hard to turn and only moved a few degrees either way. The wiring is identical according to both wiring diagrams for the 2 units. I am at a total loss here. The problem is in the motor movement (or lack of it) on the 2 valve units.

Reply to
barrowfordred

barrowfordred explained :

So far as I am aware, they all should turn freely the full 360 degrees. Someone might be able to confirm this?

Have you checked to see if the actuator when not installed on the valve works?

The seized up valve would seem as if it might explain the problems you are having.

Reply to
Harry Bloomfield

Tha actuator isn't connected to the valve yet. The new valve is in place and moves freely. The movement should be about 30=B0 each way. The actuator is the problem. It doesn't move when it should.

Reply to
barrowfordred

Sorry, I misinterpreted spindle to mean the spindle on the valve...

So that just leaves...

  1. a problem in your wiring of the new actuator (which you say you have re-checked)
  2. a new problem in the main wiring
3.a fault with the clock or room thermostat.

I don't have a copy of the circuit, but I would be inclined to check the voltage does change on the input to the valve, when the room stat is switched back and forth... Then work back from there.

Reply to
Harry Bloomfield

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Reply to
Old Bill

It is possible that the new unit is duff. The most likely is that the motor is bad. A quick test of its continuity should be a pretty good indicator. IIRC the horstmann valves move further than the honeywell on the manual lever. So when you move it it goes fully to CH and that fires the boiler which is correct. In HW only and mid position then the HW demand fires the boiler.

Given the symptoms a failed motor in the new valve would be a possible cause, including not being able to stick in mid pos.

Reply to
Ed Sirett

Try descaling the valve. In my new house in a very hard water area, the three way valve went very stiff after about 2 years, noticed in the summer as the radiators were warm. Removed the valve, with out draining the system, by use of bungs etc and found the valve stem encrusted with scale on the inside.

Descaled using descaller, re-assembled using a light coating of grease and have been fine ever since.

Reply to
Ian_m

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