Single 2 port valve

[alan999]

Hi
My friend has an old Potterton Netaheat system boiler. It is controlled by a single 2 port valve meaning the hot water must be permenantly on. There is also no room stat just a timer control, pump and of course the heat setting on the boiler.
The valve packed up. For a short while it could be operated manually by the lever. Now that too has given up the ghost. The valve is at least 20 years old. In short plenty of hot water but no central heating.

The 5 wires on this valve are very similar to the standard valve wires today. Grey, brown, blue and earth are the same, with red instead of orange. The electrician he uses is not 100% with heating controls so my friend asked me 2 questions and I wasnt sure of the answer to either.

Firstly would a modern 2 port valve be interchangeable with the old one treating the orange wire as red.
Secondly, could the wires be simply removed and the 2 port valve be substituted for a manual gate valve. That wouldnt be my choice but I would be interested in the answer all the same.
Thanks

 

[Whitespirit66]

Yes, the red and orange wires are the same. Your electrician can confirm this if he wants. With power isolated, disconnect the old valve's red and grey wires and latch the valve's lever to the 'manual' position. He should then have continuity between red and grey, as there is a microswitch between these 2 wires in the valve's head. Unlatched, there should be no continuity.

Nothing to stop you fitting a manual valve instead of motorised. Wouldn't use a gate valve though, as these are prone to seizing and breaking. Preferably a full bore lever valve.

Not difficult to fit motorised though. Unlikely, but if yours has a dimple on the vlave's metal cover, you can change the head without draining down system.

 

[alan999]

Thats a very thorough answer.
much appreciated.

 

[Whitespirit66]

Just realised you may not be able to latch your old valve, if it's kaput. Just take the head off, and you should see the red and grey wires go to the microswitch.

Good luck.