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Andrew Smith
Andrew Smith, HVAC Technician
Category: HVAC
Satisfied Customers: 3776
Experience:  Heating and Controls engineer
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I have a Promax sl three years old, and the upstairs heating

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Hi there.
I have a Promax sl three years old, and the upstairs heating circuit has stopped working.
I HAVE REPLACED THE MOTOROSIED VALVE. Still no joy, i have swopped the head units between the upstairs and downstairs stats, upstairs works downstairs, noticed that i cannot hear the stat click, and the one downstairs has an led on it, if this is put upstairs the light remains on all the time.
Any ideas ?
Michael Ball
Does it still not work if you swap the stats over?
Can you check for power at the brown wire in the head that is not working?
Customer: replied 4 months ago.
I had 240 between live and neutral
Ok, valve should open.
Now check the switch wires that fire the boiler - grey and orange.
With the valve fully open you should be able to follow the power all the way from the permanent Live through the microswitch to the boiler.
Customer: replied 4 months ago.
Thanks Andrew, I am away from home until Thursday will check then, I guess you mean manually opening the valve? Is it possible that the replacement valve is faulty, what I don't understand is why the stat from downstairs if placed in place of the upstairs one,the blue led is permantly lit, and one wire had fallen out (grey) attached to the left hand side of the connection block, so I put it in with the grey bundle would this be correct?
It's hard to tell unless I see how it is wired and follow the wires.
It is wired as an S Plan - so all greys and oranges should be live when a valve is actuated and fully open
Customer: replied 4 months ago.
If you motor the valve over manually the boiler kicks in so the supply to the limit switch is there, I believe it is not getting a command to the motor?
But you have power to the Brown?
Customer: replied 4 months ago.
Hi Andrew
Thanks for your input it would appear new valve had a sticky micro switch after p..sing about got it working
No problem.
An occasion tap might help.
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