Hi,
I've just replaced my old mechanical room thermostat with a new digital one. The wires coming out of the wall are coloured red, blue and yellow. I followed the guide (//www.diynot.com/wiki/electrics:how_to_replace_a_room_stat) but i'm now having a problem with the central heating. The setup is :
Potterton Suprima 40 boiler.
Potterton EP2000 (set to 'timed' on both HW and CH).
Honeywell DT200 room thermostat
Myson MPE322 mid-position valve.
Myson pump.
Potterton cylinder thermostat.
Only the red and yellow wires are connected to the room thermostat now. The problem is that the radiators are getting warm in the middle of the night. I ran some tests to find out what the MPV is doing as I suspect it is getting left in the CH position and conduction is doing the rest (pump off during the night). The tests were...
With the timer set to switch both CH and HW on.
Turned down both room thermostat and cylinder thermostat = Both MPV lights go off.
Turned up room thermostat = MPV CH light comes on.
Turned down room thermostat = MPV CH light goes off (both lights off now).
Turned up cylinder thermostat = MPV HW light comes on.
Turned up room thermostat = MPV CH light comes on (both lights on and value in mid position).
I also replaced my corroded mid-position value but it was like-for-like and i'm pretty sure I re-wired it correctly, although i'm having my doubts now.
Does anyone have any idea what might be causing this problem. I'd be grateful for any advice whatsoever. I'm not a plumber or electrician but I used to be a car mechanic so I tend to try and work things out for myself.
.
thanks in advance,
Bill.
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I've just replaced my old mechanical room thermostat with a new digital one. The wires coming out of the wall are coloured red, blue and yellow. I followed the guide (//www.diynot.com/wiki/electrics:how_to_replace_a_room_stat) but i'm now having a problem with the central heating. The setup is :
Potterton Suprima 40 boiler.
Potterton EP2000 (set to 'timed' on both HW and CH).
Honeywell DT200 room thermostat
Myson MPE322 mid-position valve.
Myson pump.
Potterton cylinder thermostat.
Only the red and yellow wires are connected to the room thermostat now. The problem is that the radiators are getting warm in the middle of the night. I ran some tests to find out what the MPV is doing as I suspect it is getting left in the CH position and conduction is doing the rest (pump off during the night). The tests were...
With the timer set to switch both CH and HW on.
Turned down both room thermostat and cylinder thermostat = Both MPV lights go off.
Turned up room thermostat = MPV CH light comes on.
Turned down room thermostat = MPV CH light goes off (both lights off now).
Turned up cylinder thermostat = MPV HW light comes on.
Turned up room thermostat = MPV CH light comes on (both lights on and value in mid position).
I also replaced my corroded mid-position value but it was like-for-like and i'm pretty sure I re-wired it correctly, although i'm having my doubts now.
Does anyone have any idea what might be causing this problem. I'd be grateful for any advice whatsoever. I'm not a plumber or electrician but I used to be a car mechanic so I tend to try and work things out for myself.
.thanks in advance,
Bill.
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