motorised valves

[philjw]

I have an old style boiler, hotwater tank and rafdiators. My radiators stopped coming on. I can turn them on using the manual lever on the motorised valve - its a Landis and gyr MAV-322, which you can´t get any more, but apparently a siemens cmv 322 is a direct replacement. I found a diagram for possible wiring. There are 5 wires

green/yellow for earth
blue for neutral
white, which I think is the live feed from the room thermostat
grey, which I think is the live feed from the hot water tank thermostat
orange, which is the boiler and pump connections


Does anyone know if this is a feed from the bolier and the pump or to the boiler and the pump.

I checked the signal from the room thermostat with a meter and that is getting there ok. And like I say, my heating comes on if I use the manual lever, but sometimes, my boiler turns off the heat, so I was wondering if the orange wire sends a feed to the boiler to tell it to fire up and that that´s intermittent, or whether there is something else faulty?

 

[seco services]

I have an old style boiler, hotwater tank and rafdiators. My radiators stopped coming on. I can turn them on using the manual lever on the motorised valve

sounds like the motor has failed if its not moving across when heating called for only by manual operation.

green/yellow for earth
blue for neutral
white, which I think is the live feed from the room thermostat
grey, which I think is the live feed from the hot water tank thermostat
orange, which is the boiler and pump connections

all correct apart from the grey is the hw satisfied wire not the hw calling wire from the cyl stat.
cyl stat calling connects straight to the orange which connects to the boiler/pump.

 

[philjw]

I have an old style boiler, hotwater tank and rafdiators. My radiators stopped coming on. I can turn them on using the manual lever on the motorised valve

sounds like the motor has failed if its not moving across when heating called for only by manual operation.

green/yellow for earth
blue for neutral
white, which I think is the live feed from the room thermostat
grey, which I think is the live feed from the hot water tank thermostat
orange, which is the boiler and pump connections

all correct apart from the grey is the hw satisfied wire not the hw calling wire from the cyl stat.
cyl stat calling connects straight to the orange which connects to the boiler/pump.

Thanks for replying so fast!

Sorry, I'm a bit dim on central heating (I fix x-ray machines for a living). I'm a bit lost on the terminology (calling/satisfied) thing.

I can't quite suss out how this thing works in my head.

Does that mean the grey is the live feed to the cyl stat and the orange is the feed back from that to tell the boiler to fire up? Or does the cyl stat get it's live feed from the central heating timer/programmer thingy? Or does the programmer send the live to the valve unit which then sends it out on the grey wire?

Does the orange wire send a signal from the cyl stat to tell the boiler to turn on? If it does, how does the boiler know to turn on when room thermostat switches the valve over to the radiators?

 

[kevplumb]

y plan

• kevplumb
• 19 Sep 2009
• 22

 

[philjw]

Thanks, kevplumb, that really helps, it's pretty obvious once you see the drawing.

I also found this great website with a how a motorised valve works, which might be handy for anyone else who has this problem!
http://www.sobjoy.com/motorised-valve.swf