3 Way valve not operating correct

[BINKSY1973]

I replaced the motor on my 3 way valve a couple of weeks ago as the only way i could get heating was to move the valve over manually. Now i have a different problem the heating will now only come on if the cylinder stat is calling for heat, and it seems the room stat will not shut down the heating. As anyone got any idas to where the problem may be?

If i turn down the cylinder stat it shuts down heating and hot water.

Cheers Gordon

 

[DP]

Why don't you sit down, get a cup of tea and don the thinking cap.

Fact. heating was working when lever was moved to manually open position.

Fact. Having REMOVED head and changed motor (I assume head was removed to allow motor to be replaced), when you call for HW, only then rads heat up.

Fact. Water flows through rads instead of cylinder when HW stat is calling.

In what DIRECTION should the water flow when HW stat is calling?

 

[MANDATE]

Don't know if DP is suggesting the valve is the wrong way round, but I can't see that if it has been functioning ok in the past.
If you knew how the valve functioned you would have a better idea of what the problem might be.
The boiler/pump gets its power from the cylinder stat if the valve is in the HW only position or the HW/CH shared position. When the HW is satisfied or switched off, the boiler gets its power from the valves orange wire, which comes from a microswitch within the valve head.
First question must be. Is the valve moving beyond the mid position to the CH only position. If it does then suspect microswitch faulty.
You should be able to take the head off the spindle and try it and see if all three positions can be achieved. As it moves past mid point boiler will close down and relight within a sec or so. (thats the change over from the cylinder stat to the 'orange' wire, which originates with the room stat).
While you have head off try spindle for stiffness.(that might be enough to prevent valve reaching the CH only position).

 

[BINKSY1973]

Only the motor was removed, did not need to remove the whole valve to replace the motor.

Thanks Mandate for that information i will investigate to see if im getting voltage on those wires you have mentioned

 

[BINKSY1973]

Ok have done some investigating,

when CH and HW are calling i get the following readings

(all readings took between corresponding wire and earth)

White 240v
Grey 240v
Orange 240v
Blue 0v

When only CH calling (IE cylinder stat turned down)


White 240 v
Grey 240 v
Orange 0v
Blue 0v

When only HW calling (IE room stat turned down)

White 29v
Grey 240v
Orange 240v
Blue 0v


Do the above readings look ok?


The valve is a Landis and Staefa part no MAV-322


Thanks.

 

[seco services]

no
ch / hw calling grey should be dead. (hw maybe calling at programmer but is cyl stat calling )

ch calling orange should have power.

hw calling should have power on the terminal with orange but coming from the cyl stat not orange.

 

[BINKSY1973]

hw calling should have power on the terminal with orange but coming from the cyl stat not orange.

Im a little confused over that one.

The grey of the cyl stat (HW Sat) is connected to the Grey of the valve

The Black of the cyl stat (Calling) is connected to the orange of the valve.

If im thinking that your saying that orange is CH calling it seems there is a crossed wire on the stats?

 

[D_Hailsham]

when CH and HW are calling i get the following readings

(all readings took between corresponding wire and earth)
You should measure between the wire and Neutral (the blue wire)

White 240v - Correct
Grey 240v - Wrong, should be zero
Orange 240v - Correct
Blue 0v - Correct

When only CH calling (IE cylinder star turned down)


White 240 v - Correct
Grey 240 v - Correct
Orange 0v - - Wrong, should be 240v
Blue 0v - Correct

When only HW calling (IE room stat turned down)

White 29v - wire not in use - so not significant
Grey 240v - Wrong, should be zero
Orange 240v - Correct
Blue 0v - Correct

You need to check the wiring of your cylinder thermostat and the HW terminals of your programmer.

Stat COMMON (C) should be connected to programmer HW ON
Stat CALL (1) should be connected to the same terminal as the ORANGE wire
Stat SATISFIED (2) should be connected to the same terminal as the GREY wire
Programmer HW OFF should be connected to the same terminal as the GREY wire. (This terminal should have three wires: GREY, HW OFF, stat SATISFIED)

 

[seco services]

1, + the hw off from the programmer in the block connector.

2, + switched live to the boiler in the connector block.

 

[BINKSY1973]

Right i believe i have found the problem, the pcb on the microswitch has burnt out, its black where the resistors are, and also smells of that electrical burnt smell, is there any way round this? or do i need to source a microswitch? If so any ideas where i can get a microswitch from?

 

[D_Hailsham]

You need a new actuator http://www.heatingcontrolsonline.co.uk/siemens-landis-staefa-rmh-motor-p-46.html

 

[MANDATE]

looking at that link to 'siemens' it looks like you cant replace the actuator head, unless the valve no includes the letter 'C'