HW but no CH but it's not the 3way valve?

[SMILER2]

Hi, My pump got dripped on and blew. i changed it but now the HW comes on fine but nothing happens when i turn on the CH. i changed the 3way valve motor but no luck.
I swoped the CH 'on' and HW 'on' wires in the wiring center and it fired up so i guess it's not the programer.
Room and Tank thermostats click.
Pump works with HW.
Am i right to think that the wiring box could be the fault?

Everythings Honeywell - stats, 3way valve, prog, wiring box.
Cheers,

 

[twgas]

possibly 3port valve seized

 

[foley74]

Try moving the mzv manually,or take the head off and see if the spindle will move,it should move easy

 

[Agile]

If the valve is not seized ( and I dont think it is ! ) then you will need to use a multimeter to follow through the 230 v on CH.

Thats if you are safe and competent to do so that is!

Tony

 

[ollski]

You took the pump wiring out at the junction box end?

 

[superdupergasman]

Change the whole head and not just the motor!

 

[D_Hailsham]

Hi, My pump got dripped on and blew. i changed it but now the HW comes on fine but nothing happens when i turn on the CH. i changed the 3way valve motor but no luck.
I swoped the CH 'on' and HW 'on' wires in the wiring center and it fired up so i guess it's not the programer.
Room and Tank thermostats click.
Pump works with HW.

Here is the wiring diagram for a Y plan:

It might be helpful to read How a Mid position Valve Works.

When HW is 'on' and CH 'off' the valve does nothing. The boiler and pump is turned on by the HW thermostat.

If HW and CH are 'on' the valve is in mid-position and there should be 240v on the white wire.

If CH only is 'on' and HW 'off', then there should be 240v on white and grey wires.

Note: 'On' means that the timer is set to 'on' and the thermostat is calling for heat.

'Off' means that either the timer is set to 'off' or the thermostat is not calling for heat.

 

[SMILER2]

I've replaced the whole head of the valve with no luck. If i manually move the lever and turn the HW on it will heat up the rads so guess the valve is not stuck.
I'll give the electric test a go, anyone know a good guide of what i'm looking for though.
Cheers

 

[ollski]

I thought it all worked fine immediately before you changed the pump and not after

 

[AshaDPlumber]

I had this same thing about 2 days ago, pump blew so replaced it, but when it blew it took out the programmer to. If like you say you swapped the wires from ch to hw and it fired its most definately the programmer.

 

[SMILER2]

Hmm. i thought that as i had swoped the 'on wires' around that this proved it wasn't the programmer as the HW wouldn't of worked.

 

[seco services]

why not just use a multi meter as mentioned and see if you have power at the right connections.

 

[AshaDPlumber]

Sorry didn't realise the hot water worked when you swaped the wires. I would put a tester accross the pins on the back of the programmer. Check for continuity between the connections your having problems with.

 

[D_Hailsham]

Hmm. i thought that as i had swoped the 'on wires' around that this proved it wasn't the programmer as the HW wouldn't of worked.

Correct. You have proved that the HW and CH channels of the programmer both work.
When you swapped the wires, the CH wire would have connected to the HW thermostat, which would light the boiler directly as the valve is out of circuit. The HW would warm up.

Just to clarify, is the CH not working:

1. When HW is off at the programmer
2. When HW is on and calling for heat
3. When HW is on and not calling for heat

 

[SMILER2]

When i turn on the CH the light comes on at the programmer but nowt happens.

I'll have a tinker with the voltage testing but not sure what i'm looking for.