CH Not Working to Programmer Instruction

[OscarFoxtrot]

Hello,

Just bought a new (15 years old) house. Boiler is a Glow Worm Flexicom 15HX installed in Dec 2007 (original paperwork present).

I haven't moved into the house yet so I'm not fully up to speed on the behaviour of the boiler however it should be on just now and isn't.

Its controlled by a Potterton EP2002 programmer directly below the boiler (in the kitchen) with a Potterton thermostat in the hall by the radiator with the two lock shields.

The programs are as they were from the previous owner. CH and HW from 6.30-9.30 and 16.30-22.30. When I got here this morning the heating was on as it should be. Last night it wasn't on and didn't fire up even when I switched the program to "on".

At the moment the Thermostat shows "below" with a requested temp of 20c (its only about 10c at the moment), the lights are on for both HW and CH at the programmer and according to the boiler manual the boiler is "Central Heating activated but with no demand, target temperature indicated"

The condensate terminates internally into the sink waste.

Any ideas?

Cheers

 

[D_Hailsham]

Does hot water work on its own?

 

[OscarFoxtrot]

Not sure. Will try tomorrow.

Last night everything worked as it should (I presume as there was heating on this morning and plenty hot water today)

Just now it should be on by timer but isn't.

I've switched the HW to OFF and the heating has come on. I also turned the thermostat down past 'reached' then back up to required temp. Not sure which of these has caused it to fire up.

Cheers

 

[D_Hailsham]

I've switched the HW to OFF and the heating has come on. I also turned the thermostat down past 'reached' then back up to required temp.

Do you have one of the left valve or two of the right valve? (Usually near the HW cylinder.)

View media item 5946 View media item 11762

 

[OscarFoxtrot]

One of the left![/img]

 

[45yearsagasman]

Very likely to be a sticking valve or a failed synchron motor inside the grey box.

 

[D_Hailsham]

One of the left!

There are two valves which look like this, but they work differently. Can you supply the model number from the label. If it's a Honeywell it will be Vxxxxx.

 

[OscarFoxtrot]

It's a myson mpe322.

Had the heating on 'timed' the past two days with HW switched to off. Heating appears to be working as it should and there has been plenty hot water.

Cheers

 

[D_Hailsham]

It's a myson mpe322.

Had the heating on 'timed' the past two days with HW switched to off. Heating appears to be working as it should and there has been plenty hot water.

The MPE322 is a mid-position valve, so you should be able to get CH and HW separately, or both together.

Carry out the following tests in the order shown:

Turn power off. CH Off, HW off (This resets everything)
Turn CH stat and HW stat to minimum.
Turn power ON and HW stat to max.
Boiler should light and pipe from valve to cylinder get hot
Turn CH ON and CH stat up
Boiler should continue to run. Valve should move to mid position and pipe from valve to rads also get hot
Turn HW stat to minimum
Boiler should continue to run. Valve should move to CH position and pipe to cylinder cool down.

If boiler stops
Turn cylinder stat up (boiler should start)
Turn HW Off
Boiler should continue to run. Valve should move to CH position and pipe to cylinder cool down.

Post results

 

[OscarFoxtrot]

Thank you for all this. I will try out those steps this week. Past week has been busy moving in.

Getting by at the moment with HW switched off but we are still getting heating and hot water.

Another quirk is that when we wake in the morning the heating is on as it should be, however when it should kick on in the evening it doesn't. The programmer lights up and the thermostats also lights and shows "below" but the boiler doesn't fire. If I turn the thermostat down until it clicks for "reached" and then turn it back up the boiler fires.

 

[OscarFoxtrot]

It's a myson mpe322.

Had the heating on 'timed' the past two days with HW switched to off. Heating appears to be working as it should and there has been plenty hot water.

The MPE322 is a mid-position valve, so you should be able to get CH and HW separately, or both together.

Carry out the following tests in the order shown:

Turn power off. CH Off, HW off (This resets everything)
Turn CH stat and HW stat to minimum.
Turn power ON and HW stat to max.
Boiler should light and pipe from valve to cylinder get hot
Turn CH ON and CH stat up
Boiler should continue to run. Valve should move to mid position and pipe from valve to rads also get hot
Turn HW stat to minimum
Boiler should continue to run. Valve should move to CH position and pipe to cylinder cool down.

If boiler stops
Turn cylinder stat up (boiler should start)
Turn HW Off
Boiler should continue to run. Valve should move to CH position and pipe to cylinder cool down.

Post results

Hello,

Finally got round to checking this. As always any help appreciated.

Turned everything off.
HW to on, stat to max - pipe to cylinder got real hot.
CH to on, stat to max - both pipes now hot.
HW stat to min - boiler stops
Turned HW stat to max - boiler fired
HW off - boiler running CH

Additional notes - around 50 % of the time we have to force the boiler to start for CH by turning thermostat down past 'below' then quickly turning it back to desired temp. When it's supposed to be on (by the programmer) it's not on, although all the lights are.

The myson is set to 'Auto' is that correct? I can hear it switching when testing between CH and HW durning the test there and the lights on the top are as they should've been.

Cheers,

 

[D_Hailsham]

Finally got round to checking this.

Only two months later!

Turned everything off.
HW to on, stat to max - pipe to cylinder got real hot.
CH to on, stat to max - both pipes now hot.
HW stat to min - boiler stops
Turned HW stat to max - boiler fired
HW off - boiler running CH

That means:

Either
1. There is a wiring error;
or
2. The valve is sticking and not moving over to CH only position.

What do the neon lights on the valve show when the error occurs?

Additional notes - around 50 % of the time we have to force the boiler to start for CH by turning thermostat down past 'below' then quickly turning it back to desired temp. When it's supposed to be on (by the programmer) it's not on, although all the lights are.

This does suggest that the valve is sticking.

Remove the actuator and make sure the valve spindle can be turned easily by hand.

The valve should be set to 'Auto'.

 

[OscarFoxtrot]

Thanks again!

Neon lights show what should be happening (e.g. if CH should be on the light is illuminated).

I'll have a look at removing the actuator tomorrow (its quite a neat fit under the cylinder)

Last night I set both CH and HW to timed at the programmer, both due on at 6.30am. HW came on and reached its temperature pretty quick but no CH. I had to switch HW to off before the CH kicked in.

 

[D_Hailsham]

Last night I set both CH and HW to timed at the programmer, both due on at 6.30am. HW came on and reached its temperature pretty quick but no CH. I had to switch HW to off before the CH kicked in.

That suggests a wiring fault.

Remove the cover from the cylinder stat (that's the one on the side, near the bottom) and check how many wires there are: there should be three. If you have only two, you will get the symptoms you describe.