Potterton programmer problem.

[Des Jennings]

Hello. I have a Worcester Greenstar 24 Ri boiler linked to a Megaflo cylinder. The boiler heats water for central heating, but when I want hot water only, the boiler does not fire up. I can get hot water when the central heating is on, but obviously not ideal in the summer. The boiler is only 18 months old. I use a Potterton ep2002 programmer (18 years old) and the hot water light comes on when the sliding switch is used but there is no reaction from the boiler. Could this be a programmer issue or is something else at play preventing the boiler from igniting. Help please. Thanks.

 

[picasso]

Hot water zone valve most likely.

 

[Gasguru]

And the EP2002 can do odd things too
See what the valves doing first...

 

[Des Jennings]

Thanks. Is that the valve that has a small lever that you can use to override? I used it to get hot water whilst the central heating is on.

 

[oldbutnotdead]

Thanks. Is that the valve that has a small lever that you can use to override? I used it to get hot water whilst the central heating is on.

Thats the one. Does it open automatically when the heating comes on or have you just left it latched open?
You can get replacement motors, not a difficult fix

 

[Des Jennings]

Thanks. I have left it open, but are you implying that I should be able to get hot water independently of the central heating manually? I only get it by having the central heating on as I said earlier.

 

[ianmcd]

No when you latch the valve it only opens the valve , it doesnt make the end switch that brings the boiler on, you will need to change the head or the motor

 

[Des Jennings]

Thanks for that. It sounds very much like the motor then.

 

[picasso]

If your getting hot water when the central heating is on it means the hot water valve is opening but not making the microswitch, change the complete head unit.

 

[oldbutnotdead]

Thanks. I have left it open, but are you implying that I should be able to get hot water independently of the central heating manually? I only get it by having the central heating on as I said earlier.

Not manually, no for reasons above. If there's another motorised valve controlling the heating circuit and a few other ifs then you should be able to have hot water or heating or both...pics are helpful (pipework in the airing cupboard mainly)

 

[Des Jennings]

Thanks. I'll try and get some pictures.

 

[Des Jennings]

Attached is a picture of the motorised valve, pump and large cylinder to the right.

 

[oldbutnotdead]

Honeywell valve which is good news, is there another one anywhere?

 

[Des Jennings]

That's the only valve I can find, although I would be interested to know what the attached image is showing linked to the pump. It's been hidden from my view for 13 years!

 

[oldbutnotdead]

Thats the other valve, so your system is designed for independent supply of heating and hot water.
Now to determine the fault with the Honeywell valve- this needs a multimeter.
First thing to determine is if any power is getting to the valve motor. The black flex from the Honeywell valve should go to a junction box or wiring centre fairly near it (the flex is only 500mm or so long). With hot water demand active (programmer calling for hot water, cylinder cold) there should be 240 volts across the brown and blue wires. Orange and grey should each be at 240v relative to neutral.

WARNING Testing live electrical circuits is dangerous. If you're not confident and competent using a multimeter and working with 240 volts then either get someone in or swap the valve motor, microswitch etc (you'd do that dead & its the most likely fail). Second most likely is the programmer, third most likely is the cylinder stat.