Programmer CP15 goes POP!

HI Board!

I'm here to ask for your help, again.

OK, we've had our kitchen fitted and the tiler finished yesterday. He went to put the programmer for our CH back onto the wall bracket and as he does, the thing goes POP, trying to spot weld itself to our ring mains. Black Smoke Of Dead Elastrickery escaped from the gaps in the side and as much as i tried to scoop it up and push it back into the box, i could not.

So, no heating or hot water; 14 month old daughter and no electrician till at least tomorrow.

Now, I've had plans to change the Danfoss CP15 for some time as it's old and yellow and on top of the new tiles, it's awful.

I changed the fuse in the wall, threw the RCD off and put the CP15 back on the wall after cleaning the sooty contacts. It turns on and i can activate the relays calling for HW or CH, but nothing is happening.

Does this mean that the Programmer is not sending voltage to the Pump?

What should i check and in what order?

It's an open pumped system. Y valve with motor on top next to hot water tank in bedroom with cold water tank and F/E tank in loft and a Gloworm 30FF boiler.

Thanks guys.

I forgot to say, i have a Drayton LP711 programmer here that I can use.

OK, there's no power going to the CH motor pump. In the connection box that is by the pump + valve, there's power going into the valve motor and also going in and coming out of the tank thermostat, but nothing to the pump motor.

You have a short somewhere. Was the heating fine before the programmer was removed for tiling? Has anyone drilled into the wall?

Sounds like you would be best to give up on the old programmer, and wire the new one in. You can wire it into the wiring centre if you don't want to run new wiring to the kitchen.

OK, I returned the 711 and got a 522 or something. Looking at the instructions in the sealed box, there's a compatibility chart and the 522 has a direct exchange pin layout.

I put it in, turned it on and it fires up. We have heat and hot water. Well, it's rising.

Anyway, i opened the CP15 and it seems the little battery inside might have played a part. The spring contact that holds it in had failed. It looked like someone had tried to tighten it on several occasions. Having been taken off and moved around, i think the battery dislodged and dropped into the bottom of the case to short it out when it was plugged in.

Binned.

Thank you for your response.

Glad to hear that you have found the cause.

These things are sent to try us!

Yes! All smiles here.

I'm alright with the wet side, it's just the leccy side i'm a bit unsure of.

If you were seeing smoke signals from the programmer, then the message that it was trying to send you was - FUSE IS TOO BIG

Yes, a 13amp fuse was in the spur, replaced with a 3amp.....