Thermostat calls for hot water when programmer says off

[Raspo1966]

Hi, I have a problem with my hot water system...

I have just replaced a hot water cylinder (and emersion heater) and also fitted a new hw pump as the old one was worn out. When I switched the system back on I noticed that the pump and boiler were running even though the programmer was set to off?? Have since replaced the cylinder thermostat and programmer still the same problem.

The boiler switches off once the thermostat on the cylinder reaches the set temperature but doesn't seem to be controlled by the programmer??!!
I have an oil fired boiler and wondered if this might have a fault which is overriding the programmer...is this a possibility or likely??

Any suggestions gratefully received...
Nick

 

[JohnD]

what sort of programmer?

 

[buck51]

maybe faulty zone or 3 port valve.

 

[picasso]

Double check your wiring.

 

[Raspo1966]

Thanks...
The valve seems fine and has been checked by plumber and electrician.
Not sure about the zone??
The programmer is a like for like replacement Drayton LP522...the thermostat is also Drayton like for like replacement...

 

[Raspo1966]

Think you're right...I'll get the electrician back in to check the wiring as it seems like there is a permanent live to the thermostat somehow?!
Thanks

 

[picasso]

You might have the hot water off wire connected to the wrong terminal.

 

[JohnD]

Some Drayton programmers have a Gravity/Pumped switch or jumper on the back. Yours should be set to Pumped.

You are sure the HW is timed to Off? and set to Timed?

 

[Raspo1966]

Hi John,
Yes it is set to P for pumped.
Yeah...it's set to timed and it should be off but was running also the green light on the programmer was off so it is somehow possibly bypassing the programmer

 

[Raspo1966]

Hi Picasso,
We haven't re-wired anything as such but think you might be on the right lines...I wonder if we have knocked something whilst refitting the HW cylinder as it was a very tight fit with all the extra insulation...

 

[Raspo1966]

Just an update...The electrician is a bit stumped but he thinks that when the new water pump switches on it might be sending out a pulse that is a bit too strong for the programmer and burns it out... This leaves the programmer in a permanent state of on for HW. He is going to speak to his wholesaler to see if there is a better programmer that we can use. This kind of makes sense because the programmer worked properly albeit briefly and then stopped once the pumped switched on and off a couple of times....