Boiler only turning on via thermostat

[mikeb89]

Hi guys, so my issue is I use a timer program on my boiler and yesterday I noticed even if this is set to off if the temperature in the house dips below my thermostat the heating kicks in, it appears none of the settings on off timer or once are registering with the boiler it's only responding to the thermostat so the only way I can turn off the heat for the day is turning the thermostat to as low as possible while out. Weirdly enough the hot water side of the programmer seems to be working and turning that on via the hot water timer. Any ideas? I use a Drayton LP522 5/2 Day Programmer

 

[cross thread]

Probably a duff clock, what model ? You may get a direct replacement.

 

[mikeb89]

It's a Drayton LP522 5/2 Day Programmer, strange though as it still works on the hot water side so clock seems fine and the heating light still lights up on the programmer when it hits the right time and off as it should just no activity from boiler as it does

 

[fixitflav]

It's a Drayton LP522 5/2 Day Programmer, strange though as it still works on the hot water side so clock seems fine and the heating light still lights up on the programmer when it hits the right time and off as it should just no activity from boiler as it does

Is it a new problem/new installation/new house? What system, W, Y, S-plan, or something else?

 

[mikeb89]

New problem yeah started yesterday or noticed it yesterday anyway not a new house been here 7years as for plan it's Y

 

[stem]

Has anything unusual happened recently such as a fuse relating to the heating blown, or some wiring disturbed for example? I've come across this fault about 3 or 4 times and on every occasion a short circuit has occurred and welded the programmer heating contacts together effectively making it permanently 'on' regardless of the set program.

 

[mikeb89]

Nothing I can think of no, was used more over Christmas as everyone was home all day but once return to work I've noticed it, that would probably make sense if that was the issue as other side the hot water seems fine regarding on off via timer settings

 

[stem]

The heating and hot water have separate switches inside the programmer. So, normally only one fails. There is a simple test that can be done, but only do it if you are competent to do it safely:

This test assumes that the system has been working correctly previously meaning there is not an installation fault somewhere. Isolate the mains supply and remove the Drayton programmer from its backplate.

Then move the wire from terminal 4 (heating on) and put it in terminal 3 (hot water on) with the wire already there. Now replace the programmer and reinstate the power. After this, the programmer hot water settings should control the on/off times control of heating as well as the hot water. If that's what happens and the programmer does now switch the heating on and off, it shows that the central heating control part of the programmer is faulty.

If you do make the test, make sure that you note which wire you move so you can put it back later.