Honeywell ST6300A ignoring timer programme

[NASHerts]

Hi - I have a CH and hot water system controlled by a Honeywell ST6300A thermostat unit.
In its most basic functions it works fine -ie if we turn either the hot water or the CH to on, it comes on and when we switch it off (manually) it turns off.
The problem arises when we try to use the timer function to run the CH at specified times during the day without having to manually get involved each time. Basically it simply doesn't turn on 9 times out of 10 when it should - and if it has turned on, then chances are it won't switch off when it should.
There appears to be nothing wrong with the water/heating system itself and the thermostat part of the Honeywell system works fine (in terms of temperature control) - it's just the timer is not happy.
Has anyone seen this before or have any idea how to fix it?
There is a reset button on the front of the unit but I haven't pushed this yet as I'm not sure exactly what it'll do.
Thanks in advance for any help/ideas/comments

 

[D_Hailsham]

ST6300 User Guide

 

[NASHerts]

Thanks for the manual
According to it, I have everything set-up ok so I suppose it's just a question of faulty hardware?

 

[D_Hailsham]

Have you tried resetting the timer?

Have you checked if any of the buttons are stuck?

Do the override buttons work?

How are you manually switching on and off?

 

[45yearsagasman]

Pushing the reset will put the programmer back to its default settings. Give it a try, it will do no harm.

 

[NASHerts]

Have you tried resetting the timer?
No _ I'll try that tonight

Have you checked if any of the buttons are stuck?
Yes -they're fine

Do the override buttons work?
Yes

How are you manually switching on and off]
Using the CH or Water switch to go from 'Off' to 'Continous' (the other options being @once' and Auto which is the non-working timer)?/quote]

Thanks

 

[NASHerts]

Hi - as promised I pushed the reset button last night. Then I had to reset the time and reschedule the CH timer.
I set it to come on from 0500-0700 this morning but again it failed to start. When I checked it just before seven the system was on, just not heating anything. I found that when I restarted the Honeywell then it suddenly jumped to life and started heating the house.
It then switched itself off at the correct time.
So, the running theme seems to be that it will work correctly the first schedulded start/finish time after a restart but then will most likely fail to start/stop according to schedule until the system is restarted again.
In theory I suppose this is manageable but it is a pain and pretty much destroys the convenience of an automated system by forcing daily manual intervention.

 

[D_Hailsham]

I think you need a new programmer.

 

[NASHerts]

I think you need a new programmer.

Yeah...that sounds right.
Thanks for your input and for taking the time to help.
Is this something a moderately competant DIYer can do by himself, or would I be better to get someone in who knows exactly what they're doing?