Honeywell C/H

[peteruser]

Our central heating system has suddenly developed a fault (maybe more than one fault)

We have a Honeywell ST699 Programmer and a Honeywell T6360 thermostat.

Normally we use the timer system to control both the water and the heating. A week ago we suddenly found that the water was not heating, so we have since been using the electricity to heat the water instead.

Now, within the last few days, since the weather has become colder and I have been working from home, I decided to switch the C/heating control to Continuous instead of Twice, which is the normal timer setting it is usually on.

Last Sunday the heating would not come on at all all day. Just before we went to bed I switched it off and then on again, and when we awoke the next morning we found that it had come on again and had in fact been on all night.

Yesterday, I left the heating switch on Continuous to see what would happen, and all day it worked perfectly. Then suddenly at 9pm last night it went off again. So once again we set the switch to Twice, and when we woke this morning we found it working again, but not very hot.

At 9am after the Twice setting had switched the heating off again, I decided to put it back to coninuous to see what would happen and if it would work at all. At first it did come on, but only for 1 minute, then 10 minutes later it came on for another 1 minute. This happened a few times and then it went off completely, and still has not come back on.

I would like to know what parts, if any, need replacing before I call a C/H firm in, as I do not want to be ripped off.

 

[ChrisR]

Sounds like a dud 699, unless you've got the clock 12 hours out!

You could replace it yourself in seconds - or use a dearer 799 which knows what day of the week it is. Loosen screw top right and the front comes down.

 

[peteruser]

Thanks for your quick reply Chris. I have checked the clock and timer settings and as far as I can see there is nothing wrong there.

You say that you can change the unit by removing the screw, top right and the front should pull down.

Well there isn't any screws showing on our unit, nor at the sides or bottom or anywhere that I can see. How else would you think this could be disconnected?

 

[weareleeds]

Check that your ballcock in loft on c/htg tank hasn't stuck in the upright position (tank may have run dry) This is a common cause of losing dhw first then rads on older gravity water systems.To remove a honeywell st699 it is snappec into placewith plastic lugs you will need to insert a couple of samll screwdrivers betweem clock module & backplate to force lugs down then pull forward to release

 

[peteruser]

I just checked again to see if I could get anything moving at all in the Continuous mode but still nothing, then I slightly moved the dial on the room thermostat (Honeywell T6360) and as I did so, the heater started again.

I timed it and again it lasted just 1 minute and has not come back on again in the next 20 minutes. Do these room thermostats ever go wrong and could it possibly be that?

 

[peteruser]

Still got problems. I have fitted a new Honeywell ST699 Programmer as ChisT suggested but still not getting anything. The clock is set correctly so it is not that. It will not work at all, even when we set it to "Continuous" setting.

It's getting colder around here, anyone else got any ideas what it could be?

 

[Nige F]

I just checked again to see if I could get anything moving at all in the Continuous mode but still nothing, then I slightly moved the dial on the room thermostat (Honeywell T6360) and as I did so, the heater started again.

I timed it and again it lasted just 1 minute and has not come back on again in the next 20 minutes. Do these room thermostats ever go wrong and could it possibly be that?

sounds like it could be and it`s cheap to replace

 

[peteruser]

Hello Nige F You say it sounds like it could be (something) and it`s cheap to replace

But all I saw was a little circle. I tried clicking on it but nothing happened. Sorry to be a pest, but what is it?

 

[Gasman1015]

He means your room thermostat, but check the wiring connections first.