Heating Problem

[montys1]

Hi - We have an Ideal Mexico 2 conventional boiler, basically we have had a few problems with the heating not coming on in the morning only. It is set to come on 3 times a day, but its only the morning when it doesn't come on.

We tried replacing the Programmer first, from a Honeywell ST6400C to its replacement ST9400C. This wasn't the fault - still have the same problem.
We can override the heating on the programmer and get heat if we need it its just bizarre that only the morning it won't come on. The programmer heating light is on, the thermostat is clicking, the pump is whirring but no heat.

We have just worked out the settings we have for heating and hot water have something to do with it as we have the heating and hot water set to come on at the same time in the morning, but different times during the day.

Heating 05.30 - 7.30 16.00 - 18.00 19.30 - 21.30
Hot Water 05.30 - 7.30 14.30 - 16.30 18.30 - 20.30

Last night when we went to bed we turned off the hot water on the programmer and just had the heating to come on this morning. This worked fine.

We now think maybe its the Honeywell 4073 3 way valve, I have moved the lever to Auto (I think it was in the middle) and will see what happens in the morning with heating and hot water set both for 5.30am.

One more point, the backlight on the ST9400C is on constantly, which is fine but it PULSES - is it meant to flicker on and off every other second or does that point to wiring maybe?

Any advice welcome!

Thanks

Ian

 

[lifesagasman]

could it be that your hot water is priority delaying switch to heating?

 

[montys1]

could it be that your hot water is priority delaying switch to heating?

All I know is that it has always been set in this way and we have never had any problems. I don't know if moving the lever on the 3 way valve to the Auto position is the right way to go, but its all working at the moment, but the real test is in the morning to see if it all comes on. If not then I guess I will just separate the times for both.

Just read up a bit on priority as I had no idea what it meant, and it doesn't seem to apply to this set up as we have a 3 way 4073 valve not a 2 way diverter - according to the blurb.

 

[lifesagasman]

separation should fix it

 

[heatingeng]

if you leave the hot water on all the time does it still do the same.
it could be its heating the hot water first and then goes onto the heating.

 

[montys1]

if you leave the hot water on all the time does it still do the same.
it could be its heating the hot water first and then goes onto the heating.

Not tried that, I will put that on my list of things to try! Is it okay to leave the lever on the valve in the Auto position?

 

[heatingeng]

if you leave the hot water on all the time does it still do the same.
it could be its heating the hot water first and then goes onto the heating.

Not tried that, I will put that on my list of things to try! Is it okay to leave the lever on the valve in the Auto position?

just leave it all allone . just put the hot water on constant and see how you go.
if its working the rest of the time then there isnt a problem just that maybe its heating the hot water first .

 

[montys1]

Okay - turned heating off for about an hour. Had hot water on constant for about 45 minutes - programmed heating to come on at 15.10, the light came on - no whoosh from the boiler though, went upstairs to check the rads (next to the hot water tank) all getting very hot, checked downatairs rads all getting hot - then heard boiler whoosh.

 

[heatingeng]

Okay - turned heating off for about an hour. Had hot water on constant for about 45 minutes - programmed heating to come on at 15.10, the light came on - no whoosh from the boiler though, went upstairs to check the rads (next to the hot water tank) all getting very hot, checked downatairs rads all getting hot - then heard boiler whoosh.

sorry i dont really understand what you mean .
is it working ok now ?
or is it the noise that is a issue

 

[lifesagasman]

does this mean then that you're using up your hot water at night and in the morning it's heating it up again before the switching to heating? that's just about how it's meant to work!!

 

[montys1]

Yes its working - we have heating and hot water, the problem is that it's not heating the rads first thing in the morning - when it always used to. I understand that all of a sudden its now heating the hot water first - but it never did before. Our hot water needs haven't changed I just don't get why its not doing what it always has. If all I need to do is separate the times then no worries.

 

[heatingeng]

Yes its working - we have heating and hot water, the problem is that it's not heating the rads first thing in the morning - when it always used to. I understand that all of a sudden its now heating the hot water first - but it never did before. Our hot water needs haven't changed I just don't get why its not doing what it always has. If all I need to do is separate the times then no worries.

sounds to me like its working fine .

just put the hot water on an hour before the heating on a morning job done

 

[montys1]

does this mean then that you're using up your hot water at night and in the morning it's heating it up again before the switching to heating? that's just about how it's meant to work!!

Nothing has changed with our heating/hot water useage I just don't get why all of a sudden its giving priority to the hot water. I will separate the times for the heating/hw and see what happens.

Out of interest our tank is a 900 x 450 (118l approx I think) - how long should it take to fill. Its a 2 bed mid terrace, 2 adults - non-power shower (cold mains feed - thermostatically heated) and cold feed washing machine.

Also as a guide how often should the hot water be set to come on and for how long? Just in case I am overdoing it.

 

[heatingeng]

does this mean then that you're using up your hot water at night and in the morning it's heating it up again before the switching to heating? that's just about how it's meant to work!!

Nothing has changed with our heating/hot water useage I just don't get why all of a sudden its giving priority to the hot water. I will separate the times for the heating/hw and see what happens.

Out of interest our tank is a 900 x 450 (118l approx I think) - how long should it take to fill. Its a 2 bed mid terrace, 2 adults - non-power shower (cold mains feed - thermostatically heated) and cold feed washing machine.

Also as a guide how often should the hot water be set to come on and for how long? Just in case I am overdoing it.

i leave my hot water on constat in my house .

 

[D_Hailsham]

We now think maybe its the Honeywell 4073 3 way valve, I have moved the lever to Auto (I think it was in the middle) and will see what happens in the morning with heating and hot water set both for 5.30am.

1. Are you sure it is a 4073 and not a 4044?

2. The lever is not a switch, it's there so the valve can be locked open when filling the system. To do this the lever is locked in the MAN position.

3. Can you check that the valve is the correct way round? The ports are labelled on the brass body. AB should go to the pump; A to the heating; B to the HW cylinder.

The valve may be sticking; you can check this easily:

Turn off power to heating system (not just at the programmer). This will reset the valve to the default position. The valve lever should be at the AUTO end.

Move the lever to the MAN end. You should feel a resistance as you are opening the valve against a spring.

When the lever is at the MAN end, let go and it should move back to the AUTO end, You should hear the valve closing.

Check again that the lever has resistance.