Sleepy Central Heating - Lazy Boiler?

[jockinafrock]

I checked all the voltages at the 3 way valve with a multimeter as mentioned earlier - all were ok. Tried turning the boiler up to max & all trvs to max but makes no difference! When boiler is in sleep mode switching CH from programmer has no effect.
Jock

 

[D_Hailsham]

I checked all the voltages at the 3 way valve with a multimeter as mentioned earlier - all were ok. Tried turning the boiler up to max & all trvs to max but makes no difference! When boiler is in sleep mode switching CH from programmer has no effect.

When it goes wrong again, check the voltages on white and grey with the switch in CH only position, as explained previously, and also check the voltage on the orange valve wire. If the orange is reading 240v, the problem is in the boiler. If it is not 240v, the problem is in the valve.

 

[jockinafrock]

The voltages on white and grey with the switch in CH only position are both 240v but the orange connection (HW Call) is 0v. Does this mean the 3 way switch part is duff? It was only been fitted 9 months ago!
Jock

 

[D_Hailsham]

The voltages on white and grey with the switch in CH only position are both 240v but the orange connection (HW Call) is 0v. Does this mean the 3 way switch part is duff? It was only fitted 9 months ago!

Do you mean the 3-way valve? If so, it looks very much as if the valve is faulty. One final check to confirm: disconnect the orange wire (power off when you do this) Then check the voltages on white grey and orange with switch in CH position as you did above. If the orange is still 0v while the others are 240v, the valve is definitely faulty. As it is only 9 months old you will be able to get it replaced under warranty. I would pay the extra and get a Honeywell V4073.

 

[jockinafrock]

Checked as before - with system "normal" (Boiler & Pump On) all readings (White, Grey & Orange ) are 240v. When Boiler & Pump go Off (after about 20mins!) White & Grey are still 240v but Orange is 0v. You can hear the switch roll to the power off position. I've noticed that theOrange wire has a link to another connector on it which disappears into a wiring loom!

 

[D_Hailsham]

Checked as before - with system "normal" (Boiler & Pump On) all readings (White, Grey & Orange ) are 240v. When Boiler & Pump go Off (after about 20mins!) White & Grey are still 240v but Orange is 0v. You can hear the switch roll to the power off position. I've noticed that the Orange wire has a link to another connector on it which disappears into a wiring loom!

That's why I asked you to check what happened when the orange is disconnected. When the switch is in the HW, or HW and CH position, the boiler gets power from the cylinder thermostat. When it is in CH only position, power comes from the orange wire. With the orange still connected it is impossible to tell where the power is coming from.

1. Turn power OFF
2. Disconnect orange lead
2. Set switch to CH only
3. Turn power ON the boiler should not light
If it does there is a wiring fault elsewhere (Try turning the cylinder thermostat up and down, if the boiler goes on/off the cylinder stat is wrongly wired)
5. Measure voltage on white and grey - should be 240V
6. Measure voltage on orange - should be 240v.
If it is not, the valve is faulty.

 

[jockinafrock]

Sorry! I should have said that I took these readings with the orange wire disconnected. I've just re done it & white & grey show 240v but orange is just about 10v.

Do you think that it is the mechanical valve or the actuator that is at fault?

Thanks for all your efforts but I'm thinking of finding a recommended Central Heating engineer as I seem to be chasing my tail at the moment! It's all getting a bit complicated for me - give me a computer to fix any day!!

 

[D_Hailsham]

Sorry! I should have said that I took these readings with the orange wire disconnected. I've just re done it & white & grey show 240v but orange is just about 10v.

Do you think that it is the mechanical valve or the actuator that is at fault?

Easy to check!

Remove the actuator and make sure the valve spindle can turn easily - it may only be about 20 degrees between the end stops. If stiff, try a little WD40.

With the actuator off, run the tests again, still with orange disconnected. If you still get less than 240V, the actuator is faulty. You can get replacements.

 

[jockinafrock]

Hi - valve moving quite freely - albeit witha total movement of about 20 degrees. Readings with orange disconnected and CH selected is 0v.

This morning I needed to switch HW on to get the boiler to fire! Does this still point to the actuator - or a boiler fault?

 

[D_Hailsham]

Hi - valve moving quite freely - albeit witha total movement of about 20 degrees. Readings with orange disconnected and CH selected is 0v.

This morning I needed to switch HW on to get the boiler to fire! Does this still point to the actuator - or a boiler fault?

Definitely an actuator fault. As the orange wire has 0 volts on it the boiler will not fire. When you turn the HW on as well, so the valve goes to mid position, the boiler is fired via the HW thermostat. The only problem then is that, when HW is up to temperature, the boiler will go out - therefore no heating.

Although you could get a new actuator, Salus do not have a good reputation so it might be better to change the valve for something more reliable such as the Honeywell V4073. As the valve is still under warranty there should not be much trouble.

 

[jockinafrock]

Bought a new actuator today and fitted it - all seems to be working normally but I'm not crowing yet! I'll test it out over the weekend before I believe that the fault is fixed - and not - like some have told me - the boiler!
Very Many thanks - particularly to D Hailsham for all the advice & patience in helping me (hopefully!) to solve this problem.
Best Regards
Jock[/b]