CH boiler cuts out after 4 mins. HW ok

aveatry · 2 Oct 2020

New update -- heating is now gone off.
Stat still demanding heat as turned up to 30° - clicks at 20° indicating the room temp, programmer still on and demanding. Boiler heating water temp was 60° but could of been higher when I wasn't looking.
Temp on boiler now down to 55°
Getting 246V between Blue and brown block.

Looks like its back to its behaviour where it now will not come back on until the indicated CH water temp is down to around 30°

Alec_t · 2 Oct 2020

Could it be a fault in the room-stat? If its sensor were registering a higher temperature than the actual temperature you could get premature shut-down.

Gasguru · 2 Oct 2020

The mystery is why there appeared to be a delay when you wound the room stat up in post #30
With that Honey stat you should instantly see the voltage on the brown/blue.
One the motor has fully opened the valve and operated the microswitch you should then see the 240V from orange to blue.
The boiler temperature shown will be the flow temperature....once that temp has been achieved the boiler will jump into anti-cycle mode and sit there (with the pump running and the temp will fall) for several minutes and then fire up again.

aveatry · 2 Oct 2020

Latest update, CH temp 37° 244V at blue and brown, 0V at Blue and orange. Turned on heating with stat still on 30°. Nothing happened and still got 0V at blue and orange.
Left it for 11mins and vigorously wiggled stat wheel - didnt help so turned off heating at programmer and will try again when the CH temp is lower.

It does seem to be that the boiler CH temp is a factor I stayed up till 12.30 last night stearing at the temp with everything asking for heat to try and catch at what temp it came on. But turned it off and went bed at 27°

aveatry · 2 Oct 2020

I dont know it its a factor but the boiler does have its own inbuilt frost protection.
Frost Protection
With the gas and electric supplies ON and irrespective of any
room thermostat setting, the integral frost protection device will
operate the pump when the temperature of the boiler water
falls below 8OC.
A timer is used so that the temperature can be checked
periodically. After 10 minutes the pump will be stopped if the
temperature is higher than 10OC or has already reached 35OC.
The burner will only activate if the boiler temperature does not
reach 10OC after 30 minutes or at any time if the temperature
drops to 5OC.
The burner will switch off when the temperature reaches 35OC.

Alec_t · 2 Oct 2020

Those temperatures seemed impossibly high, until I realised the character before the 'C' wasn't a zero but was meant to be a degree symbol!

.

aveatry · 2 Oct 2020

Alec_t said:
Could it be a fault in the room-stat? If its sensor were registering a higher temperature than the actual temperature you could get premature shut-down.

I know I keep stating the water temp on the boiler and its because I just don't know if its a factor but my findings are that the lower the temp on the boiler the more likely it is to all come on. But if the water in the pipes are cooling then so is the area of the room stat.
Odd as gasguru said why the delay this morning.
Who is ultimately in control of everything -- is it the room stat. Can it be bypassed to test.

We never use it and we never really use the programmer unless away in the winter or want it on for when we wake up in mid winter. If we feel cold we just hit the +1 or 2 or 3 hour and that does us.

aveatry · 2 Oct 2020

Alec_t said:
Those temperatures seemed impossibly high, until I realised the character before the 'C' wasn't a zero but was meant to be a degree symbol! .

Yeh that's odd I copied and pasted from a PDF and that is how the extra 0 has been added for some strange microsoft reason. I have also took a screen shot of the pdf which is fine.
Mabe I have a plague of fairies that are also "F"ing arround with my heating.

Gasguru · 2 Oct 2020

aveatry said:
Latest update, CH temp 37° 244V at blue and brown, 0V at Blue and orange. Turned on heating with stat still on 30°. Nothing happened and still got 0V at blue and orange.
Left it for 11mins and vigorously wiggled stat wheel - didnt help so turned off heating at programmer and will try again when the CH temp is lower.

It does seem to be that the boiler CH temp is a factor I stayed up till 12.30 last night stearing at the temp with everything asking for heat to try and catch at what temp it came on. But turned it off and went bed at 27°

Ignore the boiler temperature and concentrate on the zone valve/controls. All the boiler needs to see is 240V at its Switched Live terminal. That voltage is derived from the orange wire on the zone valve.

So you've measured 244V across the brown and blue...that's the feed to power the motor which comes from the programmer (when heating is ON) via the room thermostat (when turned up).
After the motor runs and winds the valve fully open the microswitch operates and you should be measuring 244V across the orange and blue but you say you get 0V.

So either the microswitch has operated but is broken inside, or the zone valve motor is not fully opening the valve and operating the microswitch.

aveatry · 2 Oct 2020

Gasguru said:
Ignore the boiler temperature and concentrate on the zone valve/controls. All the boiler needs to see is 240V at its Switched Live terminal. That
After the motor runs and winds the valve fully open the microswitch operates and you should be measuring 244V across the orange and blue but you say you get 0V.

I get zero in the state where things are asking and it not working but I do get 240V when it is working

Gasguru · 2 Oct 2020

So investigate why no voltage on the orange when you have voltage on the brown...

jackthom · 3 Oct 2020

Deleted.

aveatry · 3 Oct 2020

Gasguru said:
So investigate why no voltage on the orange when you have voltage on the brown...

The orange block with 2 orange and 1 grey. One orange is from the Hot water valve and the other is the CH valve - What is the grey one?

This morning the heating will not come on at all 244V at blue and brown. 0V at blue and orange. I tried the heating and water at the same time and i get 240v at blue and orange. Is that the room stat not giving power to the heating valve.

Harry Bloomfield · 3 Oct 2020

aveatry said:
The room stat is in the hallway and is usually set about 25 but really never gets anywhere near that as the rad TRVs always kick in first.

The room where the stat is, should not have a TRV fitted to it, otherwise the stat serves no valid purpose. With the room stat as installed, your boiler will be constantly cycling trying to meet a demand from the stat, but never able to satisfy it because of the TRV closing first.

aveatry · 3 Oct 2020

Harry Bloomfield said:
The room where the stat is, should not have a TRV fitted to it, otherwise the stat serves no valid purpose. With the room stat as installed, your boiler will be constantly cycling trying to meet a demand from the stat, but never able to satisfy it because of the TRV closing first.

The room stat is in the hallway and the hallway rad does not have a TRV. Sorry my fault - should of been clear "ever gets anywhere near that as the rest of the house rad TRVs always kick in first"

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CH boiler cuts out after 4 mins. HW ok

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