What the heck have I done?

Joined
24 Apr 2012
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Location
Caithness
Country
United Kingdom
Boiler: Camray 3 50/70
Burner: Riello 40 424T55 (OIL)
Programmer: Danfoss FP715
Valves (one each for Water & Heat): Danfoss HPA2
Pump: Grundfoss UPS 15-60
Hot water tank thermostat: Danfoss AT
Room thermostat: Danfoss (No model No. visible)
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Black smoke was issuing from the central heating boiler flue so last weekend I thought I would put it right.

A quick look showed that here was a wasps next in the boiler casing and over the winter it had decayed and fallen over the balanced flue airway, almost completely blocking it.

I removed the nest and whilst at it I swept the flue and removed the internal boiler plates and cleaning out all the gunge. The burner nozzle was thick with oily grunge as was the flame sensor so I replaced them both with new ones (of the correct type and size).

Everything fired up and worked ok and the programmer turned itself 'off' that night. In the morning I noticed that the pump was still running and the boiler very hot. It appeared to be working without the programmer and switching off on its internal thermostat. Tweaking the boiler temperature control would turn it burner off and on.

I tried various combinations of switching the programmer on and off but to no avail. I then removed the programmer from its base plate completely and still the boiler and pump were running.

The oddest thing is that if I leave it alone for some hours then go back to the programmer and turn it on for a few minutes then off everything goes off ok!

NOTE: When the programmer is 'OFF' the boiler runs but only heats the water.

So what the heck have I done - or is it a co-incidence and another fault has developed?!
 
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CompoinCaithness said:
The oddest thing is that if I leave it alone for some hours then go back to the programmer and turn it on for a few minutes then off everything goes off ok!

Does this mean that if you leave it long enough with the programmer off, the boiler and pump will go off? :?: :?: :?:
 
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CompoinCaithness said:
The oddest thing is that if I leave it alone for some hours then go back to the programmer and turn it on for a few minutes then off everything goes off ok!

Does this mean that if you leave it long enough with the programmer off, the boiler and pump will go off? :?: :?: :?:

No; if I leave it on all night I still have to switch the boiler off at either the mains or by switching the programmer on/off.
 
the 2 port valve for the hot water is sticking on, you should be able to replace just the actuator.

Can I test this by disconnecting the valve actuator from the mains? If so how do I determine if this is the problem?

I have been talking to SWMBO who says that the water has been very hot for a few weeks and I wonder if the problem has been there but not noticed before now.
 
Have you disturbed or unplugged any phial thermostats that plug into the side of the boiler? If I recall there's one solid one, and one coiled one.
John :)

The phials are inserted into the holes in the boiler heat exchanger as they should be but I noticed that one was a tight fit so I did not lift it for inspection. the other was free to move in and out of its hole.
 
the 2 port valve for the hot water is sticking on, you should be able to replace just the actuator.

What can I say! The flipping heating is now working correctly. It has corrected itself but no doubt only a temporary respite . I think you must have been right about the valve sticking. how does this keep power on to the boiler? :confused:
 
-- by switching the programmer on/off.

Got it now; On then Off a few minutes later and it goes off. Does this mean that if you switch it On, then Off longer than a few minutes later, it stays on? :?: :?: :?:

I'll try that this afternoon.

I tried this and it looks like the constant on-off switching may have freed the water heating valve. system now back to normal. Thank you.
 
Have you disturbed or unplugged any phial thermostats that plug into the side of the boiler? If I recall there's one solid one, and one coiled one.
John :)

This particular model (Camray 3) has two phials rather than a phial and a coil. Heating now back to normal - seems to have been a sticking valve. If it happens again I shall replace the valve as a starter for ten. Thanks for your help.
 
Boiler: Camray 3 50/70
Burner: Riello 40 424T55 (OIL)
Programmer: Danfoss FP715
Valves (one each for Water & Heat): Danfoss HPA2
Pump: Grundfoss UPS 15-60
Hot water tank thermostat: Danfoss AT
Room thermostat: Danfoss (No model No. visible)
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\snip\
So what the heck have I done - or is it a co-incidence and another fault has developed?!

Well gang, seems like it was a sticking valve in the end and a coincidence that I had piddled about with the boiler. Many thanks for your help and advice. I have updated my profile so that you can see what sort of old b*gger you are dealing with ;)
 
I think you must have been right about the valve sticking. how does this keep power on to the boiler? :confused:
In a system with 2-port valves (usually an "S plan"), the controls do not directly work the boiler. The controls (programmer/timer/thermostats/whatever work the motor in the zone valve (2 port valve) - so for example, when the programmer says to provide heating and the room stat says heat is needed, then the zone valve for the heating is wound open by the valve motor.

Each valve has a small switch which closes when the valve is open. So once the valve is open, the switch closes, and this turns on the boiler.

When demand is satisfied (programmer goes off, or room stat is warm enough) then the power to the motor turns off and the valve runs closed under spring power. As it does so, the switch opens, and if no other zone is calling for heat then the boiler turns off.

The valve should have a small lever on the side. Assuming the demand controls are off ... If you push the lever across you will hear some whirring as you spin the motor through the gears, and at some point there will be a faint click from the switch and the boiler will turn on. let go of the lever and you'll see/hear it wind back under spring power and the boiler will turn off.
Many valves also have a section where you can get the lever to stay behind a step and hold open regardless of the demand controls.
These features are useful for commissioning and fault finding.
 
I think you must have been right about the valve sticking. how does this keep power on to the boiler? :confused:
In a system with 2-port valves (usually an "S plan"), the controls do not directly work the boiler. \snip\
Many valves also have a section where you can get the lever to stay behind a step and hold open regardless of the demand controls.
These features are useful for commissioning and fault finding.

Many thanks for this information - it answers all of my questions in one go. I now understand how the system works and will be able to fault-find more readily in the future. I notice that my valves have a notch into which you can put the lever; it doesn't stay in there but returns to the 'off' position. I suspect that the water heating valve was stuck open since the boiler and pump ran and water valve was open when it should have been closed along with the heating valve. All is now working normally but should it happen again I know where to go first :eek:)

Thanks again - Compo-in-Caithness Scotland.
 

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