Boiler keeps on boiling water even heating is switched off

[luckyvictor]

The problem is, my ideal boiler logic heat h15 keeps on burning (igniting flame icon on) all the time, all day long, regardless of the programmed on off schedule for both heating and hot water.

when we have the heating turned off from the thermostat programmer (danfoss tp9000ma-si), i.e frosted protection at 5 degree, or it is "off" during the daily program. It still burning, heating water.

When we have both heating and water hot scheduled to be off, it still burning.

I can safely say that there is no demand called from the program and it just supplies. The temperature displayed on the boiler is always 70+, I expect it displays 00 sometimes to show no demand required.

I have had an engineer check when doing annual service, boiler itself is ok, but he doesn't know what this problem is, suggested is the motorized valve, but he can't prove it is not functioning, as he seems to prove that all 3 of them are working ( 2 heat zone, 1 hot water).

So any suggestions to my problem please? How may I track down the root cause and take action accordingly?

Right now the house is always burning hot, I have to manually adjust the radiator thermostat, as well as switch off the boiler itself to avoid unnecessary heat(money)

 

[Basher]

Ultimately your boiler "switched live" supply is turned on and off by microswitches in the motorised valves you have, irrespective of the setting of other controls. If one of the motorised valves is stuck, or a microswitch inside is welded closed, it would account for the symptoms you describe.
Any competent plumber or electrician ought to be able to get to the bottom of the problem, through electrical testing/ diagnosis.

 

[luckyvictor]

Ultimately your boiler "switched live" supply is turned on and off by microswitches in the motorised valves you have, irrespective of the setting of other controls. If one of the motorised valves is stuck, or a microswitch inside is welded closed, it would account for the symptoms you describe.
Any competent plumber or electrician ought to be able to get to the bottom of the problem, through electrical testing/ diagnosis.

So it has to be the motorized valves, can not be sensor or thermostat or programmer?

How may I isolate and identify the faulty motorised valve please?

Also, when I turned off the boiler itself, the heating system did gradually cool down, is it because the motorized valves 'working' and stop the hot water out? Or the valve still malfunction and draining all the the hot water out, since no fire is supplied to provide more hot water, so eventually all hot water drains out and system cools down?

My motorised valve is Honeywell 272848

 

[John.g]

You will have to remove the orange wire from each motorized valve at its nearest wiring centre when neither CW or HW programmed on and test for 230V between the orange wire and neutral (or earth), take care as one might be live with boiler switched off as the motorized valve (end switches) are supplied with a permanent live (grey wires).

 

[Basher]

So it has to be the motorized valves, can not be sensor or thermostat or programmer?

sorry to mislead you - the above items do need to be working, supplying power to the motorised valves for the boiler switched live to get power. So the room stat should be able to turn the boiler on and off, which you say it does.
Also you should have a thermostat on the hot water cylinder that supplies power, which should switch off when the water is hot enough. You don't mention that?
If that were faulty it might cause your symptoms

How may I isolate and identify the faulty motorised valve please?

I see John.g has answered this!

Also, when I turned off the boiler itself, the heating system did gradually cool down, is it because the motorized valves 'working' and stop the hot water out? Or the valve still malfunction and draining all the the hot water out, since no fire is supplied to provide more hot water, so eventually all hot water drains out and system cools down?

Valves don't drain the water out, they just stop/alter the flow. The water stays in the system and gradually cools down.

 

[fowlerboi]

Am I right in thinking that the orange on the valves gets its supply from the permanent live(grey) to the valve not the switch live which just actuates the valve (brown).

I think a stuck microswitch will fire the boiler without the programmer/ stat calling for demand.

I personally would give a different plumber a ring and get them to find out which valve it is and get them to change it. Mention on the phone it needs a bit of diagnosis as not all plumbers are electrically clued up and find one that is. I would bet good money on a stuck microswitch.

A faulty programmer could be a culprit if you’ve left your room thermostat at an unachievable level or the valves at the radiator in the same room as the thermostat has been meddled with. A good check will be if the room thermostat reads the same temperature as you think the room should be

 

[luckyvictor]

sorry to mislead you - the above items do need to be working, supplying power to the motorised valves for the boiler switched live to get power. So the room stat should be able to turn the boiler on and off, which you say it does.
Also you should have a thermostat on the hot water cylinder that supplies power, which should switch off when the water is hot enough. You don't mention that?
If that were faulty it might cause your symptoms

Yes, there is one, which is Codice 542794, I never touched it since day one so I just forgot to mention, it is set to 50 degree.
I am unable to find any manual of this thermostat, how to diagnose whether it is faulty pleaes?

Valves don't drain the water out, they just stop/alter the flow. The water stays in the system and gradually cools down.

My bad, i simply want to say that the valve didn't stop the water flow out and circulate in the heating system, and heat dissipated eventually.

 

[luckyvictor]

You will have to remove the orange wire from each motorized valve at its nearest wiring centre when neither CW or HW programmed on and test for 230V between the orange wire and neutral (or earth), take care as one might be live with boiler switched off as the motorized valve (end switches) are supplied with a permanent live (grey wires).

At the moment, I have turned off boiler, the programmer (hence hot water schedule as well as heat schedule), and I notice that 2 out of 3 of the honeywell motorised valves, the levers have 'resistance' and when i push it to manual (ON), it returns. 1 has no resistance and loose.

Does it automatically mean this one is faulty?

I cant remember what that service engineer did but he didn't manage to prove that any of the Motorized Valve is faulty.

 

[John.g]

More than likely, can you just remove the orange wire from this one.

 

[fowlerboi]

The valves typically have no resistance when open. Did you check with the power off?

If you did then I would suggest thats the culprit