Boiler doesn’t shut off

sesema

Need advice please I have a fairly new valiant boiler with mega flo.2 years old When my heating comes on as per the timer all radiators get nice and hot then when temp by the Honeywell dial thermostat reaches the desired temp set all radiators get cold apart from bathroom one which should be fine. But problem is boiler doesn’t shut off completely it goes down temp to 40 or 45 clicks off then less than a min later fires up again goes up to 65 or 70 which is a bit above target (65) then goes down again and so on keeps doing that till times it off. My installer came for service said it’s fine that’s because it’s maintaining the temp which doesn’t make sense for me as radiators are cold only gets hot when area where thermostat is gets colder then set temp. Is it normal that boiler keeps fireing every min.
No problem with thermostat as radiators get cold when they should and problem with Honeywell timer either as comes on on time and off on time. Can someone explain please thanks a lot

Alex1983

I would be checking the zone valves to make sure one has failed and keeping the boiler on.

daveyjp

Perfectly normal.

The boiler is firing on demand from the dial thermostat (if it is fixed it may be in the wrong part of the house) not the radiator temps, which are set using the TRVs.

bris

Where is the thermostat? If the thermostat is in a cold part of the house it will keep firing the boiler.


Most people put their thermostats in the hall, this is usually a large open area where no one lives. The boiler is continuing to fire but the TRV's are doing the work in the living areas so you don't realise how much heat you are wasting.

sesema

Yes it is in my hall actually it’s fairly large area also leading to an open plan kitchen/living room.
So what causing that is temp slightly drop thermostat triggers boiler but not that it heats the radiator is that right
My bill came really high so I started to check what’s happeing then noticed boiler never shuts off completely more than one min during timer but when radiators stay cold only bathroom on thought there should be something I’m doing wrong as thermostat is working radiators cool perfectly fine when they should.
Shall I move thermostat somewhere else
Thanks all

JohnB47

sesema wrote: »

Yes it is in my hall actually it’s fairly large area also leading to an open plan kitchen/living room.
So what causing that is temp slightly drop thermostat triggers boiler but not that it heats the radiator is that right
My bill came really high so I started to check what’s happeing then noticed boiler never shuts off completely more than one min during timer but when radiators stay cold only bathroom on thought there should be something I’m doing wrong as thermostat is working radiators cool perfectly fine when they should.
Shall I move thermostat somewhere else
Thanks all

You haven't actually said if your rads have TRVs fitted (individual thermostats on each radiator except one - presumably the bathroom one).

coffeehound

Is the megaflow’s thermostat set higher than the flow water from the boiler so it never stops calling for heat?

sesema

Sorry yes all my radiators have trv including the hall one opposite to the thermostat shall I turn it fully on

sesema

coffeehound wrote: »

Is the megaflow’s thermostat set higher than the flow water from the boiler so it never stops calling for heat?

No mega flo 60 central heating on the boiler is 65

JohnB47

sesema wrote: »

Sorry yes all my radiators have trv including the hall one opposite to the thermostat shall I turn it fully on

Well, I would turn it up to, say, midway and see what happens. It sounds to me like your hall stat is relying on heat trickling through from other rooms.

I think you just need to get used to what setting to go for on the TRVs.

Having said that, even with the hall radiator fully off, I'm surprised that your boiler is cycling so often. You say the room stat goes from 65 to 40 or 45 degrees in just a minute? (If I understand you). That suggests a hall with a high leakage of heat.

So yes, turn the hall rad TVR up in steps and see how it behaves.

sesema

JohnB47 wrote: »

Well, I would turn it up to, say, midway and see what happens. It sounds to me like your hall stat is relying on heat trickling through from other rooms.

I think you just need to get used to what setting to go for on the TRVs.

Having said that, even with the hall radiator fully off, I'm surprised that your boiler is cycling so often. You say the room stat goes from 65 to 40 or 45 degrees in just a minute? (If I understand you). That suggests a hall with a high leakage of heat.

So yes, turn the hall rad TVR up in steps and see how it behaves.

I put the rad opposite to stat on 3 it’s turns off fine when it should so as all other rads which I managed to balance my question is why does the boiler start getting down then clicks shut at diff temp 40 45 or 50 sometimes then after a min fires up again I hear the ticking of bathroom pipes expanding tried to turn bathroom rad off but still boiler fires up also was told one has to stay on which is the bathroom for me. It that normal that boiler only shuts down when time is up or stay is off?Can it be the bathroom over taking? Which rad should not have controls and on what setting should that rad be left on
My understanding is timer on for 4hour for example stat is on 20 area where stat is reaches 20 boiler cuts of time temp drops so low. If I’m right can my stat be that sensitive to keep firing up every 2 min though doesn’t heat the rad hope I make sense thanks a lot