Baxi duotec 24 HE

[johnc86]

Noticed a bit of a strange issue with my boiler recently. It seems to fire even though the programmer is not calling for heat and no hot water taps are open. Looking at the boiler, the green led next to the Tap symbol is always illuminated. The burner kicks in every few minutes and then goes off again after few 30 seconds or so. We get hot water and the radiators are getting hot. I'm pretty sure the pump is running when there is no call for heat though which seems odd.
We've had a leaking fibre washer on the return pipe which has led to the boiler loosing pressure and having to be re pressurised all the time. The leak has been fixed now and the system fully drained and refilled with a dose on inhibitor.
A couple of times recently I've noticed the pressure going really high. I'm 100% sure that it wasn't the following loop being left open as I checked this.
Wondering if what I'm describing is symptomatic of any particular part which may be faulty?

Thanks.

 

[kidgreen61]

Does that model have a HW preheat mode?
If so, that will be why it regularly fires up.
You can switch it off, it'll save gas.

 

[terryplumb]

"Pressure going extremely high"...
When central heating is on for an hour ,what exactly does it rise to ? And when system is cold ,what is the pressure ?
You may have a problem with your EV
( Expansion vessel).

 

[picasso]

Hot water demand stuck on .

 

[johnc86]

Cold it's at about 1.5 bar. When the heating is on it seems to slowly ramp up. It's sat at 2 bar now, the heating has been on for about 20 mins. At the moment it's showing the radiator symbol lit up, not the hot water. I've seen it go as high as 3 bar when there is call for heat.

If I set the heating to be on for an hour, it won't stay on for the full hour. It will go off but the pump will stay running and show hot water demand (even though all the hot water taps are closed).

 

[gas112]

Do you have any of your hot water pipes going to the taps run under concrete floors or suspended floor downstairs that could be possibly leaking this would show as a hot water demand
or its HW turbine bobbin is stuck in the up position boiler thinks there is a hot water demand

 

[johnc86]

Hi, I'm pretty sure there's no leaks on any of the pipes. The fault is intermittent so it sounds more likely to be a part out of those two options??

 

[johnc86]

https://www.heatingandcateringparts...-28he-33he-40he-magnetic-flow-switch-5114710/

Looks like this might be at fault. Cheap and easy fix. Is it worth trying to clean the old one?

 

[gas112]

you need to get the proper gc number of the the boiler it starts with 47
as there is 2 types of those and it needs the correct one and may not come separate but with whole housing . also they do not usually come out easy and can snap off in position

 

[MeldrewsMate]

If the hot water demand turbine/switch was falsely indicating then the radiators would never get hot, so this doesn't explain the symptoms fully, and thus cannot be the only cause of the fault.
Further evidence is needed