Baxi 105E CH getting very hot & boiler fires at odd time

[spyke749]

Hi,

Newbie here, I have already searched the forums and tinternet for some answers, however, I have a couple that hopefully someone here can assist with.

Moved into new house, which is fitted with a Baxi 105e and British Gas RC Plus programable thermostat. I've got the instructions for the thermostat and have now "paired" it with the receiver. All sorted

BUT, here is where I have problems :

1 : I set the Thermostat to call for heat, boiler ignites and get the CH water hot, very very hot. That hot that you can't touch the radiators. The CH dial on the boiler is set to point towards 1 o clock ..... all the temp lights come on, up to 80c. The boiler will eventually cut out, but, only when the CH water is boiling.

Is this normal?

2 : Secondly, the boiler will fire up in the middle of the night, or silly O clock, even when the Thermostat is not asking for heat, and no one has turned a tap on, and there are no obvious leaks anywhere

Any idea why?

3 : On the boiler, the dials for the CH and HW pre heat, seem to have a natural "stop" around the 3 o clock position, however, you can turn the dials past this part all the way clockwise.

Are the "soft stops" or "detents" at the 3 o clock position normal?

Thanks for any assistance given.

 

[Andygasman2010]

Firing up in the middle of the night is normal when it's on preheat, you can turn this function off on the facia. I can't remeber how the knobs look off the top of my head but i'm almost certain that 12:00 is off.

Do you know if this boiler has had a replacement PCB recently? It kinda sounds like the knobs have been fitted wrong. It's hard to explain but the knobs can be fitted in the wrong orientation so that off isn't actually off, but it's actually about 2/3rds on. You need to partially remove the PCB to rectify this.

 

[spyke749]

Firing up in the middle of the night is normal when it's on preheat, you can turn this function off on the facia. I can't remeber how the knobs look off the top of my head but i'm almost certain that 12:00 is off.

Do you know if this boiler has had a replacement PCB recently? It kinda sounds like the knobs have been fitted wrong. It's hard to explain but the knobs can be fitted in the wrong orientation so that off isn't actually off, but it's actually about 2/3rds on. You need to partially remove the PCB to rectify this.

Mmmm did think the knob's might be in the wrong position, this would alos explain the pre heat kicking in, even when the knob looks as though it's turned off, it may actually be 2/3rds on.

Will have a look in the morning.

 

[spyke749]

Do you know if this boiler has had a replacement PCB recently? It kinda sounds like the knobs have been fitted wrong. It's hard to explain but the knobs can be fitted in the wrong orientation so that off isn't actually off, but it's actually about 2/3rds on. You need to partially remove the PCB to rectify this.

Mate, you are soooooo right

Sorted it

All the problems are linked, and the problem is ........................ Dials on the boiler control panel are fitted 180 degree out.

Basically, the dials are 3/4 turn, from the 12 o clock position (off) and turn clockwise to the 9 o clock position (Fully on). But, because the dials are 180 degree out, when I have them set at the 1 or 2 o clock position, and only just on. They are actually set at the 7 or 8 o clock position and almost fully on.

Hence, Central heating is almost boiling hot, the Hot Water pre heat is trying to keep the reservoir of water at a high temp and firing every 90 mins or so. Also explains why the dials are stiff to turn between 3 and 6 o clock position, this section should be between 9 and 12 o clock and is not designed to be turned through.

But life is not that simple, to correct the problem, I have to take the boiler control panel off, PCB off, turn the dials 180 degree and put it all back together.

That said, there are 2 points here :

1 - which numpty fitted it like this - DIY or plumber ????

2 - previous owner must have known, so why not put it right, or at least tell us when we moved in ???


There is one thing though, a great feeling of success, finding a problem, working through it and finding a solution at the end .... especially when it's on a subject that I'm not trained in.

Thanks for the suggestion and pointing me in the right direction

 

[Andygasman2010]

I've seen it a few times now. It's a fairly easy mistake to make, we all do it ONCE... plumber or DIYer!

Pull the knobs off and drop the control box down. Remove the back of the control box and unscrew the PCB. You don't need to disconnect it just lift it up a few inches and turn both potentiometers to max. Refit it and refit the knobs, in the max position. Sorted.