Problems with Baxi 105e CH

[Twincam]

My Baxi 105e instant which is only about 1 1/2 years old has developed a problem where the CH will not work, The boiler fires up when CH is put on but only runs for about five minutes before cutting out. There is no external thermostat as I have radiator valve stats. I have noticed that the flow side of the system is hot but there is no heat in the return side (either at the rads or the boiler). I suspected an air block so have bled each of the rads. After reading the servicing guide I thought maby the gauze filter on the return pipe at the boiler was blocked, I have removed this and found it to be in perfect condition, so now I am stuck. Any help would be greately appreciated as the missus is now standing with hands on hips and a "if you think your' going to the pub while I have no heating you are soreley mistaken" look on her face.

 

[ChrisR]

COuld be several trv's are shut
Could be there's a plumber in the pub
could be 'er indoors needs a drink too.

How's the HW?

There are some funnies with these where the HW store heats up then the
boiler stops - saw a query recently.

 

[Twincam]

Went to the pub anyway, she must be in a good mood, could'nt find any plumbers there so came home (to a cold house). The hot water works fine.
hope this helps

 

[ChrisR]

This is annoying me because I read a short thread on it recently. Hopefully one of the potterton guys will know...

 

[Agile]

Do you get any unusual flashing lights when this happens?

Isn't this one of those funny pcb faults Chris?

Tony

 

[Twincam]

I do get the hot water tap light flashing while the boiler is running, one other thing I have noticed is that while the boiler is turned off during the night the rads creak occasionaly, I have checked them and they are slightly warm at the top. This happens when the boiler is switched off at the controller. I understand that the 105e instant has a 'reserve' DHW store so that the hot water can run instantly when you open a tap, this reserve is heated permently and the boiler will operate to keep it topped up to temperature. Could this topping up of the hot water reserve be getting into the CH system ?

Any ideas, I will have to call Baxi soon as the missus is now well pi***d off.

Thanks

 

[Agile]

If the hot water tap light is on when the boiler should be on heating then the boiler THINKS there is a demand for water!

The DHW flow switch is apparently operated when it should be resting. Either the switch has failed or the actuation is seized.

ChrisR is close to you and can easily deal with a problem like that.

Tony Glazier

 

[gazthepottertonengineer]

when the tap symbol flashes this means it is heating the store up and not that there is a hot water demand !
does the radiator symbol come on at all

 

[Twincam]

At work at the moment so not sure which lights are which but the power neon and the burner neon are on steady, the red temperature neons across the top gradually build up and the tap neon flashes, can't recall seeing the rad neon lit. Only stays like this for about four to five minutes then shuts down. As mentioned, the flow pipe is hot at this point but no heat in the return pipe. As far as I can tell the pump is running (it vibrates to the touch and gets hot). Hope this helps

 

[gazthepottertonengineer]

if rad symbol is not lighting up after the tap symbol flashes then i would first check for problems with programmer , room stat etc that they are telling heating to come on

 

[Twincam]

There is no room stat fitted, I think that the programmer is working OK, I have bridged the demand wires to place the boiler on permenant heating and it works the same as when the controller is operated (runs for five minutes then dies).

 

[Paul Barker]

Have you got any dripping taps? Combi boilers always favour hot water, if they sense a demand for water they won't give you central heating. By the sound of it you've never seen the heating demand light lit during this episode.

The fact the top of the rads get warm while the boiler is trying to heat the store sounds like a fault in the diverter valve also or only.

If It's more than a dripping tap; a job for the experts.

 

[Twincam]

Thanks for the advice, no dripping taps, I suspect the diverter valve also and I think I will call Baxi in to take a look.

Thanks to everyone for your comments and suggestions.