baxi Combi 105E

[Oceanic0]

Help Please my Baxi combi 105E Fires up no problem but Temperature very slow to rise.When running only have 1.5 volts at the modulating coil on the gas valve.If I give this valve 9 volts from an external source then the flame goes high and the Temperature rapidly increases.but will not modulate automatically.Also when the boiler reaches set temperature it shuts down and the safety thermostat neon starts flashing

 

[BOB D.O.L.E]

Help Please my Baxi combi 105E Fires up no problem but Temperature very slow to rise.When running only have 1.5 volts at the modulating coil on the gas valve.If I give this valve 9 volts from an external source then the flame goes high and the Temperature rapidly increases.but will not modulate automatically.Also when the boiler reaches set temperature it shuts down and the safety thermostat neon starts flashing

so you get 1.5v at first which is good then it should rise to 9v after 30 seconds does this not happen if not your mod valve needs a bin.

 

[Oceanic0]

Hi Bob thanks for the info yes the votage starts at 1.5 volt but doesnot inrease at all. If I Supply 2 - 9 volt from an external power supply then the Valve modulates ok and all works fine.
I have replaced the Safety Thermostat but this has not made any difference

Cheers

Mike

 

[spacethegas]

you will need a qualified corgi.

the burner pressure requires testing.

the high & low rate testing.

the current at the modulating coil.

an adjustment, a new valve or pcb may be required.

 

[BOB D.O.L.E]

you will need a qualified corgi.

the burner pressure requires testing.

the high & low rate testing.

the current at the modulating coil.

an adjustment, a new valve or pcb may be required.

or maybe the thermister is dud

 

[spacethegas]

i'm not 100% but i think thats more likely if the problem was that it wouldn't go down to low rate.

 

[Oceanic0]

Hi Guys thanks for the help

It would appear that the gas flow is ok as I can control the Flame by manually regulating the voltage at the gas valve coil.
Do you think it could be a fault with the PCB as i can only get 1.5 volts all the time at the valve coil or is it something else that is telling the PCB not to increase voltage at the coil.
I have run the boiler at 60o temp for 15 mins without an issue by regulating the Voltage at the coil from an external power supply

 

[spacethegas]

may i refer you to my previous but one post.

 

[BOB D.O.L.E]

Hi Guys thanks for the help

It would appear that the gas flow is ok as I can control the Flame by manually regulating the voltage at the gas valve coil.
Do you think it could be a fault with the PCB as i can only get 1.5 volts all the time at the valve coil or is it something else that is telling the PCB not to increase voltage at the coil.
I have run the boiler at 60o temp for 15 mins without an issue by regulating the Voltage at the coil from an external power supply

What are you using to regulate the voltage to the mod valve

 

[Oceanic0]

Hi I am using a 10 amp 1 to 9 Volt DC variable power supply connected directly onto the Gas supply coil

 

[Oceanic0]

Hi Guys
Followed your advice and bit the bullit and purchased a new PCB
didnot work at first try but a quick call to the Heat team revealed that after fitting a new PCB you have to hold the reset switch for 30 secs to activate. Boiler then ignited and alls well.
many thanks for your help much appreciated

 

[namsag]

There should have been a leaflet in the box telling you to do that . So box has prob been opened i would be asking myself why.

 

[landersd]

hi, i have a 105 he that developed an intermitent fault a couple of weeks ago.
at first it was just with the dhw, i.e the light was flashing to show a fault on the fan or flue. Now it,s everything and i have no dhw or heating. after lots of research on the net it seemed that this was a consistent problem with this model and that a new pcb was required, but i have fitted one and still the problem is there. can anybody help

digger