Hi all. Just fitted a new Diverter Valve assembly to an ageing Baxi 105e, and after some initial problems with leaks from the pressure sensing pipes, it was all sound and leak-free, so ready to fire up. Yesterday it started and ran to temperature normally, but this morning, after the burner lit for central heating, it went out after only a minute or so. I tried a work-around that i used last Winter, which is to turn on the hot tap nearby at the kitchen sink and then when i turn that tap off after a couple of minutes running the hot water, the burner for the central heating stays On. It stays on as long as required. I've no idea where to look for the cause of this problem, and i'm definitely hoping that it's not a Diverter problem as that's supposed to be all fixed !
Baxi 105e burner problem.
- Thread starter molegrip
- Start date
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There is a switch on the top of the diverter valve, when you select CH the pump should run, and this switch should make , does it ?
Molegrip. This is a great boiler, easy to fix by a heating engineer who understands its operation. Age is not an issue
You will be well advised to seek a knowledgeable heating engineer. In hands of a novice, things could go wrong leading to greater tears.
You will be well advised to seek a knowledgeable heating engineer. In hands of a novice, things could go wrong leading to greater tears.
Thanks Ian, yes, the pin shoots up and operates the microswitch, the fan runs, ignition happens and the flame lights as normal, but it went out after a minute or two. Running the hot water side for a while 'persuades' the CH to stay on and reach full temperature. It was doing this last Winter but i was hoping (praying) that the new Diverter assembly would have cured it. Later in the day the CH ran really well, without this burner fail - weird. Along the way i seem to have discovered a faulty external expansion vessel, in which the air pressure was zero and the Schroder valve leaking air. By tapping the vessel i've deduced it is about 90% water inside it and 10% air, so a new one has been ordered. This should fix the long-term pressure swing from 1 Bar to 2.5 Bar - just short of overflowing via the PRV. Good job i started well before Winter !
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Maybe, just maybe, the boiler pump is a little weak and it needs a few minutes to get going properly? The hydraulic resistance of the hot water generating circuit is much lower than that of the heating, so running that tap compensates while the pump is getting into its stride.
Before running that tap turn on the heating and feel the heating flow pipe (leftmost pipe?) Does it get very hot very quickly, rather than warming up gradually over 10 minutes or so?
Before running that tap turn on the heating and feel the heating flow pipe (leftmost pipe?) Does it get very hot very quickly, rather than warming up gradually over 10 minutes or so?
A service these days is a spring clean without even taking the cover off
A service should be what the manufacturer asks be carried at at prescribed intervals, This is minimum requirement
A thorough service restores the appliance to near ’out of factory’ condition and can be undertaken based on appliance operation understanding and past experience of that model.
Here the symptoms are known, OP has his own fragmented understanding. What is 10% water and 90% air ratio in th3 EV? Where does that come from? Why can the vessel not be pressurised.
A service should be what the manufacturer asks be carried at at prescribed intervals, This is minimum requirement
A thorough service restores the appliance to near ’out of factory’ condition and can be undertaken based on appliance operation understanding and past experience of that model.
Here the symptoms are known, OP has his own fragmented understanding. What is 10% water and 90% air ratio in th3 EV? Where does that come from? Why can the vessel not be pressurised.
Thanks v much, that sounds intriguing and its a new idea to me. I will get back with a report on the CH flow pipe heating up as soon as the new expansion vessel arrives and i can fire up the boiler, possibly tomorrow, definitely by Thursday. I don't know anything definite about the pump's age and history, but it is the one that was in the boiler when i moved in nearly 6 years ago, and the boiler was already several years old then, so the pump could possibly be 10 years old or more. It runs very quietly if that means anything.
Hi again. Fitted the new Expansion Vessel and the boiler fired up ok. The CH flow pipe was too hot to touch in about ten seconds, so i'm thinking there's no problem with the pump. Will run it to full temperature tomorrow and hope there's some progress and 'nothing to report', i live in hope.
It shouldnt be, think you still have a problem
With the pump do you mean ?
can be a few things dont just change the pump for the sake of it, come back and tell us what happens when you test it
Clean the return filter
Thanks, i just about remember digging a load of rubbish out of there a few years ago. Hiw to do with the Minimum of draining down ?
Sounds as if it is partially blocked/restricted, hence the poor initial flow through the system.
A fault that is easily fixed.
Take temperature reading etc around the boiler. Not Rocket science. It is evident the temperature rise is rapid during heating but fine for HW.
Did point out earlier re expansion vessel and op having ideas about water and air ratio- ends up changing the vessel. No way would the vessel on a 105e cause described issue.
Changing parts without proper diagnostics is a slippery slope
Take temperature reading etc around the boiler. Not Rocket science. It is evident the temperature rise is rapid during heating but fine for HW.
Did point out earlier re expansion vessel and op having ideas about water and air ratio- ends up changing the vessel. No way would the vessel on a 105e cause described issue.
Changing parts without proper diagnostics is a slippery slope
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