Baxi 105e Instant

[Sulli]

I had a Baxi 105e Instant installed three years ago, and up until now has caused me no problems. The problem i am currently experiencing is with the DHW. Sometimes when the DHW is called for, it supplies Hot water immediatly and yet in another instant it will run cold and the DHW will not function. Having spoken to a to Baxi, i explained that i have been guilty of using the Pre - Heat function which has been set to 3/4, to which they told me this function should not really be used, so now i have switched it off. The Central Heating system is working fine. I've also noticed that when calling for DHW and it runs cold, if i then operate the pre - heat function the DHW will operate and Warmish water will flow, but not Hot. During this operation, if i was to turn pre - heat back to zero the warmish water will stop and im left with cold water again. CAN ANYONE Suggest any procedures, or is it a case of a knackered component. Reading the fault finding page at the rear of the book sugests a pcb problem, but your the experts. I would very much appreciate any comments or feedback . Thanks, and i hope ive made sense. All the best Mark

 

[Agile]

You should be able to use the preheat function as its part of the design! However, the way its achieved causes some components to fail prematurely sometimes.

The Hot water demand switch does not seen to be getting activated and I would be starting my investigation there!

Tony

 

[gazthepottertonengineer]

and the DHW will not function. Having spoken to a to Baxi, i explained that i have been guilty of using the Pre - Heat function which has been set to 3/4, to which they told me this function should not really be used, so now i have switched it off.

Who ever told you this clearly doesnt know what they are talking about it is fine to use the pre-heat 100 % of the time if the hot water light comes on when you turn the tap on and boiler cuts out after 10-15 seconds i would say it was a sludged up plate heat exchanger however if the hot water symbol isnt coming on then i would look at the presure differential assy or the microswitch that sits on top of it

 

[Sulli]

You should be able to use the preheat function as its part of the design! However, the way its achieved causes some components to fail prematurely sometimes.

The Hot water demand switch does not seen to be getting activated and I would be starting my investigation there!

Tony

Hello Tony

Thanks for your response. This Temprature sensor switch should activate the boiler if DHW is called for i take it . Is there anyway i can check the operation of the switch, or do i just replace it ? . Ive priced one up £10 - £15 . Any response would be welcome. Cheers Mark

 

[Sulli]

and the DHW will not function. Having spoken to a to Baxi, i explained that i have been guilty of using the Pre - Heat function which has been set to 3/4, to which they told me this function should not really be used, so now i have switched it off.

Who ever told you this clearly doesnt know what they are talking about it is fine to use the pre-heat 100 % of the time if the hot water light comes on when you turn the tap on and boiler cuts out after 10-15 seconds i would say it was a sludged up plate heat exchanger however if the hot water symbol isnt coming on then i would look at the presure differential assy or the microswitch that sits on top of it

Hello, and thanks for your earlier response.

Is there any way i can test the microswitch, or is it just a case of replacing it to see if that works. All the best Mark

 

[gazthepottertonengineer]

the simple test is if the hot water light on the front of the boiler comes on and stays solid when the hot tap is turned on and goes off when you turn tap off if it does then switch is fine simple

 

[Sulli]

the simple test is if the hot water light on the front of the boiler comes on and stays solid when the hot tap is turned on and goes off when you turn tap off if it does then switch is fine simple

Hi Again

This morning i isolated the boiler ( Water and Mains ) then removed the DHW flow switch. On inspection the tip was Black, so decided to clean it with a bit of wire wool. I then replaced the switch and tested the boiler. All was ok , ran DHW tap and had instant hot water. Turned off DHW tap and waited, then tried again, all ok . Then after several minutes decided to try it again , to my disapointment , i was left with cold water as the Boiler hadn't triggered when DHW was called for. Any further suggestions or shall i just replace this DHW floe switch. All the best Mark

 

[Agile]

I dont think that you have ever clearly said if the pin is reliably pushing the microswitch operating lever.

If it is then the switch is probably intermittent.

Thats a common fault on your model. I would say that they have used a component which is unsuitable for the job.

Now the nice bit! I think that yours comes with about half the wiring harness so the cost is about £15 instead of about £4 just for the switch.

They could easily have used the same part as the system flow switch. Its a much more reliable type and has push on connectors as is simple to change. The commonality of parts saves manufacturing costs!

Could it be that they just want to make a bit of money from selling spares?

A real bodger would actually buy the flow switch and fit spade connectors to the wires and it would never fail again. Not the manufacturers recommended repair of course but its a third the cost and more reliable!

Tony

 

[gazthepottertonengineer]

cant believe you are suggesting that Tony

what we are tring to say is if its the pin not coming out that is the problem then you need to replace the pressure differential but if that is working ok then its the microswitch that sits on the end that needs replacing

 

[Sulli]

cant believe you are suggesting that Tony

what we are tring to say is if its the pin not coming out that is the problem then you need to replace the pressure differential but if that is working ok then its the microswitch that sits on the end that needs replacing

Replaced the DHW flow switch with a new one. Tested boiler, and up until now, all is working fine. Thankyou for your time and help in resolving this matter. Thanks, and all the best Mark

 

[Sulli]

I dont think that you have ever clearly said if the pin is reliably pushing the microswitch operating lever.

If it is then the switch is probably intermittent.

Thats a common fault on your model. I would say that they have used a component which is unsuitable for the job.

Now the nice bit! I think that yours comes with about half the wiring harness so the cost is about £15 instead of about £4 just for the switch.

They could easily have used the same part as the system flow switch. Its a much more reliable type and has push on connectors as is simple to change. The commonality of parts saves manufacturing costs!



Could it be that they just want to make a bit of money from selling spares?

A real bodger would actually buy the flow switch and fit spade connectors to the wires and it would never fail again. Not the manufacturers recommended repair of course but its a third the cost and more reliable!

Tony

Replaced the DHW flow switch with a new one. Tested boiler, all ok up until now. Thanks for all your help, much appreciated. All the best Mark