Baxi 105e instant pump running constant

[buildersteve]

I have a Baxi 105e instant. I had it serviced and noticed a couple days after the engineer had gone that the pump was running constantly even after it had done the heat res cycle. I called the guy back who says it may be the board but the company he works for just wanted to sell me a new boiler which at the moment would not be possible for me.
I looked on the web and found a referbished board which I gave to another firm to fit but the punp is still running all the time.
The boiler is still working perfectly giving hot water to the taps and the shower. I know these units are getting a bit elderly now but if I can get it fixed I'd prefer that to £3k for a new unit. Any help much apreciated.

 

[Wayners]

Pump controler problem maybe? It's a part that's easily swapped

 

[DP]

I have a Baxi 105e instant. I had it serviced and noticed a couple days after the engineer had gone that the pump was running constantly even after it had done the heat res cycle. I called the guy back who says it may be the board but the company he works for just wanted to sell me a new boiler which at the moment would not be possible for me.
I looked on the web and found a referbished board which I gave to another firm to fit but the punp is still running all the time.
The boiler is still working perfectly giving hot water to the taps and the shower. I know these units are getting a bit elderly now but if I can get it fixed I'd prefer that to £3k for a new unit. Any help much apreciated.

You need a boiler person who knows how boilers work not someone who only knows how to fit
Pcb replacement is on everybody’s mind and their dog but often not the culprit.

If the pump is running constantly, easy fix. Get the meter out and see, where the condition is coming from
If you still have the pcb the you removed, easy task. Pump power is from A4/6

 

[gas112]

Is there any demand lights on or flashing when the pump is running when it shouldnt ?

 

[buildersteve]

Thanks for that DP. I think I'm in the same mind as you. All these companies prefer to sell a new boiler rather than mend the fault.
This all started when the venturi valve fell to bits. It was "whistling" while the shower was running. I had to run the hot tap on the basin before the burner would strike up, then turn the shower on and close the basin tap.
After the service and valve was replaced the pump was constantly running, and it still is. When I called the engineer back he pointed straight to the board and said there were no available spare parts to buy for this boiler. The board change didn't fix the problem.
So I'm now looking for a competent boiler engineer who prefers good customer relations and a feel for some ongoing work!

 

[buildersteve]

Gas 112. There was a flashing light on the fan decal at one point before the engineer did the service but it hasn't come on since and I was there when he checked the fan. It wasn't flashing when he came to do the service.

 

[gas112]

initially i would be looking for a microswitch stuck making the boiler think there is a demand.

 

[buildersteve]

Yes, I did actually looked at the two switches on the diverter valve and they were "clicking" ok. Thats not to say they are contacting well though.
Its just finding an engineer who would work to fix problems on boilers rather than making the "quick call" and blaming the board. No testing or anything, then his office quoted just short of £600 to replace the board. The boards you buy now are all referbished and are around £50 so I'm at a loss as to where they get it to £600. Loosing faith in the boiler engineers here in Medway.

 

[DP]

Looked for pcb

Baxi 248731 printed circuit board | Wolseley

Looking for a Baxi Printed Circuit Board 248731? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

According to the link pcb still available

Gas could confirm if correct part number- man is a genius

Flashing light often suggest pcb ( fan relay worn out on it) fault. Fan relays do get hammered so often fail ( due to constantly switching inductive load). Some makers fit relays that are designed to switch inductive load so these relays last longer.

 

[buildersteve]

The board has been changed and the fan light hasn't returned. Still the pump runs though so may be either diaphagms or the switches, or both.
I'm getting ready to buy the kits. Just need an engineer to fit them. One has been fitted in the past as I can see that the ally washer wasn't completely in place when it was fitted.

 

[buildersteve]

It looks like the only parts I can buy are the diaphagms. The only complete valves I can see are for a different model boiler so I'll buy both diaphagms and find an engineer. May change the micro switched as well. Any thoughts on changing the operating head while he's here?