Baxi 105 tips needed. Please.

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Hi folks.

I'm after some advice if possible.

My baxi 105e seems to have a sticking diverter valve. C/h flow pipe is getting hot when running DHW.

I've ordered the kit to refurb the valve and know I have to drain the boiler before I remove said valve..... I also know I will have to isolate the c/h flow and return.

However the boiler is downstairs. The DHW out to the taps leaves the boiler turns up and into the ceiling void then runs to the back of the house feeding the bathroom before dropping down into the kitchen. It has no isolation valve at the boiler end.

I'm guessing that if I remove the diverter valve assembly that all the water in the hot pipe between where it drops down into the kitchen and the boiler is going to deposit itself in the boiler cupboard. Am I right in thinking this and if so how would the pros approach this to minimise the mess?

Thanks and regards.
 
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Also just thought of another question whilst waiting for kit to arrive.

What's the best way of disconnecting removing the valve? I know I have to undo the pipe from the main heat exchanger on the right, the Ch flow pipe underneath and the sensing pipes. Also the clip in bypass pipe had to come off. However on the right it looks like I can either


1. Remove the 2 Allen screws that hold the connection to the capiliary tube and leave it in place or

2. Leave that on. Disconnect the capiliary gauge pipe and pull the valve spigot out of the part that screws to the plate heat exchanger. I believe it's push fit with an o ring.

What's best?
 
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you are best advised to completely remove the PCB from the boiler before starting, you have the worst boiler for water ingress damage to your PCB, you dont need to isolate the flow and return valves, leave them alone or they will leak, you dont need to remove the diverter valve the kit is easily installed in situ
 
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Isolate you cold mans and remove the hot water pipe under the boiler. That’s what I do if I’m working on those and going HW diaphragm in say a cellar.

And Ian is right about the pcb. We’ve all been there
 
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Thanks guys.

I'm a bit confused now....
The way I see it I need to remove the bypass valve to replace one of the valve plungers. The bypass valve is on the back of the unit and so the whole lot has to come out doesn't it?

I though there were two plungers that act upon each other. One comes out through the front when you take off the dhw differential and one from the back held in by the bypass valve.

Have I got the wrong end of the stick?

Good advice about the PCB. I'ts in a really vulnerable position.
 
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no you can do the by-pass in situ if it needs it, most of the time it doesnt, but you would be well advised to change the water venturi too, it is most likely that has broken up and that is what is causing your problem
 
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Thanks Ian.

I don't want to change the bypass valve really (although the kit comes with a new one including the brass housing) but to get to the rear most plunger and spring I need to remove the bypass brass section. To remove that I need remove the copper bypass pipe that is held in with the clip.

I could remove the bypass pipe in situ I guess but I can't see how I can remove the bypass valve to get to the spring and plunger without taking the whole valve out. There doesn't seem to be access to it unscrew it even if I took off the side panel.

The plunger I'm referring to is the rear one that is pushed by the front most plunger pin that is moved by the dhw diaphragm.

Both diaphragms seem to be ok as both pins move ok and move the micro switches.

I appreciate you helping me by the way...
20200905_171617.jpg
20200905_171625.jpg
 
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yes i know what you are saying I have serviced over a hundred of these,everything can be done in situ, would be very unusual if you need to do the rear shuttle , your problem will be the water venturi,it will have broken up,I have only ever had to change the rear shuttle a hanfull of times, a bit of a pain but nothing really hard about doing it, never removed the complete divertor ever
 
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Ahh right. I see thanks.

Is the water Venturi in the brass assembly on the right near the prv? That failing would cause the symptom of the Ch flow getting hot when running the bath?

If that's the one I'm thinking of, I just need to isolate the supply do I?



Shuttle. Now I know what it's called, :)
 
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To fit your kit you will need to drain the boiler and isolate the cold water supply, then remove the old venturi and fit the new one , make sure you get all the brocken bits out, they can be a pain
 
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no need to take valve out. But as you have already ordered the kit ,once you have took diaphragm housing off 2 sensing pipes 2 grub screws just change the big castleated nut and the pin with o ring seating on it ,but in reality you dont usually need the kit as its just a bit of shyte on the pin
but a severly blocked plate heat exchanger can also cause it to go into heating when the water is on .
that is only held in position by 2 screws so you will have it all drained anyway so whip that out and get some brick acid\patio cleaner and pour that into holes top of plate for 20 mins then flush plate under tap and re do for 10 mins that will leave it as clean as whistle
 
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Thanks gas112. Im thinking it's the diverter valve.

I've isolated the Ch flow and ran the hot tap. The tap runs hotter and the boiler cct doesn't doesn't overheat and shut down so there's decent flow through the plate.

It's soft water here. We don't have lime scale at all.
 
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Thanks gas112. Im thinking it's the diverter valve.

I've isolated the Ch flow and ran the hot tap. The tap runs hotter and the boiler cct doesn't doesn't overheat and shut down so there's decent flow through the plate.

It's soft water here. We don't have lime scale at all.
the plates dont usually block with lime scale it blocks on heating side with black magnetite that coats the surfaces . same black stuff you get in the rads
 
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Ok. I'll see how it looks when I'm up to my ears in bits. Thanks.

I'll report back.
 

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