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Marc, Plumber
Category: UK Plumbing
Satisfied Customers: 1594
Experience:  Plumbing and Heating expert with 25+ years experience, 21+yrs self employed as a contractor.
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I have a baxi 105e instant. I changed the diaphragms on the

Customer Question

I have a baxi 105e instant. I changed the diaphragms on the diverter valve assembly but now the boiler keeps going into hot water mode when there is no tap running.
Submitted: 1 year ago.
Category: UK Plumbing
Expert:  Marc replied 1 year ago.
hello and thank you for your question, I will do my best to assist you today.
Expert:  Marc replied 1 year ago.
I commend you on the replacement of the diaphragm on the diverter valve. Unfortunately, It appears it did not fix the problem for you. my recommendation is to replace the entire diverter valve assembly at this point as it appears that the diverter has failed and is stuck. the thermister can also be the problem however, replacing the entire diverter will give you all brand new parts and will take out the guess work of any other parts being faulty.
Customer: replied 1 year ago.
I shall try changing the diverter valve assembly & let you know how I get on. Do I have to completely drain down before removing the diverter valve assembly? Would it be possible to give brief instructions?
Expert:  Marc replied 1 year ago.
the boiler does need to be drained down, if you have isolation valves at the boiler for the feed and return, it will be much less painful of a process and should be only a few litres of water. you can then access the diverter valve and losen the diverter connections preparing it for removal and replacement. before removal, cover the pcb board with plastic, as water will leak out all over from different directions and cause the board to short out. Ensure that all of the washers for the diverter are correctly in place, you may wish to have a few extras on hand when replacing the diverter. Once replaced, you can then use the filling loop and top the boiler off to 1 to 1.5bar.
Expert:  Marc replied 1 year ago.
Unfortunately, your boiler is discontinued and the manual shows no exploded view so I did locate the following information to make it a bit easier for you: TO DO THIS TASK A COMPETENT PERSON WOULD HAVE TO SHUT OFF THE GAS AN ISOLATE THE ELECTRICAL SUPPLY TO THE BOILER. THE UNIT SHOULD BE COOL BEFORE OPENING TO AVOID THE RISK OF SCALDING. Then the under the unit the shut off valves for the water inlet and the heating in and out can be closed.If the unit is cool, remove the front panel and the 2 screws to allow the control panel to flop down. The diverter valve is bottom left on the base of the casing retained by 2 screws.The boiler can be drained using the drain valve on the right hand side. Be careful because there is some quantity so be ready to catch it!Removing the valve involves taking off the micro switch on the front. Detach the two small pressure differential pipes with a 10mm spanner, releasing the two screws behind the retainer for the front diaphragm housing and with drawing the housing.The two cap screws on the right hand side can be removed where it is connected to the part that attached to the heat exchanger. The connection to the heating out pipe can be released from underneath the boiler.Remove the top micro switch further back for access then carefully disconnect the pipe in the back which is attached as push fit with a retaining clip.Remembering the two retaining screws it should be possible to remove the diverter valve.The body of the valve itself comes apart by retaining the body and unscrewing the back of the housing. Reverse the process to install the new diverter assembly.
Customer: replied 1 year ago.
Many thanks Marc, I have ordered a replacement diverter valve assembly.Fingers crossed it will go smoothly and solve the problem.. I'll let you know how it goes. Tx Paul
Customer: replied 1 year ago.
This is getting expensive.... Changed the diverter valve assembly and the thermister. Still the boiler keeps going into hot water mode when there is no tap running.Now when I run the hot water tap the water does not get hot I also noticed that the 60 degree red led is flashing, it has a triangle within a circle symbol below the led. The manual states this means fault on pump or low pressure.. Its 1.5 bar at the moment which should be fine ..Also the tap symbol is flashing which the manual says is a fault on hot water sensor.. Surely changing the diverter valve assembly and the thermister should have solved the problem, not made it worse?
Customer: replied 1 year ago.
By the way the 60 degree flashing red led with the triangle within a circle symbol below only flashes when the hot water tap is turned off. When the hot tap is running just the green tap flashes.
Expert:  Marc replied 1 year ago.
Customer: replied 1 year ago.
Can you please assist me with my problem?

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