baxi 105e central heating problem

[cdel2005]

hi guys,

the boiler fires up runs for about 20minutes from cold then lockout with 6 neons all red (not flashing) 23-28 in the manual.

I checked the expansion vessel while the system was depressurized with drain valve open and this was below the recommended 0.5bar and was repressurized to 0.5

the dhw works as it should on both dhw only and central heating and dhw

sometimes the central heating comes back on briefly after dhw is used but the flame (burner on indicator) then goes out with the fan and pump still running

there is a slight leak from the diverter valve grub screw but not sure which of the two diaphragm would cause this?

my plan is to firstly replace the central heating temperature sensor

secondly isolate /drain/empty boiler then check both diaphragms

if these two fail then the plate heat exchanger has a blockage or pcb faulty which i will have to get heating engineer in.

any advice will be appreciated

 

[gas112]

Righthand connection there is a filter in it take it out and check that its clean

 

[cdel2005]

hi gas112,

thanks for your reply,can you specify please pdf manual page 35.

http://www.ultimatehandyman.co.uk/forum1/baxi-combi-105e-installation-manual-t47073.html

 

[gas112]

nope nothing in the manual about it i can see.
Under boiler you have 5 pipes. the right hand one (return) has a filter in the front of it .
Boiler needs to be drained then remove the filling loop(if it has one attached) then undo the front of the valve and there is a gauze filter in there

 

[cdel2005]

hi gas112,

circulation problem causing lockout,i shall have a look thanks for your replys

 

[cdel2005]

i have checked the dhw diaphragm and its fine,but i replaced with an new one ,the return filter was also clean as suggested by gas 1122.

the leak is coming through the diverter manifold via the push rod (see attached picture) would this indicate the ch pressure stat diaphragm is split ?

the leak happens when the central heating is on and the dhw is turned but not on ch only or dhw only

View media item 45883
any feed back is appreciated

cheers

 

[Agile]

The tailpiece in your picture is leaking and needs replacing.

I dont see why you imagine that diaphragms are the only parts to fail!

Tony

 

[cdel2005]

hi agile,

I never said that the diaphragms are the only parts to fail,but it would be the first obvious place to look, why spend £120 plus labour for a new diverter valve and maybe a new heat exchange plate £60 when you can replace both diaphragms if it is them for under £20 I am sure you would agree a problem should be indentified prior to jumping the gun uneccessarily,it might be the case that the diverter is knackered due to the age of boiler wear an tear etc