Baxi Combi Instant 105e DHW problem
- Thread starter dave1664
- Start date
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no it cant be checked with the system full.
& as i said, if the vessel is almost empty it will take a lot of pumps.
+ check the valve isn't leaking (spit on it).
& as i said, if the vessel is almost empty it will take a lot of pumps.
+ check the valve isn't leaking (spit on it).
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Because the little air in it is pushed back by the water and pressurised to the water pressure!
You can confirm my remote diagnosis by removing the cap and pressing the centre of the valve until the water comes out.
Wear protective glasses though so that it does not hit you in the eye! ( We take safety very seriously! )
If you dont get any water out then your statement "When I tried pumping it up after I changed CH diaphram I could not get any air pressure into it." is incorrect! I can only diagnose your problem based on what you have told us!
Tony
If I get water out of the valve there is a hole in the diaphram?
If any air present is dispersed but no water comes out then the the diaphram is ok? I would then drain down and repressurise in the normal way? Thanks Dave.
If I smash it off the wall do I need to isolate everything first?
I am also unfamiliar with the analogy regarding 'beware of items weighing less than the manual'.
If any air present is dispersed but no water comes out then the the diaphram is ok? I would then drain down and repressurise in the normal way? Thanks Dave.
If I smash it off the wall do I need to isolate everything first?
I am also unfamiliar with the analogy regarding 'beware of items weighing less than the manual'.
you may get water out of the valve but that does not necessarily mean the diaphragm is damaged. it may be a build up of condensation.
if it was originally pressursed with nitrogen then that might be a different story. but thats too much information & is irrelevant.
you drain down first.
if you smash it off the wall you have either lost your temper & will need to call someone in, or have been taking everything people write on this thread far to seriously.
the signature at the bottom of my posts is a quotation from one of Terry Pratchett's books (you have misquoted it), & this is also irrelevant.
if it was originally pressursed with nitrogen then that might be a different story. but thats too much information & is irrelevant.
you drain down first.
if you smash it off the wall you have either lost your temper & will need to call someone in, or have been taking everything people write on this thread far to seriously.
the signature at the bottom of my posts is a quotation from one of Terry Pratchett's books (you have misquoted it), & this is also irrelevant.
I would disagree! Condensation is caused by water condensing out of air. As air does not carry much moisture thats very unlikely to be significant in a boiler EXV.
Usually its as a result of a small leak of water to the air side which is not enough to pass the air you pump but enough to allow some watter to pass over a considerable time.
Under normal conditions there is a pressure equilibrium between both sides so no movement of water normally occurs.
In this case we can expect the usual fault every 2-3 years of a failed diaphragm.
Tony
Agile.
years ago thousands of Vaillant vc110,vc112,vc142 were fitted in the local authorities housing stock. within 3 years it was found that an unusual amount of expansion vessels had been changed. the authority got the manufacturer involved. over a period of time all the exchanged vessels were saved & returned to be tested.
over 90% were found to be perfectly fine.
as you may know the valve is at the bottom on these models. when the pin is pushed up anything up to 1/2 mug of water escaped.
Vaillant gave the reason i wrote & i have no reason to doubt them.
i have encountered it loads of times. the vessel will take a charge & keep it, its not a problem.
years ago thousands of Vaillant vc110,vc112,vc142 were fitted in the local authorities housing stock. within 3 years it was found that an unusual amount of expansion vessels had been changed. the authority got the manufacturer involved. over a period of time all the exchanged vessels were saved & returned to be tested.
over 90% were found to be perfectly fine.
as you may know the valve is at the bottom on these models. when the pin is pushed up anything up to 1/2 mug of water escaped.
Vaillant gave the reason i wrote & i have no reason to doubt them.
i have encountered it loads of times. the vessel will take a charge & keep it, its not a problem.
Even if there is a little water on the air side it will still work.
However that water should be ejected before repressurising. Unfortunately the FAQ on this site does not take that into account.
However the Baxi instant is another situation where the diaphragm regularly fails.
Do a few sums on water in air and that does not make any sense on the Vaillant.
In reality if a small amount of water has leaked then that should be drained and then the EXV can be repressurised. If the two sides are in equilibrium there little water will ever leak unless the air side had become depressurised.
I dont find people repressurising EXVs from scratch on a service!
Tony
However that water should be ejected before repressurising. Unfortunately the FAQ on this site does not take that into account.
However the Baxi instant is another situation where the diaphragm regularly fails.
Do a few sums on water in air and that does not make any sense on the Vaillant.
In reality if a small amount of water has leaked then that should be drained and then the EXV can be repressurised. If the two sides are in equilibrium there little water will ever leak unless the air side had become depressurised.
I dont find people repressurising EXVs from scratch on a service!
Tony
After all this I just wanted to let you chaps know the latest on my troublesome 105e.
Changed the diaphrams etc as spoke about at beginning of thread.
Boiler was ok apart from getting 'stuck' in preheat mode and only getting luke warm water. Now would you believe it - after a few days it seems to have settled down and now I am getting nice hot water and the system pressure is steady @ 1.5 bar. I don't know why this is but I am not going to push my luck any more with this thing and have subsequently taken out a contract with BG for £13 a month. Watch this space!
Thanks to all.
Changed the diaphrams etc as spoke about at beginning of thread.
Boiler was ok apart from getting 'stuck' in preheat mode and only getting luke warm water. Now would you believe it - after a few days it seems to have settled down and now I am getting nice hot water and the system pressure is steady @ 1.5 bar. I don't know why this is but I am not going to push my luck any more with this thing and have subsequently taken out a contract with BG for £13 a month. Watch this space!
Thanks to all.
Guys just a quick heads up to let you know the outcome of my DHW problem. I took out a contract with British Gas as advised. They were extremely good at solving the problem and replaced several parts including diverter valve, heat exchanger plate, valve differential. In fact it took them a few visits to narrow down the problem. In the nut shell if the professionals sometimes struggle to fix these boilers what chance do DIYers have? Anyway piping hot water again on demand! Well done British Gas. I will have to pay for the first visit as it was a previously existing fault but that is only fair. Other than that £13 a month all in? Well worth it in my view.
Why do you seem to think that any boiler repair should ever be a DIY job?
They need considerable skill and knowledge as well as the training to ensure that the boiler is going to be safe.
No DIyer will ever have that knowledge!
You dont see people doing their own appendix operations do you!
Tony
Tony..... I might have guessed. Well perhaps because its a DIY website maybe??? Are you perhaps a little vexed because you suggested it might have been the EX vessel at fault? Whatever, I was only giving a little feedback in return for all the helpful advice I recieved. If you are only going to dish out helpings of 'I told you so' then what is the point of offering advice on boiler repairs in the first place??? Stick to what you do best - repairing the things, not telling misguided people they cannot. I suspect that I have completely misread the point of this forum.
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