No central heating on BAXI DUO-TEC COMBI 24 HE

[DP]

DP - on the baxi model mentioned in the OP's post, there is only one connection of the expansion vessel to the radiator circuit, therefore only one way "in" for the water. The schrader valve is open to atmosphere, with no connection to anything else. So I have a failure to see where water in the "air" side could come from. It's a direct copper pipe connection to the expansion vessel from the radiator circuit. BUT, thanks for info.

I for one will NEVER say that I an right every time and can fix EVERY boiler every time. Come here to learn
Having said this, Re expansion vessel, how do you know the membrane dividing the air and water is not permeable to allows microscopic amount of water to permeate to air side. Seen this happen on brand new vessels after a few weeks. Granted such a vessel could be defective out of factory but surely not almost every vessel on one particular boiler

A regular, who is also an instructor, person of vast knowledge, concedes that a vessel with water air side need not be goosed- let the water and air out while system is at working pressure until air side is empty, then pressurise to working pressure with primary at zero pressure.

I too will thank you for educating me on make up of expansion vessel, how it works etc. I have been in the dark for thirty years, light has been switched on with your explanation on construction of this rocket surgery component

 

[HH1]

Replies, that state there may be other causes, but with no pointer TO the other causes, are not helpful for learning what the other causes could be.

I didn't think, at the time of the small permeability factor, therefore thanks for mentioning it.

It can happen after a few weeks? I wouldn't want to be refilling every few weeks if the vessel is doing that every few weeks.
It's therefore time to change it.

 

[ianmcd]

Or is it that I have gave too much info away?

Quite the opposite you havent given enough information away, pressing the schraeder valve tells you absolutely nothing, any water can be condensation held within the bladder, the pressure from the boiler MUST be released, an open drain point MUST be left open, then and only then attach a pump and start pumping, observe that more water is now expelled, this proves it is not a blocked communication hose/pipe, once all water is expelled then now start pressurising the vessel to the correct rating, then and only then close the drain off point and re-pressurise the system, there are further steps that a pro might take to ensure, that the bladder hasnt stuck to the inside of the vessel, but the above is the absolute minimum that must be carried out, and no the PRV is 3 Bar if you are in the UK, if you dont carry out ALL the steps above , then there is absolutely no point in doing anything

 

[HH1]

Well thanks for posting.

Why didn't you explain that in your post instead of trying to say "Disregard". EH?
If any mistakes were present, you should have used that opportunity to correct them.
Or posted your procedure for the OP to try, or indeed any others who may face a similar problem with their boiler.

Pressing the schrader valve will tell you if there is pressurised water in the air bladder.
That's a fact ! been there-done it.
If the water comes out to greet you, then it's a possible vessel change, right there.

If you read the edit, you will see the depressuried comment?
And the comment regarding 4bar 3bar.... my error, as didn't know the pressure setting, I was going by the mention of 4 bar in the original description.
It's not the first time that safety valve settings and gauge reading to tie in with each other.

 

[ianmcd]

Pressing the schrader valve will tell you if there is pressurised water in the air bladder.
That's a fact ! been there-done it.

doesnt mean a new vessel is required

 

[Servotech]

COOL,
Thanks for replying folks.

servotech - Don't want any gas police knocking on the door. But some basic checks can get problems resolved quickly, or at least give an indication as to repair time and cost. Is this repair in need of a gas safe technician as it's on the water side on the particular baxi boiler? I didn't think it would have.... but I may have been mistaken?

Forgive me it was just my own rather cynical attempt at humour kicking in.
One thing that we've not mentioned that happened to me yesterday is that the air valve might be faulty on the ExV.
Best to always give it a spray with leak detection fluid after the recharge.
Who's that knocking on the bloody door at this time of night?

 

[FiremanT]

Nothing at all is wrong HH1 with your above statement.
The ExV is always your first check with this type of fault.
Just keep it to yourself though or the "Gas Police" will come a knocking on your door!!

I assume that is you, Roger Bisby? Did you ever get Gas Safe Registered? probably not. Even his opening line is wrong.

 

[DP]

All this “I know better than you” talk but no further with no heat from boiler the question asked by the OP.

While the pressure rise is a defect that needs looked at, main issue that no one has broached yet is boiler is running to heating demand but no heat at the radiators. I wonder if OP is still watching the post

 

[FiremanT]

All this “I know better than you” talk but no further with no heat from boiler the question asked by the OP.

While the pressure rise is a defect that needs looked at, main issue that no one has broached yet is boiler is running to heating demand but no heat at the radiators. I wonder if OP is still watching the post

if you are indicating me, DP, my comment was a direct reference to Bisby (servotech), who was knocking RGI's - and congratulating the OP on his post.

 

[DP]

if you are indicating me, DP, my comment was a direct reference to Bisby (servotech), who was knocking RGI's - and congratulating the OP on his post.

I am not Fireman, look at other posts, you soon realise the regular RGIs that work with boilers everyday to clear all types of faults are now getting challenged by diyers who have varied degree of knowledge about their own boiler.

You will no doubt be conversant with midposition MV valve in a Y Plan that fails to release due to spurious line voltage induction. Being challenged on that, a fault I have cleared a few times. Then go on to claim W plan is not all that different? Mind boggles

 

[Servotech]

I Agree, we've all gone off track on this one and in doing so let the original poster down.

 

[HH1]

I assume that is you, Roger Bisby? Did you ever get Gas Safe Registered? probably not. Even his opening line is wrong.

The opening line may have been wrong, I was just going by the OP's posting stating gauge going to 4 bar, so assumed that was the pressure the safety valve was working at, I don't think that's way of course with that facts known at the time. I have since been educated that's it should only be 3 bar max. on all UK boilers.

All this “I know better than you” talk but no further with no heat from boiler the question asked by the OP.

While the pressure rise is a defect that needs looked at, main issue that no one has broached yet is boiler is running to heating demand but no heat at the radiators. I wonder if OP is still watching the post

The "no heat at radiators" was taken care of in the first line of the second post in the thread. With further confirmation on post #3
Up until that time no one had mentioned the possible E.V.'s fault.

I am not Fireman, look at other posts, you soon realise the regular RGIs that work with boilers everyday to clear all types of faults are now getting challenged by diyers who have varied degree of knowledge about their own boiler.

The so called challenge exists when the post is "disragarded" with others thanking and liking.... with no explanation of why, especially when, while some parts of the post are wrong, at least some parts of the post are essentially correct.
EVEN more so, when it took a while before peeps started explaining why, that should have been done in the next post.

My original post may have contained some errors (?).. BUT, it did contain some information for OP to act upon (if he was able in a technical sense), NO one else had pointed out a POSSIBLE expansion vessel problem.
It's not always a case of saying go get a tradesman to look into your problem as the OP was then going to do on post #4, unless of course your made of mega-bucks and can afford to jump in to such an action.

It is a wonder what the OP ended up doing, if she/he is still around their head must be spinning.

 

[ianmcd]

It is a wonder what the OP ended up doing, if she/he is still around their head must be spinning.

Well if some people would stop constantly taking requests for advice, completely off topic for their own Ego, then the OP might have got the correct advice

 

[Servotech]

It's what always happens when you get groups of experts together.

 

[DP]

It's what always happens when you get groups of experts together.

An expert is a person who will say his piece when he knows it and stay mum when he does not, unless he is looking for attention

Not casting any asparagus