combi boiler - radiators and water boiling, plus losing pressure

[notnoweric]

The mains comes in at the bottom of hose and enters a valve at top above earth cable. It is this valve that is failing for some mysterious reason (will fill a cup in minutes, not seconds).
Provided the hose stays on, this is enough to withstand leak. Not ideal, but will do for now.
I didn't understand your reference to capping. It would need to be temp cap so that system could still be filled if required.
I can imagine replacing the valve at some point after draining system. However I am curious as to why it should fail. Coincidence an unrelated to other issues?
Rest assured I have a pot underneath, and everything is as dry as a bone.
I accept that it could leak slightly over time

 

[terryplumb]

You could remove the loop and fit a blanking cap nut and seal ,just screws on, to both valves.
The higher valve is a non return valve ,and shouldn't allow water to come out ,so it's failed and needs replacing. If it lets water out your pressure will drop.

 

[notnoweric]

Totally understood. How usual is it for a non return valve to fail? I'm going to assume that this is totally unrelated to my original issue (EV)

 

[terryplumb]

Not too common for them to leak, but not exactly unheard of either.
The EV has nowt to do with it.

 

[notnoweric]

Hello, I know that ideally I need to get someone on. But in the meantime I thought I could find out the state of the expansion vessel (YouTube advice is to find out if it contains water ie needs replacing, or if it contains air maybe I could repressurise it.)
The problem is (which may well worry some of you,). I can't actually identify the part or even the valve.
I attach photo plus screenshot. Number 44 is apparently an expansion tank.
Its biasi M96 28 sm/c2.
I do know my limitations but my research so far suggested that this would be a relatively easy test to do.
Thanks.
Incidentally since I reduced overall pressure from 1.5 to 1
The system has been behaving for long periods of time with no drop in pressure an excel of water outside.
I still have issue that radiators are simply too hot, with no means of reducing temp, but the system is working in terms of providing heat and hw

 

[terryplumb]

The EV is at the rear of the boiler. Get yourself above the boiler and look down,at the rear.
By the way it's not unusual for a small amount of water to come out of the Schrader valve ( looks like a car tyre valve on top of the EV)

 

[notnoweric]

Looking at this sketch, it seems to be quite sizeable. Is there any chance it is in the upper chamber. And am I allowed to look?
I know some people get very edgy as soon as you take a cover off an appliance. Testing the expansion vessel seems to be something a consumer is allowed to do.

 

[terryplumb]

The EV is at the rear of the boiler. Get yourself above the boiler and look down,at the rear.
By the way it's not unusual for a small amount of water to come out of the Schrader valve ( looks like a car tyre valve on top of the EV)

Do as said. You do not need to remove any panels at all to see it. It's quite a big tank.

 

[notnoweric]

Sorry, I didn't see your reply while I was writing my next one. Yes, once the kitchen is free again(!), I'm going to climb up and look down. I very much appreciate you answering my somewhat naive questions, and appreciate you not telling me off. (I had in-laws up last weekend, one with the view that whatever the householder does it illegal - the type of person who would get an electrician to change a plug.
I am absolutely not cavalier but there are times when there's things I can do.
Thanks again.

 

[notnoweric]

Great news. Found it. Pushed valve and air came out, no fluid whatsoever.
I think my next job will be to find out what pressure it has. My understanding is that I turn heating off. Bleed ch system until it shows little or no pressure, then pressurise EV up to about 0.9
I have a manual pump for car / bikes which has a reading so am hoping I can use that. Job for tomorrow.

 

[terryplumb]

You need to leave a drain cock open on the heating system ,preferably connected to a hose pipe to a drain ,whilst pumping up the EV .
You are correct re turning off the Boiler ,and draining out to drop system pressure, Which would obviously happen when opening the drain cock.

 

[notnoweric]

Hello again.
I decided to save the job til weekend.
I'll change the faulty non return valve at same time.
I assume I will have to lose all my inhibitor so I bought some more. They type that goes into radiator.
Would you recommend hi ING the system a really good flush in any case?
Also final qu, assuming all goes well, if I ever have to drain system again, does the EV retain its pressure? Or does it need resetting each time system is drained. (I'm assuming it will be independent and will hold its pressure regardless)
Many thanks for your help.
I'm hoping to post a very positive ending on Sunday. (?)

 

[terryplumb]

The EV is charged / pressurised by air ,so draining the heating system water will not affect its pressure.
As your issue originally was that of excessive temperature on radiators ,it's unlikely that you need to flush the system !

 

[notnoweric]

Thanks

 

[notnoweric]

Job done on Saturday. Here's how I got on, but first, many thanks to Terryplumb for his patient advice, and for also not judging me. (ideally we would get someone in, but in this rural area, it is hard to persuade someone. Yes I am sure someone will sell and fit a new boiler. But repairing one 13 yts old is not that enticing.)
Anyway. First I drained down and changed the valve that allows water in. It had been failing. I got away with a straight forward replacement, and used the same olive! Depth must be identical (are they standard depths?) because it is a nice tight fit. I know that ideally you cut the old olive off, but well you know!
I then repressurised the EV with a hand pump meant for bikes/cars. I am convinced there was an issue as it did feel quite empty, I then started to get a resistance and filled to a suitable pressure.
Next I put some inhibitor in a radiator (the one I had used to drain). Despite watching videos this did not go well, and I have vowed never again to buy the more expensive squirty ones.
In the end I thought I may as well take a radiator off and pour some normal type in manually. I locked the one side, turned radiator sideways and poured it in. Then I bunged up where I poured (with polythene so it didn't tear).
It was then just a case of whipping out the bung quickly before shoving into pipe. I hardly lost any. One day someone can show me how to use the fancy ones, but for now I am happier just getting the stuff in manually.
Finally I repressurised with mains water. Then have done several rounds of bleeding, as I find one round often doesn't find all the air
It's working OK and pressure is a lot more stable. Water is on 1bar and it moves up to about 1.5 possibly more but not as erratic as before.
What I haven't solved (and the original title! ) is things still feel very / too hot.
There's something failing. However I suspect it will be too expensive for an expert to diagnose or even obtain the part. Last Feb when diverter valve was changed (by an engineer) he told me Biasi was considered cheap and he gave no guarantees that he could leave us with a working boiler, so we took a gamble, and got another 11months out of it.
I'm pleased that I've learnt about EVs. Maybe I have extended the life a little. At present we have a working boiler. It isn't on all the time like an old folks home because of bills /environment and Russia. We tend to have thermostat at 18 max which makes me laugh when consumer programs recommend turning *down* to 20. Maybe it wouldn't last long under heavier conditions, but for us it's doing its job.
Thanks.