Britony combi 80

[Johnboy54]

My daughter bought a house with this installed.
The boiler kept igniting, but stopped and started.
A friend 'in the know' told her the diverter/3 way valve was the problem.
Today, I changed the valve, which cost £60.
Turned the boiler on, but there's loads of air in.
The boiler still ignites, but much the same as before - stops and starts.
Now, I realise all the air should be out of the boiler first.
But, as there's no manual to refer to, is this boiler self-bleeding?
I've run it for 30 mins.
Once, the pressure dropped to zero, so I presume that was air being vented.
I left it to cool for an hour, and re-pressurised.
It's still full of air.
So, I have 2 questions -
1, Does the previous intermittent firing sound like the 3 way valve - and has she wasted £60?
2, How do you bleed the boiler, if needed?
Thanks in advance.

 

[chrishutt]

Does the previous intermittent firing sound like the 3 way valve - and has she wasted £60?

No and yes. Be sure to thank the "friend". Keep the old valve as a spare anyway. Diverter valves on this boiler are prone to failure, so chances are it will be useful one day.

The boiler has an AAV (automatic air vent) above and behind the pump. Providing the small red plastic cap on it is open, it should vent the air. You probably need to find a boiler engineer who understands how the Britony works.

there's no manual to refer to

There is a manual, but perhaps you haven't got one. The best manual for this boiler is the manual for the Baxi Genesis (which is virtually the same boiler) - try the Partsarena site.

 

[Johnboy54]

Thanks for that.
I'm on my way now to bleed it.
A further development -
The guy she bought the house from says he had the same problem.
An engineer changed two thermisters at a cost of about £20.
He showed him how the old ones had scaled up.
Problem solved.
Once I get hold of a manual, I'll find and change them again.
Fingers crossed.

 

[chrishutt]

Once I get hold of a manual, I'll find and change them again.

Perhaps you didn't read my last post - look at Baxi Genesis manual on partsarena site.

 

[Johnboy54]

Sorry, I didn't make it clear.
I read your post and meant, 'once I get hold of a manual from the partsarena site'.
Been there and found the info I needed.
Thanks for that.
The boiler still doesn't work after changing the 3 way valve, bleeding the boiler as you suggested and checking the thermisters for scaling (still looked like new).
The pump runs constantly, and the boiler still tries to fire up intermittently.
I swapped the wires over to the 2 thermisters, and it worked a treat, until the boiler didn't stop boiling and made a noise like a jet taking off.
After I'd ducked a bit, I checked the wiring diagram to make sure and put them back onto their correct thermisters.
The 'friend' is adamant that the 3 way valve was the problem, and after 16 years in the trade, he says he knows what he's talking about.
Which leaves me, as a qualified fitter/mechanic/engineer for 35 years as the idiot who apparently can't fit a simple valve correctly.
Decided to call in British Gas and pay them the £132 to sort it out.
I'll let you know when they've been if I am that idiot - or if the egg is on someone else's face.
My daughter's still £60 out of pocket, plus the British Gas charges.
I suppose there's a moral in there somewhere?

 

[Johnboy54]

Just to finish this post -
British Gas came to my daughter's today - within 2 hours of me ringing them!
The fault was nothing to do with the 3 way valve.
They found the flow-pressure valve faulty.
This possibly caused one thermister to go out of calibration.
(So much for my visual check of the thermisters)
They changed both parts and all was at peace with the world.
Less than an hour, including paperwork.
Great service and great result. (No, before you ask, I'm with NPower)
All for a measly £132 all-inclusive charge.
Thought I'd let you know in case anyone else has a similar problem.

 

[ChrisR]

They found the flow-pressure valve faulty.

Eh?
Do you mean the CH flow switch, item 9, page 5 on the mfrs intructions?

Sounds like the basic problem was the air in the system. -Was the auto air vent screwed shut? . The CH flow switch should have stopped the boiler if it was low on water.

By the way the different looking Chaff Instrs are at
http://www.chaffoteaux.co.uk/uploads/img42943a1f76f8e1.pdf

 

[Johnboy54]

Hi, ChrisR.
It was either item 9 or 10.
I may have got the name wrong.
They changed the complete part - and the corresponding thermister.
All I know is, it worked when they'd done.
And I watched them.
Plus, it's not really in their interests to tell me porkys, is it?
They don't get any more money for it.

No, the pressure was fine and the system quiet once I vented the air as instructed previously with the AAV.

The AAV -
It has a red cap?
The cap was screwed down.
I unscrewed the cap, vented the air, and rescrewed the cap down.
Are you saying the cap should be left permanently unscrewed to vent the air?
Either way, if it was purely air in the system, once I'd vented the air, the boiler should have fired, no?
And, the boiler didn't fire in either hot water or ch mode.
I know for a fact the red cap has never been touched before the problem started.
I don't mean to sound like I'm arguing, cos I don't know enough about boilers to be able to argue.
I'm just stating the facts, and the questions they raise in my mind.
I'm grateful for any help and advice anyone ever gives me.

 

[ChrisR]

Thanks for coming back. No I'm not arguing, I'm just interested to know what the problem was and there isn't a part with a name anything like you were told!
These are the names from the manual:
8 Automatic Air Seperator and Vent
9 Flow Switch Heating Circuit
10 Flow Switch DHW Circuit (= tap water)

Yes most definitely the red cap must be left open, or air can collect. Inside part 9 there's a switch which detects the flow of water (boiler side).
If it stuck in the "flowing" position even when there was air in there, you might expect the symptoms you got.
What happens is that the pump has nothing to pump except air, and the water can't get out of the boiler so it boils (jet engine noises!).

If it (9) was sticking - generally, it could also have been what stopped the boiler firing when there was water flowing.
It's a straightforward bit to diagnose, being electrical. With the thermistor, about £30, must put my prices up!

 

[Johnboy54]

When I see my daughter again, I'll have a look on the invoice.
They listed the 2 parts on there.
They had to fill in the cost of the parts, and they said they were about £60?
I'll reply in a couple of days.

 

[marrer]

My boiler was working ok until british gas services it ..........................what had he done ............whilst cleaning the burner I think he had caught the thermocouple .....by bending the thermocouple so that it was nearer the pilot light this cured the problem of the boiler locking out intermittenty and resulting in the boiler needing to be reset (the thermocouple controls the gas valve if it is not being heated enough by the pilot light it shuts the gas valve off)