Basic megaflo compact. Strange issues, no hw.

[armyash]

Went to this job today and was there quite a while, it's a baxi boiler, unvented cylinder upstairs.

I get get there, boiler works fine on ch, put how to constant nothing, light comes on at programmer but no 'click' sound. So quick job swap programmer over - no change.

but if I turn he to constant, divertor powers over. Got 240 between earth and orange and also at grey. So electrically everything seems ok. Just the boiler won't fire.

Another thing, with old programmer divertor does not power over. So this at least to me proves dodgy programmer plus another fault.

With ch running and hw valve held open cust will have hw.

technical were stumped, they said there is no reason the boiler shouldn't fire following these tests. He said try changing the hydraulic pressure sensor. Have ordered this but not entirely confident this will solve the issue.

could there still be a prob with the divertor? Actually leaning toward pcb myself but tech said it can't be that.

Also pressure on boiler is fine, and no error codes.

 

[kris]

Im maybe getting mixed up but is it a baxi system boiler with 3 way zone valve ash ?

 

[kris]

Check the cylinder stat os ok as if knackered then it wont bring the boiler on but if you manually open and put on ch then it will heat the hw,

 

[armyash]

It's a system boiler with unvented cylinder.
No cyl stat - unless it's built in somewhere I can't see but cyl stat is a possibility, if there is one.

There is a separate electrical thing on the cylinder something about the element and something to do with the boiler but tech said can't be those.

2 2 port div valves

 

[armyash]

Boiler has a pressure gauge and filling loop too.

I'm getting more confused the more I think about it

 

[kris]

The element is the thermostat army, it will be wired to the 2 port valve to tell it to close when water temp is reached,

 

[armyash]

This the type of cylinder

 

[kris]

some unvented tanks the stat is next immersion and others come with a litlle element /phiall thats inserted into a sock and bolted to side of tank but vthere will be a cyl stat

 

[armyash]

The element is the thermostat army, it will be wired to the 2 port valve to tell it to close when water temp is reached,

Ok that makes sense, not sure how to test, there was a reset but couldn't do anything with it. Wasn't getting voltage there though.

 

[armyash]

some unvented tanks the stat is next immersion and others come with a litlle element /phiall thats inserted into a sock and bolted to side of tank but vthere will be a cyl stat

Looks I'll be going back, I was there ages bet it's a 2 min job lol

 

[kris]

the stat is next to immersion under the grey cover

 

[kris]

Sounds like thermostat , there should be cable with a pair of wires , one of the wires comes from timeclock when hw is switched on travels through the stat then the other comes out of stat down onto the brown wire of your zone valve, so check theres power coming back from stat through the brown wire, if there is then the stats fine, if not then its either up to temp or stat is gone . good luck

 

[armyash]

Thanks, sounds more likely than what tech were saying.

I had my doubts but not familiar with these cylinders so wasn't in a position to doubt him.

 

[armyash]

Just noticed thread title says basic megaflo - should say baxi, using the girlfriends iPad and it's got terrible predictive text.

 

[kris]

No worries ash , go online and study a diagram of a S PLAN wiring guide , infact 2 secs il get one,,


https://www.google.co.uk/url?sa=i&r...nUitlFTYSfaauIozfdTsMquw&ust=1446504257218042

 

[ShaunCorbs]

here you go

but still if the 2 port (cylinder) has got power then that means the boiler should fire(cylinder calling for heat)

 

[stevetheplumber]

actually there two stats under the grey cover one is a resetable overheat usually a push button

 

[stevetheplumber]

actually theres three stats as the immersion probably has one as well but not relevant to boiler firing i would bet on it being the overheat stat as its probably wired as a break in the orange wire hence your getting live in the junction box on orange

 

[armyash]

Thanks for all the replies will update when I have been back.

 

[armyash]

Going back last job tomorrow. Great, need to be in and diagnose ASAP. Will head to the cylinder and check out the stat.

 

[stevetheplumber]

i always wire the overheat stat to break the orange wire from the hot water valve ive seen them wired to break the brown to the valve but ive seen to many valves with the contacts stuck to on even when the valve is closed
if its wired the way i do it that would explain the valve working and boiler not firing

 

[armyash]

Very strange, got there last night and still the same as before.

Ch will come on selected at programmer. Hw nothing.

Can only get hw with ch with valve held open.

So went through it all again, with programmer valve does not move over on hw, so like last time put the new programmer on and turned hw on. Valve now moves over but boiler still won't fire.

Took cover off cyl stat/immersion turned cyl stat up and down. Boiler fired.
Went downstairs made sure ch off at stat and programmer.

Turned hw on and off a few times to make sure it was working all good.

Assume the cylinder stat was playing up and now ok. Not sure why.

Customer didn't want to pay our prices for new programmer so put old one back on and left.

 

[armyash]

Very strange, got there last night and still the same as before.

Ch will come on selected at programmer. Hw nothing.

Can only get hw with ch with valve held open.

So went through it all again, with programmer valve does not move over on hw, so like last time put the new programmer on and turned hw on. Valve now moves over but boiler still won't fire.

Took cover off cyl stat/immersion turned cyl stat up and down. Boiler fired.
Went downstairs made sure ch off at stat and programmer.

Turned hw on and off a few times to make sure it was working all good.

Assume the cylinder stat was playing up and now ok. Not sure why.

Customer didn't want to pay our prices for new programmer so put old one back on and left.