NEW Veissman vitodens 100 open vent problems

[Dan83]

Hi Everyone

hoping someone has some bright ideas for me!

just did an install removed an old ideal ff and replaced it with a veissman as above.

first day of install yesterday, all piped ready to go, I tried to refill the system, blockage in the dreaded feed / vent tee, cut that out replaced pump system seemed to fill ok, but....

boiler shows it's calling for heat but cycle starts lasts 30 seconds (main burner doesn't even kick in)

speak with technical and end up linking out the flow switch briefly boiler fires as it should and starts to heat.
tech say air or flow and return wrong... I piped it the way the old boiler was and checked it enough times but out of desperation re-piped it the other way, then I've basically spent the remaining 5 hours of today bleeding blasting water back in to the boiler, in case of air.

Im beginning to draw blanks, my only thoughts are now, really poor unseen pipe work (really airy) or a blockage in the primary flow/ return.


hope that's enough info for any suggestions.

many thanks
Dan

 

[ShaunCorbs]

if your 100% sure the system is full with water (no airlock) its a flow issue, did you check on old boiler which is flow and return, if old using cast iron heat exchanger top pipe flow

 

[Frog67]

Think firstly you got to determine which way round the flow and return are.
Check pump for good circulation
Electrical issue? 3 port / 2 port valves opening ok.
Drain system and flush through using the mains should help see if you've got a blockage somewhere.

 

[Dan83]

Hi mate I double triple checked the old flow and returns and piped up how it was don't get me wrong I can't be 100% on the air but bleed in the airing cupboard full all rads full and water flying out the boiler drain off

 

[Dan83]

Hi Frog67
Brand new pump and checked its working its a 3 port on there admittedly it's the only thing I haven't taken off, however I opened it to mid position it felt ok but I guess it's not impossible that it's stuck up... just seems to operate with no problem??

 

[hammers4spanner]

My guess would be air , switch over to hot water demand only and bled through pump may take a while to settle .
Can be a pig sometimes on these types of systems .

 

[ShaunCorbs]

As above got to be air have you got a mag filter above boiler ?

Or drain offs on flow and return ?

 

[Dan83]

Hi Sean
I did have and then I binned it off when I switched flow and return over
(that was the point I was trying what they suggested)
It does sound a little sloshy still if I'm being critical, but I'm used to boilers doing that after install, but I've worked at this all day near enough! It's one of those ones mate I've looked at it that long now my heads gone!

 

[ShaunCorbs]

Hi Sean
I did have and then I binned it off when I switched flow and return over
(that was the point I was trying what they suggested)
It does sound a little sloshy still if I'm being critical, but I'm used to boilers doing that after install, but I've worked at this all day near enough! It's one of those ones mate I've looked at it that long now my heads gone!

so thats a no then?

the reason why turn the return off (via mag) and open flow drain off and leave for 10 mins and do the same with the return but use mag to turn flow off

 

[Stoney Ground]

Hi Sean
I did have and then I binned it off when I switched flow and return over
(that was the point I was trying what they suggested)
It does sound a little sloshy still if I'm being critical, but I'm used to boilers doing that after install, but I've worked at this all day near enough! It's one of those ones mate I've looked at it that long now my heads gone!

Take a step back and think.

You know 99.99% that you piped F&R correct, they are only surmising they are wrong.

Have you tried running it on HW only maybe it will push out some air, then CH only and try the same. alternate to see if it clears.

Last solution is stick an expansion vessel on and a PRV.

 

[Dan83]

Hi thanks for your input!
I've just had it running on both, to be honest I was thinking down the same route as you seal it off then I know I can get that air out if it is indeed air!
Question is do I switch my flow and returns back to their original as it hasn't worked, so difficult to know!

 

[Stoney Ground]

Hi thanks for your input!
I've just had it running on both, to be honest I was thinking down the same route as you seal it off then I know I can get that air out if it is indeed air!
Question is do I switch my flow and returns back to their original as it hasn't worked, so difficult to know!

If you believed you had them right I would say yes, change them back.

 

[ShaunCorbs]

as above if your 90% certain you had them right do it but if you find there wrong drain down

 

[hammers4spanner]

I assume you have comp fittings connected on the boiler end , if you have break pump out and what you think is flow by the boiler and blow down it .

 

[hammers4spanner]

Or many a time i have had that lightbulb moment when relaxing in the evening chomping through crisps and suddenly ping!!! Thats what i never done , don't stress your self over it .

 

[Dan83]

Cheers hammers4spanner
Yes got compression fittings on there thought about doing that with the wet vac, hopefully the god of plumbing will visit me in a vision tonight for some fresh inspiration lol!

 

[joni os]

Please don't take offence if I state the obvious, but with all this discussion about flow and return pipework. Is your new pump set up to pump in the right direction?

 

[Last Plumber]

Is the flow switch faulty ?