Vaillant turbomax plus 828e central heating shutting down

[lennysher]

Hi, i'm new to this forum, so please excuse me if I don't give all or correct info needed straight away.
I tried to fire boiler lately, after loading system to over 1mb and bleeding rads, only boiler fires up, goes into ch mode, reaches temperature of 82 degrees very quickly and shuts down then when temperature drops it fires up again up to 82 degrees again and repeats this cycle!
There is no fault code showing, status shows it going through S2, S3, S4 then when it shuts down it shows S7 and then cycles again?
Please can anyone tell me if they've had the same problem?
I've changed the diverter valve, checked operation and this works fine!
DHW works fine, would that show pump working too?
Please help....
Thanks.

 

[Agile]

Seems you have restricted flow through your heating system!

Have you turned the TRVs or rad valves off during the summer/

tony

 

[Bunnyman]

Have u opened the isolation valves on the flow and return? And u didn't unhook the motor on the valve to check it did u??

 

[lennysher]

3 TRV's were set to mid position upstairs, 1 TRV (in kitchen) shut off, ALL TRV's are now set to maximum and turned up and down a few times to operate valve stems in case they were stuck!

I have noticed pressure dropped twice over two days to just above 0, refilled and bled rads again.

Do you suggest I drain, flush and refill system?

Because there's not any faults showing, I think it could be system fault, airlock etc?

 

[lennysher]

Bunnyman, I'm sorry, you've lost me on your reply?
Please explain, as my basis is in Electrical and as we're cold and short of cash, I have to sort this out myself.
Thanks.

 

[Bunnyman]

Did u unscrew the brass motor from the top of the diverter valve at anytime?

 

[lennysher]

Bunnyman,
When diverter valve replaced, checked operation of motor, valve etc and replaced motor spindle over ball and fitted correctly.
DHW works fine, it's only when it switches over to heating this occurs.
I've also manually put valve into heating position and same occurs as when motor fitted.

 

[Bunnyman]

Check the flow an return isolating valves are back on, it can only be this or divertor or all trvs or rad valves turned off

 

[lennysher]

ALL TRV's are ok, all set to max, diverter valve is operating ok, (even proved manually, same scenario!), flow and return valves are closed after filling system again to 1.5bar.
I'm at a loss what it is?
Every rads shows no sign of air, water coming clear out of all rads!
Totally blowing my mind now!
Especially as hot water works fine!

Boiler fires up on heating then shuts down on boiler temp at 82 degrees, then cycles on a loop doing exactly the same!
I've seen about pushing both bottom buttons putting boiler into chimney sweep mode, I tried this, got a weird whooshing sound then boiler cut out in same manner at around 82degrees?
As I said no fault modes showing either?!
Any thoughts would be appreciated, thanks people.

 

[Bunnyman]

I am trying to help u, forget anythin electrical it can only b one of the 3 things i said, the isolation valves on the heating flow and returns should both be left in the on position ie the screw slot in line with the pipe not across it? U say you have closed them? You must close the fill loop obviousky when you have finished filling it but the isolating valves must be open , as these isolate the heating 😉

 

[lennysher]

I appreciate what you're saying, thanks, but the filling loop is permanently fitted to this boiler and if both valves are in line with the pipework, it will keep filling the system?
I have filled the system this way for years and bled rads ok.
Boiler worked fine, this is first time, except for diverter valve that has gone wrong!
Flow pipe is red hot, return pipe stone cold and no sign of warming up at all?

 

[lennysher]

Just got home, looked under boiler and see what you mean about flow and return valves now!
I found the flow valve shut in the off position?
Don't know how this has occurred, also slots been graunched with wrong sized screwdriver?!
Wonder if boiler engineer did it when serviced last time (in summer)
Needless to say, we're warm again.

Thanks to all who gave their advice, especially bunnyman.

 

[Bunnyman]

thats why we never use a screwdriver on them. there is a hole in the middle of the screwdriver slot, if you look carefully you use a 3 mm allen key

 

[bazdaman]

My handy pump head removal key works a treat on the iso valves

 

[Agile]

thats why we never use a screwdriver on them. there is a hole in the middle of the screwdriver slot, if you look carefully you use a 3 mm allen key

? I use a 4 mm Allen "T" key!