Suprima 70HE in sealed system - ground floor rads wont heat up?

[Viper Gas]

Hello All,

I've just visted a property where the down stairs rads dont heat up.
Here are the facts

1- two level property 11 rads, mostly single convectors
2- sealed system with two, two port valves and indirect cylinder up stairs
3- boiler downstairs directly underneath
4- boiler Suprima 70HE with only approx 24kw heat input and about 20kw output
5- room stat in hall downstairs
6- system used to be open vented then a new like for like boiler was installed and a system alterted to sealed, then problem started.
symptoms -
-The 5 downstaris rads dont work -
-boiler goes to lock out with heating temperature selector set to max but operates with dial set to medium.

all the rads up staris work and before i start pulling things apart and tearing up floorboards i'd really appreciate some hints or clues.


Thanks very much

Merry Christmas and a Happy New Year to all.




DD368

 

[diamondgas]

Well it sounds like a circulation issue! The Airsep in the picture were prone to pumping over/surging issues! But where do you start? Personally I'd want the system cold and then start up on hot water only whilst measuring the temp diff across the flow and return at the boiler. Reason being I'd want to know how badly the system flow is restricted and/or is it in the primary circuit hence hot water only, greater the temp diff above 20 degC the more compromised the flow through the boiler! Is the pump the original? May pay to replace/check that out as if it isn't working fully then neither will the system be? I'd concentrate on the original system and not the boiler 1st thoughts

 

[stevetheplumber]

id start with pump have you checked its running?

 

[Viper Gas]

PUMP, checked. running strong

 

[diamondgas]

PUMP, checked. running strong

It can be running but it may not be strong DD Impellars could be choked up! Do you know if the system was flushed by the installer?

 

[Mbear]

It may be airlock, have u tried turning off all the upstairs rads to maybe clear the air and force the heat downstairs. Or even turn one downstairs rad on to get circulation. It's also not beyond possibility that the installer accidently left summit in a pipe (or summit fell in a pipe) like a small bit of rubble of anything of that size. I'd change pump in the 1st instance though

 

[Viper Gas]

i was thinking that , he did say he flushed it but only each rad, not connected to the flow and return.
can i check the pump is on the right way round?

 

[diamondgas]

Right or wrong it would still circulate ... Pump has an arrow on it though telling you flow direction!

 

[Gray0689]

All the symptoms do point towards a pump/circulation problem
Could also
Be air locked

 

[PlumbBobBob]

i'd go for the pump as already suggested

 

[Viper Gas]

well if the boiler is over heating when i put the boiler stat on max then id think there is a restriction in the water leaving the boiler, i er against a blockage nhte heat exchanger itself becuase its a new boiler but if all other checks show ngative then i may just have to flush the whole system again. any thoughts on that?

 

[diamondgas]

Check what its like on h/w ... may just be the c/h ... however if its trippin then it sounds like the main circs ... I'd personally be cutting out/checking around the airsep i and outlets for restrictions!

 

[Viper Gas]

OK guys, well start at the pump

 

[Viper Gas]

thanks very much to all for taking the time and effort to reply and leave comments,
I wish you all a very merry christmas and a happy new year.

DD368

 

[diamondgas]

You're welcome DD368. Have a goodn' yourself