half the radiators not working

[misguided fool]

hi

i have been fighting with the central heating system since a week before christmas and am at my wits end.

i have a potterton suprima boiler which supplies both hot water and heating. this was fitted in sept last year along with a new pump, timeswitch and a small silver box on the same pipe as the pump. hot water is fine. there are two loops one runs from the boiler into the small bedroom down to the bathroom the back to boiler, the second loop tees out of the first and supplies the two other bedrooms and the two downstairs radiators.

i noticed one of the upstairs radiators was leaking from the thermo valve, so the system was drained, the valve fixed and the system refilled & bled

now i have warm radiators upstairs cold radiators downstairs, i have bled the radiators daily for over a week. i have also tried draining the system again and starting from scratch in case of an airlock.

but the problem remains, any ideas?

 

[kevplumb]

did you lock the diverter in the open position wnen you filled up ?
did you open the air bleed which is usually near the pump ?

 

[misguided fool]

when i refilled the system i left all rad vents open
locked off downstairts as hissing stopped
then locked off upstairs rads again when hissing stopped
then bled the pump by loosening the centre screw
water dripped from the middle so prefummed ok

do not know what the diverter is
i do not know what the air bleed is
what do these look like?
is there something else i should have bled?

 

[kevplumb]

silver box has a lever on the end to man open it
vent is usually a brass cep on a stub pipe pointing upwards

 

[misguided fool]

silver box has lever underneath it

should i move it?

and sorry to sound like a dummy but
brass cep is this an abbrievation ?

 

[kevplumb]

yes move the lever it hooks open
brass cap (my typing )

 

[misguided fool]

i hooked it open in the manual open position

i have found a brass pipe with a screw end cap half way up the
hot water tank which is above the boiler

if i loosen this nut off with a screwdriver i have water no air

 

[kevplumb]

1st check the pump is acually running undo the screw again and put a small screwdriver in the hole and see if the shaft is turning

 

[misguided fool]

yes i have removed the central brass nut and i can see the pump spinning when i look down the hole and water is coming out

 

[kevplumb]

try turning the hot rads off

 

[misguided fool]

ok ive done that

i guess we trying to force the hot water down to the cold rads

and now we wait to see if thay get hot

 

[kevplumb]

yup got it mate i think youve got air trapped somewhere

 

[misguided fool]

well i left the upstairs rad valves off last night for 3-4 hours with the diverter locked in the the manual open postition. there was lots of gurgling and banging from the boiler cupboard and lots of hissing and popping from the loft.

but all rads stayed cold

i turned it off via the room stat when i turned in for the night and tried again this morning, still nothing

i have turned the thermo valves back on upstairs and the rads up there are warming back up.

 

[kevplumb]

how many pipes go into the valve ?

 

[misguided fool]

3 pipes into the diverter
1 from the pump/boiler
1going up
1 going down to rad pipes