all radiators cold

[rik12]

hi all,
i am in need of advice re ch system.

My house has a simple gravity feed ch system with gloworm fuelsaver f boiler. I reckon its about 20 years old.

I had some building work done in the summer and a radiator was removed temporarily and then replaced. I turned the system on last week and the radiators will not heat up.

I have hot water and the boiler and pump appear to work .

I have bled each rad and removed lots of air but still no heat. When i bled the rad nearest the boiler it temporarily warmed up ( warm water entered via the non return valve but not the normal thermostat valve) and then went cold.

I have a drain tap by the front door which i opened and drained slightly, the same thing happened with the rads nearest the boiler; heat entered 'the wrong way' into the rad and then went cold.

I am going to buy some cleaning agent and add it to the tank in the loft and then drain the system.. but am slightly unsure as to what this involves.. other wise i don't have a clue what to do... it was all working fine last winter...

 

[kevplumb]

is there water in the tank in the loft ?

 

[rik12]

thanks for the reply..

yes, the tank in the loft has water.. and it fills up when water is drained from the system..

my gut feeling is that there must be an obstruction to water flow through the radiator circuit... i can't find where though

 

[kevplumb]

check the trvs are opening first

 

[rik12]

dont know if they are opening or not.. ive never touched them and the system was working before the builders were in..

would there be a valve which would normally send water around the central heating system and if so could this have malfunctioned??

how can i have buckets of piping hot water and ice cold rads?

please advise..

 

[shaneo]

so the boiler must fire up, then hit tempreture quick and turn off?
the boiler does fire up dosent it? piolet is on etc
if you are still getting air out of the rads then keep bleeding even if it takes hours, every rad need water to be full, that includes any extra vents in the airing cupboard if there is any

failing that the blockage will most likley be, at the t peice there the cold feed t's into the system! (cold feed = pipe from header tank)

 

[rik12]

thanks..

the boiler fires up and heats the water, it turns off every now and then.. so all i get is a tank of hot water..

i cant see a vent in the airing cupboard.. what would it look like?

im very grateful for any ideas..

when i tried to drain the system using the drain outside, i could hear water filling the tank in the loft..

cheers
rik

 

[shaneo]

i doubt u would have one, would be sitting on top of a pipe pointing upwards, its air mate, just keep venting and venting and soon the boler wont keep switching off, air is a reall buger in some systems

 

[rik12]

nope, no air vent there.. ive bled all rads and theres no air left. im beginning to think there is no option other than to get help..

can you explain why water isnt circulating even though when i bled and drained the system slightly some heat entered through the no return side of the rads?

thanks again

 

[Bahco]

Could be the three port valve is stuck in hot water mode only and not letting central heating water through. Try manually moving it to central position.
Failing that bleed the pump and see if that helps

 

[rik12]

eureka!!

moved the switch on the valve and hey presto.. must have been moved accidentally..

many thanks.. my radiators are piping hot..

 

[brumylad]

can't be, that advice came from bahco, he's not up to the job.......trooper said so, and he's been a plumber for 23 years!!!

 

[kevplumb]

 

[Bahco]

Well, they do a great training course at B & Q you know

 

[kevplumb]