cold rads

[collme]

hi, i was faced with an emergency when a friends rad sprung a leak at the inlet valve, i am no plumber but i fitted new valves to both sides of the radiator and while doing so lost alot of water from the inlet pipe side of the rad. once finished i bleed the radiator and checked all the other rads in the house for bleeding. i now have pure clean water coming out of every radiator but no heat. the rad i put new valves on gets warm only, right to the top but all other rads are cold in the house. there is a lot of knocking seemingly from the pipe from boiler to the header tank. there is only 2 water pipes to the boiler and no valves or gauges, in the loft is an emmersion tank and 2 header boxes, both 2/3 full. pump is running and pipes on both sides of the pump are hot, there is not one single bleed valve amongst all the pipework in the attic. how do i get the air out of the system and return the flow of hot water. the rad i worked on is only one warm and i let it bleed for 4 hours yesterday as bleed nipple could direct water direct into the toilet in upstairs bathroom. any help would be appreciated and i think maybe a damsel in distress will have to call on someone who knows more next time.
many thanks. colin

 

[wonderb0y]

Is the central heating pump on full speed? did you drain down system when you replaced the valves?

try and connect the drain valve upto a mains tap and back filling the system to force out any air, just be sure to keep an eye on the expansion tank and watch it doesn't over flow.

 

[gas4you]

Hot water off, heating on, pump on full speed, by-pass shut, turn off all rads bar 1. Let pump push air into this and get hot then move on to next rad and so on and so on. Hope this cures it

 

[collme]

pump is on full speed, i did not drain full system, when i got there, she had turned off the main stop cock to the house and after plenty more water had ran out of the leak, emptying the header tank i suspect, i just removed rad and vaves, about 2 gallon of water came out of the inlet pipe when i removed the valve before it stopped. with all the rads having thier valves open i bleed all of them after replacing the valves on the faulty rad, the whole system seems to be fresh clean water to every rad now, just no heat to any of them. will try connecting drain to a tap and back flushing as i am sure it must be an air lock due to all the banging and knocking, just seems to be no way to bleed the air out except on each rad individually

 

[wonderb0y]

You must have had a lot of water come out then if you didn't drain down the system is it an upstairs rad?

Might be an idea to drain down completly from drain off point and just re-fill, or one of other suggestions.

 

[collme]

yes it was an upstairs rad, i will have to locate the drain off point and start the system from saratch i think, will try the above suggestions first though. thankyou for your suggestions