new central heating radiator not heating

[ancell98]

Hi all Just installed a gas boiler to replace solid fuel. Thanks to advice received on this board--gas supply installed-meter installed--new boiler installed--new gas pipe[internal] installed and tested--zone valves fitted--complete wiring--new control panel and hot water thermostat. System fired up and ran perfectly-------------almost--well chuffed. My problem is a new radiator was installed-- it is the furthest from the boiler about 20 feet--it will not warm up. The TRV works in both directions so I have tried it both ways---no joy. I have bled both input and output by slackening the lockshield and TRV connections to obviate an air lock. All TRVs were turned off to boost flow to the radiator--no change. Pump is set at mid range. The radiator will heat slightly when the bleeder is opened and the TRV controlled input will get hot. The whole central heating system is only 3 years old using a "classic"

22mm main ring with 15mm feeds to the rads on the flows from one side and returns on the other basis. The system is at normal atmospheric pressure--non-pressurised. I have run out of ideas please advise. tam

[Andy Burns]

Could it have somehow been plumbed it between flow and flow (or return and return) rather than between flow and return?

[Ed Sirett]

There is a pipework problem or a blockage. Why did you choose to go for a vented primary circuit?

[ancell98]

ide quoted text -

Could the blockage be in the new radiator. Could there be an airlock in the return--the flow pipe heats up so there is flow there?. The pipework is pretty basic a 22mm ring main up the hallway-- about

12 feet long with the flows off one side and the returns off the other--the minimum separation is about 6 feet--all the other 4 radiators work ok. I went for a vented system because the header tank and expansion pipework was already installed as part of the solid fuel set up. tam

[Roger Mills]

There could well be. Fully turn off the valve on the flow side (if it's a TRV, use the decorator's cap) and bleed a couple of litres of water out through the bleed screw. For good measure, reverse the process - by bleeding with the flow valve open and the return valve closed.