Rad not warming up

[thedigger]

Yeah, I'm slowly giving up hope on it being an "easy" solution.

Is your hunch that this is sludge related, or perhaps something to do with the system being unbalanced?

 

[rich4nancy]

Just a thought, u say the rad is at the top of your house? Do you mean in like a loft conversion? Is your heating open vented? Ie is there a feed and expansion tank somewhere and how does the position of it if u have one relate to the problem radiator??

 

[rich4nancy]

Just a thought, u say the rad is at the top of your house? Do you mean in like a loft conversion? Is your heating open vented? Ie is there a feed and expansion tank somewhere and how does the position of it if u have one relate to the problem radiator??

 

[stem]

With a one pipe system, the radiator sits atop a single pipe to which the radiator flow and return are both connected.

Can you check to see if this pipe is actually hot? The reason I ask is because although in theory single pipe systems are comprised of one loop, sometimes badly designed systems or later modifications add a second loop or branch. These rarely work well as the majority of the water will take the easiest route. In an attempt to overcome this, sometimes balancing valves are fitted to the pipe system where it splits. (Don't confuse these with the balancing valves on the radiators, which on a one pipe system have no effect whatsoever on the flow of water around the 'loop' itself)

If this pipe is hot and I mean really hot. Not tepid or warm, then the fault is with the circulation around the radiator, The pipes must slope upwards from the 'single pipe' to the radiator without any dips or drops. The water flows around the pipe with pressure of the pump, but relies on gravity to assist with the flow around the radiator. Is it possible that the pipes were moved when the radiator was removed for re-plastering causing a dip somewhere?

If the pipe below the radiator isn't hot, then you probably have a branch or second loop which for some reason isn't getting its fair share of water.