new radiator is cold.

Joined
23 Oct 2007
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Location
Stirlingshire
Country
United Kingdom
I am hoping that you can help me with a problem. I recently had a refurbished cast iron radiator installed (wife insisted) in our living room. The connection was teed off the flow and return from an existing cast iron radiator feed in the same room (so I am told by the plumber). I had fancy Bentley valves installed to complete the look. I filled the system and added inhibitor. I bled the system and not much at all came out of the radiators in the room in question. The problem is that the new radiator doesn’t get hot at all. I have closed off every other radiator in the house (all 15 of them) in an attempt to get some heat out of it but nothing! The inlet valves does get hot but the radiator is still cold. I checked the flow into the radiator by turning off the outlet valve and bleeding water from the top of the radiator... it shot out under pump pressure with no trapped air. I then tried closing the thermostatic end and opening the outlet valve, and again water came out with no air. I bled basin full (5 litres) The run between the new and old radiator is only about 6 feet So I reckon that this should have been enough to move any air lock. The water coming out was lukewarm at best (35C).
I then looked at the temperature on the boiler and according to the front panel the water cycling through it is 75C and both flow and return pipes were too hot to touch. I am a bit stumped as to what is going on. Could it be an air lock? If so why am i getting water shooting out when i open the valves separately?. And why is the water so cold?
Boiler Vaillant 428 open vented... working correctly.

Any thoughts appreciated
BS
 
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Either a blockage in the radiator or blockage in the piping to the radiator.

Remove the radiator and fit a normal radiator valve to each side pipe.
Attach a hose to one valve and open the radiator valve does flow out
of the hosepipe.
Repeat with other valve.

If this is ok then there is a fault in the radiator or maybe the plumber has connected flow and return at the radiator to the flow or return pipe instead of both so no circulation is going on.
 
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If everything else is turned off and the flow and return are both hot at the boiler but the radiator is still cold then the water is finding another route. Possibly an incorrectly adjusted bypass or a link where there shouldn't be one.

I replaced a radiator for a customer recently and the new one wouldn't get hot. When I checked I found that someone had linked the flow and return together under the floor.
 

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