for the past few months i have not been able to get the downstairs radiators to work......
i have been through everything that i can think of, i have bled them copious amounts of times and there is no air lock in them, i have flushed the system and the water is running clear. the pump works and i have been through the forums to check this out.
if you run water out of the system on the downstairs radiator then the water will run hot and the radiator will get hot but as soon as you close the outlet on the radiator is cools down. i get hot water fine and the boiler is working fine.
i think that there maybe a problem with the 3 port valve?? are the cogs in it meant to be turning when it is working??? can this be the cause of my problems and the lack of heat downstairs?
My motorised valve blew due to water leakage from the main valve gland. The water had dripped onto control circuitry beside the quadrant-gear and pinion, and fried it. Main clue was water below the valve, and zero response to the thermostats;--the one in the hall for the radiator system, and the one on the indirect hot water cylinder. My valve has a pointer on the side, which shows the state of the valve;--down for radiators,-up for hot water, and horizontal for both. A white label is stuck on the underside, with an arrow pointing left,and right. The blown valve had stripped the quadrant and pinion----SCRAP!!
On another occasion the thermostat in the hall needed replacing, and this time the electrical factor knew to get the type of unit which had an air-temperature sensor below the bi-metallic strip/switch, not the type for under-floor heating, which I had presented.
My replacement diverter valve has an auto setting for the side-lever;- the lever does not move when in this mode, although the actuator does operate the quadrant gear and valve spindle, as I separated them and watched the response to operation of the thermostats. I have read that manual setting of this lever is used when bleeding air out of the radiators, with the pump switched off (after cooling the system). This is needed when refilling. Your test of one of your downstairs radiators sounded like a success, so why did you shut it down by valving off the water outlet valve? (I presume you had also bled it.) I would expect that repeating your procedure one-by-one on your downstairs radiators would get them all running hot, then you can partially open the outlet valves on them all, and balance them, so that none has a scalding-hot outlet. (Note that most thermostatic inlet-valves are just that;- they need inlet pump pressure to lift the needle-valve;-- some are bi-directional;-- so there is a possibility that a worn-out or cruddy pump may not have the oomph;- restricting the valve settings on your upstairs radiator outlet valves should conserve pump pressure for your downstairs ones----Balance your outlets, and rely on your thermostatic radiator valves for room comfort;- don't let outlet valves get more than hand-hot, and hopefully you won't need to call in a plumber. A new pump is cheap enough at Â£65, but including the costs a plumber would charge can make it a Â£250 job.