my rads still cold.

[mw]

I took off two rads at the weekend and flushed them out, as the were not getting hot.
They still don't get hot but if the heating has been on a while one valve gets warm on both rad, inlet??,

I dont think this is an air lock as one rad is down stairs and the other up.

maybe this is a problem with the exhaust valve staying closed even though it looks open??? I originally though it was sludge in the system but there wasn't any sign of sludge when I flushed them out.

also when I put the rads back on the wall they only filled up via one valve, i would have though it would have filled for either end, (my system was turned off gravity feed)


anybody please, if this helps the one upstairs (that stays cold) is fitted with two lock shield valves, i've been told that this is classed as the by pass, therefore water can alway circulate!!!!!!! through my system??

i've also put my pump upto speed 3 orignially on 1, this makes more noise but seems to help with the flow to the rest of the rads.

 

[breezer]

i know its obvious, but as you havent mentioned it i will ask, have you bled them?

 

[MANDATE]

I can only think of 6 causes for the radiators not to get hot.
1. Pump not working or needs bleeding
2. Insufficient or no water to pump round system
3. Air lock in pipe work (not radiators)
4. Air in radiator
5. Sludge in radiator or pipe work or valve causing blockage
6. valve not open.
I think when you remove a radiator and flush it out it is a good opportunity to make a fitting with a hose to attach to each valve in turn so you can run off a bucketful or two of water.
This proves the valves do open, removes any air lock in pipe work and flushes out sludge from pipe work. This leaves only the bleeding of the radiators.
I have a clear hose that I can fit at either end or across the two valves in lieu of the radiator, so I can also see direction of flow, cleanliness of water and any air passing along

 

[mw]

cheers lads for your replies

I did do a full drain down of the system as well.

When I re-connect the rad should it fill from any off the valves (ie the return would back feed and the forward would just feed as normal) cos as I remember it only filled up from one side (i tried both individually).

my system was turned off and is gravity feed from a small tank in the loft.

It could be the valves but for two to go on separate rads at the same time mmmmmmmmm thats strange???? or unless I broke then when removing the rad???

 

[MANDATE]

I'm a little puzzled how you know the radiator filled from only one side when the valves on both sides are open.
The 'feed pipe' to the radiators and the 'return pipe' from the radiators form a complete circuit so the water being gravity fed from your tank goes both ways so it will fill from any/both.( not that it matters).
Because it is fed from both ends you can sometimes get air trapped in pipe work and bleeding a radiator will not shift it. If it's trapped in the radiator it's easy to bleed off.
As you also drained the system you could have air trapped in pipes so I would try the method i suggested earlier.