Question for PigletJohn - towel radiator

[thehopefulgardener]

Hi @PigletJohn, I'm hoping you can advise please.
I recently moved into a rented flat and the towel rail in the bathroom (not electric, plumbed in to the floor) is proving difficult.
It can work, but then stops.

There are 2 valves at the bottom, one on either side. They look identical, both turn clockwise and anticlockwise to a point, neither has any markings. I have seen slight leakage from the one on the right, so I think that might be water in, however when the heating is on, the piece of copper pipe coming from the (tiled) floor below both doesn't seem to get warm.
I have managed to get it working twice since we moved in, by just trying various combinations of turns of both / either valves. I got it going last night but this morning it was cold again. Last time it worked for about 3 days before stopping.

It doesn't gurgle so I don't think it needs bleeding.
There's another the same in a bathroom cloer to the boiler location which works fine.

Any ideas what the issue is, and how I could fix it?

The heating works off a simple boiler with water tank. The overall system looks quite old, but these I think are slightly newer additions.

Thanks for any advice!

I think you mean you have a hot water cylinder. The towel rail might be plumbed so it is heated when the boiler is heating the cylinder. This will typically be during and after running a bath or shower, which is ideal and a very superior method. Tinker with the timer for your HW so it runs for half an hour before, and continues half an hour after, your usual bathtime.

The cylinder thermostat will turn off the boiler once it is up to temperature, so this will not use up extra gas.

I would have thought that you need to turn both valves anticlockwise to open. Like taps.

Thanks, the heating for the whole flat is on a timer, and the rail is plumbed in, so I expected that the towel rail would be on at the same time as the radiators (that's the case in the other bathroom with the second rail).

When the 'magic ' combination of valve turning works on this one, it does seem to heat, but then stops randomly again, and it's off more than on....

If it comes on when the cylinder is heating, tinkering with the valves will not make any difference

For balancing, the lockshield valves should be nearly closed.

Thanks PigletJohn I appreciate your help here, apologies if I didn't explain it clearly.
It's pretty much always cold. I would expect it to come on when the radiators do. It doesn't. By fiddling with the valves while the heating is 'on' i.e rads hot (part or full turns then leaving it for an hour to see) I can sometimes (been successful twice from about 8 combinations) get it to warm up. The first time it worked for about 3 days in time with the rest of the flat, then stopped.
I'm afraid I don't know what a lockshield valve is - both valves look identical.

Both valves fully anticlockwise is fully open.

If it doesn't get warm with the rest of the system it may be a valve is blocked, pipe work is blocked, there is an air trap or the system needs balancing.

I'd start by turning off a valve on all other radiators so the towel rail circuit is the only one open

....MN is playing up...if the rail doesn't warm up straight away there's a major blockage/valve fault.

That should clear air blocks or sludge in pipes.

If after opening valves on the other rads the rail cools back down the system needs balancing which evolves reducing the flow to other parts of the system, usually rads nearest the boiler by partially closing the valve you don't normally use (the cap doesn't turn the valve and pulls off

Are you certain it doesn't run with the hot water timings, rather than central heating? We have 2 towel rails in separate bathrooms and this is how they were set up - by previous owners. So the ensuite comes on only when the heating is on, and the family bathroom comes on when the hot water timer is on.

Thanks hedgehog and surplus - all food for thought. We noticed that last night it came on again, but was cold this morning - could be the hot water timing thing. Going to see what happens this evening and investigate further from there.