bathroom radiator/towel rack control knobs

[extopia]

We have large (2m high) combined radiator / towel rack units (chrome) in bathroom of a nearly new house we moved into a couple of years ago. These rads seem to have two regular control knobs at the bottom, rather than the usual valve and lock shield combination that are on all the other radiators.

Is there a trick to using these knobs? I only recently noticed them when I was trying to bleed the system (the towel racks in the two top floor bathrooms are not heating all the way to the top and I haven't succeeded in bleeding them all the way - still cold at the very top few inches).

Any help appreciated.

 

[Leo]

One valve will likely be acting as the lockshield. The lockshield would normally be the one on the out-feed if you can determine flow direction. There might not be sufficient water pressure in the system. Top of those will be considerably higher than that of all other rads.

 

[PMU]

I’ve one of these. First, ask the person who services your central system to check it out. This should be part of a normal central heating service.

Or if you want to try it yourself, check the top of the rads. There should be a valve on the top of each pipe, i.e. on the left and right side. (There is on mine.) Start on one side, and adjust the valve very gently, bit by bit, until you bleed the rad. You may need e.g. an Allen key to do this. But your first port of call should be as part of your regular service.