Our house is three storeys high, and the boiler is on the ground floor but the airing cupboard and central heating pump are on the top floor. All the rooms have thermostatic valves, but the heated towel rails on the top floor bathroom and middle floor bathroom and the radiators on each landing don’t.

When we moved in, the radiator in the hallway hardly heated up presumably because it was the last in line, so no hot water was left. So I throttled back the upstairs hallway radiators and towel rails to almost fully shut to force more hot water down to the ground floor.

This worked, but how do I know if I’ve over-done it. If the water return is too hot I’ll have problems, won’t I? And those non-thermostatic radiators are such because they have to dissipate a certain amount of heat, right?

All heating systems should be balanced so that all radiators give off a similar amount of heat. This is done by measureing the inlet and outlet temperature and adjusting so that each radiator has the same temperature drop.

Have a look here for a better idea. Most plumbers can do it from feel and experience. Clip on thermometers are available pretty cheaply.

http://www.diydoctor.org.uk/projects/balancingcentralheatingsystems.htm

But the downstairs one needs to produce much more heat than the top floor one because the hallway is usually freezing and the upstairs is boiling.

I’m considering a bigger rad for the hallway – could be a better solution.

But after the radiators are balanced each one can be adjusted afterwards with the TRV to set the room temperature for each area.

After balancing you can turn the upstairs rads down a little, once balanced you will be getting the maximum heat out of the downstairs radiator, if this is still not enough then the only option is to upgrade the radiator to a larger size or possible a double core if it is currently a single type.

There are no TRVs on the hallway ones.

Unless there is a fixed bypass plumbed into the system, you need one or more non-thermostatic rads to make sure that the whole system cant stop flowing (i.e. all the rad vales closed)- which is v. bad for the pump etc.

That’s what I am saying!

Or buy a pump which adjusts it’s flow to the # of open rads – mine can measure resistance and adjusts it’s speed accordingly.

http://www.grundfos.co.uk/web/homeuk.nsf/Webopslag/DMAR-6EGDHG

Quickest way to balance a system is to buy an IR thermometer from Maplin and measure the temp drop across each rad and tweak them all to be the same (normally 11C).

You still have a valve at both ends of the radiator, one which is a lockshield type should only be adjusted to balance the whole system and the valve at the other with a knob fitted which you use for everyday use to adjust the temperature of the specific radiator depending on the heat needed. Unless the whole system is balanced you will always have some radiators that you can’t get up to their full temperature.

Just the towel rail will give a route for the water to stop any problems with the pump burning out.

So it is safe to adjust the radiators until the system is properly balanced.