Spreading heat for winter
Chris Hogan, 19th October 2015, Household
If you've just turned the radiators on and noticed that some are hotter than others, then you might be interested to know that you can probably sort the problem out yourself. It might be that you have to do it yourself anyway, because, as we recently discovered, plumbers are very reluctant to do it!
Assuming you've bled your radiators and there isn't a problem with the supply of hot water (we'll cover those in a minute) then the job you need to do is to balance the radiators.
This isn't difficult but it can be time-consuming, involving a lot of running between radiators and waiting for them to get up to temperature, which is why plumbers aren't that keen. But if you take it step by step you can do it quite easily yourself and enjoy a better distribution of heat around the house.
Things to check first
If some radiators are colder than others there may be a deeper problem, so you need to check before you start balancing. It will also be different if you have thermostatic radiator valves - we'll tackle that situation later in this article.
Bleeding radiators
No - we're not swearing, bleeding refers to removing air from the radiators as it can block the flow of hot water. With the heating on, feel the radiator and if most of the radiator is warm but there are cold patches, particularly at the top, then that could be due to air in the radiator.
To let the air out you must wait until the radiator is cold again to avoid burns. The bleed valve is small and square and will be at the top at one end of the radiator. Get a radiator key, put a small bowl under the valve and a rag or old towel around it before undoing the valve very slightly - a quarter turn should be enough.
You'll hear a hissing and bubbling indicating the air escaping. When when that stops and there's a steady stream of water coming out, the radiator is bled. Tighten the valve up and put the heating back on.
Other blockages
If you've bled all the radiators and you still have patchy heat, particularly colder towards the bottom of the radiator, that may mean there's a buildup of sludge in the radiator and it'll be time to call in the experts.
Check the temperature of the hot pipe feeding the radiator; it should be hot, and hotter than the pipe at the other end. If that isn't the case it indicates a problem with getting the hot water round the system so again it's time to call in the plumber.
Identifying valves
Assuming you've bled all your radiators and hot water is circulating around the system, you need to identify the lockshield valve.
At one end of each radiator there'll be an on/off valve, usually with a large white plastic cover marked with arrows to indicate the right direction to turn it. Make sure this is fully open (on) but don't screw it tight against the stop as that may cause it to seize in the future. Just open it fully then back it off a quarter turn.
At the other end there'll be a smaller white plastic cover with no markings - this is the one you're interested in. The cap may just lift off or it could be secured with a small cross-head screw on the top, just undo this and the cap should then lift off.
Some radiators, particularly if your system is very old, may not have a lockshield valve, just an on/off valve and nothing at the other end. If that is the case, you'll have to leave it fully open and just accept that you can't tune these for heat, except possibly by closing the on/off valve. You may be able to fit a thermostatic valve to control the heat level in that radiator but take advice from a plumber before doing so.
A word about thermostatic valves
If you have thermostatic valves then they will probably be fitted at the on/off valve end. If that is the case, just turn them to the hottest setting and carry on as described below.
If they are at the other end (which might be the case in a modern system) then there is little you can do except make sure the on/off valve at the other end is fully open, then control the heat to the radiator using the thermostatic valve. If that still doesn't encourage heat into the radiator, it's time to get the plumber in.
Correct spanner
The lockshield valve is a bit like a bleed valve but rectangular in section rather than square, quite slim and easily damaged. Unless you're lucky enough to have a spanner that fits it exactly (here's a hint - you probably haven't!) then use a small adjustable spanner on it.
Try to avoid using pliers as they are likely to damage valve spindles and make them hard to adjust them in the future.
Balancing
Finally - it's time to balance. If you've got thermometers, turn the heating on and working from the boiler outward, tuning all the radiators one by one.
A plumber will have thermometers which clip on to the in and out pipes of the radiator, will adjust the lockshield valve until there's a 11C difference between each pipe, then move on to the next radiator. Some guides say 10C, others 12C but as you probably won't have the thermometers, it's not worth worrying about.
You can set it up to a basic level without the thermometers but it's best to do it with the system cold.
Initial setup
Close the lockshield valve completely on the first radiator, then open it a quarter turn. Go to the next one, close it and open it three-eighths of a turn, the next one half a turn and so on, opening each one an eighth more than the previous one, until you come to the last one.
Once you're done, wait for the system to heat up and for the rooms to get to temperature. Check the rooms to see how they feel and check the radiators for cold patches - if there are any then there is still another problem.
Then fine-tune the setup by turning valves up or down, but only by an eight of a turn each time, and wait for it to settle before adjusting again. This is the time-consuming bit!
Thermostatic valves again
If you've got thermostatic valves, keep them open while you're doing the tuning and set each radiator a little hotter than you like it. Then you can use the thermostatic valves to turn them down a bit and you'll know that you've got a little extra in reserve for a particularly cold snap.
Quick fix
If, like us, you have most of your radiators working but two or three that aren't, you can do a quick fix.
Bleed all the radiators and check that all the on/off valves are open (that turned out to be the problem in our kitchen - no idea who had closed it or when!) then close the lockshield valves on each affected radiator down and open them a quarter turn.
Then wait for the radiator and room temperature to settle and fine tune from there, but only by an eighth of a turn each time. That was enough to get us by a cold patch in September and then the job was done properly the next time we had a free Sunday.
That's it!
We're now basking in the glow of reasonable heat throughout the house - or as best as we can get it. It's like heating a colander as the house is very old and we can't fit thermostatic valves, so it will always be just the best we can get. Hopefully you can do better!
