A BALANCED BLEEDING BIT OF INFORMATION

ABOUT YOUR COLD SPOTS

The importance of ensuring that your installer balances your system

and bleeds your radiators

You’ve received your radiator and now comes the

installation part. In this case we are talking wet

system radiators. Whether you’re the handy sort and

installing yourself. Or you’ve booked in a plumber, the

crucial part of ensuring that your radiators work

perfectly, is bleeding and balancing. What comes

first? Bleeding? Or balancing? Well, the first thing

an installer will do is to make sure that your system

is flushed, has inhibitor in and is vented (bled). If your

system doesn’t have inhibitor in, it could become

corrosive causing major, terminal issues to your

radiators.

If your system isn’t bled and balanced, then you’re

going to experience annoying cold spots on your

radiators. This isn’t terminal so don’t worry, your

radiator isn’t damaged and you haven’t received a

badly designed radiator. It’s a very simple and a very

common issue. A huge majority of technical calls are

from people that haven’t had their system bled

and balanced properly as a matter of course on

installation. Venting, or bleeding as it’s more

commonly known, means to fully remove all of the air

in the radiators. So you need to bleed your radiators

first. Most of you will know how to bleed a radiator

but what’s important to remember is that you need

to turn off your heat first before bleeding. This is

because as an active heating system can introduce

more air into the system. You want your radiator’s

contents to settle completely before releasing the air

trapped within. Allow time for the heat in your system

to dissipate, then feel all over your radiator for heat. If

any part of your radiator is still hot, wait for it to cool

completely before proceeding to the next step. If in

doubt about bleeding your radiators, check out the

Eskimo technical help file ‘venting procedure‘.

Then comes the balancing, not so commonly

understood but easily learnt. If you want some

thorough technical help, have a read of our Eskimo

technical help file ‘radiator balancing’. However, at its

simplest, balancing just means adjusting the radiator

valves so that the radiators all heat up at the same

rate. If a radiator is too cool, it needs more hot water

flowing through it, and if another is too hot, then the

flow through it needs restricting.

Balancing may be necessary any time radiators are

fitted in an existing system or upon the installation of

an entire heating system. If a system is not properly

balanced it will result in one or more radiators not

heating up properly, or not heating up at all. A basic

explanation of what balancing involves is helped by

an understanding of the way water behaves when

flowing through any pipe-work system and what is

meant by pressure drop. Pressure drop describes the

effect of friction on the water flowing through

pipes – the resistance to the flow of the water. This

resistance is increased by twists and turns and will

be higher in a smaller diameter pipe than it will be in

a larger one. It’s also increased every time the water

flows from a pipe of one diameter to a pipe of a

different diameter or through a valve. Pressure drop

is measured in Bar or PSI and essentially the water

pump has to generate enough pressure to overcome

the total pressure drop (can also be called pressure

loss) in the system. Every radiator will have a differ-

ent pressure drop. Combine this with the fact that the

pipes flowing to and from each radiator will be of

different lengths and take straighter or more

circuitous routes and you’ll see that the water will

have to work harder to flow round some radiators in

your system than others. Lazy water – the water

flowing around your system is essentially lazy. It will

follow the path of least resistance. If radiator A and

its associated pipe-work has a lower pressure drop

than radiator B, then more of the water will flow to

radiator A. If the pressure drop through radiator B

and its pipes are much higher than radiator A then it

won’t bother going through radiator B at all.

That’s why, we often hear that a radiator upstairs

or on the far end of a system, is the one that is

having problems.

Balancing is a simple operation that any competent

householder should be able to do too. I stand by

that because I’ve done it myself and I had a fear of

carrying out such a heuristic and seemingly technical

activity. Your installer will have completed this for you

though as a matter of course, but if for some reason

this has been missed, give them a call as they’ll want

to rectify this. So we know that balancing is the name

for the procedure that ensures that each radiator in

the system has a roughly equal pressure drop and is

done by using the lockshield valve on the return side

of the radiator (the downstream side).

Start by fully opening the main wheel valves or TRVs

on all the radiators. Then unscrew or prise off the

plastic caps on the lockshield valves. In most cases

this will reveal a half-moon-section brass spindle

sticking out of the top of the valve, which can be

turned using a small adjustable spanner. Try to avoid

using pliers, as the jaws might slip and burr the spindle.

Then, starting with the radiator nearest the boiler,

close the lockshield valve completely off (fully clockwise)

and then open it a one-quarter turn. Do the same

with the next radiator, this time opening it three-

eights of a turn. And so on until the radiator furthest

from the boiler, which should have the lockshield

valve fully open.

With the boiler and pump running, see how quickly

the radiators warm up and how comfortable the

rooms are. Make further small adjustments until the

system is balanced to your satisfaction. Then replace

the plastic covers on the lockshield valves.

A more precise method is to use a pair of clip-on pipe

thermometers on the flow and return pipes at either

end of the radiator. Starting with the radiator nearest

the boiler, adjust the lockshield valve until you get a

temperature drop. This temperature drop will usually

be something between 10oC and 20oC depending on

your system – if in doubt go for 12oC across the two

pipes – they key is to ensure that the temperature

drop is the same across each radiator. Then move on

to the others in turn.

Bleeding and balancing makes a World of difference

once you know about it because there is nothing

more frustrating for customers when their radiators

are just not heating up or have cold spots.

What we can reassure you is that your radiator is not

faulty. Bleeding and balancing is the issue and it’s

easily solved. So don’t get mad with your radiator,

vent your radiator instead and experience a more

balanced home.

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