How to Balance Heating System Radiators – Plumbing Tips

Posted by in Plumber Talk, on May 18, 2017


A brief video on how to balance heating system radiators. Includes lockshield positions and TRV’s. Plumbing Tips – diy.

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Today, I’m going to tell you about balancing heating systems. Why you should do it, the symptoms that mean you might have to do it and how to do it. Firstly, lets have a look at the general layout of a heating system. Have a look at schematically because that will help you understand why balancing a heating system is so important. Let’s say we have two stories, level one and ground. We have the boiler at the bottom. Coming out of the boiler we have a pump that goes up, through diverter valve, through some radiator’s upstairs. And, then downstairs, with common returns, going back to the boiler. Okay, so we’ve got radiator’s here. The first reason that heating systems should be balanced is even if there is a pump on the heating system, hot water naturally likes to gravitate up. And stay upstairs and then make it’s quick route back to the boiler. So what we often find, is the radiator’s upstairs are getting loads of heat when the ones downstairs, are still really quite cold. So what you should do, is go to the lock shield on the radiator’s upstairs, close them and then open them about a quarter of a turn. You won’t necessarily see any difference in the radiator’s heat capacity or not but you will noticethat more hot water flow is diverted to the radiator’s downstairs. Now, you go downstairs make sure those radiators are open and that means the heating system should be balanced. Another reason you should balance your heating system is, say, this radiator is getting hot, that one’s getting hot, and this one’s getting hot, the last radiator on the line isn’t getting so hot. That’s because these three radiators are effectively pinching all the hot water flow delivered by the boiler and the pump. What you do then, is remove the lock shield on these radiator’s here, straddle those two up there, down, shut them, give them a quarter of a turn. This one here, bring that down, shut them, then give a quarter of a turn.
We also do a video on one radiator isn’t getting hot ’cause it can be more than one reason, not just the fact the system isn’t balanced. But, that is a brief idea of how you balance the system and why. Now, let’s take a quick look at the lock shield, how to shut it and also, give it that quarter of a turn to make sure it is all balanced. So, here we are, upstairs, okay. Now the radiator’s up here get really hot, so let’s have a look at how we’re gonna straddle this one down and balance this system. So, here we are with our first upstairs radiator. There is four in this system upstairs and do the same thing to each one. Here’s the lock shield here, note the T on the end. Pop the lock shield cap off, and close it by turning it anti-clockwise. Once it’s fully closed, just slack it back a quarter of a turn. Do that to each radiator upstairs, and you should find then that each radiator side of the heating system is balanced.
Now, let’s have a look at what you can do to balance out the hot water coil on your heating cylinder, if you have an indirect one. Right, so we had a look at how to balance the radiators on a heating system. Now, we are going to have a look at how to balance the hot water coil on the indirect cylinder. A lot of houses in the UK have indirect hot water coils on the cylinder. That means, hot water from boiler is passed through a coil in the cylinder and that heats the water up. Now, often these coils are 22 mm in pipe size and when the valve opens up to let hot water through that coil, it pinches loads of heat from the radiators. Therefore, the indirect hot water coil should also be balanced and regulated. Most plumbers when installing an indirect hot water cylinder, will put a flow regulating valve on the return side of the coil. Let’s have a look at it.
So, you have your boiler, your pump and your three port valve or if you have less plan, it will just be a two port valve for each side. You have all your radiators with their frozen returns. We have the flow coming up here from the boiler, goes through the valve into our hot water coil and our cylinder and then back out. And, it’s here that we fit the flow regulating valve on the return side of the hot water coil. That will go back into the return side of the boiler. So, to recap, we have the boiler, the pump and our diverter valves. The radiators upstairs have been straddled down and regulated. The ones downstairs are getting a good flow of hot water. We’ve also straddled down the return on the indirect hot water cylinder and the whole heating system is now working properly.

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