Why Radiator Balancing is One of the Most Frustrating Jobs in Heat Pump Commissioning

If you’ve ever commissioned a heat pump system in a property with more than a handful of radiators, you’ll know the feeling: hours spent fiddling with lockshields, endless trips back and forth between rooms, and the growing pressure to wrap things up—but still get it right.

Manual radiator balancing is often seen as a necessary evil. It’s time-consuming, imprecise, and easily undone by things completely outside your control.

Let’s take a closer look at why it’s such a pain—and why so many installers find themselves back on site days or weeks later dealing with the same cold rooms all over again.

It Takes Forever

On paper, radiator balancing seems straightforward. You open or close the lockshield valves to restrict or increase flow to individual radiators until the return temperatures equalise.

In practice? Not so easy.

Every single adjustment you make to a lockshield might take 15 to 20 minutes to show its full effect on the return temperature. And that’s assuming you’re in a stable system with no other variables changing while you work.

If you’re working with ten or more radiators—and you usually are—it’s a long, slow, and repetitive process. Small changes can lead to big swings. Overshooting, retracing your steps, going back and forth—it’s easy to lose an hour or more just tweaking one part of the system.

Balancing a Heat Pump System is a Whole Different Beast

With traditional high-temperature systems—say a gas boiler running at 70°C—you can get away with a lot more. Imbalances still exist, but the sheer heat output tends to mask them. A radiator getting slightly less flow still usually gets hot enough to satisfy the room.

But with a heat pump, running at 35–45°C (and lower), everything changes.

The system is designed to run efficiently at lower flow temperatures. That means there’s less margin for error.
A radiator that’s slightly underperforming on flow or return won’t just be “a bit cooler”—it might not heat the room at all.

So what was a minor issue in a gas boiler system becomes a major comfort complaint in a heat pump system.

In low-temperature systems, every mistake, every imbalance, every underflow is amplified. That’s why getting it right is so critical—and so difficult.

The Return Visit: “This Room’s Still Cold”

You’ve been there: the job’s done, paperwork signed off, customer happy… until they call.

“The small bedroom radiator isn’t heating properly.” “The bathroom’s freezing in the mornings.”

And of course, the installer gets the blame. You return to site, only to find that the flow temperature has been cranked up to 50°C to try and force heat through the cold spot—completely undermining the system’s efficiency.

You go back to adjusting valves. You re-balance. Maybe it works… for now.

But the real issue isn’t the installer—it’s the method.

An Outdated Practice in a Modern Industry

Manual radiator balancing comes from an era of static systems and simple boilers. Today, we’re installing advanced, highly efficient heat pumps that are sensitive to every change in the heating circuit.

Expecting a one-time, manual balancing job to maintain perfect comfort in a dynamic, real-world home is wishful thinking at best.

Installers are working harder than ever to hit performance targets—and being held responsible when systems don’t perform perfectly. But with balancing still done the same way it was two decades ago, we’re asking a lot and giving them very little.

Time for a Rethink?

Radiator balancing is a perfect example of an old method clashing with new technology. The process is manual. The results are temporary. And the pressure on installers to get it “just right” is increasing.

It’s not laziness or lack of skill—it’s the reality of trying to fine-tune a living, breathing system using static tools.

Maybe it’s time the industry looked for smarter, more reliable ways to approach radiator control and system balancing. Oh sorry, yeah- That’s COP Angel!

For more information on how COP Angel will automatically balance your emitters and commission your heat pump system, and then continue to do so dynamically as your loads change, email our inventor directly mike.kellett@copangel.com