Heat Pump SCOP Arms Race

I’m Nigel – Heat Pump Installer Extraordinaire. I’ve been installing air-to-water heat pumps for heating in UK homes for decades. But recently, something strange has been happening in the industry – what I like to call the SCOP Arms Race.

No longer is the goal to simply keep your home warm in winter with lower energy bills. Nope. Now, it’s all about one thing: squeezing out the highest possible Seasonal Coefficient of Performance (SCOP) from the system, regardless of whether it makes a lick of sense for you, the homeowner.

Gone are the days when the first question was, “Will this keep you warm when it’s freezing outside?” Instead, installers are obsessed with ranking highest on Open Energy Monitor, showing off their systems’ delta T and reducing compressor starts like they’re in some sort of engineering Olympics.

Here’s a peek into the madness I’ve seen over two weeks of installations.

The Buffer Tank Believers

First up, the Buffer Tank Believers. Their philosophy? Bigger is always better – especially when it comes to buffer tanks. They swear by the idea that loading your system with as much thermal mass as possible makes everything run more smoothly. “Your heat pump will thank you,” they say.

So there I was, installing a buffer tank the size of a small car. It took up half the client’s utility room. According to the SCOP fanatics, this extra water mass would reduce compressor starts and make the heat pump more efficient. But guess what? The SCOP actually dropped to a disappointing 2.8. Turns out, all that water slowed down the system so much it was like trying to turn the Titanic around.

Still, the installer I worked with was thrilled. “Look at the compressor start graph!” he said, proudly pointing to Open Energy Monitor. The system was crawling, but hey, we’d cut down compressor starts! Shame the homeowner had to wait hours for the house to warm up. But that’s not the point, right?

The Anti-Buffer Brigade

Next up, I ran into the Anti-Buffer Brigade. To them, buffer tanks are the enemy – “a waste of space,” they said, “and energy… and money.” Their approach? Lean and mean. Get rid of the buffer and just let the heat pump do its thing.

So out went the buffer tank, and in came a system with direct flow. And you know what? The SCOP jumped to 5.6. Success! Or was it? Now the heat pump was short-cycling like a caffeine-fuelled squirrel, constantly starting and stopping every few minutes. But did that matter? Of course not! The SCOP looked great, and the installer couldn’t wait to upload his latest achievement to Open Energy Monitor. “We’ll be close to the top of the leaderboard with this one, for sure.”

The fact that the homeowner would probably need a new compressor in a few years due to all that short cycling? Well, that’s just future Nigel’s problem.

The High-Volume Fanatics

Then came the High-Volume Fanatics. These guys believe the key to heat pump nirvana lies in flow rates. What you need is maximum water volume rushing through the system.

So, I installed a maze of pipes, extending into every nook and cranny of the house until the client’s basement looked like a plumbing exhibition. The result? A SCOP of 6.7. We’d apparently reached “thermal stability,” whatever that’s supposed to mean. But let’s be honest – what homeowner wants a basement that looks like it’s hosting a water treatment plant?

Of course, the installer I worked with was overjoyed, eagerly showing off his Reynolds number calculations and volumetric flow rates. Never mind the fact that the system had become more complex than a London Underground map – what mattered was that SCOP number.

The No-Volume Rebels

Finally, I met the No-Volume Rebels. These folks are convinced that the less water in the system, the better. Their philosophy? Minimise everything. Strip down the system to the bare essentials and keep that delta T as sharp as a razor.

So, we installed a system with the barest trickle of water. And wouldn’t you know it? The SCOP hit an impressive 7.1. The installer was practically doing a victory lap. “Look at that delta T!” he shouted, as though it had single-handedly solved world hunger.

SCOP, SCOP Everywhere – But What About Your Heating?

After two weeks of SCOP-fuelled chaos, what have I learned? Well, one thing is crystal clear: the industry is a mess. Some installers swear by buffer tanks, while others think they’re the worst idea ever. Some push for high water volume, others advocate for the leanest possible setup. And all of them have their own conflicting methods to tweak the system.

And where does that leave you, the homeowner? Confused and overwhelmed. Most of you don’t care about SCOPs, delta T or the latest performance graph on Open Energy Monitor – you just want a reliable heating system that works for your home without draining your bank account. But here’s the catch: you have no idea which system is right for you. With so many different approaches, it’s a gamble as to whether you’ll end up with an installer who truly knows what he’s doing, or if you’ll get stuck with someone who’s happy to slap in any old setup, cross his fingers and hope for the best.

The reality is that there’s currently no consistent standard for heat pump installations in the UK, and that leaves you, the homeowner, at the mercy of your installer’s competence – or, let’s be honest, incompetence. And after spending thousands on a system that’s supposed to be efficient, you could easily find yourself stuck with something that’s anything but. It’s no wonder UK homeowners are worried. They’re being sold on efficiency, but whether they actually get it depends on the luck of the draw.

Maybe one day, the industry will clean up its act. Maybe we’ll stop treating SCOP like the Holy Grail and start focusing on real-world solutions that actually work for homeowners. Until then, it’s a roll of the dice – and let’s hope you pick an installer who’s not just chasing numbers, but knows how to give you what you really need: a home that’s warm and efficient without the headache.

Note: This is a parody. Nigel is not real, but the article reflects real frustrations with competing heat pump theories that confused and overwhelmed homeowners in the UK, and many turn to the forums at Renewable Heating Hub because they need advice.