So there are lots of horror stories of companies installing systems that don't work very well and cost a lot of money to run, which makes people think heat pumps are crap. But usually people like Heat Geek trained installers can fix such systems without changing the equipment - often both providing more comfort than gas (less thermal cycling because heat pumps with inverters can modulate their output more precisely instead of hard switching on and off) and costing less to run than gas.
COP is only an instantaneous measurement though, and changes depending on the outside temperature. So if you need heating for five months a year, and it's usually exceeding COP of 5 for 80% of that time but dips down to a COP of 3.0 on the three or four coldest days of the year, it's not really correct to say it's either >5 or that it's 3.0 - so SCOP is used as a 'seasonal' COP that is averaged over a longer time period, so you can compare different systems over the longer term.
SCOP (seasonal coefficient of performance) is a weighted average of performance at different load conditions that represent different outdoor conditions based upon an average binning of weather conditions.
No different this time round I imagine.
It's so infuriating - literally handing money to conmen
In the summer our temperature regularly reaches into 90s (above 30C) and the house is very comfortable on those days as well with the same heat pumps
I had mine fitted last year. Retrofitted to existing radiators with 8mm pipework. With natgas backup/hot water boiler. At the end of this month I intend to go back and correlate the bills against the previous year (both kWh and £), because like a lot of discussion in this thread I think the installers have made some poor decisions. There's too much poorly insulated external pipework.
The table in there assumes pretty high quality insulation and the neoprene-looking stuff doesn't meet that standard so would have to be thicker. Note that the way the performance of pipe insulation varies non-linearly with the pipe and insulation radius so it's a bit unintuitive.
How do I know? I had the same problem with my installers.
Luckily an inverter heat pump can run down to about 25% full load so even with them coupled and in an imbalanced heat/cool environment you can still see good performance year round.
SEER2
HSPF
BTU
Feel free to post the model #’s as well.
He argues in one of his videos that there aren't enough qualified installers who actually understand heat pumps, and the government incentives are encouraging cowboys, basically, to take the government cash and provide unsuitable installations. Then secondly, a lot of the insulation installers also don't know what they're doing and are creating damp problems by neglecting ventilation.
Even as someone who is a huge fan of heat pumps, it's hard to disagree with him. There are a lot of difficulties with retrofits in the UK, where we have a lot of old terraced housing stock with poor insulation, no mechanical ventilation, and small gardens. Then on top of that, there are almost no tradespeople who actually understand the technology or why that housing stock is unsuitable without extensive improvements.
To be frank, even regular gas plumbers are shocking here. They don't install correctly rated systems, don't set the temperature correctly and don't enable the weather compensation functionality that is built into all modern combi builders and can save you 30%. They just install an over-sized boiler and whack the temperature up to maximum. At least it keeps the house warm, at the cost of inflated bills. That's without getting into the FUD about chemical water softening (and use of magic magnetic "water conditioners" instead), continued use of loft header tanks and not understanding how to improve or balance water pressure.
they claim also to be mainly motivated by the climate crisis and are even, now, developing an open source water heater, which... you don't often hear about in industries such as home appliances or heating: https://www.youtube.com/watch?v=uFBbArwAXS8
i'd love to install an air-to-water heatpump myself, but i'm untrained and i guess i'm feeling a bit of the dunning–kruger effect while learning from the heat geek videos.
Another good point is that even an old house with poor insulation can benefit from heat pumps. It just depends on sizing things properly and dialing things in properly. The UK has a lot of old houses that are quite old. This doesn't have to be a show stopper. There are a lot of myths and half truths around this topic. Of course you'll need more kwh for heating if your insulation is bad. But you should still get the same energy coefficients. And you'll pay a fortune in gas as well to get the place warm. Whether that's worth it with or without investing in insulation, windows, new roofs, etc. depends on a lot of things.
Most of the nonsense about heat pumps not working at lower temperatures is easily refuted by the notion that much of Scandinavia runs on these things for decades. Most of the people having issues with heatpumps are simply buying the wrong stuff, or having it installed wrong, or both. People have proper arctic winters in Scandinavia. Also there's a reason lots of Scandinavians ended up in places like Montana: it feels like home to them but with better summers (it's much further south). If people can do heat pumps in northern Norway, Montana is a walk in the park.
They're an interesting company who's trying to fill in the lack of training that traditional gas heating installers have to properly install air-to-water heat pumps in the UK. They also do homeowner training courses and a guarantee scheme on their certified installers (they'll fix the system for free if the SCOP is below a designed level).
They did a series of videos with Skill Builder[1] (who's a bit of a heat pump sceptic) where they fixed a badly installed heat pump that was causing a lot of issues. That install is currently 7th on the linked website[2] with a SCOP of 4.5 (450% efficient). Obviously a bit of a sale pitch from them, but there's loads of interesting information about WHY they're making the changes that they are.
[0] https://www.heatgeek.com [1] https://www.youtube.com/watch?v=BesfqnHPxLU [2] https://heatpumpmonitor.org/system/view?id=196