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Heat pumps require some domain-specific knowledge to build a system that costs less than gas for the same building (the crossover point is near a seasonal avera
by stephen_g 3y ago
Heat pumps require some domain-specific knowledge to build a system that costs less than gas for the same building (the crossover point is near a seasonal average COP of 4.0 at UK's gas and electricity prices, as mentioned in other comments SCOPs of 4.5 are very possible). Yet there are subsidies available and installers without the knowledge (who would normally be installing gas systems) are installing them basically without sizing radiators correctly or by doing things that reduce performance (big buffer tanks, lots of zoning, extra pumps that are unnecessary, etc.).
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.
- stavros 3y agoI see, thanks. This provides a counterpoint to the sibling comment of "they don't perform but everyone blames the user for doing it wrong", but also sounds true, so hopefully as installers learn more about how to correctly install heat pumps, they'll perform better.
- darkwater 3y agoWhat do COP and SCOP acronyms mean in this context?
- stephen_g 3y agoCOP is Coefficient Of Performance, basically the heat they produce divided by the electricity input, so a COP of 4.5 means that 1kW of electricity produces 4.5 kW of heat (it's taking heat from the environment so you can say a COP of 4.5 means it's running at 450% efficiency, but that's only in terms of electricity use, not actual overall efficiency - but electricity use is what we care about). 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.
- rainbowzootsuit 3y agoCOP (coefficient of performance) is taken at a full load condition with specific indoor/outdoor conditions. 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.
- switch007 3y agoMost if not all energy/green subsidy schemes in the UK in the past couple of decades resulted in tons of cowboys rushing after the gold, and doing a terrible job and even causing serious long-term damage to the property. No different this time round I imagine. It's so infuriating - literally handing money to conmen