Comment by oakesm9 | Hacker News Reader

Comment by oakesm9 | Hacker News Reader

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A lot of these are UK based systems which are installed by installers with Heat Geek[0] training.

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

I watched a few of their videos as well. Great stuff. Key take away is that there are a lot of installers that have no clue what they are doing. Which results in poorly performing systems. The issue is not the technology but the lack of training and experience.

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.

it's funny actually, i've been binging their videos the past few weeks, since i'm looking into buying a home in need of renovation, and was happy to see their logos as part of one of the default columns.

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.

What's Skill Builder's skepticism based on? Don't heat pumps deliver on their promises?

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.

I 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.

What do COP and SCOP acronyms mean in this context?

COP 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.

COP (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.

Most 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

Maybe. However a heatpump sized to cool your house in summer cannot heat your house when the temperature is below about -3C. The heatpump might be able to produce heat to -25C, but it is too small to produce enough. Thus my system (in the US) that I just paid a lot of $$$ to install last fall leaves me using the backup gas heat a lot more than I wanted last winter which is disappointing. (It did get below -25C last winter for 2 days so I'd need that backup heat anyway, but I was expecting only 2 days not most of a month)

A properly sized system will be based upon the worst of the heating or cooling conditions.

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.

Try to train the hvac profession of that.

They are required by code to do a load calculation, so you might wish to continue shopping around until you find one to do it.

British note: UK govt subsidies for some insidious reason are not available to "reversible AC" style systems, so the dominant form here is air-to-water.

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.

If it's of any help in your battle with your installers the relevant part of the building regulations for external pipework is section 4.26 of approved document L: https://assets.publishing.service.gov.uk/government/uploads/...

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.

I have this outdoor unit https://cooperandhunter.us/product/ch-hyp36lcuo. This past winter the temperature dipped into -20C (-11F), had no issues maintaining temperature in the low 70s in the house. I was running them in heat pump only mode (resistive strips were not used).

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

your heat pump is sized correctly for your house.

Hmm, that's interesting, we have fairly large temperature swings (typically -15 C in the winter to 40 C in the summer), so it'd be interesting to see if the heat pump could replace the AC unit and the gas heating.

I'm in a similar zone and replaced (delivered) propane with a ground source heat pump 2 years ago. Constant temperature indoors (3C warmer in summer than winter) with plenty of AC capacity to spare. Breakeven is about 5 or 6 years.

They work okay in my area for -1C to 46C, imagine for your range maybe you just get a model that has improved heating over a basic one, whether that means ground source, more stages, or a heating element.

What are the following specs for your unit?

SEER2

HSPF

BTU

Feel free to post the model #’s as well.

I've watched a few videos of his and I'm not sure I'd characterise him as entirely skeptical of the technology as a whole, but more skeptical of the government incentives to retrofit.

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.

No they don't and it's kind of like agile everyone tells you it's not done the right way otherwise it would work. But when is sold it's sold as is it's great.. Very deceiving for customers

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