Talk:Heat pump

Who are the readers of this article?
I guess most of the readers of this article are either:

1) Homeowners considering buying a heat pump

or

2) Teenagers being taught about heat pumps

But I don't have any evidence to back up my guess. Does anyone have a better idea who the readers are? Chidgk1 (talk) 17:19, 4 October 2023 (UTC)


 * The article focuses on the practicalities of heat pumps, but it also relies in one or two places on the concept of the reverse Carnot cycle and the second law of thermodynamics. This distinction is significant for our present discussions. The Carnot cycle and the second law are high-level topics typically only taught in college-level courses in applied physics and mechanical engineering. My point is that I think this article will attract a high proportion of its readers to the practical information about heat pumps; but only a small proportion of its readers will have knowledge of, or an interest in acquiring knowledge of, these two high-level topics.
 * In pursuit of WP:Make technical articles understandable we must provide a path through the article that avoids Carnot and the second law. The article itself, and one or two of it’s subordinate articles, present the math associated with the Carnot cycle so we must provide a path that allows readers to side-step this math if they wish. One example is the linear algebraic equation that defines the COP in terms of two temperatures - one high and one low. The Table titled “Variation of COP with output temperature” is the means by which readers can see clearly the way in which COP varies across each row, and down each column, and thereby avoid the algebraic equation associated with the reverse Carnot cycle.
 * In the bottom 4 lines of the Table, readers can see the way in which COP varies in a perfect heat pump operating on the reverse Carnot cycle. In the top 6 lines, readers can see that in real, practical heat pumps, the COP varies with output temperature in exactly the same way. This is a quick and easy way for the majority of readers to absorb this information. Dolphin ( t ) 01:52, 6 October 2023 (UTC)
 * OK so I take it you agree with me about who most of the readers are. As I suspect the 2 groups have somewhat different needs I am going to start a couple more talk sections below to try and keep things clear and will reply there to your interesting points about the theory. Chidgk1 (talk) 06:42, 6 October 2023 (UTC)

What do homeowners want from this article?
I totally agree with you that very few of these readers will want the reverse Carnot cycle and the second law of thermodynamics and if they do they can click through to those articles.

By "homeowners" I also mean people with commonhold of flats. I think homeowners will need

1) The basic idea that they work like a refrigerator and are more environmentally friendly than fossil fuelled heating.

2) Overview of the types so they can rule out some of the options and click through to a more detailed article - for example someone with a small garden will rule out GSHP and likely click through to ASHP, whereas someone in a flat in a block which already has fossil fuelled district heating will likely want to (also) go through to GSHP to prepare for talking to the managers of the block or local politicians for the district.

3) A little info comparing the types so that someone with a lot of land or building their own new house can have an idea of the pros and cons of GSHP versus ASHP. For example that GSHP will likely be more expansive to install but use less electricity especially in cold weather.

4) To know that they need to decide whether they want cooling as well as space heating and whether they want water heating. But not lots of detail as that can be in the articles such as ASHP. Possibly also a link to Heat recovery ventilation for people building their own new house.

5) To know that some governments give purchase subsidies so they can then find out subsidy details either in a country level article such as Energy policy of Australia or non-Wikipedia national sources. Or if the incentives stay here they should be put in a table which can be split off to a new list article if it gets too big.

I may have missed something but this article should not have detail which is better put in more specialized articles. Chidgk1 (talk) 07:22, 6 October 2023 (UTC)


 * Oh yes I think just the most common refrigerants with a link to the details article Chidgk1 (talk) 08:02, 6 October 2023 (UTC)
 * I have had a number of conversations with new purchasers of heat pumps who are suspicious of claims that 1 kJ of electricity can cause significantly more than 1kJ of heat to be transferred into a house. They think this claim might contravene the law of conservation of energy; and they know it would be impossible from a combustion heater. Dolphin ( t ) 08:25, 6 October 2023 (UTC)

What do students want/need from this article?
Well of course they want the answer to their homework but without the person marking it complaining they copied from Wikipedia. Or they want the answer to the question on tomorrow's exam. However we should probably give them what their teachers/lecturers want them to learn. So I think they need a wide overview of the subject with wikilinks in case they need to drill down to details - including scientific theory, technology, environmental benefits, economics and maybe more Chidgk1 (talk) 07:42, 6 October 2023 (UTC)

Easy calculation?
The theory section says the calculation of COP and work is easy. Can anyone help me to explain it to readers - maybe in the footnotes?

Coefficient of performance says

$$ {\rm COP}_{\rm heating}=\frac{T_{\rm H}}{T_{\rm H}-T_{\rm C}} $$

Chidgk1 (talk) 09:50, 22 February 2024 (UTC)


 * ok I think I found my mistake - please check - also it would be great if other editors could improve this article more as it is so important Chidgk1 (talk) 10:39, 22 February 2024 (UTC)

US states previous incentives
I moved the below here as perhaps no longer active so too much detail?

Some US states and municipalities have previously offered incentives for air-source heat pumps:


 * California
 * In 2022, the California Public Utilities Commission allocated an additional $40 million from the 2023 gas Cap-and-Trade allowance auction proceeds to the existing $44.7 million budget of the Self-Generation Incentive Program (SGIP) Heat Pump Water Heater (HPWH) program, in which single-family residential customers can receive an incentive of up to $3,800 to install a HPWH. Half of the incentive funds are reserved for low-income utility customers, who are eligible for a maximum incentive of $4,885.


 * Maine
 * The Efficiency Maine Trust offers residential heat-pump rebates of up to $1,200, as well as heat-pump rebates for low and moderate income Mainers of $2,000 for their first eligible heat pump and up to $400 for a second eligible heat pump.


 * Massachusetts
 * Mass Save, a collaborative initiative between Massachusetts' natural gas and electric utilities and energy efficiency service providers, offers an air-source heat-pump rebate of up to $10,000, which covers the purchase price of the heat pump and installation costs.


 * Minnesota
 * Minnesota Power offers an air-source heat-pump rebate of up to $1,200 if the pump is bought and installed by a Minnesota Power Participating Contractor.


 * South Carolina
 * Dominion Energy South Carolina offers a $400–$500 rebate for purchasing and installing an ENERGY STAR certified heat pump or air-conditioning unit.

Chidgk1 (talk) 12:17, 22 February 2024 (UTC)