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Comment by serpix | Hacker News Reader

Modern air pumps work with good efficiency even down to around -15c which is a rare temperature for post global warming world.

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Aren't air pumps less power efficient then ground ones?

Also, is it possible for air pump to heat a liquid in pipes?

I mean can I have air pump that provides heating to the floor?

If the floor is warm then body thinks it is warm.

I know air pumps only as air conditioners and they just blew warm air around, which is not that comfortable if you are just where the warm wind blows :)

One way to classify heat pumps is by the source and destination of the heat.

  - air/air
  - air/water   (i.e. an "air pump that heats a liquid in pipes")
  - ground/water

are all commercially available, at widely varying prices:

https://www.nibe.eu/en-eu/products/heat-pumps

The efficiency depends on the pump, the house and the weather. At +10 (Celsius) ambient temperature, the air source pumps will generally come out ahead, at -20 the ground-source pump is going to win.

Aren't air pumps less power efficient then ground ones?

Only when the air temperature is less than the ground temperature. On average, yes, air source is slightly less efficient than ground source, but the initial cost of ground source is so much higher that you will not make up the difference in the lifetime of the pump. Air source is fine.

Also, is it possible for air pump to heat a liquid in pipes?

Yes.

I mean can I have air pump that provides heating to the floor?

Yes. This is generally considered the best way to do it as the water does not need to be as hot as with conventional radiators, so it is somewhat more efficient. However, conventional low temperature radiators work fine, too.

I know air pumps only as air conditioners and they just blew warm air around, which is not that comfortable if you are just where the warm wind blows :)

To each their own. I grew up with forced air heating and prefer it to radiated heat.

Yes, and that was Canadian houses, I assume, with dozens of vents in the floor on every level of the house.

In Europe we mostly see air-to-air heat pumps in cottages, and there is then only one vent for the entire house. Which if fine and efficient for a small cottage in the fall and spring and maybe a few weekends in the winter.

But it would be hopeless in a Canadian winter.

>Aren't air pumps less power efficient then ground ones?

Not modern ones. When outside temperature is above 5C, they're actually more efficient.

> Also, is it possible for air pump to heat a liquid in pipes? I mean can I have air pump that provides heating to the floor?

Yes, via a heat exchanger. This isn't new techonology, I have a 10 year old version of this warmning my house as I type: https://www.nibe.eu/sv-se/produkter/varmepumpar/luft-vattenv...

>I know air pumps only as air conditioners and they just blew warm air around, which is not that comfortable if you are just where the warm wind blows :)

The pump linked above connect to the water based heating system in my house. Works like a charm and I heat ~260 m2 (badly isolated) with 1500 kWh per month (wintertime)

There are many companies that deliver air to water heat pumps, e.g. Daikin, Mitsubishi etc.

Most of these — these days – seem to be for both cooling and heating, but I know Mitsubishi Ecodan have models for just heating. If you live in a building with pipes installed, the pipes need to be specially insulated to carry cold water, if not the moisture in the air will seek the cold pipes and form condensation thus causing humidity problems.

If you are looking into installing an air to water heat pump for heating your home, you can either use it for floor heating and/or different types of radiators (many solutions also offer sanitary water heating as well, for showers etc.) Sometimes you can use the radiators that are already installed in your home and just install the water pump system, but that requires that the water warmed up by the heat pumps is sufficiently warm (and that depends on the company/model chosen). If the water is not sufficiently warm, you either need to install a bigger radiator or newer types of radiators that are called low temperature radiators. The latter radiators are "smarter" and gives more heat at a lower temperature, but typically are also more expensive.

Here are a couple of links for more info. The video is more for illustration purposes, as models changes all the time. It is also important to point out that – in general – there are lots of different solutions on how these machines are assembled. Sometimes the outdoor unit contains technology that in other models are stored in the indoor unit. Sometimes the water container is stored together with the indoor unit itself, sometimes these are separate. It all depends on available space, or if you like things compact or not.

I have nothing to do with Daikin or Mitsubishi, I have just been looking into installing this in our own home. I am looking into an air to water air pump, and only for heat as our pipes are not properly insulated.

https://www.ecodan.de/en/heat-pumps/hydroboxes/ https://www.youtube.com/watch?v=0h-XHJmEtZU&t=171s

Except some places in Russia it's still common to go below -20, and in a post-global warming world, these areas will likely experience a new ice-age. Electricity is the best bet, as gas can freeze too, while copper just becomes able to carry higher loads.

What’s the total population of <-20C areas, worldwide?

And why should anyone outside that area care if the equipment they use will or won’t work in weather that they won’t experience?

It's not relevant what the total population is. Even if it's 1, you can't tell that person to use a heat-pump.

So one person uses a different heat source. So what? Why is that important? Nobody else has to just because they do.

If the total population is low then you can tell them to _not_ use a heat pump.

> gas can freeze too

Man, please look up methane freezing point

Nope it does not work like that. The temperature extremes are increasing too, so the number of -15°C days decreases only slightly.

For example, despite last year was on average warmest on record, my tomatoes still suffered from sudden frost in May and then again in October.

Actually most of the warming is due to milder winters and at more extreme latitudes. So even if variation increased, it could still result in fewer very cold days.

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