DIY air-to-water heat pump - part 2

Heat pump prime cost, heating costs

If necessary, an alternative to blue fuel can be not only a solid fuel boiler with a heat accumulator, but also a heat pump. Want to save on gasification? FORUMHOUSE offers a story from a user with a nickname batt87, which heats the house with a homemade heat pump instead of piping gas.

Self-assembly costs for a 3.5 kW heat pump system

T. e. the cost of the internal heat exchanger, without split, about 10-15 tons. depending on how much power you want to take from your heat exchanger.

An external 24K BTU split unit can be found for 10 tr., A universal split board costs 3 tr., In the end for 15 + 10 + 3 = 28 tr. it is possible to assemble an air / water heat pump of 9 kW / h in terms of heat, which will consume 2.5-3 kW / h.

But these data on heat will be at an outside air temperature of +5 C ° and higher, if the temperature is lower, then the difference in consumption and heat production will be less, therefore it is necessary to calculate that at subzero temperatures up to -5 C ° the system will work with the coefficient 1.5-2, i.e. consuming 2.5 kW from the network, it will give 3.5-5 kW for heat.

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An external 48K BTU split unit can be found for 20 tr., A universal split board costs 3 tr., As a result, for 15 + 20 + 3 = 38 tr. it is possible to assemble a heat pump air water for 18 kW / h by heat, which will consume 5-6 kW / h.

But these data on heat will be at an outside air temperature of +5 C ° and higher, if the temperature is lower, then the difference in consumption and heat production will be less, so it is necessary to count on the system to operate with a coefficient 1.5-2, i.e. consuming 5 kW from the network, it will give out 7.5-10 kW for heat.

I also spent a lot of money on piping heat pumps and inserting into the existing heating system. But these expenses will be very different for everyone, depending on the complexity and steepness of the boiler room. For example, one crane with a 1 ”squeegee costs about 900 rubles.

By the way, it is not difficult to remake the external block from air to water from a well, in Krasnodar the water in the well is +15 C ° all year round. The coefficient of conversion of electricity to heat will be stable all year round, about 4-5, i.e. having consumed 2.5 kW, we will receive 12 kW of heat, but there will be consumptions for the pump, which will supply water from the well and you need to drain water from the well somewhere, you can enter another well or a river / lake. But according to my calculations, in my case it is not very profitable, since the experimental pump gives about 2-3 kW of heat and if it gives 4 kW I simply will not notice.

Therefore, the water / water heat pump will be the next one for 15 kW / h in terms of heat output.

Why it doesn't make sense to conduct gas

Let's go back to GAZ, below are simple calculations, from which it is clear that connecting GAZ is no longer profitable for me, even at normal prices for installing a gas pipe.

The main consumers of electricity in the house are the boiler and heating.

Boiler

We consume an average of 7 kW per day (me, wife and child 2 years old): 7 kW × 30 days × 12 months × 5.38 rubles = 13600 rubles. If I use my new DHW heat pumps from April to November, I have to save at least 50% of electricity in these months, it turns out 7300 rubles.

Heating

According to my calculations, with new pumps, I will spend 5900 rubles on heating. per month, instead of 9500 rubles, calculations with a margin, in the end, I hope, will be even more economical.

5900 RUB × 4 months = 23600 RUB

TOTAL: 23600 + 7300 = 30900 rubles.

I would spend on GAS

Boiler

7 kW × 30 days × 12 months × 0.64 × 1.1 = 1800 rubles.

Heating

2282 kW × 4 months × 1.1 = 10,000 rubles.

GAZ still needs to add service of 3000 rubles.

TOTAL: 10000 + 1800 + 3000 = 14800 rubles.

If the planned costs of gas installation are 280,000 t. put in the bank at 6%, we get 17,000 rubles. in year.

DIY air-to-water heat pump:

1. DIY air-to-water heat pump - part one

2. DIY air-to-water heat pump - part two

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Do you think it makes sense to install gas or is it better to put money in a bank?