Geothermal energy, not convinced by the air / water cap

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nmujdzic
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Geothermal energy, not convinced by the air / water cap




by nmujdzic » 15/02/08, 16:23

Hello, I want to install a heat pump at my house (120 m²). It is an old stone house with walls at least 40 cm thick. I am currently using fuel oil (1 liters since November 300) with radiators in the form of steel or aluminum (?). Some people (including pros) recommend installing an air / water heat pump, so to heat the water in the radiators (around 1 ° C). Can someone explain to me how an air / water heat pump, having to heat water to 60 ° C, can be more profitable than an air / air heat pump, which must heat air, roughly at 60-20 ° C. It does not pass in my scientific mind!
I specify that I live in lower Normandy and that the temperatures, when they are negative, seldom drop below -1 / -4 ° C. I also specify that I am putting double glazing everywhere (with a coefficient of 1.4).
So ? Air / air or air / water heat pump in my case?
Thank you
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loop
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by loop » 15/02/08, 19:34

hi nmujdic (not easy to remember!) : Shock:

The air-water heat pump has the advantage of being able to replace a boiler in a house already equipped with central heating
Last month, I went to visit a friend who has just had this type of equipment installed, a Mitsubishi air-water unit, to replace his old fuel oil boiler.

Regarding heating, theoretically, heating air or radiators is the same thing, it's the amount of total heat that matters. We talk about KiloWattHours to calculate this amount of heat, or KiloWatt for instantaneous power.
In terms of comfort, it is clear that heating with inertial radiators is better because there is a little radiation in addition to convection and above all, no circulation of hot pulsed air.
Regarding the performance of the installation, we must beware of promises because heating water to 60 ° degrades the performance of the pump. It is better to heat continuously at 40 ° than 60 ° intermittently.
You should also know that in the event of a sharp drop in the outside temperature, it is a resistor that will heat the water directly, and there the electric consumption flies away.
To think of the Canadian well in front of the outdoor exchanger is to cleverly foresee this scenario.

Last thing, are you thinking of making additional insulation?

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by Christophe » 15/02/08, 19:37

You are right to doubt!

Many PROs do not even know what they are selling you because to heat to 60 ° C with an air heat pump, resistance risks doing better ...

Here are two links to read in detail before "investing" (especially in an investment which may not be one):

https://www.econologie.com/pompes-a-chal ... -3534.html

And above all this technical doc with lots of yield curves: https://www.econologie.com/la-technologi ... -3389.html
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by Other » 15/02/08, 20:29

Hello
Can someone explain to me how an air / water heat pump, having to heat water to 60 ° C, can be more profitable than an air / air heat pump, which must heat air, roughly at 20-30 ° C. It does not pass in my scientific mind!


Fully agree to heat water to 60 c with a PAC is nonsense, the performance degrades suv the type of freon to 40 ca 45c and at 60c it is not even 1,5 autand take a pure electrical resistance what to operate a gas plant ..
I heated my domestic water (Balloon) in winter for several years in this way to 45c I stop and the electric elements take over (it is profitable when the water in winter is 8c it rises quickly to 30c the yield is around 3)

For your climate an air air heat pump is the simplest, in addition in summer they are reversible for air conditioning
In winter it goes out to 32 see 36c in the ventilation outlets but the volume of air is important, it gives nothing to make restrictions and to mount the air outlet to 40c that harms the performance of the machine
In my case in summer I do air conditioning and on the other side I do my domestic hot water, a simple freon water exchanger at the outlet of the compressor for the tank and a circulation pump that I activate only in air conditioning,
in the summer when i air condition i make two 60 gallon hot water tanks per day in fact when it is hot i can't consume my hot water.


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nmujdzic
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by nmujdzic » 15/02/08, 23:18

In terms of comfort, it is clear that heating with inertial radiators is better because there is a little radiation in addition to convection and above all, no circulation of hot pulsed air


Why "especially no circulation of hot pulsed air"? It's nice to feel warm air, isn't it?
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by Other » 16/02/08, 00:26

Hello
nmujdzic wrote:Why "especially no circulation of hot pulsed air"? It's nice to feel warm air, isn't it?


How do you make air conditioning with a water system?
At first I reasoned like this, just a good heating system, as the system is reversible a simple valve
it does both, after having tasted it on the hot humid summer days, I think I would keep the system more for air conditioning.

The first thing to do in your homes is to invest in insulation. What consumption of fuel oil would that give with -20 as regularly? winter begins in mid November and ends in early April.

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by loop » 16/02/08, 08:09

Hello

Reply to nmujdzic

If you read the subject of this forum on heat pumps, you can find the testimony of a person equipped with splits when he had a classic central heating installation
Here is what he wrote (COU)

I am very disappointed by the heat pump that I just installed: it does not heat well, it makes wind noise in the house; it stirs the air all day long for so little result! my fuel oil boiler causes cold.
In one month I consumed for 250 eur of electr with the CAP
against 450 of fuel 200 eur times 4 months of winter = 800 eur of savings per year. for 14000 eur of investment. At this rate the CAP is amortized in 10 years (tax credit 4000). EDF which is winning now! And my banker who granted me the loan at 6%. And I only have my eyes to cry with tears (not even hot!)



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by jean63 » 16/02/08, 11:48

loop wrote:Hello

Reply to nmujdzic

If you read the subject of this forum on heat pumps, you can find the testimony of a person equipped with splits when he had a classic central heating installation
Here is what he wrote (COU)

I am very disappointed by the heat pump that I just installed: it does not heat well, it makes wind noise in the house; it stirs the air all day long for so little result! my fuel oil boiler causes cold.
In one month I consumed for 250 eur of electr with the CAP
against 450 of fuel 200 eur times 4 months of winter = 800 eur of savings per year. for 14000 eur of investment. At this rate the CAP is amortized in 10 years (tax credit 4000). EDF which is winning now! And my banker who granted me the loan at 6%. And I only have my eyes to cry with tears (not even hot!)



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The ideal it's low temperature underfloor heating with a boiler (condensing if possible) ...... in fact we put what we want: wood, pellet, gas, oil boiler, solar collectors (in addition) ..... PAC water-water (if there is sufficient water underground and a good flow) .....

Air-to-air heat pump to be eliminated: we have already had several testimonies that confirm.
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by loop » 16/02/08, 23:42

The ideal heated floor?
We can find arguments that are unfavorable to him

The first is under renovation, it’s not easy to break up the existing one to redo the floor and interior partitions

The second is the gray energy expended to pour a 20 cm thick concrete slab. Besides, concrete, I'm against it. It is not removable, nor recyclable, difficult to modify

The third is the difficulty of managing temperature variations quickly in the home

Regarding the electrical energy necessary for the operation of a heat pump, it is true that there is a controversy entirely justified because in France, it is mainly produced by nuclear power. In other countries, it is from other fossil fuels, which is not much better.

The fact remains that the heat pump is a awesome principle which transforms mechanical energy (compressor) into heat, by capturing calories in a "cold" source.
If there were enough hydroelectric power stations or wind turbines, the discussion would stop there.

There remains the price of the equipment, very much overcharged by installers who know very well how to exploit the image conveyed by this technology and what is more, defended by the State with great blows of subsidies.

For me, in renovation, the least bad choice for an existing central heating installation, and after having done the maximum in insulation (exterior when possible) is to invest in solar collectors with a large high thermal buffer temperature and keep the boiler (fuel oil, gas, or wood) to make additional heat when necessary.
I seriously think about it for my home but I have to solve the problem of high temperatures (50 to 60 °) for my conventional radiators.
I launched a subject on this subject but unfortunately, without having felt a great enthusiasm on the part of the experts of this forum .

https://www.econologie.com/forums/tampon-the ... 10-10.html

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by jean63 » 17/02/08, 23:46

For me, in renovation, the least bad choice for an existing central heating installation, and after having done the maximum in insulation (exterior when possible) is to invest in solar collectors with a large high thermal buffer temperature and keep the boiler (fuel oil, gas, or wood) to make additional heat when necessary.
I seriously think about it for my home but I have to solve the problem of high temperatures (50 to 60 °) for my conventional radiators.
I launched a subject on this subject but unfortunately, without having felt a great enthusiasm on the part of the experts of this forum .

You mean rather:

1st: use of the boiler

In 2nd: complement by solar collectors ...... when there is enough sun ...... and a good thermal buffer.

You also have a very good example with Christophe's installation => ask him if he can heat his house with his thermal buffer of 70 m3 of water and 70 m2 of solar collectors?

Its buffer varies between 21 and 30 ° C approx (maximum reached exceptionally after 2 weeks of sun over Europe! Thank you high).

I think you are dreaming a little.

Regarding the floor heating, we can discuss it: the downside is inertia, but it can be an advantage to store calories with solar collectors during the day and keep the floor warm enough until next morning and leave with the sun if it is present.

For this, we can make direct solar: collector to underfloor heating ..... it is a solution proposed by installer located in the Alps.

Check it out if it's not a good idea too:
https://www.econologie.com/forums/une-superb ... t4809.html
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