Heat pump and geothermal: the reality not rosy of the moment

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
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RV45
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Heat pump and geothermal: the reality not rosy of the moment




by RV45 » 11/03/08, 21:28

Good evening everyone,

I can give you a summary on nearly 175 feedback from individuals over the past two years on Chaleur Terre:

http://www.chaleurterre.com/forum/viewforum.php?f=18

This is not an exact reflection of the situation in France because there is not yet feedback from Sofath experience for example, but it is better than that: it is the reflection of enlightened individuals who have inquired before their installations :D or who inquire after : Cry: but who make the effort to understand their facilities.

This is also why we don't have Sofath presentations for example, but to find you like on all forum a lot of descriptions of individual actually having problem with Sofath it should not be denied : Frown: even if it is no longer a reflection of the market today.

I confirm that a very large part of the installers take advantage of the market craze and the tax credit. So watch out for the margoulins : Shock: make several quotes and submit them to earth heat : Idea:

That said, we must recognize the major interest of this technology when it is used in the rules of art which is not actually always the case. the use of aerothermal energy in cold regions of eastern France for example, over-dimensioning problems or, more rarely, under-dimensioning., questionable installations with equipment which is not always up to par in some case but more rarely.

So what should we do?

Prepare your project well by not rushing on an Aerothermal solution without studying the other solutions in order of the most efficient yield, so you have to study the 4 main solutions without preconceptions:

- On the water table, checking the water level in the well which must not be more than 15m deep ...

- horizontal sensor if your terrain allows it, the sensor should ideally be between 80 to 120 cm deep, but not 60 cm as we see too often.

- vertical probe this solution is studied when there is no water table, no sufficient ground and that for questions of too low reference temperature below -7 ° C the aerothermal solution is in this case not desirable for example in Alsace -15 ° C reference, but the solution is more expensive and the amortization of the sensor will be done over a long period of 20 years the cap must be amortized over 7 years for example.

Then if you have an oceanic climate see Mediterranean you can and it is even desirable to take this solution. 25% of cases normally.

There is therefore indeed a problem of choice because the solution on air represents more than 50% of the choices whereas it should only represent 25%. This is due to a very strong inappropriate marketing and commercial pressure, but also to solutions in succession of boiler for the renovation or this is after all a less aberrant use in cold region.

It is a project which will take you seriously 6 months to see more if you associate it with solar for example 8)

Always check the skills of the craftspeople who are overwhelmingly incompetent to say the least : Cry:

They will have you particularly validated the calculation of the loss of your home and check the dimensioning which will be proposed to you. A cap is not a boiler, it is very necessary to calculate are dimensioning it is essential 9 times out of 10 the installers do it with a big ladle to say the least : Evil:

you will need an installation diagram and check it: buffer tank or not, well pump well dimension EDF subscription for power ect ....

there are a lot of points to check

Calculate your return on depreciation but also your annual operating costs.

It's good to take a cap on air cheaper than a tablecloth solution but if your electric bill plus subscription comes back to you 50% more expensive per year and that over 20 years you will have bad surprises.

Likewise if you take a solution on a tablecloth and your installer puts a big well pump on you which will consume 1kw / h for 2m3 / h you will very quickly end up with a cop of less than 3 : Cry:

So Pac solutions are excellent economic and ecological solutions but they are reserved for individuals who want to take the trouble and we must not fall into the clutches of incompetents who are effective we must recognize it legion :?

So good luck with your research.

As for me, I will continue to use my cap on the tablecloth with a cop greater than 5 when the solar does not do the work alone :P
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by Capt_Maloche » 11/03/08, 23:33

yes, yes, but stop, you're going to discourage them all :D

a little advice, if you want to invest in a heat pump, have a study done by a design office for the budget, the technique and the simulations of consumption and return on investment, it will not be wasted money, it is a profession

in addition, it will soon be compulsory to justify a good COP, pay attention to the settings, operate your heat pump preferably during the day when the T ° are higher for example

I would advise to undersize or rather, to be more precise, to dimension it for losses up to 0 or -5 ° C and plan in addition a wood insert for example for the few days at negative T ° per year, even if today's heat pumps can operate down to -15 ° C, soon see -25 ° C with CO2 as the refrigerant.

unless you live in siberia : Cheesy:
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by bham » 12/03/08, 09:22

Thank you RV45 for bringing all these details which partially answer or confirm what I wrote there:
https://www.econologie.com/forums/post74563.html#74563 and it's true that if we want this kind of technique, it is an obstacle course to avoid being tricked.

Capt, can you provide details on the CO2 heat pumps?

Do any of you know the margins of artisans or at least the cumulative margins from import to sale on this type of equipment?
Are they excessively high compared to similar products?
If so, would the public subsidy money not be used to run the liberal economy, which would be completely abnormal?
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by Christophe » 12/03/08, 10:25

Thank you RV for this "rant" subject which says aloud certain truths that professionals (more and more Chinese importers for many) EdF and Ademe seek to hide ...

France Géothermie tripled its staff last year it is not for nothing ...

For us econologists (with some exceptions like Maloche) geothermal energy powered otherwise than by a green or renewable source of electricity is ALL EXCEPT GREEN AND ECOLOGICAL ...

By cons a heat pump coupled to a micro cogeneration, and op we have an overall yield of 150% or more ! That's good :) and as I have a micro cogeneration project ... I will seriously study this scenario (even with air air in addition it remains interesting) ...
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by Capt_Maloche » 12/03/08, 11:32

Christophe wrote:
For us econologists (with some exceptions like Maloche) geothermal energy powered otherwise than by a green or renewable source of electricity is ALL EXCEPT GREEN AND ECOLOGICAL ...

By cons a heat pump coupled to a micro cogeneration, and op we have an overall yield of 150% or more ! That's good :) and as I have a micro cogeneration project ... I will seriously study this scenario (even with air air in addition it remains interesting) ...


What? :D I prefer a heat pump to a filthy fuel boiler, that's my point of view, I'm still not happy to be dependent on EDF ... that's why I campaign for independent housing, I work on the subject to build my future home, practically autonomous, I would not fail to create a subject once ready.

What do you want to cogenerate with a heat pump in heat mode which makes you cold air in winter ???
In cooling mode, the heat pumps are often equipped with a water exchanger which allows the DHW to preheat.

bham wrote:Capt, can you provide details on the CO2 heat pumps?


CO2 is R744
see this document from page 39 HERE

This allows DHW or heating to 60 ° C by -10 ° C with COPs of 3, and of course, the COP rises with the outdoor T °
Image
The compression ratio is only 2, but the pressure of the circuits is around 100bar

With this type of heat pump and a network of low-temperature heating floors, it is easy to reach an average COP of 6 per year

therefore, a small CO2 heat pump for DHW and additional heating in winter seems to me a good way
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by bham » 12/03/08, 11:51

Capt_Maloche wrote: CO2 is R744
see this document from page 39 HERE

This allows DHW or heating to 60 ° C by -10 ° C with COPs of 3, and of course, the COP rises with the outdoor T °
Image
The compression ratio is only 2, but the pressure of the circuits is around 100bar

With this type of heat pump and a network of low-temperature heating floors, it is easy to reach an average COP of 6 per year

therefore, a small CO2 heat pump for DHW and additional heating in winter seems to me a good way


Nice your Capt document, thank you. On the other hand, a pressure of 100 bars, how long will it be waterproof?
And then the average annual COP of 6, uh, don't you exaggerate a bit ?? : Lol: with an outside T ° of 50 ° c, ok but not in France then.
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by loop » 12/03/08, 12:29

Hi

To return to cogeneration

What do you think of a solar thermal / photovoltaic installation (2 in 1 collector) which would supply a heat pump?

The investment would be substantial but entirely autonomous

A+
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by Capt_Maloche » 12/03/08, 12:53

medium if no sun, and hello the surface of collectors to produce effective 1.5kw from morning to evening, plan around 30m²
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by Capt_Maloche » 12/03/08, 23:19

bham wrote:
Nice your Capt document, thank you. On the other hand, a pressure of 100 bars, how long will it be waterproof?
And then the average annual COP of 6, uh, don't you exaggerate a bit ?? : Lol: with an outside T ° of 50 ° c, ok but not in France then.


Ach, che see ya fendre :D

It's not the pressure that matters, we could go up more, it's the size of the molecule that keeps the networks tight over time

COP of 6 for an average T ° ext. annual temperature in France of 12 ° C and a low T ° heating network at 30 ° C
Direct expansion VRV or DRV systems have achieved annual average COPs of 5 in recent years
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by bham » 13/03/08, 05:50

Capt_Maloche wrote:
bham wrote:
Nice your Capt document, thank you. On the other hand, a pressure of 100 bars, how long will it be waterproof?
And then the average annual COP of 6, uh, don't you exaggerate a bit ?? : Lol: with an outside T ° of 50 ° c, ok but not in France then.


Ach, che see ya fendre :D

Warum do you speak like a Halsacian? : Lol:

Capt_Maloche wrote: It's not the pressure that matters, we could go up more, it's the size of the molecule that keeps the networks tight over time

Ah and the molecule of R 744 is it big or it is small?

Capt_Maloche wrote:COP of 6 for an average T ° ext. annual temperature in France of 12 ° C and a low T ° heating network at 30 ° C
Direct expansion VRV or DRV systems have achieved annual average COPs of 5 in recent years

VRV DRV?
COP 6: on the basis of your graph with water production at 60 ° c it is not possible; for water production at 30 ° c, maybe yes.
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