Transform a solar DHW tank (or fuel oil) into a thermodynamic water heater with a small swimming pool heat pump?

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Christophe
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Transform a solar DHW tank (or fuel oil) into a thermodynamic water heater with a small swimming pool heat pump?




by Christophe » 08/11/21, 16:57

How to transform an old coil water heater into a thermodynamic water heater? (uh ... if it's possible?)

To save some money and improve my energy performance, I would like to study the possibility of transforming my (very) old (and very strong and heavy) solar DHW water heater (with double exchanger) of 300L in a "homemade" thermodynamic water heater (or almost because the idea is not to design a cold unit eh but to adapt an existing one ...)

I would like to study the transformation of this one for a maximum budget of 500 € because a thermodynamic water heater of 300L is 2500 € without installation or delivery ...

It is an old solar water heater with double exchanger of the 80s (it is 40 years old it should still hold the same thing ... especially at 4 months a year ...).

Photo of the top exchanger which has not been used since it was installed more than 10 years ago (used at the time):

Water heater.jpg
Chauffe_eau.jpg (70.62 KiB) Viewed 562 times


It is currently used 4-5 months as an electric balloon in re-rise of temperature when the temperature of my solar system is lower than 35 ° C. The water gets there at a minimum of 20 ° C so ...

I plugged in 50% of the 3000W resistor, so it consumes 1500W. I have to be around 2 to 3 kWh per day during the winter (250 to 350 kWh each year ...)

I found small 3 kW fully integrated swimming pool heat pumps for less than 400 € with COPs of 3 to 6 ... this would be perfectly suitable from an energy balance point of view ... like the Poolex Nano 3kW (exists even in reversible ...): https://www.poolex.fr/fr/produit/2020-p ... ano-action

Poolex_nano.jpg
Poolex_nano.jpg (70.01 KiB) Viewed 562 times


Notice_Nano_ActionR_FR.pdf
(2.04 million) Downloaded times 50


Except that there are the following points that hold me back:

a) Max temperature 43°C 40 ° C (but apparently it is the same on thermodynamic water heaters generally it is 45 ° C max in heat pump mode then relieved by an electrical resistance beyond ....)
b) Requires a high flow rate (that of a swimming pool pump ...)
c) Usually plastic connectors, not plumbing connectors
d) Not done for a pressure circuit = what admissible pressure? You can't ride it on a 3 bar circuit, I guess ...
e) 1st prize pool gear, I have doubts about reliability at 10 or 20 years ...

In addition, ideally I would have liked to work in a thermosiphon to do without a circulator. in addition ... but I fear that with delta of T ° as low (25 ° C max ...) that is not possible ... especially for the flow rates requested by the manual ...

So tell me if this project inspires you ... the pros?
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by sicetaitsimple » 08/11/21, 18:34

The idea sounds nice, but I'm afraid the results will be disappointing at least in terms of savings.
A priori, I understood that 43 ° C is the maximum outside temperature. The maximum hot water set point temperature is rather 40 ° C, with a COP of ????, but certainly degraded compared to the optimal ..
Besides, you need a pump for sure. In short, your annual kWh savings will be very low.

I absolutely do not want to relaunch a debate on "the counter running backwards", but in your case, wouldn't it be easier to equip yourself, if possible, with an additional panel of around 300W? by keeping the installation as it is?
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by Christophe » 08/11/21, 18:42

Yes I share your technological and economic fears *

If in the best case I manage to save say 200 kWh per year it will take me 8 years to make profitable ... well 8 winters ... I fear that this kind of small heat pump will not last as long especially with prolonged shutdowns 8 months in the year ...

For 43 ° C it was on another small model that I had seen ... but thermo water heaters rarely exceed 45 ° C even from big brands like Chapée or De Dietrich ... pure resistive

Yes do not revive: do not mix everything! : Cheesy:

* but I like challenges!
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by GuyGadeboisTheBack » 08/11/21, 18:43

How many cubic meters is your swimming pool?
Why do you want to heat it?
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by Christophe » 08/11/21, 18:44

: Shock: Did you not understand anything Guy or did you hang out with ABCile today? : Mrgreen:

I want to use a swimming pool heat pump to heat my DHW!
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by GuyGadeboisTheBack » 08/11/21, 18:52

Christophe wrote: : Shock: Did you not understand anything Guy or did you hang out with ABCile today? : Mrgreen:

I want to use a swimming pool heat pump to heat my DHW!


Ah ... well ... time for me. : Oops:
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by GuyGadeboisTheBack » 08/11/21, 19:38

Christophe wrote:Don't do your ABCile !! : Cheesy:

Pffff ..... when I screw up, I readily admit it. What relationship with the other ass ???
: Shock:
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by izentrop » 08/11/21, 20:25

new record https://www.cabesto.com/fr/piscine-pomp ... 00023.html
Data for COP 5 at 15 °

This morning 3 ° under shelter
Mine is given for COP 5.4 at 12 ° and 3.55 at 2 ° and 1.76 at -7 ° with 55 ° on the hot water outlet.

Already, isolating a balloon can save 1 month of electricity, have you done it? https://www.apper-solaire.org/Pages/Fic ... /index.pdf
https://www.apper-solaire.org/Pages/Exp ... index.html
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Re: Transform a solar DHW tank into a thermodynamic water heater with a small pool heat pump?




by Christophe » 09/11/21, 00:22

Thank you 250 € it's cheap but this HS35 model that I had seen at hot splash is a bit of a toy, isn't it? After for the test that I want to do as much not to put too much in it ... : Mrgreen:

Which model is yours? 55 ° C is a lot!

Yes it is isolated behind the ugly orange thing ... (I removed the insulation from the fittings and the resistance for the photo) ... I will study the pdf. There is 6-7 cm of foam ... I will look in detail tomorrow ...
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