Chilly hydroconfort 80 to CAP STIEBEL ELTRON wpl25as

[xxx74]

Hello,

I just changed my heating system, formerly a chilly propane hydroconfort 80 gas boiler for a stiebel eltron wpl25as heat pump.

Having torn up the old boiler out of curiosity, I was able to observe that there is an air / water exchanger at the level of the burner that I would like to recycle for a "double flow" vmc project.

The question I ask myself is the following, would it be possible and interesting to use the hot water produced by my heat pump to heat the air via this recovery exchanger to breathe the incoming air from my vmc?

If yes, on which part of the heat pump should hot water be taken?

On the buffer tank?

The chess ball?

Directly on the floor heating circuit?

I know that the principle of a double flow vmc is to use an exchanger and recover the calories from the extracted air, and if I wanted to use this principle, would it be possible to use the air / water exchanger and use it as an air / air exchanger?

Here is a photo of the exchanger I would like to use:

https://www.econologie.com/fichiers/partager3/1451129937DXAhpB.jpg

Thank you in advance for your answers.

[simplino]

A very hot air exchanger (from 700 ° C to over 100 ° C) to water at 70 ° C does not have the same exchange surfaces (much less) than warm water 35 ° C to air 25 ° C, which demands much more on the surface given the small temperature differences T and therefore the result will be unsatisfactory, unless putting in series a collection of recovery exchangers.
It is possible to measure in a test the T of the outgoing air by passing hot tap water through the exchanger according to the air flow rate sent by a fan (even a hair dryer).
The possible air flow may be too low, because too small a difference in T max 10 ° C instead of several 100 ° C and therefore the possible air flow will be reduced accordingly, roughly.

[xxx74]

Ok thank you for the answer.

So do you think this exchanger will be of no use to me?

[simplino]

It is necessary to quantify and measure the needs and flow rates of CMV and thermal before rejecting the idea, but a priori the heat exchange surface will not be sufficient in m2, if we read on econology the forums passed in search "double flow exchanger" which is even better recovering the heat rejected outside by a single flow CMV without consuming energy !!
A similar example is a large surface finned air heat exchanger (ideal for recovery of dead heat), but that of the gas boiler does not have a comparable surface of fins, an example of course to read :

https://moodle.insa-toulouse.fr/file.ph ... ngeurs.pdf


gives an order of magnitude of 10 to 25W / m2 ° C (in fact especially the low thermal conductivity of the air in a thin layer of a few mm) and therefore this fixes the surface of the fins with the air necessary if we know the required power (fixed by the air flow at the peak at a factor of 4 in the range close to KW) and the temperature difference to be heated (old boiler over 100 ° C and VMC a few degrees)

http://bookshop.europa.eu/fr/-tude-d-ch ... 7-026-FR-C
https://www.polytech.univ-savoie.fr/fil ... on1219.pdf

http://www.ifip.asso.fr/sites/default/f ... omeu07.pdf

a car or truck radiator would be better but also not enough surface because water at 100 ° C and strong air flow.

http://direns.mines-paristech.fr/Sites/ ... rique.html


https://www.econologie.com/forums/vmc-fabric ... 3-130.html
https://www.econologie.com/forums/vmc-fabric ... 3-150.html
https://www.econologie.com/forums/vmc-fabric ... t6023.html


It is possible to measure or test these claims in a test with the T of the outgoing air by passing hot tap water through the exchanger according to the air flow rate sent by a fan (even hair dryer on cold at low air flow).

[xxx74]

Very good, thank you for devoting your time to me and for all this information.
I'm going to read all of this and think about it.
Thank you again and have a good holiday ...