forums energies: society, ecology and clean technologies

Hello to the noble assembly.
As a newbie, I have to be polite.
I live in the Tarn, altitude 200 meters!
I plan to replace my old fuel boiler, which serves as a complement to a Solisart heating installation (thermal solar panels).
The house has 140 m² of living space. I consumed on average 1600 liters of fuel and with the installation of the panels I fell to 800 liters.
But when it is not sunny, very cold and at night the fuel boiler takes over.
I was thinking of a simple geothermal heat pump with geothermal walls. Easier to install, not very expensive.
For the heat pump I also saw the Nextherm brand, without electronics.
I would like to have opinions, ideas, experiences with these materials.
Cordially. Thanks.

Bonjour.
Hmm, if you've already done half of the way, the second may be more complicated.
But you don't specify how your house is heated? Underfloor heating, radiators, floor for solar and radiators for fuel oil, other?

sicetaitsimple wrote:Bonjour.
Hmm, if you've already done half of the way, the second may be more complicated.
But you don't specify how your house is heated? Underfloor heating, radiators, floor for solar and radiators for fuel oil, other?

Yes, I forgot. It is floor heating throughout on the ground floor with tiles plus a small office (25 m²) in the heated basement with a large radiator.

And you want to change your boiler because it's really out of breath and probably won't last another year or two or you want to change it to replace your 800l of fuel oil with something else, which is perfectly honorable, but not necessarily wise?

sicetaitsimple wrote:And you want to change your boiler because it's really out of breath and probably won't last another year or two or you want to change it to replace your 800l of fuel oil with something else, which is perfectly honorable, but not necessarily wise?

My boiler is a little over 20 years old and whoever does the annual maintenance tells me that it will be difficult, if not impossible, to repair or replace the burner if it breaks down.
I don't know how much the expense will be with a geothermal heat pump. If it costs me 500 € less expenditure per year, I tell myself that investing 8 or 10000 € so that it brings in 500 € per year will be better than the Livret A.
I don't know how much the installation might cost. I have the price of the Geomurs and the Nexttherm boiler.
In short, basically I don't know anything and I want to inform myself before doing something.

Thank you for your answers ! If it was that simple I wouldn't be here!

there are also AIR-WATER heat pumps.

less installation investment.

With my parents, the VIESSMANN boiler dates from the 80s and we are beginning to no longer be able to maintain it due to a lack of parts (in particular the electronic control/regulation). We plan to put an air-water heat pump as a replacement, in order to keep the entire plumbing installation (hot water tank, circulator, radiators)

If your region is not too cold, the COPs will remain decent. In the Tarn at low altitude, it seems playable.

Heat pumps with an underground exchanger are more for very cold regions, where you have to have the opportunity to dig (eg a swimming pool, or an earth embankment at the time of construction.

Honestly, I can't see myself giving you advice on a Pac+geothermal wall solution, I don't really know and anyway the geothermal wall can be of a dimension varying from say 1 to 10, which changes everything in terms of cost. So no value of an opinion without having comparative quotes.
On the other hand, I think it is important that you have a good idea of ​​the temperature required at the inlet of your heating system (essentially underfloor heating if I understood correctly) in the harshest conditions of the year. Because here it is your comfort that is at stake, the heat pump (if heat pump) must be able to provide the necessary temperature and flow.
Have you thought of a small means of auxiliary heating like a wood stove for the toughest days? It's not necessarily always possible, there are constraints, but it's very simple and it ensures you a minimum heating in case of failure of the main system.

Well, I am well aware of bringing more questions than answers! Sorry!

Thanks for the answers !
I don't really expect any or the solution but exchanging helps to better understand the problem and it allows me to see other approaches.
I like geothermal energy because of the higher COP than the AIR-WATER system, in principle.
With my Solisart solar thermal panels, these are live on the floor. So as soon as it's sunny, even with 0° degrees outside, the temperature rises to 20/30° which goes into the floor. And the surplus goes into a 400 liter tank for domestic hot water and a reserve for heating. There is an electronic regulation which makes it possible to manage everything and which triggers the current boiler if necessary.
It is difficult to assess the need. I do have a chimney but really I would like the simplest possible system.
To install a geowall you need a trench 7,7 meters by 3,2 high and 20 cm wide. It's not very constraining, at least it seems to me.
I'm waiting for a study to find out how much it would take.
Afterwards, the idea of ​​cooling in the summer came to me, but that complicates things and my underfloor heating is old.
For the water temperature, at the entrance to the floor it is rarely at 40 degrees.

laverdarie wrote:With my Solisart solar thermal panels, these are live on the floor. So as soon as it's sunny, even with 0° degrees outside, the temperature rises to 20/30° which goes into the floor. And the surplus goes into a 400 liter tank for domestic hot water and a reserve for heating. There is an electronic regulation which makes it possible to manage everything and which triggers the current boiler if necessary.

At the risk of joking, that's a bit of a problem! Your thermal solar heating installation seems to be working so well, with a 50% reduction in fuel consumption, that the "next step" is really complicated!
Do you have photovoltaics in addition to your thermal panels?

At a glance, I would say that a good arrangement of the fireplace with wood would be the cheapest, but bringing wood is a constraint.

The heat pump solution is also interesting, and if reversible, would allow air conditioning for the summer. At this time the installation of some solar panels seems an intelligent complement. I would put more money on the PV than on the "geothermal wall" which does not seem to me really justified in the climate of your region.