Switch to a monosplit heat pump?

[Forhorse]

Hello everybody

After my reflection on a heating mode for a distant project heating-insulation/platelet-boiler-envisageable-autonomy-t17403.html

I came to think about a shorter term project concerning the heating of our accommodation.

Currently we heat with "oil" (CLAMC) with an "electronic" stove of the kind that is easily found in DIY supermarkets.
It has never been ideal (especially in terms of health, with combustion emissions that end up in the room to be heated) but until now it was relatively practical, relatively inexpensive, and relatively adapted to our housing situation. "provisional" (under construction for 10 years).

I had already made a comparison of the price per kWh of heating 2 years ago, between CLAMC and 100% electric and then the CLAMC (at less than 1€ per liter) was a winner, which encouraged me to do nothing change...

Today the CLAMC is almost at 1.9€ per litre, and our stove is starting to show signs of fatigue (from memory it is 5 years old) so it is certainly its last winter (time to burn the last cans we have in stock purchased before the massive price increase)

So before replacing it and foolishly reinvesting in an increasingly expensive and unhealthy heating mode, I redid my calculations... but I have a doubt.
If the pros of energy equivalences could check and confirm my assumptions.

The accommodation to be heated is a little less than 50m², but only one room is heated (the ground floor) apart from the bathroom, which is occasionally heated by an electric fan.
The insulation is weak, even non-existent (10cm of glass wool + 15mm wood chipboard on the exterior walls)
The oil stove currently used is given for a maximum power of 3000W with a nominal power of 2000W
I was thinking of replacing it with a 3400W mono-split reversible air conditioning (given for a SCOP of 4)

Here is my calculation:
1 Kg of CLAMC gives it seems 12kWh of heat
at the price of 1.875€ per liter it therefore gives 0.15625€/kWh (I simplified 1l=1Kg even if I know it's wrong, if someone wants to refine...)
At this price, it still seems profitable to heat with CLAMC rather than pure electricity (toaster...) because the kWh EDF is at 0.1841€/kWh
BUT, considering a heat pump with a COP of 3, that gives us 0.06137€/kWh of heat;
Am I good so far?

Now, if we consider:
- on the one hand the oil stove with an initial investment of 0€ because I already have it (thus ignoring the fact that it will soon have to be replaced) and also ignoring its own electricity consumption (between 70 and 90W) which costs 0.15625€/kWh
- on the other, the installation of a reversible air conditioning unit which currently costs €790 (installed myself with the kit which is fine) which costs €0.06137/kWh
If we put the equation
x.0.15625=790+x.0.06137 gives us the profitable heat pump after 8326kWh (x in the equation)
does it still suit you?
If we take the performance of the CLAMC (within an approximation) that gives us 694 kg of oil, or roughly 35 cans.
Starting with a winter that is not too cold (like this one) we consume an average of 4 cans per month, taking a heating period of 4 months per year on average, roughly in 2-3 years max the investment in the PAC is profitable.

I'm good, does that seem correct to you, or did I screw up somewhere?

Thank you in advance for your informed opinions.

[sicetaitsimple]

I haven't checked the calculations, but the reasoning seems good to me. Three comments though:
- the one you have already made on the l/kg ratio of your fuel.
- why do you take a COP of 3 when the SCOP, which is normally representative of an average COP over a heating season, is displayed at 4? Especially since in Normandy there are rarely very low temperatures compared to the calculation reference, which I believe is Strasbourg.
- last point, the rebound effect. If you have a device that is more practical, non-polluting, and of a lower proportional cost, there is a good chance that you will use it more, for the benefit of better comfort of course. Your annual consumption (in kWh heat) will certainly increase a little.

[Macro]

the noise and drafts of a heat pump in heating ... Yuck

[phil59]

For a long time, I heated with kerosene stoves as an extra.

You can last almost 10 years with one, considering that every day I filled about 4L of the tank, so they all spent a lot of liters, in the middle of winter.

I've had up to 5 at a time.

Consumption of around 600W at start-up, for less than a minute.

Already all disassembled and reassembled several times, I overturned the stove, just to empty everything, and a mixture of 0.5L of oil and 0.5L of E85, which I left it "burning outside" ... to clean.

I still have 2 that I gave to one of my daughters in emergency, in addition.

I stopped in 2018, when I installed my boiler wood stove.

Regarding the score in the middle of winter for a pac at 4, I have doubts. Why not 2 diffusers?

[Obamot]

Given the price of heat pumps, the fact that when you need them the most, their performance drops, drafts as Macro says... I was never convinced.

In addition, we are tempted to buy a first-price model or else the expensive models can just as well break down, and all that makes you heat up with nuclear power... Nan vade retro.

And why not a self-built rocket stove or mass stove? With the latter, you heat your house for almost nothing, an average log lasts 24 hours!!! (40cm x 15cm)

What I don't understand is that you don't have a fireplace yet!?

EDIT: I saw your other thread, you have enough to warm yourself up for free with the mass stove!

Course to learn how to build it 120€
https://www.atelierdusoleiletduvent.org ... e-de-masse

I think there is a possibility for an internship to take place at home (in certain associations). After that, it's only refractory brick and a fireplace....

https://wiki.lowtechlab.org/wiki/Po%C3% ... sse_OXALIS

After there are others, I participated once...

[phil59]

As already explained, wood is good, but it needs to be fueled with oil, a heat pump, a fuel or gas boiler, it's automatic.

It's especially for the night, when I had nights here between -8 and -2, without a gas boiler to keep the tp, gla-gla.

[Obamot]

Well no, it's the whole principle of the MASSE stove, the comfort, and which has nothing to do with other types of wood heating, where the fumes have temperatures close to those of the brazier and the losses are huge.

[Forhorse]

If I could heat with wood it would already be done.
The current accommodation is "provisional" (for 10 years, but hey...) and its surface makes it complicated to install a wood stove: basically it's a 24m² room (6x4) which contains the kitchen/ living room, a bathroom (6m²), a stairway upstairs.
Perimeter walls are 60cm wide.
The only possible place would be at the location of the stairway... which implies relocating it to an undeveloped part of the house (outbuilding)
Currently I find that it is far too much work for something that will remain temporary (one day we will finish the work of the real housing... one day...)

I've never been a fan of PACs, I always had the impression that it was a scam based on planned obsolescence (especially the €20.000 installations that don't last as long as promised... and whose spare parts are, as luck would have it, unfortunately no longer available when it breaks down) and that the COP announced was bogus (hence the fact that I prefer to count on 3 where the manufacturer announces 4...)
But for 800€, made profitable in 3 years, I thought it could be tried... even if it only lasts 5 years, it will have been "profitable" (not for the environment, that's for sure).

The idea is also that it is reversible and that it does air conditioning in summer, using the photovoltaic surplus (3.6kWp awaiting installation)
Currently we use a mobile air conditioner (very little, only to be able to sleep during the few summer heat waves) but the very principle of this type of device means that the performances are bad anyway.

We don't heat up a lot, only when we're present, only the main room (never the bedroom upstairs) and only during the day (never at night when we sleep) with a thermostat set at 17°C to prevent the thing from turning thoroughly all the time.
The Norman climate is rather mild in terms of temperature (this winter the cold record is currently -7°C for 1 night only, during the day the temperature is rarely negative, it only happened for 2 weeks this winter)

Afterwards there is indeed the risk of a rebound effect as mentioned by sicetaitsimple, when you are not aware of the consumption (the can of oil to be filled...) you are naturally tempted to heat more...

But yeah, if we could heat ourselves with wood, the question wouldn't even arise! (well I know in advance who would be doing wood chores, but too bad)

[Obamot]

I don't know your situation, and without trying to convince you, I would like to report that I have a friend who has an old farmhouse with this type of wall thickness, and a heat pump in winter with 60cm walls and l thermal inertia that it represents, well I'm afraid you'll regret it bitterly. Think hard.

A solution on 'the right corner' perhaps?

Here I discover the 'Mass stove in kit' to assemble yourself, design all in height and not expensive! 1h30 of soaring and it heats up for 24 hours with three times nothing of wood...

Screenshot_2023-02-02-00-48-42-98_40deb401b9ffe8e1df2f1cc5ba480b12.jpg (107.11 Kio) Consulté 1612 fois

https://www.coeurdefoyer.fr/coeur-compl ... -33-2.html

[phil59]

We don't heat up a lot, only when we're present, only the main room (never the bedroom upstairs) and only during the day (never at night when we sleep) with a thermostat set at 17°C to prevent the thing from turning thoroughly all the time.
The Norman climate is rather mild in terms of temperature (this winter the cold record is currently -7°C for 1 night only, during the day the temperature is rarely negative, it only happened for 2 weeks this winter)

Afterwards there is indeed the risk of a rebound effect as mentioned by sicetaitsimple, when you are not aware of the consumption (the can of oil to be filled...) you are naturally tempted to heat more...

But yeah, if we could heat ourselves with wood, the question wouldn't even arise! (well I know in advance who would be doing wood chores, but too bad)

You're lucky, we didn't heat the room for a long time, and sometimes the window was open, even if it was only 5° outside....
Now, Madame is chilly, and 15° is the minimum for the bedroom.
I confess that I am beginning to appreciate a little heat.

With your 3 kWp of panels, you should erase a good part of your consumption, excluding December-January.

Look anyway at the "2023" EDF price list....

https://particulier.edf.fr/content/dam/2-Actifs/Documents/Offres/Grille_prix_Tarif_Bleu.pdf

A little battery wouldn't hurt....