Wood energy: calculation volume of a thermal buffer

[the middle]

it's interesting.

[Christophe]

because the refractory brick has a bad conductivity suddenly it stays hot for a long time

Yes but that was a good question: with water it would stay hot longer ...

Is steatite a refractory brick? I did not know...

[david adv]

precisely, I also sought to compare the calories stored in water, soapstone or other mass material, taking into account that for water we use a delta of 40 °, 60 max (from 25 to 85 °) while the soapstone of a mass stove at a delta of 200,300, 500 °?
But it may be another subject.

Christophe for your heating need per day, I think you were wrong:

We assume our needs at 50 kWh / m2.year (semi passive house) or 7500 kwh / year

ok

or 20 kWh per day.

No, you don't heat 375 days a year. let's say 100 to 150 so a need for 50kwh per day?
To verify with a thermal study or more simply with the experience of your current heating.

After, the whole question is to know if you want to operate the stove 5 hours continuously every 2 days or 10 hours every 4 days (values ​​at random).

My stove will be in the living room so if we charge it from 17 p.m. to 23 p.m., i.e. 6 a.m. or 8 a.m., that's fine. Longer, it will be binding ... and not less long, for sure: it is precisely the interest of accumulation: avoid heating 2 hours morning and evening of a stove without accumulation.

If I take a 6 kW stove, I generate 36 kWh in 6 hours. One part directly heating the room and the other heating the water in the battery. The water will circulate when the temperature drops: in the early morning or when I want (order by proggramateur on 15d)

6kw may be a bit small to both heat the room and accumulate in the boiler. To be confirmed with the thermal study of the building and the contribution of the solar panels (10m² for hot water and heating).

The final objective is to stick to the most comfortable temperatures (19 ° the day, minus the night) because we often see big variations in the houses which heat with the wood stove (no pbs with the boilers which regulate by water, radiators, thermostat): 22 to 25 ° at the end of heating, 16 on waking or when you come back from the taf.
And each excess degree is 7% wasted, each degree less is discomfort.

[david adv]

Some figures to support the previous message:

So, I would like to take a stove with a boiler + 10m² of panel for DHW and heating (minority). Buffer tank.

I calculated that 1000l of buffer tank stores about 1Kwh per degree. So I plan to store 40 to 60 kWh which will be returned as desired in the underfloor heating with a classic thermostat + programmer, or 10 hours of automatic heating, or 1 to 2 days of autonomy without restarting the stove.
if I cook for 6 hours in the evening taking, for example, the Wodtke "momo" 8kw in 2.5 direct and 5.5 for water, that gives 20kwh direct (for our comfort from 17 p.m. to 23 p.m.) and 33kwh stored to heat the morning and day.
Which covers without bp, I believe, 24 hours on gray and cold days.
With our 20m² of glazing in the south + solar panels, we should only need one day of wood heating on 2 on average over 5 months or 75 days of heating.
6 hours of stove at 8 kW with a yield of 66% (given for 70%), it's 8x0.66x6 or 72kwh of wood.
The m3 of very dry oak gives 2100 kwh, the pine 1700. Let us say that it is not perfectly dry and that it gives on average 1440 kwh, I need 0.05m3 per heater or 17kg. and 3,5m3 of wood per year. (200 euros per year).

Verification of the calculation: 75dx72kwh = 5400 kwh of input by the wood stove.
Today, I consume 7700 kwh of gas for DHW and heating in a rental house a little smaller but with conventional insulation.
So 5400kwh of wood + solar supply 10m2 or estimate 1500 kwh over 5 winter months or 7000kwh (mixed wood / solar) to spend the winter and 6500 kwh (solar only) for the DHW of the other 7 months ... C 'is consistent.
Remarks?
an idea of ​​the cost of installation?
- the momo stove is 3500/4000 euro.
-10m² of sign and a large balloon: 8 to 10000 euros installed
-I have interest to have 2 balloons? a 300l for DHW and a 1000l for heating? or can I save a balloon?

[the middle]

i just learned
One of my colleagues has a wood boiler, he wants to enlarge his buffer tank from 700 to 2000 liters.
I don't know more about his system.
I'm going to ask her a few questions when I get back to work.

[jean63]

Some figures to support the previous message:

So, I would like to take a stove with a boiler + 10m² of panel for DHW and heating (minority). Buffer tank.

I calculated that 1000l of buffer tank stores about 1Kwh per degree. So I plan to store 40 to 60 kWh which will be returned as desired in the underfloor heating with a classic thermostat + programmer, or 10 hours of automatic heating, or 1 to 2 days of autonomy without restarting the stove.
if I cook for 6 hours in the evening taking, for example, the Wodtke "momo" 8kw in 2.5 direct and 5.5 for water, that gives 20kwh direct (for our comfort from 17 p.m. to 23 p.m.) and 33kwh stored to heat the morning and day.
Which covers without bp, I believe, 24 hours on gray and cold days.
With our 20m² of glazing in the south + solar panels, we should only need one day of wood heating on 2 on average over 5 months or 75 days of heating.
6 hours of stove at 8 kW with a yield of 66% (given for 70%), it's 8x0.66x6 or 72kwh of wood.
The m3 of very dry oak gives 2100 kwh, the pine 1700. Let us say that it is not perfectly dry and that it gives on average 1440 kwh, I need 0.05m3 per heater or 17kg. and 3,5m3 of wood per year. (200 euros per year).

Verification of the calculation: 75dx72kwh = 5400 kwh of input by the wood stove.
Today, I consume 7700 kwh of gas for DHW and heating in a rental house a little smaller but with conventional insulation.
So 5400kwh of wood + solar supply 10m2 or estimate 1500 kwh over 5 winter months or 7000kwh (mixed wood / solar) to spend the winter and 6500 kwh (solar only) for the DHW of the other 7 months ... C 'is consistent.
Remarks?
an idea of ​​the cost of installation?
- the momo stove is 3500/4000 euro.
-10m² of sign and a large balloon: 8 to 10000 euros installed
-I have interest to have 2 balloons? a 300l for DHW and a 1000l for heating? or can I save a balloon?

great your study, but hey it's still very theoretical.

When do you plan to install your system? (new house very well insulated I suppose).

Keep us in touch.

In your costs of installing solar collectors, have you deducted tax reductions and regional aid?

I am interested in improving my installation (natural gas boiler + heated floor on the ground floor + low temperature acova radiators in the upstairs bedrooms) by solar collectors. I would like to put a 1000 liter storage tank at the highest possible temperature.

What do you think to put as sensors?

There are nice facilities here www.chaleurterre.com (some have PACs in addition but that does not detract from the quality of the rest, some are very top).

[david adv]

budget: installation of 10m² panel and 15000ttc balloon excluding aid.
boiler 4500ttc without aid.
In short, a large 20 cwt excluding credits (vat 000).

Does that sound great to you?

it can be made 2 times cheaper with a simple solar DHW installation at 5000 and a pellet stove at 4500.
there, I say a pellet stove to have the practical side of the programmer (useless with a storage tank). or less than 10 ttc but no solar backup for heating and no wood backup for DHW. (or an additional cost of wood / elec consumption of 000/20% compared to the 30ttc solution, according to my estimates)

the panels will, a priori, be ESE brand: quality Belgian production, good performance in comparative tests. West France importer: EKLOR in Niort.

thank you for the link, I have to pofine all this but at the moment, it's more the choice of the building that poses me pb: I want to do it in hemp brick. construction begins in March

[jean63]

budget: installation of 10m² panel and 15000ttc balloon excluding aid.
boiler 4500ttc without aid.
In short, a large 20 cwt excluding credits (vat 000).

Does that sound great to you?

Yes it seems a lot, but I have no recent reference because I built more than 20 years ago. My underfloor heating (100 m2) on the ground floor + 5 acova radiators upstairs powered by a wall-mounted condensing gas boiler including domestic water heating + regulation and distribution of the 6 circuits by the floor m ' had cost 70000 francs in 1985 (or 11000 euros).

This is what still works today (except the boiler that I had to replace 2 years ago after drilling the heating body: cost = 2000 euros).

Soforum, there are connoisseurs for stoves but

You have to go see the facilities of http://www.chaleurterre.com/wiki/doku.p ... tallations there are some installers of wood boilers solar installations which shows his achievements and also www.apper-solaire.org which offers group purchases for solar http://forum.apper-solaire.org/portal.php

[jean63]

i just learned
One of my colleagues has a wood boiler, he wants to enlarge his buffer tank from 700 to 2000 liters.
I don't know more about his system.
I'm going to ask her a few questions when I get back to work.

Can you have more specific info on its installation and what it will supply with its new 2000 liter tank, what water temperature in the tank does it think it will get + what heating autonomy.

[the middle]

I hope to see him on Monday or Tuesday ...
I have a lot of leave ....