Wood energy: calculation volume of a thermal buffer

[Christophe]

Does that sound great to you?

Uh this price is with radiators or PCs or without?

FYI, here is a provisional budget for the 15kW Deom that I just mounted:

- boiler: € 1500 special price for a prototype outside the catalog never recovered by the sponsor
- enamelled solar tank + regulation: € 1000 used (with 3 solar panels of 2 m² not mounted) but very little used (1979 )
- thermal valve: 120 €
- fitting and various accessories: around 200 € (I haven't got the bill yet).
- self-construction and study: 0 €

I think I forgot nothing, in short less than 3000 € for a wood boiler installation on DHW and heating.
All this without any AIDS or SUBSIDIES...Who says better? But admit that I was lucky to find the ball at this price!

[david adv]

effectively, it is without the heated floor, that is 3/4000 more.

All these prices are public prices, set by professionals.

please compare what is comparable so no self-construction,
except for the purchase of equipment, if it is new and available.

[Christophe]

Yes david but ... we must admit that bonuses and subsidies unfortunately drive prices up.

In terms of quality of achievement, with the pros, it's often a poker game. It can be done very well as it can mess around ...

It depends on who you come across.

Anyway in my case: NO pro would have wanted to make such an assembly because too "out of the ordinary" .... so no choice: I had to install myself.

[Christophe]

After 14 months of use: in practice we are very far from this necessary volume. The factors to correct are I think:
- lower wood PCI
- Filling rate less than 50%
- Deom efficiency lower than 81% (60 to 65% I would say)
- Various losses in non-insulated pipes: - 5% let's say

To estimate the real yield (pkoi I have not thought about it before?) I will weigh a load of wood and I will watch the evolution of the T ° of the DHW tank over the same period without drawing a liter of hot water of course. Thus we will have an idea of ​​the actual effective return!

[david adv]

so, were you able to measure performance?

me, I have something new on the prices: clearly, it will cost me an eye!

-heated floor on 89m² at 46ht / m2 or 4090ht

-10m² of solar + 2 tanks (300l DHW and 1000l buffer) + underfloor heating regulation with electronics with indoor and outdoor sensors and installation: 12146ht

-high temperature additional loop for towel dryers and radiators (in case because I removed the heated floor upstairs to reduce the bill by 5000 euros!): 725ht
I pass you the prices of radiators and towel dryers + installation 1500ht

additional wood option in DHW: 500ht

i.e. 19000ht, 22660 ttc

and it lacks the stove at 4000ht + installation of the stove, the poujoulat, the regulation of the stove.

I am comfortable at 30 ttc for the DHW and heating station!
tax credit on the ceiling for a family of 4: 8000 euros, remaining 22000, it will take a long time to pay off if EDF does not increase its rates!

a simpler and less expensive solution?
-a classic solar DHW at 5000ttc
-a wood stove or better, with pelet (between 4000 and 8000ttc installed)
-for chilly: an electric floor in case: 2000ttc
i.e. 10 to 15000 euros
minus 5000 tax credits, i.e. 5 to 10000 euros of investment.
either 2 to 4 times cheaper than my solution

[Christophe]

so, were you able to measure performance?

Yes and it's not famous: https://www.econologie.com/forums/rendement- ... t6977.html

[ulyssesourd]

Hi everybody,

Easy to calculate the volume of the buffer tank!

The parameters must be on hand:

1) Kg = the maximum number of kilograms of wood in the hearth of the boiler with the heaviest wood possible for the same volume, for example the same volume of fir weighs less than that of oak.

2) R = boiler efficiency in%.

3) fixed parameter: to increase by 1 ° C 1 liter of water = 1.1186W

4) fixed parameter: 1kg of wood = 4000Wh average

5) Delta = 90 ° C - Min T ° of the balloon

Formula: V = (((Kg * 4000) / 1.1186) / Delta) * R

Example:

Boiler at 80% efficiency with a maximum load of 20kg,
Delta = 50 ° C (min = 40 ° C)

V = (((20 * 4000) / 1.1186) / 50) * 80%
V = 1144 Liters

Please note this parameter is valid in NO HEATING mode.

I have a 20kW boiler at home, with a 20kg load, I saturate my 800L tank at 90 ° C in heating and DHW mode, and the combustion lasted approximately 3:30.

A+

[thierry63]

I'm not sure I'm on the right subject !!!
I have a PS500 regulus buffer tank, having served 2 winters that I wish to sell (due to change of boiler)
Is there a demand or not?
I think selling it between 400 and 500 €: is it too expensive or is it a fair price?
Thank you for your answers.