Will Burrows
Data Sheet for Recoheat stove heat recovery
Updated: Nov 3, 2020
Here are the calculations for heat output of the Recoheat unit, based on the readings taken in the little demo I did that you can see in the video at https://youtu.be/zlEMADUz0Ak
Essentially, that shows - what is completely consistent with the Recoheat's output over the last two years - that air pumped in at about 15°C is pumped out at about 515°C (I'm understating it a bit).
So how does that translate into output in kilowatts, such as your stove is rated with? The stove I was demonstrating it with is a 5kw Ecosys.
Here are the calculations:
Calculating the heat transfer value
Area
Surface area is
@100mm length of 8mm internal diameter s
tainless steel tube = 0.00251 m2
@ 1830mm length of 8mm internal diameter stainless steel = .045933 m2
Properties of Air
1 litre per second = 0.001 m3/sec = 3.6m3/hour
Temperature in approx. 15 °C
Temperature out approx. 515°C
ΔΤ = Change in temperature ≈1.205 kg/m3
Flue gas temperature ≈ 500°C - 600°C
U = for air to air heat exchanger 10-40 W/m2 °C
Heat Transfer
Q = UAΔT
Q = Heat transfer (watts)
U = Overall Heat Transfer Co-efficient (w/m2k) = 40 w/m2k
A = Surface area =.045933 m2
ΔΤ = Change in temperature = 500°C
Therefore:
Q = 40 x .045933 x 500 = .91866w
Q = .91866kw
Yes, that's right. A small fire in a 5 kw capacity stove is producing an ADDITIONAL .9kw of heat within 4 minutes of lighting.
