Solar heating with a wood log boiler: feedback
Here is a testimonial from a customer Nicolas who bought:
- .
- a wood log boiler,
- a 500L self-draining solar tank with 5 collectors,
- a double flow ventilation at Lacentrale-eco.com in 2013.
He shared his experience with us following the purchase of his equipment.
Tell us about your green house project
Our green house project started with the desire to build a very energy efficient house, using natural materials for comfort and quality? Our goal was also to move to a place that would allow us to reduce our daily commute (work, school, shops, and activities) as much as possible. While looking for energy savings.
What heating and ventilation solution did you choose?
For the design of the heating system, I relied on the advice of Lacentrale-eco for the entire installation.
Not having any particular plumbing skills, they advised me to make hydraulic connections with insulated corrugated stainless steel pipe and flanged fittings. Not very conventional but very effective and cheaper than calling a plumber.
Our heating system consists of a self-draining solar water heater (Rotex) with 10m2 of solar thermal collector on the roof and a 500 litre tank that provides DHW and hot water that feeds the hydraulic underfloor heating.
To complement the solar thermal, we have a wood log boiler with a 2nd 500 litre buffer tank. The 2 tanks work together to increase the storage capacity of the 2 systems.
.Depending on the season we reverse the loading priorities of the tanks from one to the other... In summer the solar storage tank charges the buffer storage tank, and in winter it is the other way around, taking into account time slots and other criteria...
The solar heating system is very simple and clever! I can maintain it by myself and it's very comfortable.
To reduce our electricity consumption as much as possible, we made the choice not to put in an electric backup heater for the DHW.
The air renewal is ensured by a Double-flow ventilation system. Still with the idea of reducing electrical consumption, we chose a very energy-efficient model without bypass. This allows us to have "clean" air without losing all the calories during the flows.
In summer, the ventilation is turned off. The air is renewed naturally through the windows: tilt and turn at all times or alternating "night opening" / "day closing" in periods of high heat.
.What are the advantages of a wood-fired boiler?
The advantage of a wood-fired boiler with solar thermal backup over a simple wood stove, is precisely the fact that the temperature is constant in the house thanks to a soft diffusion via the underfloor heating and its regulation on water law (very pleasant when you get up in the morning).
We also appreciate the fact that we don't need to be present to heat the house. In the coldest part of winter, we turn on the boiler every other day. If it's not too cold and there's a bit of sunshine, we can last 3 to 4 days with a blaze (for a temperature of around 21°).
We're next to St Etienne and it's not the sunniest region in France, but it works.
How does the wood-fired boiler work and how do you use it?
When we light the log boiler, we fill the firebox to the maximum, it runs for about 5 hours and heats the 2 hot water tanks to 75-80°.
The other side of the coin is the constraints linked to wood, in particular the maintenance of the installation: In winter, the boiler has to be cleaned (de-ash) once every 3-4 weeks (or rather every 10-15 flames); this takes about 45 minutes.
The chimney also has to be swept once a year and this takes about 1 hour. The other constraint of wood is storage and handling, but given the volumes (3 to 4 steres/year), this is not a big chore either!
To sum up, wood heating is not adapted to all lifestyles, but the constraints are relatively low with an excellent level of comfort (for a wood log boiler + hydraulic underfloor heating system).
How do you use solar hot water?
We are also very happy with the self-draining solar thermal system as it works really well. Apart from the water level of the tank ROTEX to be done twice a year (add between 5 and 10 litres of water), it requires no maintenance. No Glycol and no overheating in the summer.
One of the limits of the system is the safety shutdown when it's very cold at night (like -3 -4, the pumps don't restart even if the panels reach the set temperature).
The efficiency of the panels is really impressive. In mid-season with some sun, even in October when the sun is low, with a 50% tilt, the panels really provide energy, up to 3KW.
This is enough for the heating needs of the house. Our energy consumption is optimised thanks to them.
Are you satisfied with your solar combi system?
So, we are very satisfied with the wood-solar thermal package conceptualized and sold by Lacentrale-eco.
If we had to do it again, I would opt for the same installation but I would probably oversize the tank linked to the boiler (like 2000 litres) to increase the storage capacity.
But it would have required more space in the technical room, but that would allow, once the boiler is at temperature, to link 2 or 3 flames and have an autonomy of 4 or 5 days (and thus limit the constraint linked to the necessary presence).
Lacentrale-eco advised us well for the installation of the equipment. We have in fact used them for other solar thermal projects, but for professional activities.
