Firewood, electricity and SMS - we keep the temperature in the country house cheap
Hello, Habr!
Our first publication is dedicated to the current issue at this time of the year: home heating. Many solutions ideas based on our products come to us from the outside. So this time, a client called us and asked to help automatically maintain the temperature and create a remote heating control for a house equipped with two wood-burning stoves. We laughed sincerely, but the problem must be solved.
So, at the entrance we have a qualitatively insulated house, where the owners live only on the weekend. Actually, we can consider this a summer residence. The house has two wood-burning stoves (what kind of cottage is this without a fireplace, right?), And there is an external power source, an electrical network with a low night rate. What do you need to get output? Economical heating throughout the week, and not just on weekends, and the ability to intervene, if necessary, through SMS.
Decision
In order to heat the house on weekends, it was decided to use all the same stoves. The advantages of a brick oven are obvious - it heats up quickly enough, and gives off heat for a very long time, while maintaining an acceptable temperature in the room (acceptable for the safety of the room itself, where there is no excess moisture, there is no risk of freezing pipes and other "joys").
But how to provide heating of the furnace on weekdays when there are no owners of the house? The solution is unexpected - an electric heater (TEN) with a power of 1 kW is installed in the cleaning hole for the main furnace, and 0.5 kW for the auxiliary. Power is selected in such a way that it was possible to maintain the temperature in the house in the absence of the owners. The goal of fully heating the house was not set. For this, there are just wood stoves.
The heater is not installed tightly, so that the clean door, if necessary, retains its functionality.
TEN management
In order to be able to remotely control the heating of the furnace on weekdays, a connection is used through an automatic machine, which also houses a control unit with an SMS module.
What was used:
BM8039D - "Guardian" main unit - 1 pc.
BM8070D - power relay 16A - 1 pc.
BM8079D - power supply - 1 pc.
NM18B20 - set of 2 temperature sensors - 1 pc.
Programmable timer IEK - 1 pc.
How to connect it?
To save money and parts, temperature sensors were connected directly to the DB9 connector on the front of the BM8039D. It took one powerful relay BM8070D, able to cope with a current of 7A (the relay can withstand a double load). Temperature sensors were connected using twisted pair.
How it works?
In total, two thermostats are used, the main one (with monitoring the room heating at night, temperature - 20 degrees) and the auxiliary one, which makes sure that the temperature does not drop below 8 degrees above zero.
The whole system works from 11 pm to 7 am at a cheap night rate. During this time, the stove heats up and gradually releases heat to the room during daylight hours, preventing the temperature from dropping to negative values (here it is worth remembering the auxiliary thermostat, which monitors the temperature at any time of the day, preventing it from dropping below 8 degrees above zero. If there are severe frosts on the street, then the thermal energy accumulated by the stove may not be enough to maintain the temperature above 8 degrees C. And if anything, the emergency / auxiliary thermostat starts to work, heating the house to 8-12 degrees Celsius due to Orogen daily rate.
In this case, the homeowner receives SMS-notification about the temperature in the room. If something goes wrong, using SMS, you can turn on the heating system.
The circuit of the heating system
The thermostat L1 supplies voltage to the heater only if the “night” timer has tripped. But the auxiliary thermostat energizes immediately, directly.
The owner of the house and two wood-burning stoves is pleased with the result. And we are an interesting task. Toss it up;)
UPDATE: We are criticized in the comments for the use of heating elements as not the most efficient heat sources. And for heating the air in the furnace, and not directly its mass. The fact is that the client created the thermal part himself, based on the presence of heating elements and the unwillingness to carry out construction work. Our task was to help him manage all this. We have completed this task. Moreover, the electronic part will work with any other electric heaters - the main thing is that the relay power is enough.
Your master whale