Preparing the sparge water during the temperature rests.
Most beer brewing recipes, after all the rests have been completed and the wort has been drained, use sparge water at a temperature of about 80°C, to rinse the spent grain.
What can go wrong: the maximum power the electrical network can supply. If you heat the boiler and the sparge water vessel at the same time, the network may not handle the load.
There is a solution. Heat the water in the sparge vessel while the temperature rests of the mashing program are being carried out.
This is easy to arrange.
Connect the control (permission to run) of the sparge vessel heater to the normally closed (NC) contacts of relay No. 4, which controls the boost heating element.
How it works.
If you fill the sparge vessel with water, you can switch the heating on, even if Samovar is not switched on, because the contacts of relay No. 4 are closed.
When Samovar starts working and the command to run the mashing program is given, relay No. 4, which controls the boiler's boost heating element, switches on, opens the NC contacts and the heating in the sparge vessel stops.
When the set temperature is reached, relay No. 4 switches off, the NC contacts close and the heating of the sparge vessel continues.
For those who actually use a boost heating element, which means there is enough power, this is simple to do. Relay No. 4, switching its contacts over, will turn on either the boiler's boost heating element or the sparge vessel heater.
Notes on the diagram:
Switch S1 is used to turn on the thermostat; S2 closes the connector so the device can work without Samovar.
The 16 A circuit breaker provides protection and is used to turn the heater on and off.
The AC-DC 220-12 volt module and the thermostat powered from 12 volts are used to increase safety. You can use a thermostat powered from 220 volts and an AC-AC solid-state relay.
The STC-1000 thermostat has two operating modes: heating and cooling, and accordingly two relays. One is responsible for heating, the other for cooling, which allows you to use this device on its own, able to maintain a set temperature in the fermentation vessel without using Samovar.
Note.
The control of relay No. 4 by the ACCELERATION_HEATER_DELTA parameter described below works in the build with a UART voltage regulator. In the relay build (without a regulator), relay No. 4 turns on together with the main heating element while the mash is colder than the setpoint by more than HEAT_DELTA, and turns off when it switches to temperature holding.
For those who do not use a boost heating element.
The wiring diagram is exactly the same, but…
According to Samovar's logic, the boost heating element turns off a few degrees before the target temperature is reached, and with our wiring the ranges overlap:
The main heating element is still running at full power, and the second heating element has already turned on.
To avoid this, in the Samovar_ini.h file, in the line
#define ACCELERATION_HEATER_DELTA 4
replace the value 4 with 0 (zero) or, even better, with –(minus)0.3
This gives the following operating algorithm:
1°C before the set rest temperature (set in the line #define HEAT_DELTA 1)
Samovar switches to PID control: the main heating element will receive, through the regulator, no more than the voltage from the "Regulator volt./power in temperature holding mode" («Напр./мощность регулятора в режиме поддержания темп.») field (Settings - Beer («Настройки - Пиво»)).
When the temperature reaches the set value, the main heating element stops heating, relay No. 4 also switches off, the NC contacts close and permission is given to heat the sparge vessel.
If the line #define ACCELERATION_HEATER_DELTA is set to -0.3, the relay is de-energized only when the boiler temperature is 0.3°C above the target; this guarantees that the two heating elements cannot be on at the same time, even for a few seconds.
Added.
If you achieve an almost perfect approach to the temperature rests, the setting described above in the line
#define ACCELERATION_HEATER_DELTA
with values of both 0 and -0.3 may not work fully. The water in the intermediate vessel will not have time to heat up, because the temperature will first overshoot the target slightly, by about 0.4, but then drop and will be either equal to the target or 0.1-0.2°C below it. In that case the heating element in the additional vessel simply does not turn on.
A different setting is suggested.
For example:
With these values:
Regulator volt./power in temperature holding mode: 150 volts
#define HEAT_DELTA 2
In the line
#define ACCELERATION_HEATER_DELTA enter the value 1.5
And limit the power of the heating element in the sparge vessel to 1 kW
When 2° remain to the target temperature, 150 volts starts being supplied to the main heater. First continuously, then in pulses.
1.5° before the target, the heater in the intermediate vessel turns on at a power of 1 kW.
The network is not overloaded. The second heating element has enough time to heat the sparge water during the temperature rests and to maintain the temperature
