@mschaeffler/node-red-thermostat

A Node Red node to control an (electric) heater.

Install

$ npm install @mschaeffler/node-red-thermostat

Closed Loop Control

A heating device that just can be switched on and off, can be closed loop controlled:

The on / off cycles are done like this:

The on time is calculated in this way:

with this values |value |description | |:------|:---------------| |t_on |time of on cycle| |T_nom |nominal Temperature, parameter nominal| |T_act |actual temperature, msg.payload.temperature| |s |minimal Delta, parameter summand| |f_cycle|$1.4$ for the 1st cycle, $1.2$ for the 2nd, then $1$| |f_msg |control coefficient, msg.payload.factor| |f_node |control coefficient, parameter factor| |t_cycle|time of complete cycle, parameter cycleTime|

Input

|msg. | type | description | |:-------|:-------|:----------------------------------| |payload | object | data to control the thermostat |

There are two different ways to control the thermostat:

direct control

msg.payload is a destinct value:

|msg.payload| type | description | |:------|:------|:------------| |true |boolean| starts heating according to already set data | |false|boolean| stops heating | |on |string | starts heating according to already set data | |off |string | stops heating | |1 |number | sets the cycle count to 1 and starts heating | |2 |number | sets the cycle count to 2 and starts heating | |3 |number | sets the cycle count to 3 and starts heating | |4 |number | sets the cycle count to 4 and starts heating | |5 |number | sets the cycle count to 5 and starts heating | |0 |number | stops heating |

control with objects

msg.payload is an object with at least one of these members:

|msg.payload.| type | description | |:------|:------|:------------| |temperature|number | actual temperature for the closed loop control | |block|boolean| blocks the heating (e.G. open window)| |nominal|number | nominal temperature | |factor|number |multilies the control coefficent (parameter factor) with this value | |cycleTime|number | sets the cyclic time | |cycleCount|number | sets the nuber of cycles |

Outputs

state feedback

This is the general feedback: heating is on or off.

|msg. | type | description | |:-------|:-------|:----------------------------------| |topic | string | parameter topic| |payload | | value according to parameter feedback|

control output

This controls the heater according to the cycles.

|msg. | type | description | |:-------|:-------|:----------------------------------| |topic | string | parameter topic| |payload |boolean | control value to switch the heater|

Parameters

|config | type | description | |:---------|:-------|:----------------------------------| |topic | string | topic value for the output messages | |nominal | number | nominal temperature for the closed loop control | |minDelta | number | actual temp must be by this value lower then the nominal to start heating | |summand | number | additional summand for the closed loop control | |factor | number | control coefficient for the closed loop control | |cycleTime | number | time period of one heating cycle | |cycleCount| number | number of heating cycles | |feedback | string | style of the state feedback |

feedback formats

There are four formats for the state feedback:

|feedback type| description | |:------------|:----------------------------------| |Boolean | boolean value | |"on" / "off" | strings "on" or "off" | |1 / 0 | numbers 1 or 0 | |cycle count | numbers cycleCount or 0 |

Example Flow

example flow

Author

Mathias Schäffler

License

LGPL-2.1