Combination of Home Assistant and Node-RED to control our complicated home HVAC.
- We have 3 zones - den, upstairs and office
- We have 5 time periods - early_morning, morning, afternoon, evening, and overnight
- We have 3 scenarios - WFH, weekend, at_work
Whatever the scenario, evening and overnight are the same. Office only needs heat when WFH.
This all started as our Gen-1 Nest Thermostats now have dead batteries and lose connectivity all the time. I want to use multiple sensors in each zone to control the boiler, and have the Nest be a dumb input into the system, permanently wired to the 24v transformer and not control anything directly.
Originally this was all done in Home Assistant with some automations and scripts, but then I discovered Node-RED and it seemed to offer better control. This is my first Node-Red project, so it's probably not the best way of doing everything, but it works.
We've split the day up into 5 segments using Home Assistant
binary_sensor:
# Early Morning
- platform: tod
name: TOD_EarlyMorning
after: "06:00"
before: "08:00"
unique_id: tod_earlymorning
# Morning
- platform: tod
name: TOD_Morning
after: "08:00"
before: "12:00"
unique_id: tod_morning
# Afternoon
- platform: tod
name: TOD_Afternoon
after: "12:00"
before: "16:00"
unique_id: tod_afternoon
# Evening
- platform: tod
name: TOD_Evening
after: "16:00"
before: "21:00"
unique_id: tod_evening
# Overnight
- platform: tod
name: TOD_Overnight
after: "21:00"
before: "06:00"
unique_id: tod_overnightWe use a series of 'input number' entities to set the temperature target for the day.
Using a 'binary input' we can tell Home Assistant if we're working from home that day or not and to adjust the temperatures accordingly using a series of gates. The gates also know if it is the weekend or not.
The brains function isn't as smart as it once was, but if it's warmer outside than inside it tells the target device to turn off. Mainly for the Heat Pumps as they get confused easily.
The 'Router' function is now the one doing all the hard work, splitting the inputs into information for each target device, and detecting if there is a manual override in place.
---
Title
---
flowchart LR
tod(Time Of Day) --> t1
tod -.-> t2 & t3 & t4 & t5
t1(early temp) --> brains
t2(morning temp) -.-> brains
t3(afternoon temp) -.-> brains
t4(evening temp) -.-> brains
t5(overnight temp) -.-> brains
id2(outside temp) ---> brains
brains(brains inside/outside) --> UI
UI(Nest UI) --> Router
Router(Router) --> c1 & c2 & c3 & c4
c1(Nest Thermostat)
c2(Heat Pump)
c3(Boiler Relay)
c4(Loop) --> UI
style brains fill:#ffa500,stroke:#FF5733
style Router fill:#ffa500,stroke:#FF5733
// the internals
var outside, stat, hvac_state;
var nest_temp, nest_mode;
var minisplit_temp, minisplit_mode;
// the inputs
var temp = msg.payload["target_temperature"];
var mode = msg.payload["hvac_mode"];
var bias = flow.get("bias");
var source = msg.payload["source"];
// the outputs
var lock = {};
var nest = {}; // heat or cool only
var minisplit = {}; // heat, cool or off
var generic = {}; // heat or cool only
var loop = {}; // original message with new topic
// the clever bits
if (source == "UI") { // change the source lock
//node.warn("UI");
lock.payload = "UI";
} else if (source == "loop") {
//node.warn("loop");
lock.payload = "loop";
} else {
//node.warn("brains");
lock.payload = "brains";
}
if (temp > flow.get("temp_bed")) {
hvac_state = "heating";
} else {
hvac_state = "off";
}
nest_temp = temp + bias;
minisplit_temp = temp - bias;
nest_mode = "heat";
minisplit_mode = mode;
nest.payload = {
data: {
"temperature": nest_temp,
"hvac_mode": nest_mode
}
};
if (minisplit_mode == "off") {
minisplit.payload = {
service: "turn_off",
data: "off"
};
} else {
minisplit.payload = {
service: "set_temperature",
data: {
"temperature": minisplit_temp,
"hvac_mode": minisplit_mode,
}
};
}
generic.payload = {
data : {
"temperature": nest_temp,
"hvac_mode": nest_mode
}
}
loop.payload = {
"ambient_temperature": flow.get("temp_bed"),
"target_temperature": msg.payload["target_temperature"],
"hvac_state": hvac_state,
"hvac_mode": msg.payload["hvac_mode"],
"has_leaf": msg.payload["has_leaf"],
"away": false,
"source": "loop"
}
flow.set("bed_last", loop.payload ); // used for reinjecting when on lock
stat = "nest: "+ nest_temp+ " / msp: "+ minisplit_temp;
node.status({ fill: "green", shape: "dot", text: stat });
return [lock, nest, minisplit, generic, loop];As the outside temperature gets colder the efficiency of the heat pumps also drops, so to compensate there is a bias.
At the moment this is set up as follows:
| Temp Range | Bias |
|---|---|
| < 0 | 2 |
| < 37 | 1 |
| < 50 | 0 |
| > 50 | -1 |
The bias number is added to the setting for the gas heating Change to The bias number is subtracted from the heat pump target temperature
var stat;
if (msg.outside < 0) {
msg.bias = 2;
stat = "really frickin cold [2]";
flow.set("bias", 2);
node.status({ fill: "blue", shape: "ring", text: stat });
} else if (msg.outside < 37) {
stat = "frickin cold [1]";
node.status({ fill: "yellow", shape: "ring", text: stat });
flow.set("bias", 1);
msg.bias = 1;
} else if (msg.outside < 50) {
stat = "cold [0]";
node.status({ fill: "green", shape: "ring", text: stat });
flow.set("bias", 0);
msg.bias = 0;
} else {
stat = "not bad [-1]";
node.status({ fill: "red", shape: "ring", text: stat });
msg.bias = -1;
flow.set("bias", -1);
}
return msg;
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