Explainers

Explainers

The wiring and system questions to settle before you buy.

12 items
Heat pumpsHeat Pump Thermostats: O/B, Auxiliary Heat and Emergency Heat

What a heat pump thermostat has to do that a furnace thermostat doesn't: the O/B reversing valve, compressor stages, auxiliary and emergency heat.

ComfortHot and Cold Rooms: Room Sensors, Zoning and What Each Fixes

Why some rooms run hot or cold, what thermostat room sensors can and can't do, and when zoning with dampers or a zone panel is the real fix.

InstallationHow to Replace a Thermostat: The Steps, the Photos and the Checks

The order of work for swapping a low-voltage thermostat: power off, photograph, label, mount, wire and test, plus the signs that you should stop and call a pro.

ComfortHumidistats: Controlling a Whole-House Humidifier or Dehumidifier

What a humidistat controls, how it differs from a thermostat's humidity reading, how it wires, and when a smart thermostat's humidity terminal can do the job.

SystemsLine-Voltage vs Low-Voltage Thermostats: Which One Your Heat Needs

Why electric baseboard and wall heaters need a line-voltage thermostat, how to tell from the wires, and how to match a thermostat's rating to the heater load.

SystemsMillivolt Thermostats: Gas Fireplaces, Wall Furnaces and Floor Furnaces

Why gas fireplaces, wall furnaces and floor furnaces with a standing pilot need a millivolt-rated thermostat, how to recognise one, and which thermostats say they fit.

SystemsSingle-Stage, Two-Stage and Multi-Stage Systems: Choosing the Thermostat

How to tell whether your furnace, air conditioner or heat pump has one stage or two from the thermostat wires, and what a thermostat needs to run them.

ChoosingSmart vs Programmable Thermostats: What You Gain and What It Takes

What a smart thermostat does that a programmable one doesn't, what each needs from your wiring, and how to decide which is worth it for your home.

WiringThermostat Terminals and Wire Colours: What R, C, W, Y, G and O/B Mean

What each thermostat terminal letter controls, why wire colour isn't a reliable guide, and how to read your wires before you buy a new thermostat.

SystemsThermostats for Boilers, Hot Water and Radiant Floor Heat

How boiler and radiant systems differ from forced air at the thermostat: two-wire heat only, zone valves, slow response and the settings that suit them.

WiringWhat a C Wire Is, and What to Do If You Don't Have One

The C wire gives a thermostat constant 24-volt power. How to tell if you have one, why smart thermostats want it, and the four ways to add one.

SavingsWhat the ENERGY STAR Label Means on a Smart Thermostat

How ENERGY STAR qualifies smart thermostats from real-home data, the 8% heating and 10% cooling run-time thresholds, and what the average saving figure means for you.