Are you in a long-distance relationship with your furnace? Do you know what it's up to when you're not home? Save money and become more energy efficient with these furnace tips provided by users at Q&A site Stack Exchange.

Jay Bazuzi Asks:

I want to keep track of when my furnace is on, with an eye to reducing how much energy I use to heat my house.

Reasons for wanting to do this:


I could compare it with weather data (temperature, wind speed, precipitation).

I could see what it saves to turn the heat down when we're out.


I could tell my kids exactly how much it costs when they leave the front door open.

How might I go about this?

Doresoom Answers:

You could mount a wind speed logger in your ductwork or in front of your air intake vent. It should have negligible drag effects on airflow through the system. I'm not sure how accurate the results would be though. The air movement from your furnace running is going to be a lot less than outside wind levels, which is what most wind speed loggers are actually designed for.

You can pick one up on Amazon for about $100.

Or you could go the direct approach with a breaker-installed power use monitor. This option's about twice the price, but monitors your whole house. Unfortunately, this method won't tell you exactly when your furnace comes on, although you should be able to figure it out, since it gives you a time history of power usage. Just note when you get a big spike, and then a big drop and match it to when your furnace turns on and off. Then look for that same magnitude spike in later data, without bothering to manually keep track of furnace cycling.

blalor Answers:

I have an ancient oil-fired steam boiler with a "tankless" hot water heater. I built an Arduino-based board that connects in parallel to the thermostat wires at the furnace. It uses a MID400 AC optocoupler to detect when the thermostat is calling for heat (24VAC when not calling for heat, 0VAC when it is), and then sends that to a computer via an XBee module.

From that you can keep track of how long the furnace runs. It's a very simple system with several shortcomings: It doesn't make a distinction between when the main zone of the house is calling for heat vs when hot water is called for, and can't tell when heat's being called for, but it can tell you when the low water or high temperature cut-outs have kicked in.

Not perfect, but it should give you some idea of your energy consumption.

shirlock homes Answers:

If you need to monitor just the furnace (what kind of furnace?), a very simple Amprobe chart recorder will do the job by monitoring the electrical inputs to the burner or pumps without any invasive wiring or computer interface. Old fashioned, but used in industrial applications for decades.

SamtheBrand Answers:

The Hohm power monitoring service used to be a great way to keep tabs on energy consumption (check out BQ's awesome answer), but in mid 2011 Microsoft discontinued it just as Google discontinued its competing service, Powermeter.

But while the tech giants seem to have abandoned home energy monitoring, several smaller players now offer similar services:

myEragy: A free web-based energy consumption dashboard that provides subscribers with real time, historical and projected info and sends alerts via email or SMS when you go overbudget or a specific circuit uses too much energy. myEragy supports several electricity monitors, including Blueline PowerCost Monitor with WiFi, TED 5000, and eGauge.

PlotWatt: Currently in beta, PlotWatt is a free service that plots energy usage in a user-friendly way, and according to the FAQ, tracks individual appliances using "algorithms." Suspicious, certainly, but promising. The service is compatible with TED and WattVisions monitors.

There are also more integrated options out there, such as Opower & Honeywell's thermostat product, which lets you adjust and monitor your thermostat from anywhere, and MyEnergy, which lets customers track electric, gas and water.

It's an exciting space out there with a lot of promising options. This is just a start.


Illustration by Sean Gallagher.