Thursday, June 21, 2012

Cost of running the furnace circulation fan

I decided to work out what it costs to run my furnaces air circulation motor.  I thought running the circulation through the night without the AC on would help get the cooler air from downstairs to upstairs as we slept.

It seems to be helping, I don't think the AC was activated too much overnight.

Here are my calculations.

Typical late night hourly power consumption when not much is going on is 0.20 Kwh
Typical late night hourly power consumption when fan motor is on is 0.30 Kwh

So this difference of 0.1 Kwh is my basis to calculate how much the fan is costing me.

Off peak is 6.5 cents for 12 hours a day
Mid peak is 10 cents for 6 hours a day
Peak is 11.7 cents for 6 hours a day

This works out to 20 cents a day rounding up. 

So conceivably running the furnace fan every day of the year can cost me $73 a year(or another way $9 a month).

Well, thats nice to know.  Now to decide if that is affordable or not.


  1. If it makes a discernable difference, $9 a month is completely worth it and a massive savings compared to AC. If it keeps you from turning on the AC, or allows you to set the thermostat really high, you are making a wise choice by running the fan. I have an AC unit packed away but haven't set it up at my farmhouse. Even during the recent 30+ Celsius, 100%+ humidity days, I just used a fan I bought at Wal-Mart for $17.77. During "peak heat" times when it got really hot we spent time strategically - we drove the (air conditioned) car, we did errands in town at air-conditioned stores like Wal-Mart, we visited both sets of grandparents who live in retirement living residences that are kept cool, etc. I love air conditioning, but it's just the devil when you get your hydro bill.

  2. Thanks for your input Timeless.
    We are finding that the second story is just too warm during the heat waves. The temperatures are going to get up into the thirties today and we are set to put the A\C on today.
    The circulation fan seems to work ok when temperatures are in the mid twenties, but once the humidity and higher heat comes, the house just can't ventilate enough.

    My two problems are that I have tow zones that I can't easily adapt to the temperatures outside. The upstairs just gets too hot. So I'm pondering the usefulness of awnings over my upstairs windows and possibly insulating the roof more even though I meet current standards. I'm also considering extra insulation in the upstairs exterior walls, but that mean re-doing all the aluminum siding. SO there are costs there to consider.
    Upstairs cross ventilation can be good as I have some good sized windows and when there is a reasonable breeze and not too hot out, it can be livable up there.
    Downstairs is a bit different. The front of the main floor has no opening windows and the large living room window just bakes the room in late afternoon. What to do!