Quote:
Originally Posted by RodFarlee  To estimate your hot tub's electric heating cost, you need three numbers:
(1) temperature drop per day.
Flip the hot tub heater breaker off (leave the circulator/ozonator breaker on, if it has a separate breaker). Wait 24 hours, and measure the hot tub temperature (can use the electronic thermostat, noting the center of the temperature range in which the "Ready" light is on).
(2) Volume of the hot tub in gallons.
(3) Your electric rate, cents per kilowatt-hour, on your electric bill.
In my case, in current weather (40 F day, 30 F night):
(1) temp drop 8 F per day
(2) 330 gallons
(3) $0.062 / kWh
Multiply these three numbers and divide by 13.7 to get dollars per month.
8 * 330 * $0.062 /13.7 = $12/month
Add roughly 10 cents per hour that the hot tub is open, plus 10 cents per hour if the jet pump is also running (each is roughly 1 to 2 kW).
Your hot tub shouldn't be adding significantly to your total electric bill. They are pretty well insulated nowadays.
(Where does that 13.7 number come from?
(3413 BTU/kWh / 8.3 lbs/gal) * 30 days/month = 13.7 F-gal/kWh-month) |
Sweet farlee. You are da' man. Sounds like we got similar backgrounds. The hard calculation is the evalporation rate, but this formula should get a pretty good response.
PDX, it could also be a misread meter. Used to deal with that all the time (I work for an electric utility). But that would need to be a minor misread.
Was there a rate increase over the last year? You need to look at kWh's not actual bill.
You have to be VERY careful with covering your floor vent. On the west coast, trapping moisture in the crawlspace can have very negative effects.
If your crawlspace is not insulated, indeed that would be a bigger bang for the buck than even windows (investment vs return). With a well insulated crawlspace, covering the vests should not have a big effect on the feeling inside the house (unless it is extremely windy), so it sounds like your crawlspace needs insulation.
That however, is separate from the issue of your bill being higher.
does your utility supply you with the avg. temp between the two periods? If so, that would help.