Cost of running a pool heater

michaelr0

Active member
Mar 26, 2018
35
Omaha, NE
Second season pool owner here and after getting a grip on the water chemistry last year, I spent some time to understand the heater and its cost a little better. I am posting this mostly to share the info and as all of this is freshly googled knowledge, if I am wrong somewhere, I appreciate feedback.

I have a 300k BTU / hour heater. My gas company charges per therm currently $0.3996. 1 therm = 100k BTU. The cost to run the heater one hour is 3 therms * $0.3996 = $1.20. I have a 20,000 gallon pool. One BTU raises one pound of water by 1 Fahrenheit. There are 8.34 pounds in a gallon, so it takes 8.34 BTU to raise a gallon of water by 1 F. A 20,000 gallon pool requires 166,800 BTU or 1.67 therms. Given my price of gas from above, it costs 1.67 therms * $0.3996 = $0.67 to raise my pool by 1 F.

I heated the pool from 65 F to about 85 F a couple of days ago for a total of $13.35. This was much less than I expected.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,695
Northern NJ
Your heater is about 80% efficient. So your 300K heater only delivers about 240K BTUs to the water. The rest goes up the exhaust.
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,872
Damascus, MD
This does not sound correct. I calculated my 400kbtu heater at $4.50/hour. Are you factoring in gas transmission costs? My therms are almost twice as much when calculating that in. Take your total gas bill cost and divide by your total therms used.
 

Silver_2000

Gold Supporter
LifeTime Supporter
Nov 29, 2015
560
Carrollton tx
we heat our pool up for about a month in the spring and extend the season a month in the fall. Set the temp to 85 ish, and it costs us about $150-200 ish additional gas each of those 2 months.
I tried taking pictures of the meter before and after and doing the gas bill math and decided I didnt want to know...
 

jimbethesda

Gold Supporter
Jul 2, 2018
443
Austin, TX
This does not sound correct. I calculated my 400kbtu heater at $4.50/hour. Are you factoring in gas transmission costs? My therms are almost twice as much when calculating that in. Take your total gas bill cost and divide by your total therms used.
I calculated mine and got $1.75/hour for my 400kbtu heater, more in line with the OP.
 

Silver_2000

Gold Supporter
LifeTime Supporter
Nov 29, 2015
560
Carrollton tx
some data - april bill was $80 - May bill was $300
May Details 4/3/3030 to 5/4/2020
CURRENT GAS CHARGE TOTAL 277.93
Residential R020 Customer Charge 19.60
Consump Chrg 458.000 CCF @ 0.17423 79.80
Rider GCR 458.000 @ 0.3898 178.53
TAX/FEE CHARGE TOTAL 30.26
Rider FF @ 0.07600 21.12
Reimbursement of MGRT 6.09
City Sales Tax 3.05
CURRENT CHARGES 308.19

$308/458=$0.672

Also turned the Hot Tub Schedule back on as well. It heats to 99 every night for a few hours.
 
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PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
4,872
Damascus, MD
I have a Master Temp 400. A couple weeks ago, I heated my pool from 65 to 85 degrees. It took 12 hours (1.67 degrees per hour) @ $1.12 per therm. It cost me over $50.
You are paying more along the lines of what I pay. I guess in TX gas is CHEAP!! If my gas cost that little I would be in the pool right now. They pay less than 1/2 what you and I pay.
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,598
Rancho Cucamonga, CA
You are paying more along the lines of what I pay. I guess in TX gas is CHEAP!! If my gas cost that little I would be in the pool right now. They pay less than 1/2 what you and I pay.
Yep...the good thing is I rarely have to use the heater. Winter left and spring came suddenly. Since I bumped up the water temp, it's stayed in the 80+ degree range.
 

michaelr0

Active member
Mar 26, 2018
35
Omaha, NE
Thanks for all the feedback. Interesting how much more some of you are paying for gas. Wow. I had no idea what a delivery charge is. In my case there isn't any. My gas company charges the base fee and an infrastructure replacement fee. That's it. I'd have to pay this fee anyway for the range and grill, so I am not counting it toward heating the pool.

2020-05-23_8-11-47.jpg
 

etuser

Well-known member
Mar 28, 2020
130
Houston
For those looking at the total bill for the month, it doesn’t really seem fair to include all the base and fixed fees in the analysis (unless there are no other gas needs for the property). Seems like only variable cost ought to be considered. Just my 2 cents.
 
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