Cost to heat not as bad as I thought??

[jlamb5990]

Someone please tell if my math is way off here. We are thinking of heating this pool this weekend and having some people over. Temp should be in the mid 80s. Water temp is currently around 72-73 and I want to get it to about 90. We have a master temp 400.

I used a generic pool heater calc and it came out to about 4 hours or so. Based on what I’ve read, the mastertemp 400 runs about 4 therms per hour. Gas Price where I’m at is about $1 a therm (roughly). So based on that math - 4 hours x 4 therms = 16 x $1 = $16??

Am I doing something wrong or should cost less than $20 to get us to 90 this weekend??

 

[BMerrill]

Great spreadsheet to Estimate your cost to heat a pool link on TFP

 

[thezookman]

I used an excel sheet that someone here on the forum made up. For me, 1 hour of heating is about $5.42, according to the spreadsheet calc. So it would be about $22 for four hours. I am at about $1.38 per CCF, so about $1.35 per therm, If i converted correctly.

 

[jlamb5990]

I used an excel sheet that someone here on the forum made up. For me, 1 hour of heating is about $5.42, according to the spreadsheet calc. So it would be about $22 for four hours. I am at about $1.38 per CCF, so about $1.35 per therm, If i converted correctly.

Yep it sounds like my math works out about the same. $3.88/hour to heat (.97/CCF) so $15.52 to heat for 4 hours (roughly, I’m using a 1:1 for therms to ccf since it’s close enough)

 

[HeyEng]

Our rates are around $8 a dekatherm (or about .80 per therm) which translates to $3.20 and hour or $77 a day. I have found the 80% efficiency (400K BTU = 320K BTU) to be pretty accurate over a few years of keeping detailed records of heater use.

 

[Toxophilite]

Our rates are around $8 a dekatherm (or about .80 per therm) which translates to $3.20 and hour or $77 a day. I have found the 80% efficiency (400K BTU = 320K BTU) to be pretty accurate over a few years of keeping detailed records of heater use.

I'm playing with the above calculator, and paying $2.89/gal of propane. How does that math out on cost/therm? Time works out good for me on one part, but the cost is way off and sure just not converting correctly. I'm told by the gas company that fills that I should expect about 1 gallon per hour burn.

 

[HeyEng]

I'm playing with the above calculator, and paying $2.89/gal of propane. How does that math out on cost/therm? Time works out good for me on one part, but the cost is way off and sure just not converting correctly. I'm told by the gas company that fills that I should expect about 1 gallon per hour burn.

Oh, that I am not sure of. As I understand, a gallon of propane is about 91,000 BTUs, so I don't *think* that the one gallon per hour holds weight (your sig line shows a 400K BTU heater). If it is 80% efficient, then I would guess it would burn closer to 3.5 gallons per hour...so $10'ish an hour by my back of the napkin math. I am sure someone here that is smarter than me (there are a lot of them!) will confirm/correct my thoughts/math.

 

[thezookman]

I'm playing with the above calculator, and paying $2.89/gal of propane. How does that math out on cost/therm? Time works out good for me on one part, but the cost is way off and sure just not converting correctly. I'm told by the gas company that fills that I should expect about 1 gallon per hour burn.

From what I have read, a safe bet for propane pool heaters is 1 gallon per 100,000 btu per hour. So a 400,000 btu heater would be about 4 gallons per hour. So your cost per hour would be about $11.56. This is at full on for that hour. To maintain a temperature, the cost per hour goes down since the heater won't be on the whole time...

 

[Toxophilite]

Oh, that I am not sure of. As I understand, a gallon of propane is about 91,000 BTUs, so I don't *think* that the one gallon per hour holds weight (your sig line shows a 400K BTU heater). If it is 80% efficient, then I would guess it would burn closer to 3.5 gallons per hour...so $10'ish an hour by my back of the napkin math. I am sure someone here that is smarter than me (there are a lot of them!) will confirm/correct my thoughts/math.

Yep, that's what my calc issue was showing me, about so, but had that gallon/hr stuck in my head too. Sheesh what a number!

 

[Toxophilite]

From what I have read, a safe bet for propane pool heaters is 1 gallon per 100,000 btu per hour. So a 400,000 btu heater would be about 4 gallons per hour. So your cost per hour would be about $11.56. This is at full on for that hour. To maintain a temperature, the cost per hour goes down since the heater won't be on the whole time...

Thanks, I was basing on 1 therm = 1.1 gallons. In Texas, I think NG is a good bit higher than the $1/therm of OP, but haven't been on NG for 4 years since moved, so don't know. The cost calc was shocking me in comparison to that and figured it was me and my conversion, but, it ain't.

 

[Rocket J Squirrel]

Wow wow wow, you folks are lucky. I pay $2.53/therm per latest bill. Only the spa gets heated with NG.

 

[BMerrill]

$1.41 CCF here. Was $1.04 a year ago.