heat, Heat, HEAT!

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jerryk1234

Bronze Supporter
Jan 22, 2018
118
Hayward, CA
So we got our 60-foot lap pool together and filled - my wife's 30 year dream finally come true! We heated it for two days. I did some math, and the power bill just came in, and we decided together that we can't afford to heat it. I think the heat was something like $75/day, although the bar graph from the utility is a little confusing.
Lessee - $75/day times 30 days a month - over two grand in utility cost. Too rich for my blood.

We have an autocover and a solar water heating system, but no solar heat this time of year....

I wonder if a heat pump would be any better? We have a 7.5kw photovoltaic system. It's enough to drive our electric bill ( pre-pool ) down to zero.

A 140,000BTU heat pump pulls about 30 amps. Oh no, our electrics are maxed out. Can't do that.
...or could we? The sauna has a 30A circuit. We could replace the sauna heater with a gas one, freeing up 30A for a heat pump.

Maybe later. Right now, the wallet is a little stressed.

One of the pool guys said he had only ever encountered one customer who heated an uncovered pool full blast all winter. She was a Google VP...
 
A heat pump should be significantly cheaper to run than your gas heater, especially with the cover. What heat pump are you looking at that's 140k BTU and pulls 30 amps? A Raypak 8450 is 140k BTU and min circuit ampacity is 42.
 
kairus00 said:
A heat pump should be significantly cheaper to run than your gas heater, especially with the cover. What heat pump are you looking at that's 140k BTU and pulls 30 amps? A Raypak 8450 is 140k BTU and min circuit ampacity is 42.
Click to expand...

Hayward HP21404T. They say it requires 50A "protection", but pulls 7.2 KW. At 240V, that's precisely 30A. There's probably a starting surge for the compressor.


We not only have the cover, we have a solar system with 10 Gull Industries Sun Coils.

- - - Updated - - -

...and 7.5KW of Photovoltaics. In general, I am happier with high one-time investments than with high monthly expenditures.

- - - Updated - - -

My wife dreams of an all year round pool, and it pains me not to be able to give it to her.
 
A heat pump and covering the pool when not in use will cost FAR, FAR, FAR less than your calculations. Depending on many factors, I would guess $200 monthly.

Your calcs are off to begin with......I would guess a 400k gas heated pool to be around 400 monthly but a heat pump would be a much better option for you, I think
 
Dave S. - how much does natural gas cost in your area? Here, it's $1.85 per therm. That's "tier 2". There are two tiers. They give you a teaser rate of $1.35 per therm on tier one, just so you have enough to cook and not freeze to death. The tier 1 stuff is long gone by the time we get to heating the pool.

If I could heat the pool during the winter for $400/month, I would do so.

My best read of the utility company's tiny bargraph is that in three days of heating the pool, I spent $150. That's $50/day. A complication - they hadn't installed the autocover yet. Also, it included a day getting it from 62 degrees ( as filled ) all the way up to 80.

The first night with a functional autocover, it lost 8 degrees; from 80 down to 72. Here's where things get strange: We know what a BTU is - it's defined in terms of heat energy to heat a pound of water 1 degree fahrenheight. My spreadsheet tells me that we should be getting 1.5 degrees per hour of heating. Yet we were
actually getting more like 1 degree. That calculation took into account the quoted 83% efficiency of the heater, and another 20 percent lost to the gods of heat.

If we are actually delivering 400K BTU, that's about 4 therms an hour ( my spreadsheet used the actual # ), or $7.40. 8 hours of that is about 60 bucks.
 
I don't have natural gas in my area so I was basing my response on what others have reported over the years. Most are in that $400 range but I overlooked your California address.

Secondly, not using the pool cover is HUGE. Most of your btu loss is radiant at night (unless the winds are REALLY high) and the cover will drastically reduce both. And, as you recognize, elevating the temp from 62 to 80 is wa-a-ay different than maintaining 80 for 24 hours.

Others will chime in with real usage on gas but I think it will be closer to $400 than you think.

A heat pump would still be a better alternative but the front money on a new heat pump will be hard to recover since you already have a gas heater.
 
jerryk1234 said:
Dave S. - how much does natural gas cost in your area? Here, it's $1.85 per therm. That's "tier 2". There are two tiers. They give you a teaser rate of $1.35 per therm on tier one, just so you have enough to cook and not freeze to death.
Click to expand...
OUCH! Here in Illinois, my gas is roughly $0.45/therm, including delivery, not including fixed monthly customer charge. Not sure if there are tiers, we use it for cooking and heating our 1200 square foot townhouse so we don't use a whole lot.
 
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