Heating the pool

SeanB

TFP Expert
Platinum Supporter
LifeTime Supporter
#1
I suppose this fits here as well as anywhere else.

People always ask how much it costs to heat up the pool (gas bill) so I thought I would share my experience.

We have heated our pool two times. The first was over Thanksgiving when the water temp was around 60°F. I started the heater the morning of the day before. By that evening, it was already near temp and I was concerned about how big the gas bill would be so I shut off the heat for the evening. I restarted the heater the next morning and the pool was ready around 10:30am. The estimated cost was around $100-$120. That included heating the hot tub off and on that day as well.

The second time we heated was over spring break. We kept it heated for 5 days. I started it the night before about 7pm and the kids were swimming by 11am the next day. We had some bad weather that week so we could not swim each day. On the days we swam, I left the pump running and let the heater cycle off and on as needed. On the rainy days, I left the heater on, but left the pump on the timer so it only heated during the hours the pump was on - about 6 hours a day (3 in the morning and 3 in the evening).

We just got the gas bill and it looks like it cost less than $200 to heat it for the entire week.

So, it's not the sort of thing I'm going to do everyday, but at least it won't break the bank to do it once in a while.

I'll probably heat it one more time in about 2 weeks and hopefully that will be enough to carry us on into summer.
 
G
#2
How much it costs to heat a pool depends on a lot of factors. The first is the type of heater. Heat pumps are much more economical than gas or electric heaters and solar is much ore economical than a heat pump. The size of the pool, the ambient temperature, and whether a solar cover is used on the pool at night also come into play.
 

induce

LifeTime Supporter
Apr 13, 2007
92
Murfreesboro, TN
#4
we kept our last pool (32k) @ 88 degrees late april to early oct using an EUS heat pump. the average cost was about $100.00 a month without a solor cover. it was in the open sun, but also in the open wind. EUS (now a hayward company) claimed if you used a solar cover on that size pool, you could heat it for $45.00 a month. We tried the SC for a while, but it was a hassle for us. However, you could see steam (and $$$) in the morning leaving the pool without the cover.
Love the heat pump!!
 

Rockcrawler

Well-known member
May 8, 2007
174
El Paso, Texas
#5
Go Solar

By all means I am not a Global Warming Geek, but I am a tight wad, solar panels are the way to go, I've had my for 2 yrs, I have 4 sets of 4x20 so for about $600 I can start swimming beginning of April until end of Oct with no cost, granted I am in El Paso, I have had my pool up to 95 and had to turn the panels off. Granted I have not tried to warm my pool in the winter, so I would probally need a conventional heater.

Rob
 

kirbinster

Well-known member
Apr 30, 2007
293
NJ
#6
Its fairly simple to figure out how much it will cost to raise the temperature of the pool. The hard part is figuring out what it will cost to maintain the temperature as their are many variables such as ambient temp, wind, rain, solar cover or not, etc..

To calculate what it will cost all you need to know is how many gallons you have, what the current temp is and what you want it to be, the price of your gas and the efficiency of your heater.

For example, let's say you have a 30,000 gallon pool that you want to bring up from a starting point of 45 degrees up to 80 degrees. Multiply the gallons by 8.34 pounds per gallon and multiply that by (80-45 the temperature difference) - that comes out to 8,757,000 which is how many BTUs you need to add to the pool. If you are paying a deliverd cost of gas of say $1.50 per therm (a therm is 100,000 BTUs) Then it would cost you $131 in a perfect world - but the world is not perfect as your heater does not operate at 100% efficiency. Since it probably only operates around 80% efficinet you would actually spend about $164 to initially raise the temperature with a gas heater.
 

JCJR

LifeTime Supporter
May 4, 2007
267
Miami
#7
I live in Miami, so theoretically I can be swimming almost year round. The two options that most people have down here is a heat pump or solar. Every one who has solar that I have talked to do not recommend it because it does not produce enough heat as promised. I ask if they use a solar cover and every one says that they do not. Well, maybe this is the reason why. Most people install heat pumps but use it one or two times per month and end up with huge electric bills usually $300 plus dollars extra. I asked my PB and he said it is like the AC down here, if you turn it on and off it triples your cost, if you set it at one temp then it will be more efficient. He said I should expect to pay $120 per month (my 24,000 gal 20X40 pool) if I set it at 88 deg in middle Sept and leave it on till April. It makes sense because I leave my AC at 78deg all the time when not at home and pay a lot less than most people who shut if off to go to work. I want to install solar but am taking it it slow. I just installed my pool last month and will probably try a solar cover first to see if I am disciplined enough to leave on and remove when needed. Also, most people are worried by the hurricane winds ripping the panels off. The vendors say that with new technologies and installations methods the panels are rated to 150 mph winds. I will do more research and post after the hurricane season. One thing for sure, 80 deg water is pretty chilly when the outside temp is in the 90's.
 

Rockcrawler

Well-known member
May 8, 2007
174
El Paso, Texas
#8
Solar Heater Check

Came home today, my pool is 95 degrees, 13,000 gallons, solar heaters do work, yes I do have a "solar cover" a cheap $90 one, but it serves another purpose which is saving my clorine, so in turn it pays for itself, if you don't have a cover, then I must expect "your" swimming every minute of the day

if you are real cheap, and I remember this from my dad, when we had our pool he ran 500 feet of 1 inch flexiable black plastic tubing on our roof and plumbed it into the pump, it work and was only about $200 worth of supplies, this was done in So Cali, and the pool would easily break 90 degree w/ a cover

if your solar heater is not producing the promised heat, then you probaly are not using the recommended solar panels, now that is being real cheap

Rob
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#9
In the San Francisco area where I live, the solar heating is great during the hotter summer months (around June through August) but its more iffy in May and especially September while gas is most certainly needed from mid-April, most of October through mid-November. Of course, that's because our pool is used for therapy so is kept at 88F. If we could live with 80-85F temperatures, we wouldn't need the gas much at all. We have an opaque automatic safety pool cover and that saves a lot on the heat loss and on pool chemicals (protecting chlorine from sunlight). However, using a bubble cover would likely result in about twice as much heat retention (half the drop in temperature overnight). My pool loses around 4F in cold weather, 3F in spring/fall, 2F in summer overnight.
 

kirbinster

Well-known member
Apr 30, 2007
293
NJ
#10
Solar is the cheapest way to heat, but you need to have panels that are roughly 60-70% of the surface area of the pool. The next cheapest is a heat pump, then gas then propane. All of these costs go up significantly without a cover. While these numbers are dated I recall seeing a government study that showed to heat a pool in my area for our 5 month season would cost $200 with a solar cover and $1,200 without a cover. Not to mention the additional savings a cover provides in chemical savings and water loss.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,256
Pleasanton, CA
#11
chem geek said:
In the San Francisco area where I live, the solar heating is great during the hotter summer months (around June through August) but its more iffy in May and especially September while gas is most certainly needed from mid-April, most of October through mid-November. Of course, that's because our pool is used for therapy so is kept at 88F. If we could live with 80-85F temperatures, we wouldn't need the gas much at all. We have an opaque automatic safety pool cover and that saves a lot on the heat loss and on pool chemicals (protecting chlorine from sunlight). However, using a bubble cover would likely result in about twice as much heat retention (half the drop in temperature overnight). My pool loses around 4F in cold weather, 3F in spring/fall, 2F in summer overnight.
I live a bit south of you but I got my water into the mid 80s in late March with solar but I am on the other side of the hills which makes a big difference. I have been maintaining 85-90 since then so with solar and a cover, I have managed to extend my swim season quite a bit.
 

peterl1365

LifeTime Supporter
Mar 28, 2007
219
Murrieta, CA
#12
kirbinster said:
Solar is the cheapest way to heat, but you need to have panels that are roughly 60-70% of the surface area of the pool. The next cheapest is a heat pump, then gas then propane. All of these costs go up significantly without a cover. While these numbers are dated I recall seeing a government study that showed to heat a pool in my area for our 5 month season would cost $200 with a solar cover and $1,200 without a cover. Not to mention the additional savings a cover provides in chemical savings and water loss.
I think your ranking of relative cost is only partially correct. While a heat pump is indeed very efficient, here in California it would probably be more expensive than gas. That's because of the relatively high cost of electricity here. Any analysis of energy efficiency should take into account the cost differential between electricity and gas. Unfortunately when I was spec'ing my pool last fall, I wasn't able to find such an analysis.

Just fyi, the marginal electric rate (what you pay when you've exceeded certain "baseline" allocations) is about 45 to 50 cents per kWh. This is as much as 5 times what many parts of the US pay.

Just for kicks, I found this heat pump from AquaCal. Link to HR155

It has a 6.1 COP, which is pretty good, but it draws 5.8 kW. So for my area, at 47.5 cents/kWh, this heat pump would cost me about $2.75 per hour to get 120,000 BTU output. In comparison, my Pentair 400,000 BTU heater, at an assumed 80% efficiency, would draw 4.8 therms at about $1.50 per therm. That would cost about $7.20 per hour to operate.

Doing the math, the cost per 100K BTU works out to $2.29 for the heat pump and $1.80 for my gas heater. So the gas heater winds up costing about 20% less AND heats the pool or spa 3-4 times quicker.
 

kirbinster

Well-known member
Apr 30, 2007
293
NJ
#13
That is a very good point you make - but your situation is quite unusual - in almost every other part of the country a heat pump is more economical.

You also must look at capital costs to be 100% correct. While a heat pump cost more than a gas heater, many people fail to include the cost to run a gas line which is much higher than the cost of another electric circuit at the pool.

Just goes to show there is no one size fits all solution.
 

peterl1365

LifeTime Supporter
Mar 28, 2007
219
Murrieta, CA
#14
kirbinster said:
That is a very good point you make - but your situation is quite unusual - in almost every other part of the country a heat pump is more economical.

You also must look at capital costs to be 100% correct. While a heat pump cost more than a gas heater, many people fail to include the cost to run a gas line which is much higher than the cost of another electric circuit at the pool.

Just goes to show there is no one size fits all solution.
Absolutely. I just wanted to point out that people shouldn't blindly purchase a heat pump without doing the math first. Gas lines generally need to be buried, while electrical conduit can be run almost anywhere.

BTW, I'd venture to guess that California has about 12% of the country's population and maybe 15-20 percent of the nation's pools. It wouldn't surprse me if CA, FL, TX and AZ together represented more than 50% of all the pools in the country.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
#15
We recently needed to have a new gas line put in for a backup generator, a situation very similar to what a pool would require. Because it needed so much gas (as a pool heater would) the meter had to be upgraded. Between the plumber and the gas company it took six weeks and cost almost $3500. Plus having the higher capacity meter pushed us up into a higher pricing bracket, so we pay a little more to heat the house all winter on top of the gas for the generator. The electrical run to the generator was about $1200 for the same distance. A generator needs heavier wire than a heat pump would, but that was probably not a large price difference.

A similar thing can happen with a heat pump, if you need to have your electrical service upgraded to a higher peak amperage. This is far less likely to happen though. A gas pool heater is likely to more than double your gas usage, using more gas than heating your entire house plus a gas range plus a gas dryer. A heat pump, on the other hand, will probably only increase your electrical usage by 10-25%. Thus the gas meter upgrade is far more likely to be required.
 

kirbinster

Well-known member
Apr 30, 2007
293
NJ
#16
Very good to have hard numbers for this. That $2,300 difference is more than the cost difference between a heat pump and a gas heater - further showing that you are generally better of with a heat pump.

While this maybe too late for you - when I put an addition on my house I had a similar situation with the gas for a second furnace. The gas company agreed to put in a larger line and meter at their cost since I would be using more gas which would benefit them.
 
OP
OP
SeanB

SeanB

TFP Expert
Platinum Supporter
LifeTime Supporter
#18
That's nice. My gas compnay didn't use to until they realized people who needed the meter were going to do it even if they did charge an extra $250; after all you're already spending about 30k on a pool, they know they've got you on the hook. :roll: You'd think they would be thrilled to put in larger meters since it just means more revenue for them.
 

RAA

LifeTime Supporter
Mar 28, 2007
46
The Woodlands, TX
#19
I paid Centerpoint $350 for them to upgrade the gas volume regulator, they didn't change the meter. My pool builder asked me for a copy of the bill and they reimbursed me.
 

HardTrance9

Platinum Supporter
LifeTime Supporter
Oct 2, 2009
184
Los Cabos
#20
Hi all,

I know this is an old post from 2007 but I was looking around trying to find out about heating your pool using propane vs. electric vs. natural gas (we don't have here) vs. solar vs. etc.

We have another two bleach pools (not SWG) which have each a pool heater or a pump heater? (don't know yet the proper term).

The owners of both houses were concerned about the high electricity rates down here and we know that if people down here has a pool with an electric pool heater, the bills just skyrocket like crazy!

During my research on the forum I learned today that there are now "heat pumps" which are supposed to be the pumps that saves you a lot of power consumption and $$$.

I took some pictures and have the specs on the two pump heaters installed.

Could you tell me if these are ok to save as much power consumption/$$$ as possible? (I know there are many factors involved)..

Desert type, windy in winter and not much in the summer (with some hurricanes threats july-oct)
Weather high: 102ºF
Weather low: 55ºF (at nights)

House 1:
---------
- Chlorine pool, 13,284 US gallons, rectangular, plaster
Pump Heater: http://www.heatsiphon.com/2006website/p ... ze5HP.html
Residential
Model: Siphon Model Analog SX5 HP
Type: Scroll
PH: 1
BTUH: 95,000
COP: 6.8
Power Req./Voltage: 208/230V 1-60 Hz
Max. Circuit Breaker: 50 amps
MCA: 42.2 amps
MOP: 74.3 amps
Compressor: 32.1 RLA 148 LRA
Fan motor: 2.1 RLA 0.39 HP

House 2:
--------
- Chlorine pool, 8,541 US gallons, rectangular, plaster
Pump Heater: http://www.heatsiphon.com/2006website/p ... .25HP.html
Residential
Model: Siphon Model Analog SX3.25 HP
Type: Scroll
PH: 1
BTUH: 70,000
COP: 6.2
Power Req./Voltage: 208/230V 1-60 Hz
Max. Circuit Breaker: 40 amps
MCA: 28.9 amps
MOP: 50.3 amps
Compressor: 21.4 RLA 137 LRA
Fan motor: 2.1 RLA 0.39 HP

The owners are scared and they are thinking in probably changing this heat pumps for propane or other source, but after reading, I think this wouldn't be a good idea?

Any help or overall comments would be greatly appreciated!
 

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