Hi All! Question from a new pool + spa owner (currently in the middle of construction). We have a 400k BTU Raypak heater in place, and the current plan is to have it connected to our 1000 gallon propane tank that serves the house. The run from heater to tank is about 60-75 feet, and I'm curious what thoughts are on going with the plan as-is, or installing a dedicated 320 / 500 gallon propane tank just for the pool/spa? We'd likely be running the spa in the winter, as we're told we can do this (possibly a question for a different post!), and then run the heater for the main pool to extend the season by a month or so on each end. We are in the north east region of Maryland.
New Pool / Propane Heat Question
- Thread starter pooldewd
- Start date
- Jun 7, 2017
- 9,192
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
I would run from the existing tank. You do realize how much that propane heater is going to cost right? Especially in the winter?
- Jul 21, 2013
- 53,601
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Would you like to discover that your entire house is out of gas because your pool heater consumed it all?
A separate propane tank for the pool will firewall off the pool/spa gas usage from affecting your house.
I think you will find keeping your spa open in the winter impractical but the devil is in the details of how your pool and spa were designed and your equipment.
What model number Raypak heater do you have?
A separate propane tank for the pool will firewall off the pool/spa gas usage from affecting your house.
I think you will find keeping your spa open in the winter impractical but the devil is in the details of how your pool and spa were designed and your equipment.
What model number Raypak heater do you have?
- Jul 21, 2013
- 53,601
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
I'm in southeastern PA (southern Chester County, close to the border with Cecil County MD). I'll relate a story from my pool builder when we were considering the open-spa-all-winter option. They had a client who insisted on building the pool and spa so that the spa could run while the pool was closed. In the first winter they spent about $10,000 on propane, mostly for freeze protection. After that, they just closed the spa along with the pool. I think conventional wisdom is that if you want a year-round spa you should get a stand alone hot tub as they are much better insulated than an attached spa.
We have our heater attached to the house propane tank (500 gallons). It's never been an issue, although in addition to the propane heater we have a heat pump and mostly use that for pool heating and just use the propane heater for spa sessions.
We have our heater attached to the house propane tank (500 gallons). It's never been an issue, although in addition to the propane heater we have a heat pump and mostly use that for pool heating and just use the propane heater for spa sessions.
About $6.76 an hour, with our current propane prices. For the pool itself in the spring / summer, with the autocover and being south facing, not really sure how many hours we'd be looking at to keep it around 85... Season 1 will be a bit of an experiment.
As far as for the spa component in winter, keeping the spa water at 58 F until we plan on using it, I'm actually less sure on that one... but welcome to tips!
No no, definitely don't want to discover all my house out of gas
! Having the firewalled off tank was certainly in the thought process. We might very well find keeping the spa open in the winter to be impractical, and I appreciate the data points to see if it's something we should attempt.
Model 406A
I know about how much it will cost to run per hour yes (~$6.76), but I don't have a clue how many hours I'm looking at to sustain a 58F spa temperature (with a bump to ~101F when we plan on using it).
$10,000 on propane, that is... high. The heat pump / gas heater combination was actually something I asked about but was talked out of; so I'm happy to hear someone else has that combination and is enjoying it. Their thinking was that being a south facing pool, with a navy blue autocover, we'd have enough solar gain to make the heat pump with gas overkill. I did ask the electrician to run a line from the service panel to the equipment pad in case we opt for this route one day, so that might be worth exploring in the near future.
The thinking is to keep the spa (covered of course) at a temperature of 58F when not in use, then bump the temp when we want a spa session. While the idea is nice, like mentioned before it may indeed be impractical.
- Jul 21, 2013
- 53,601
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Do you have a backup generator for power outages and will it be able to run your pool equipment?
I also have a 400k btu (input) propane heater for my pool / spa. Propane is about 91.5k btu per gallon. Running the heater for an hour uses about 4.4 gallons of propane. Propane delivered costs me $3.40 a gallon = about 15 bucks per hour to run the heater. I use the heater for the spa often — takes about a half hour in the Fall or early Spring when the water is below 70 degrees F, much less if the water is warmer. But quick to heat is also quick to cool. Keeping it warm 24/7 would be very expensive. I’ve used the heater to heat the entire pool exactly twice, for pool parties. I has been a while since I did the calculations but I recall for my 15k gallon pool, it costs me over $100 to raise the temp by 20 degrees F, one time. Every day, not a chance. Had to make it clear to my dear wife early on, ah, no, we won’t be regularly heating the pool lol.
We also have the 1,000 gallon propane tank, underground. I forget the numbers but it was much less expensive for us to get a high pressure tap off that tank and run over 100’ of gas pipe to the heater, than it would have been to obtain and have installed a second tank. Our propane co. makes a Spring delivery that runs the pool and smaller stuff all Summer, and makes a second delivery just after Christmas that then runs the heat for the house, so there’s not any risk of running out, but if the pool heater were also active in Winter, it would be a different story.
If you’re still contemplating heating the spa in Winter, a separate tank isn’t really a “fire wall” against running out because if the separate spa tank runs out, sure, the house is warm, but the spa equipment and piping might be destroyed. Either way you’d be well served to calculate* the propane needed by the spa based on historical temps. You can also use that to determine if you really need a second tank or just more frequent deliveries. The propane co. can likely help with that. I’d also note it’s easier to remember to every so often keep an eye on the propane level in one tank than two, but if you have a good memory, that might not be a factor.
The way my spa is set up (I assume most are set up similarly), it is possible to completely isolate the spa from the pool and leave the spa open in the cold but our builder advised against leaving it open if freezing is expected. Lots can go wrong that is really hard and expensive to fix.
*calculating propane use is pretty easy: 1 btu will raise 1 lb of water by 1 degree F. A gallon of water is about 8.3 lb. A gallon of propane supplies about 91.5k btu. Your heater is likely about 80% efficient in using those propane btu’s.
We also have the 1,000 gallon propane tank, underground. I forget the numbers but it was much less expensive for us to get a high pressure tap off that tank and run over 100’ of gas pipe to the heater, than it would have been to obtain and have installed a second tank. Our propane co. makes a Spring delivery that runs the pool and smaller stuff all Summer, and makes a second delivery just after Christmas that then runs the heat for the house, so there’s not any risk of running out, but if the pool heater were also active in Winter, it would be a different story.
If you’re still contemplating heating the spa in Winter, a separate tank isn’t really a “fire wall” against running out because if the separate spa tank runs out, sure, the house is warm, but the spa equipment and piping might be destroyed. Either way you’d be well served to calculate* the propane needed by the spa based on historical temps. You can also use that to determine if you really need a second tank or just more frequent deliveries. The propane co. can likely help with that. I’d also note it’s easier to remember to every so often keep an eye on the propane level in one tank than two, but if you have a good memory, that might not be a factor.
The way my spa is set up (I assume most are set up similarly), it is possible to completely isolate the spa from the pool and leave the spa open in the cold but our builder advised against leaving it open if freezing is expected. Lots can go wrong that is really hard and expensive to fix.
*calculating propane use is pretty easy: 1 btu will raise 1 lb of water by 1 degree F. A gallon of water is about 8.3 lb. A gallon of propane supplies about 91.5k btu. Your heater is likely about 80% efficient in using those propane btu’s.
Last edited:
- Nov 12, 2017
- 11,950
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Random thoughts...
Caveat: I've never owned any kind of spa, but I've been in each kind plenty enough to know that if I was to build a pool and spa, I would never want a built-in spa. If I wanted pool and spa integrated, it would be faux, where a stand-alone spa was somehow sunken and incorporated into the deck next to the pool, but not actually share the pool water. This goes double if I wanted to use it year-round, and triple if I lived in a cold climate.
Even if you went crazy with a built-in, asking for as many steps and levels and jets as possible, it's still going to be concrete seat in a concrete box. You might get one jet to yourself, digging a hole into the middle of your back. And you could get it to bubble if you want. It's a fun place to socialize, and warm up, but that's it. It bleeds heat (and so your wallet) because they're difficult to cover, concrete is a lousy insulator and you've got to pump water all the way back and forth to your equipment pad to get it heated. Really inefficient.
Vs a standalone: smooth fiberglass with at least four stations, contoured into multiple positions for multiple sizes of people, recliners, head rests, jets all over your body, neck and feet. All adjustable, many of them separately adjustable. That's what I think of when I think jacuzzi, not a concrete whirly pool box.
It would cost less to heat. It would heat up faster. Much easier to cover to retain that heat. And they're insulated to save heat (and money!). And as I said, you can build it into your pool deck if you want to, to get all the advantages of a built-in, but with so much more features. Or you can isolate it elsewhere in your yard for ultimate privacy. If you're set on getting that spillover look, you can have that too, with a cleverly installed water feature. The waterfall would be pool water, and your spa would be isolated.
For the cost of a built-in, you could probably buy at least two stand-alones! You should price each.
I never understood the appeal of a built-in, because I've been in a stand-alone. If it's not too late, and if you haven't already, try out a few built-ins (at a friend's pool or at a hotel or local spa) and then try out a few stand-alones. That way you could make a more informed decision. If your construction phase is already past this point, then sorry, uh, never mind.
Caveat: I've never owned any kind of spa, but I've been in each kind plenty enough to know that if I was to build a pool and spa, I would never want a built-in spa. If I wanted pool and spa integrated, it would be faux, where a stand-alone spa was somehow sunken and incorporated into the deck next to the pool, but not actually share the pool water. This goes double if I wanted to use it year-round, and triple if I lived in a cold climate.
Even if you went crazy with a built-in, asking for as many steps and levels and jets as possible, it's still going to be concrete seat in a concrete box. You might get one jet to yourself, digging a hole into the middle of your back. And you could get it to bubble if you want. It's a fun place to socialize, and warm up, but that's it. It bleeds heat (and so your wallet) because they're difficult to cover, concrete is a lousy insulator and you've got to pump water all the way back and forth to your equipment pad to get it heated. Really inefficient.
Vs a standalone: smooth fiberglass with at least four stations, contoured into multiple positions for multiple sizes of people, recliners, head rests, jets all over your body, neck and feet. All adjustable, many of them separately adjustable. That's what I think of when I think jacuzzi, not a concrete whirly pool box.
It would cost less to heat. It would heat up faster. Much easier to cover to retain that heat. And they're insulated to save heat (and money!). And as I said, you can build it into your pool deck if you want to, to get all the advantages of a built-in, but with so much more features. Or you can isolate it elsewhere in your yard for ultimate privacy. If you're set on getting that spillover look, you can have that too, with a cleverly installed water feature. The waterfall would be pool water, and your spa would be isolated.
For the cost of a built-in, you could probably buy at least two stand-alones! You should price each.
I never understood the appeal of a built-in, because I've been in a stand-alone. If it's not too late, and if you haven't already, try out a few built-ins (at a friend's pool or at a hotel or local spa) and then try out a few stand-alones. That way you could make a more informed decision. If your construction phase is already past this point, then sorry, uh, never mind.
Last edited:
Haha yes, we don't plan to be heating the pool itself often, and certainly not in the winter! I've found decent data to calculate energy / costs to heat the spa... modeling the heat loss is a different can of worms. The spa is built to be run completely isolated, AND fit under the autocover which the PB said would seal around the edges of the spa (in the winter) and keep at least some heat in; but there are a lot of variable to consider just how practical / impractical this would be. The good thing we have going for us is over the last year our propane price per gallon delivered has ranged 1.49 - 1.69 per gallon delivered (we own the tank).
Attachments
- Nov 12, 2017
- 11,950
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
So sorry, I didn't know you were that far along with construction. Please excuse the comments about stand-alone spas.
The auto cover will not help much at all, if any, with the heat retention, other than what is provided by reduced evaporation. In the winter your spa will be surrounded on three sides by ice cold water, insulated only by the concrete (which is no insulation at all). In your calcs, I'd say you can count on heating the spa from scratch each time you use it. The spa temp will start at whatever the temp of the pool will be. And it will spill it's heat quite quickly when the heater goes off, no matter how it is covered (even with an insulated spa cover). Sorry for the spoiler.
The auto cover will not help much at all, if any, with the heat retention, other than what is provided by reduced evaporation. In the winter your spa will be surrounded on three sides by ice cold water, insulated only by the concrete (which is no insulation at all). In your calcs, I'd say you can count on heating the spa from scratch each time you use it. The spa temp will start at whatever the temp of the pool will be. And it will spill it's heat quite quickly when the heater goes off, no matter how it is covered (even with an insulated spa cover). Sorry for the spoiler.
Last edited:
No worries! In general, we knew stand-alone spas would be better for efficiency etc., we chose this route on aesthetics. The practicality of running it year round, we'll see. For maintaining a "standby" temp of 58F, I'm really curious how quickly it "spills the heat" to gauge my tolerance for keeping it open year round.
Can you elaborate more on the ineffectiveness of covering a pool / spa to reduce heat loss? This seems to run contrary to everything else I've read, but at 8:22 PM after a long day I could totally be reading that the wrong way
.
- Nov 12, 2017
- 11,950
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Covering a pool does mitigate heat loss. I believe it has more to do with blocking evaporation than anything else (evaporation cools). What I meant was: you're going to have so much heat loss right through the concrete walls of the spa that any help a cover might provide will hardly make a difference.Can you elaborate more on the ineffectiveness of covering a pool / spa to reduce heat loss? This seems to run contrary to everything else I've read, but at 8:22 PM after a long day I could totally be reading that the wrong way
Covering a pool to keep it warm in the summer works because of the evaporation factor. The pool water is surrounded by concrete, which provides very little insulation, but outside of the concrete is typically dirt, which provides a bit better insulation. Plus, while the dirt (in summer) might be cooler than the ambient air temperature, it won't likely be cold.
Because your spa is inside the body of the pool (as opposed to up above it, or off to the side, it's going to be virtually surrounded by water (not dirt). That water in the winter is going to be cold. Mine gets down to 45° here in California. I expect pool water in Maryland will be even colder (does it freeze?). So you've basically got a massive heat sink that will suck all the heat out of the spa. Unless you heat your pool in the winter, the cover won't do anything to keep the pool water warm, so the cold pool will draw heat from where it can: your cozy spa. The cover over the pool or the spa might retain a little heat, but not enough to make a difference in your spa heating costs.
I'm no thermodynamic expert, by any means. I'm just basing this hypothesis on two things I know to be true: your pool is going to be in the 40s (or colder) and the concrete around your spa will not provide much, if any, insulation.
Put another way: picture floating a Tupperware bowl full of warm water in an ice chest full of 40° water, covered with a tarp (not the ice chest lid). How long will the warm water stay warm? And even if you covered the bowl separately, do you think the Tupperware lid would make any difference?
Let's see if @JoyfulNoise or @JamesW can punch any holes in my theory.
Last edited:
- Jun 7, 2017
- 9,192
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
MD does freeze. Sometimes a hard freeze. I can't imagine remaining open. That's going to cost you a fortune just in electric since the freeze protect is going to be constantly engaged. Your entire pool will need to be maintained just for the hot tub portion. I suspect you'll be spending close to $1k/month in propane and electric and perhaps more.
I found some rough rules of thumb. Until experts come by, a little noodling just for s&g: According to Dr. Google, Ph.D., surface area of the water is the driving factor of pool heat loss, about 80%. So rough rule of thumb for surface heat loss in btu / hr is surface area times delta t (in degrees F) times 5 (yeah, rough rule of thumb lol). So let’s say 8x8 spa and delta t of 58-32 = 26. So about 8,300 btu / hr. about 6 million btu / mo. and using 80% heater efficiency = about 82 gallons of propane per month. Divide by 0.8 to account for the other 20% guestimated loss other than surface and presto, when outdoors is hovering at freezing and the spa is maintained at 58, expect 102 gallons of propane use per month.
Latent heat is ignored — spa is pretty shallow and that also gets too complicated lol. There will also be losses through the plumbing and equipment, etc., etc. Add another % fudge factor and say 120 gallons / mo.
If Dr. Google is correct, it might, in theory, be possible. Still very risky but at least sort of do-able. Since you’ve made the commitment to have the spa, maybe experiment in the Fall and see what your actual heat loss looks like. My bet is I’m way off but who knows lol.
Latent heat is ignored — spa is pretty shallow and that also gets too complicated lol. There will also be losses through the plumbing and equipment, etc., etc. Add another % fudge factor and say 120 gallons / mo.
If Dr. Google is correct, it might, in theory, be possible. Still very risky but at least sort of do-able. Since you’ve made the commitment to have the spa, maybe experiment in the Fall and see what your actual heat loss looks like. My bet is I’m way off but who knows lol.
Last edited: