Gas heated hot tubs?

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Hi, Does anyone know if the major hot tub manufacturers make hot tubs heated with natural gas? I know you'd still need electric for filtering and pumps but I would like to heat it with gas. I've seen aftermarket heaters but why add almost $1000 to the price if you don't have too. Thanks, Jeff
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If you had to shove a (low BTU) tankless WH in one I would expect at least $1K upcharge. Inline electric heaters are small and fit inside the tub shape easily, gas would be much bulkier no matter what.
If you insist, you might try plumbing a small gas tank WH in the crawlspace or nearby and rig up some sort of recirculation system with it in the loop. This would require a bit of creativity and rework. Definately not standard and causes you to put gray water through the WH tank which might have its own problems. It also adds >25Gal to the tub capacity requiring more chemicals etc.
Do you prefer gas or are you trying to avoid upgrading your breaker box from 100A to 200A? That's a better investment than a wacky hot tub IMO. Electric is more efficient than gas too, check the cost per BTU heating for gas vs electric in your area (try your utilities website)
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PipeDown wrote:

While I would agree that an electric heater makes the best sense for an above ground fiberglass spa (ie well insulated) as opposed to a concrete in ground spa.
I must take issue with the comment that
"Electric is more efficient than gas"
In Orange County, CA here are the numbers
15 cents per kwatt-hr
$1.40 per therm (100,000 btu)
3411 btu per kwatt-hr
So.......................1 therm is ~ 30 kwat-hr
equal amounts of energy (100,000 Btu).............. $1.40 for natural gas vs $4.40 for electricity
unless I made a mistake in my calcs, electricity costs about 3x more for the same amount of energy
At least in my town, electricty would have to be less than 5 cents per kwatt-hr to be equal in cost to nat gas.
cheers Bob
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For most of the US NG is still 50% cheaper than electric. Do the math with your local rates, long term for me Ng would be cheapest. I use a 450$ Bosch for all my HW and save more than 50% over an electric tank I replaced. A good electric may require a service upgrade if you are loaded on use now.
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On Thu, 30 Mar 2006 06:27:09 -0600, snipped-for-privacy@webtv.net (m Ransley) wrote:

My hot tub is kept at 102 degrees, 24/7 x 12.... location is in Western Maryland.( 20 minutes to Pa, 15 to either WV or Va.. 60 miles from DC...
Cost averages out to about 20 bucks a month ..for that kind of money having the tub ready to use at any time is, at least in my opinion, cheap...
It could be made slightly cheaper by installing more then standard insulation inside the enclosure... plus if you want to wait to use it later inthe day...just keep it cooler... tuen it up a few hours before use and save a buck ...
Just my opinion... Electrifc rates here are about 7 cents a KWH after they add tax, fees, (and distrubution ..delivery... charges (???) etc...
Bob G.
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wrote:

WHAT!!! Electricity is more "efficient" than gas - ya gotta be kidding.
Yeah, I've heard those arguements that electricity is 100% efficient at the point of use.
That arguement totally disregards the losses at the power plant, losses in the transmission lines, in the pole transformers, etc, etc.
In New England resistance electric heating is over 3 times MORE expensive than gas. In most of the US the situation is the same.
The only areas that might have cheap electric heating are those areas served by hydroelectric generating plants. That's not much of the country.
However, I agree with you about the potential difficulties of retrofitting a standard hot tub with gas heat.
Doug
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A agree. Expensive or costly is a much better way of putting it, as opposed to efficiency, which is misleading.
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I did mean efficiency!
You've mistaken efficiency for cost of ownership. (though I did leave room for y'all to fill in what you wanted, I'm not suprised by the confusion)
I should have gone on further to say: "Electric is more efficient than gas too, check the cost per BTU heating for gas vs. electric in your area (try your utilities website) [To see which ends up costing less]. (With current trends, it may only be a few more years before Electric is cheaper)
I was referring to the fact that 100% of the electric energy is converted to heat while a gas system has to vent at least some heat out the flue with the combustion gasses.
Efficiency is the ratio of energy spent to that used to do useful work (in this context). And that's the way I used it. I would have used the word value or cost if I meant that.
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PipeDown wrote:

Then I don't know what you're talking about here. You said:
"Electric is more efficient than gas too, check the cost per BTU heating for gas vs electric in your area (try your utilities website) "
Why would anyone care which is more efficient? The real issue is which is going to cost more for fuel to get the same amount of heat and the above statement you posted makes the claim that electric is cheaper than gas. I don't anywhere that you can heat anything with electric for less than natural gas. There probably is some screwy place where that exists, but by and far, electric resistance heating is the highest cost way of heating anything, which is why it's used as a last resort.
The efficiency issue is a red herring because while gas may be 80-95% efficient, vs electric at 99.9% at the point of use, that still doesn;'t make it anywhere near as cost effective as gas. And then if you want to take some environmental view and look at the big picture, electric becomes way less efficient because the prime mover used to create it isn't 100% efficient and there are significant losses in distribution. In fact, some electric is even produced from natural gas to begin with. You still think it's more efficient burning gas 500 miles away, converting it to electric, sending it down a line and then running it through a resistor, as opposed to just burning it there?

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Now your just turning this into a physics NG, I was just clarifying an incomplete sentence.

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Make sure you understand this correctly...
In many applications, at the point of delivery electricity is 100% efficient, something a gas combustion burner will never approach. An electric hot water heater may be said to be 100% efficient minus whatever heat leaks out through the casing and the attached pipes.
However, even with the inefficiency of gas, this ignores the economics that give gas a much higher heat content, so that even a gas hot water heater that is only 65% efficient is still cheaper to run than an electric, even though about 35% of the heat goes up the flue.
Beachcomber
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Electric is more efficient at the point of use than gas (although more expensive), but it certainly isn't more efficient overall. Most of that electricity will come from burning a fossil fuel, and it is more efficient to burn it directly at the point of use.
Cheers, Wayne
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replying to PipeDown, R. Lamar wrote:

Gas heating of a hot tub is far cheaper than electicity. I have done my homework on this issue and have found your info to be incorrect in my region of the world. I can also get longer life from a natural gas heater versus the electric heater supplied by the tub manufacture. This results in less money spent on maintenance. I am a master plumber by trade and am currently involved in purchasing a natural gas hot tub system or building what I want. I would love your input on tub manufactures and heater manufactures. Who knows, I may even start my own natural gas hot tub company.
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message

Neighbor has a electric hot tub. We have a NG hot tub heater that does the pool as well. I can heat the poll and hot tub for less than the neighbor spends on his hot tub alone. End result we get three +/- months extra use of the pool each season (N Texas).
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On Tuesday, March 3, 2015 at 11:25:21 AM UTC-5, NotMe wrote:

I don't believe it's possible to realistically heat an entire swimming pool with nat gas for less than it costs to heat a hot tub. Typical pool has 100X the water that a hot tub has. I have an electric hot tub and don't even notice it much on the electric bill. I don't keep it hot all the time, I turn it up before use. But even if you kept it a 100F, it's fairly well insulated. A pool is not. Folks here in NJ have gas bills in the thousands if they try to heat a pool. The freaking heaters are 300 - 400K BTUs. I don't spend that much on the entire house electric bill. The whole thing in winter, hot tub included is $140. The typical hot tub heater is maybe 8KW. Even though electric is the more expensive fuel, the amounts of energy it takes are vastly different, ie a 40,000 gallon pool and a 400 gallon insulated hot tub.
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On Tue, 3 Mar 2015 09:31:27 -0800 (PST), trader_4

I have an 11kw spa heater and it costs $1.54 an hour to run. I get about 10 degrees an hour when I am heating it up.
We assume it costs us about $5 every time we use the tub, typically a few hours at a time. I have solar collectors that I can switch over to the tub and that easily cuts the heating time in half, starting from warmer water but now I have some trees that are encroaching on my solars. It is fixn to be chain saw time.
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On Tuesday, March 3, 2015 at 1:27:37 PM UTC-5, snipped-for-privacy@aol.com wrote:

That sounds reasonable. It obviously comes down to how many times you use it. Here, it typically only gets used a couple times a month, so it's not that noticeable in the electric bill. It also depends where you have it located. In a previous house, I had one inside and that makes a big difference.
I think you'd agree, even if it cost $100 a month in electric, there is no way you could heat a swimming pool plus spa using nat gas in that same kind of environment for anywhere near $100. If it cost $100 to run a hot tub here in NJ with electric, it would cost $1000 in nat gas to heat a swimming pool. Unless you're talking about just raising the temp of the pool by one degree or something. And then you have the huge loss of heat from a pool compared to the far less loss from a well insulated hot tub.

I think solar can work well for pools, provided you have enough room for the collectors and don't mind what they look like on the roof or someplace on the ground. I'm kind of surprised that with what it costs to heat pools, I don't see any here in NJ. It would extend the season by a month at the beginning and end and keep it more comfortable the rest of the season too. You would think people just don't care, but then they put in new pools with nat gas heaters here all the time. I only know a few people who use the gas heaters though, for obvious reasons. It's also funny because instead of the dopey nat gas heater, that involves not only the cost of the heater, but also running gas lines, possibly resizing the meter, etc, you could pay for most of the solar install and after that it's almost free.
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On Tue, 3 Mar 2015 13:44:41 -0800 (PST), trader_4

My wife runs a country club with 7 heated pools, heat pump/electric. I can get the bills if anyone is interested. They still have a real hard time getting much more than 10 degrees above ambient air.

Solar heaters work well if you cover the pool but uncovered you will only get 8-10 degrees above ambient air with a collector area the same as pool area. The main problem is how much heat you lose at night without a cover. My neighbor has more collector than pool and a cover. She can make it uncomfortably hot on all but the coldest days (in South Florida) They normally say collectors get you a month on each side of the season ... here. YMMV up north.
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On Tuesday, March 3, 2015 at 7:02:49 PM UTC-5, snipped-for-privacy@aol.com wrote:

Yes, that's what I've gathered from what I know about solar too. A lot of heat is lost at night from the surface. But the downside is I would think taking the cover on and off is a pain, plus the pool with a cover is going to look ugly. And maybe if you have leaves and stuff, that can blow onto the cover, that becomes a pain too. But if you can get 8 deg without a cover, that's not bad. It would be enough to level out the temp all of the regular season here in nyc area and would extend the season by probably two months, ie a month on each end.
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Heat pumps are effective/efficient within a comparatively narrow range and basically worthless if the ambient air is below 40 F. Likewise heating water to 100F is with a heat pump also techniclly difficult.
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