One of the ongoing debates in the spa and hot tub business, is whether or not to use gas heat for hot tubs vs. the more commonly used electric heat option. There are several factors to take into consideration before you make a final decision on this choice and that’s what we are going to explore in this blog post.
THE 5 MAIN CONSIDERATIONS Using Gas Heat for Hot tubs:
- Water Volume
- Insulation of the unit
- Availability of Gas
- Climate
- Yearly usage
Let’s take a look at each one of these factors and see how they come into play for making your choice.
FIRST- WATER VOLUME
The more water you have to heat the more your operational costs will be, that’s just a fact. However, there is line where the scale begins to tip in the favor of using gas heat. With all other factors being considered equal, we’ve generally found that line to be around 700 or more gallons for a spa or hot tub. Interestingly, that much water volume covers about 97% of the units you can buy ready to go, the big exception of course being swimspas.
Most portable spas have a water volumes that fall in the 350 to 550-gallon range. Using electric heat might take 7 to 8 hours to bring that spa up to set temperature. Using gas heat for hot tubs can cut this time to maybe only take 3 to 4 hours, (depending on the gas heater size). However, the bigger they are the more they cost.
We have also found that the cost of using gas heat for hot tubs vs electric heat will typically add around $1500 to your purchase cost, but that doesn’t take into consideration the cost of running a gas line to the gas heater. So for arguments sake let’s just say your total extra cost was $2000 to go with gas. Now let’s say that by using gas heat for hot tubs you saved an average of $30/mo. in heating costs over electric heat. Divide $2000 by $30 and it will be 66 months before you have completely offset the extra upfront costs of using a gas heater.
The problem is that you may now have gone beyond the average life expectancy of your gas heater. Sure it could last another 5 years or it might need replacing in 6 months. It’s one of those unknowns that are hard to predict. That being said, unless a number of other savings were realized, for smaller spas and hot tubs the extra expense of going with gas heat may be hard to justify.
INSULATION FACTOR OF A SPA OR HOT TUB
The degree of how well a spa or hot tub is insulated plays a definite role in the operational cost of that unit. The better a unit is insulated, the less it costs to operate it. I’m going to cover spa and hot tub insulation in depth in a future blog post, but for this post let’s just look at the two extremes. A poorly insulated spa or hot tub, costs more to operate. When gas heat for hot tubs is used instead of electricity, the negative effects could be somewhat offset. But by the same token, if it was electrically heated and poorly insulated, it will drive up your operational costs needlessly. So choose wisely when you look at how well a spa or hot tub is insulated. All spas are not created equal and some units have serious design flaws when it comes to using proper insulation methods.
GAS AVAILABILITY
If you have gas available as a heating source that’s great. But, if the cost of getting a gas line to the gas heater gets out of control, then again gas might not be the best choice for heating your spa or hot tub. You may have to have a plumber with gas certification, come and install a new gas line off your present meter and line system. This may require not just shutting the service line down to tap into it, but also trenching path for the gas line to the heater itself. That line distance could be short or long. The longer you have to run the line the more expensive it becomes to install. And, you never know what you are going to run into when you dig.
Maybe your gas choice is propane. Even though the propane tank itself can be set conveniently close to the gas heater where trenching might be minimal, propane heat may be expensive in the area you live. Propane does give more BTUs per gallon than natural gas so that also becomes a factor when making this choice. Quite often your local propane dealer will be able to run a cost comparison analysis for you, so you can make a more educated choice on the product to use.
CLIMATE AND YEARLY USAGE
I like to tie these two factors together because they have a direct effect on each other. For example, if you live in a warm climate area and use your spa year round, the operational cost will not be as much of an impact on your wallet as if you lived in a cold climate area and used your spa year round. The obvious reason is that it would cost a lot more to heat your spa in the middle of winter in Minnesota, (example), than it does to run your spa in the middle of winter in southern California.
So this is where all the factors come together. If you are heating a large water volume, you have a poorly insulated spa or hot tub, you use electricity to heat and your run the unit in the winter, it could be very expensive to keep this unit heated. More on this subject can be found in my hot tub building books, www.custombuiltspas.com.
If you have small water volume with a well-insulated spa in a southern climate the heating costs will be very reasonable. And of course you have every combination in between those two extremes.
What I do when working with new DIY spa or hot tub customer in the planning stages of his or her project, is get all the information I can as to how the spa or hot tub is going to be used, where it’s located, how well it’s going to insulated and anything else I can find out about their project. This way I can cover in great detail all the factors that are going to come into play for determining the choice of heating. This kind of pre-planning is important because it may well have an impact on the design of their spa or hot tub.
I hope you found this posting on gas heat for hot tubs educational as well as useful. You may be considering building your own spa or hot tub, maybe even a swim spa. Feel free to contact me if you have any questions regarding this type of project.
Gene Trumbull
Custom Built Spas
