Internal vs External Heaters?

Which is Better for You: Internal vs. External Hot Tub Stoves

As you explore the wood fired hot tubs on Redwood Outdoors, you’ll notice that you have a choice between internal (also called submersible) and external stoves. Both are good options and there isn’t a “wrong” choice. However there are slight differences in how they operate, so chances are, one variety will be better for your lifestyle. On this page, we’ll give you a crash course in hot tub stoves, so it’s easy to choose the right one.

Internal Hot Tub Stoves

Internal hot tub stoves are submerged in the water. They are partitioned from the main seating area by a fence made of cedar slats which allows water to flow freely and provides a buffer of safety. Fuel wood is loaded at the top of the unit, so you can add more anytime you wish without leaving the tub. Our stoves (both internal and external) are made of durable 304 stainless steel, which is naturally resistant to rust and corrosion, ensuring they stand the test of time whether they’re in an aquatic environment or exposed to the elements.

Pros of Internal Hot Tub Stoves

Faster Heating: Because the heat source is fully submerged, all heat generated transfers directly into the water. This makes internal hot tub stoves more efficient than external ones. Heat exchanger pipes also reroute heat that might otherwise be lost through the chimney back into the water. Therefore, a smaller hot tub could take as little as two hours to fully heat, though times will vary based upon the weather and starting temperature.

Safer for Families: Your internal heater offers built-in protection because it’s submerged and behind the wooden partition. External stoves can be a concern for busy households if children and pets may potentially come in contact with the heat source.

Cons of Internal Hot Tub Stoves

Lost Seating: The stove and partition take up a small amount of interior space. You lose one or two seats.

External Hot Tub Stoves

External hot tub stoves sit on the ground outside the tub. They connect to the unit with dual pipelines and warm the water via a process called “thermal siphoning.”

Pros of External Hot Tub Stoves

Extra Interior Space: Because the stove is located outside the tub, no interior space is lost. There’s room for one or two additional people compared to a tub same size with an internal stove.

Easier Stove Cleaning: Because the stove a traditional style front-loading wood stove, many customers find it easier to manage their fire and clean the ash from the stove. 

Cons of External Hot Tub Stoves

Slower Heating: It takes longer for an external heater to get the water to an ideal temperature, simply because some of the heat is lost to the air around the stove. Whereas an internal heater might take two hours, an external one will likely be closer to four.

Internal vs External Hot Tub Stoves: Which is Better?

Pricing between the two models is comparable and they both allow you to operate your hot tub without any electricity. That means either is ideal if you’re setting yours up in a remote location or simply don’t want the hassle of hiring an electrician or the expense of paying for power. (Yes, wood fire hot tubs are cheaper!) Furthermore, you probably aren’t going to need to add wood to your stove once you’re enjoying the water all that often, so although internal stoves are better in this respect because you don’t need to exit the tub to add more wood, it’s more of a minor win.

Ask Yourself Two Questions

1) Do I need additional seating space? If losing 1-2 seats poses an issue, you’ll want to go with an external heater or purchase a larger size tub.

2) Will an external stove pose a safety risk in my household? If children, pets, or even inattentive adults may come in contact with your external stove, it’s probably better to go with an internal heater.

Know Which Wood Fire Hot Tub is Better for You Now?

Head over to our online shop and explore hot tubs with internal stoves or hot tubs with external stoves now. You can also visit our FAQ section or contact us directly if you have additional questions.