Indoor Tankless vs. Outdoor Tankless Water Heater

April 9, 2019

Tankless water heaters are available as indoor or outdoor appliances. For the in-home units, their talent for cutting energy knows no bounds, at least as long as they’re vented properly. There’s also that range of option-expanding outdoor tankless systems. They function a lot like their sheltered cousins, except for a handful of notable design exceptions.

Outdoor Tankless Differences

There’s no water-filled containment chamber inside, so extreme temperature dips shouldn’t cause too much trouble. All the same, outdoor tankless water heaters, especially when compared against similar indoor models, need effective supplementary frost protection mechanisms. Additional insulation is also a must-have feature, as is a casing that provides an IP (Ingress Protection) rating. That latter system attribute exists to prevent dust and moisture from getting inside sensitive mechano-electrical parts. In this case, it’s the moisture rating that causes most concern.

Reviewing Conventional Indoor Models

Energy efficient and compact, an interior unit has its gas/electricity connection and venting apparatus. The vent blows system exhaust gasses outside, where they dissipate harmlessly. Because of this requirement, there’s some light construction work to be done. It usually takes place on a side wall. Then there’s an active exhaust blower to fit. That component comes in the form of a fan, which is incorporated inside the appliance. And there’s the biggest difference, for only indoor models need powered exhaust systems. An outdoor tankless water heater doesn’t require an intricate venting system; its exhaust gasses dissipate safely outside, perhaps as some lazy breeze swings past the equipment.

Kit Selection Installation Issues

To review the matter, outdoor tankless models are weather resistant. When mounted on an outside wall, they ventilate freely. Indoor tankless systems don’t need as much Ingress Protection planning, that’s true enough, but they use all kinds of modular exhaust fittings. Someone is going to have to plan out the knock-through phase of this indoor work in order to open a venting channel. The modular kit pieces can follow. Incidentally, the outdoor unit, although a more exhaust-friendly solution, will require a water-proof electrical connection. Rubber grommets and/or galvanized steel conduits come to the rescue at this point, but that’s the kind of installation work that’s best left to an electrical contractor.

Two immediate differences exist between indoor and outdoor tankless water heaters: an indoor unit requires an active venting mechanism, plus a set of exhaust ducts, but the outdoor model doesn’t. Outside-mounted tankless water heaters don’t need complex venting systems, but there’s always that weatherproofing feature to plan out. Also, a frost protection mechanism and IP rating are both essential when installing outdoor tankless systems.

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