Hot Tub Heaters

Hot Tub Heater Installation and Repair

Installing a new hot tub heater or repairing an existing unit may seem complicated, but it is actually easy to manage if you follow the path of the water and fuel (gas or electricity). Since the heater combines water, electricity, and gas, it is important to use extra care when you are working around these units, following all manufacturer's warnings and procedures.

Installation

RATING: PRO

This section deals with installing a stand-alone heater regardless of the fuel source. Any heater installation is composed of four basic steps location (including ventilation), plumbing, gas connections, and electrical connections.

Although installing a hot tub heater uses simple skills described throughout this book, it is rated Pro because any mistakes can be disastrous. No matter what the fuel, improper installation of a hot tub heater can result in fires, explosions, and injuries. If you feel ready to tackle the job, exercise extreme caution with each step and follow the manufacturer's guidelines and installation instructions. The following steps are meant as general guidelines only.

1. Hot Tub Location Hot air rises. Very hot air rises very quickly in large volumes, requiring replacement by adjacent cooler air. Burning fossil fuel, such as gas, results in by-products such as carbon monoxide, which is deadly. These simple concepts are at the heart of the decisions about where to locate your heater.

Most residential heaters are designed to be installed along with the pump/motor and filter at an outdoor or indoor location. When purchasing the heater, you ask for a stackless heater for an outdoor installation, meaning there will be a draft hood on top of the heater, but no additional vent pipe or "stack" to remove excess heat and the products of combustion (carbon monoxide). If your installation is to be indoors, ask for the stack heater, which comes with a vent hood for attachment to a stack pipe.

Never use a "stackless" top on an indoor installation. Burning gas produces carbon monoxide, and even if the heater is small and the indoor location large and well ventilated, this is a deadly gas. Of course electric-fuelled heaters do not have this problem, and the exterior case does not heat up.

Take the heater out of the box and look for instructions. Read them! I have installed over 500 hot tub heaters in my days, but constantly changing designs mean I still read those instructions before working with any new unit.

Open the front panel on the heater. Inside you will find a plastic bag with installation hardware (the owner's manual may also be packed in here). Set the heater near the filter, but remember you will need to do future service work on both the filter and the heater, so leave enough space for moving around. The other spacing guidelines are provided by the American National Standards Institute (ANSI) and are devised to keep carbon monoxide from entering closed living spaces of your home and to allow enough draft area around the heater. Electric heaters simply require 6-inch (15-centimeter) clearance on all sides and 18 inches (45 centimetres) on top and in front for maintenance access.

Set the heater on a solid, level, non-combustible base. Although heat rises, the metal cabinet (of gas heaters) will get quite hot underneath as well. Heaters have their own "feet" or runners to hold them off the surface; however, even these get warm and would not be compatible with, say, a wooden floor or carpet. The best flooring is a concrete pad.

2. Venting Hot Tubs As noted, outdoor installations require no additional venting; they are vented sufficiently within their stackless tops. In windy areas, however, you may want to consult the manufacturer's recommendations and add a short stack and cap (about 3 feet total) to cut down on excess drafting. Refer to each manufacturer's specifications on this.
For indoor installations, follow the guidelines in the heater booklet. Working with stack pipe made of flexible sheet aluminium, which you get at your supply house, is no tougher than working with PVC, except there is no glue—they just snap together.

Vent pipe comes in lengths of 2 to 6 feet (60 to 180 centimetres) and diameters of 3 to 12 inches (7 to 30 centimetres). You also buy preformed 45- and 90-degree elbows and connector sleeves just as with PVC plumbing.

Going through walls or a roof to get outside, however, is trickier, since you need to use double-wall pipe, flashing, and waterproofing to make the passage safe and rainproof. Some local codes require a permit and a licensed building contractor to handle this part. If your indoor installation is a replacement of a heater that otherwise worked well (and your replacement has the same Btu output), you really only need to connect your new heater venting to the old vent on up and out of the building.

But if it is a new vent stack that means cutting walls and a roof, I'd hire a roofing contractor to handle that part of it. It is well worth the small added cost.

In either case, it is your responsibility to make sure the clearances meet the ANSI code so the heater works properly. One simple way to perform a rough test of the venting is to light a match and hold it under the draft hood the smoke should be drawn up into the vent system and out of the building.

Some howling, whistling, or other ventilation harmonic noise is normal and acceptable. As mentioned, a very large volume of air is rushing up through the heater, and as it passes over vent fins, it might "howl." Notice what is normal for the hot tub heater, and then compare that to any future noises. Changes in the sound, however, may denote problems.

A few minutes after the heater fires, a knocking noise which may actually rock the heater is not normal. This denotes overheating for some reason and is caused by the superheated water expanding and trying to escape. Some high-pitched whining is caused by debris in the gas line. That line should be disassembled, cleaned, and reassembled.

Electric hot tub heaters do not vent significant heat, so there will be no drafting or noise.