Hot Tub Heaters

Hot Tub Heater Installation and Repair

3. Plumbing for a Hot Tub Connections No other aspect of installation could be easier, as there is one pipe in and one pipe out. The manifold (the end where the plumbing enters the heat exchanger) is set up for VA- or 2-inch (40- or 50-millimeter) pipe. Most spa heaters will use simple threaded fittings.

Be sure to check the manufacturer's recommendation regarding the type of pipe that can be plumbed directly to the hot tubs heater. Some are designed to accommodate ordinary PVC, but others will require the greater heat tolerance of CPVC, a special variety of PVC pipe. Not all local codes permit use of CPVC for this purpose, and not all heaters are designed to allow it either. So check with your local building code and manufacturer's requirements before using it.

CPVC will glue together with ordinary PVC, but check the manufacturer's recommendation for how long the CPVC plumbing needs to be before switching over to the less expensive PVC pipe.

4. A Hot Tubs Gas Connections In replacing a heater, you will generally hook the new heater up to the existing gas line. If you are making a new installation, be careful to note that gas plumbing must follow rigid guidelines, because obviously a gas leak is a greater hazard than a water leak.

Each manufacturer will specify the required size of pipe to ensure an adequate supply of gas, depending on the size of the heater and the distance from the source of the gas (natural gas meter or propane tank). Generally, these will be 3/4 to 1% inch-diameter (19- to 40-millimeter) pipes.

Gas plumbing may be steel or special PVC pipe. Some building codes permit special gas PVC pipe for underground runs (a heavy-duty PVC pipe material which is green-tinted to denote gas). It can be argued that especially with underground pipe, PVC might be better because it won't rust. The disadvantage is that anyone digging in the yard can more easily rupture a PVC pipe than a metal one. If you do run PVC gas pipe, it must be accompanied in the ground by a 16-gauge tracer wire, so the gas line can later be found by a metal detector, if needed. Most codes also require that PVC gas lines be buried at least 18 inches (45 centimetres) below ground [12 inches (30 centimetres) under concrete].

Finally, any risers (lines coming up out the ground) or lines aboveground must be metal anyway, so you must transfer from the PVC to metal before leaving the trench. Metal gas pipe must be 12 inches (30 centimetres) below the ground or 6 inches (15 centimetres) below concrete. Metal gas pipe is painted green (to denote gas), and any underground portions must be wrapped with waterproof 10mil-thick gas tape to at least 6 inches (15 centimetres) above the ground. Lines should be run as close as possible to the meter at one end and to the heater at the other. Most building codes prohibit the use of flexible pipes for gas lines.

Gas hook-ups must include a shut-off valve just before the hot tubs heater, followed by a sediment trap (just a drop of pipe off a T that can collect impurities in the gas before it gets to the heater), followed by a threaded union.

When you need to service the heater, you can close the valve, break the union, and remove any parts of the system without shutting off the gas to the entire house. Similarly, if a leak or other emergency problem develops in the heater, you can quickly shut off the supply of gas in a convenient location.

If this is a new installation, be sure to check the ability of the gas meter to supply the required amount of gas, especially if your house is simultaneously using a gas clothes dryer, gas water heater, gas stove, or other gas appliances. If in doubt, check with your local gas supplier.

Gas lines must be pressure-tested. Building: Manual shut-off valve codes determine how much pressure the line must hold, and special gauges are available at plumbing supply stores. However, I suggest hiring a licensed plumber to conduct this test for you. He or she has the tools and knowledge to conduct this important safety check. When putting a heater into service, however, whether a new installation or just replacing a heater to an existing gas supply line, you can conduct a simple test of your own.

Turn on the gas supply to the heater, and wipe liquid soap over any joints or unions (ammonia in a spray bottle will also work well). Escaping gas will make the soap or ammonia bubble, so you can detect any leaks quickly. Never leak-test with a match you might end up in the next county!

5. Hot Tub Electrical Connections If the heater has an electronic ignition, you must supply the electricity. Wire should be 14-gauge copper, run in its own waterproof conduit (not shared with wiring for other purposes). For either 120- or 240-volt supply, run three wires. One wire the ground wire is green. On a 120-volt supply, the other two wires should be black or red (hot line) and white (neutral). On a 240-volt supply, both wires may be black or red.

Electronic ignition heaters are designed to operate on either 120 or 240 volts with the simple reorganization of the wires that supply power to the transformer. The heater control circuit works on 25 volts regardless of the voltage supplied. Carefully study the wiring diagram provided by the manufacturer to make sure you are connecting 120 volts to 120-volt connections or 240 volts to 240-volt connections.

Where should the electrical supply come from? I prefer to run the wiring from the system time clock, so that the heater can't operate unless power is also being supplied to the pump/motor. This can't guarantee that the heater will come on only when water is flowing, but it is one more safety measure. The ground wire should be attached to the ground lug or bar in the clock and to the ground lug inside the hot tubs heater cabinet. Always connect the heater (and pump/motor) to the load side; otherwise the wiring to the heater will always be hot.

Some manufacturers suggest including a "fireman's" switch. This switch is mounted in the time clock and is designed to shut the heater off about 20 minutes before the time clock shuts off the pump. The idea is that by running cool water through the heater for 20 minutes after it has been operating, you will cool the heater components and extend their life. Most time clocks have predrilled holes for standard fireman's switch installation (and directions are provided in the switch package).

Electric-fuelled heaters need heavier-gauge wire since they consume large amounts of electricity as the heating fuel. Follow the manufacturer's guidelines for these installations, or bring in an electrician to make the hook-up. Because of the load factor, the wiring to the time clock will likely be inadequate to supply the electric heater as well, so plan on running a separate conduit and wires from the breaker box.

Basic Start-up Guide

Whether you have just installed a new heater or are firing up a hot tub heater that has not been used in some time, these tips will get you through it safely.

1. Bleed the Gas Line If the gas supply line is new, bleed the air out of the pipe by opening the line at the union near the heater and opening the shut-off valve. When you smell gas coming out of the pipe instead of air, shut off the valve and reconnect the union. There is still, obviously, air in the remaining 1 or 2 feet of pipe and in the combination gas valve inside the heater; but this will bleed quickly if gas is present in the line up to the shut-off valve. Open the gas shut-off valve.

2. Leak-Check Make sure the heater on/off switch is at off. Turn on the pump/motor and make sure the air is out of the water system. Check for leaks!

3. Fire Up the Heater If the heater has a standing pilot, follow the instructions in the adjacent text box to light the pilot, or look for instructions provided with the heater. It may take 60 to 90 seconds to get a flow of gas in the pilot tube the first time, as the air bleeds out and is replaced by gas. Never try to light an electronic ignition pilot with a match or other fire source. After you light the pilot, turn on the on/off switch and turn up the thermostat as needed to fire the heater.

If the hot tub heater has an electronic ignition, turn the valve on the combination gas valve inside the heater to on. Turn on the on/off switch, and turn up the thermostat as needed to fire up the hot tub heater. It may take a minute or two the first time to bleed air out of the system and replace it with gas, so don't worry if it seems to take awhile for the pilot to ignite and the unit to fire the first time.

4. Check for Normal Operation When the heater first fires, the heat will burn off the oil that is usually applied by the factory to the heat exchanger as rust prevention. Light smoke for a few minutes is normal. Also normal is some moisture condensation as very cold water runs into the very hot heat exchanger. The condensation will drip down onto the burner tray and sizzle—a little of this is normal, too.

Observe the heater for the first 10 minutes. Make sure the smoke and condensation stop and that there are no leaks. Use your eyes and nose (gas leaks?). Turn the hot tub heater off and on a few times to be sure it operates properly. Do this from the on/off switch and the thermostat a few times. Remember, if the water is colder than about 65°F, the thermostat won't shut off the unit because it doesn't register that low. Now shut off the pump. The hot tubs heater should also shut off within 5 seconds. If it doesn't, the pressure switch needs adjustment.