Hot Tub Heaters
Heater Installation and Repair: Hot Tub Heater Repairs
Now that we have reviewed the list of the most common things that can go wrong, let's turn to more detailed troubleshooting and repair procedures for each of them.
HOT TUB WATER SYSTEM
RATING: EASY
If you can answer yes to all the water flow questions posed in the checklist, yet the flow of water is still too low, the problem may be inside the heat exchanger. Over time and with improper water chemistry, scale (calcium "liming") can build up inside the tubes of the heat exchanger, slowly closing the passages, somewhat similar to fat closing the arteries in your body. You can ream out the heat exchanger, but it requires some specialized tools and a willingness to disassemble the entire heater, so you may want to leave it to a service technician. You can, however, prevent it from happening again by taking steps to balance the water chemistry.
TRICKS OF THE TRADE: GOLDEN RULES OF HOT TUB HEATER REPAIR
• Always turn off the heater when you are making repairs. Preferably turn the pump off as welt and disconnect or shut off any source of electricity. If you don't, you may complete the repair or touch some wires together and cause the heater to restart when you don't really want it to. By shutting everything down, you control the entire process—you check your work and control the test-firing when you think you're done and want to check the work. Otherwise, the heater controls you.
• It is generally better to replace components than to repair them. If it's a well-worn heater with other parts that will soon give out, too, replace the entire heater instead of adding new parts every month ad infinitum.
• Hot Tub heater parts fail for a reason. Find out why a part failed in the first place, or it will happen again.
• The majority of heater failures are the result of dirty filters (or obstructed water flow from the hot tub). In short, the failure has nothing to do with the heater at all. Look around at the entire installation before you start on what has been called in as a "heater problem."
• If the heater has been running prior to any repair you are making, watch out for hot components. Pilots generate over 1100°F, so they stay hot for a long time after they've gone off. Cabinets and other metal parts get hot, too, so watch what you grab. |
HOT TUB GAS SYSTEM
RATING: ADVANCED
Check that your hot tubs heater has been supplied with gas. If this is not apparent (from a working pilot, for example), shut off the gas valve and open the union near the heater. Make sure there are no other open flames or sparks nearby that might ignite the gas; then turn the gas valve back on and listen for gas flow (you will hear the hissing before you will smell the gas). If there is no flow, go to the source—the main meter or propane tank.
TRICKS OF THE TRADE: LIGHTING (OR RELIGHTING) THE PILOT
RATING: EASY
This procedure applies to standing pilot units only since the electronic ignition is automatic unless something is broken. Instructions are almost always printed on the heater itself. Look for these and follow them. If the directions for your particular heater are obscured or missing, the following procedure is most commonly used:
1. Shut off: Turn the gas valve control to off, and wait 5 minutes for the gas in the burner tray or around the pilot to dissipate (safety consideration). Turn the on/off switch to off.
2. Light the pilot: Turn the gas valve control to pilot and depress. If the area is quiet, you should hear a strong hissing sound as the gas escapes from the end of the pilot. If you do not, it may be clogged by rust or insects (see below for removal instructions). Light the pilot and continue to depress the control. Hold the control down for at least 60 seconds. This allows heat from the pilot to generate electricity in the thermocouple to power the gas valve (which will then electronically hold the pilot gas valve open and power the control circuit, which ultimately opens the main burner gas valve). Release the control, and the pilot should remain lighted.
3. Verify: This step is not usually included in instructions printed on the heater—verify that the pilot flame is "healthy." That is, look to see that a strong-burning, blue flame of 2 to 3 inches extends toward the burner tray and that a secondary flame of equal value is heating the thermocouple. Make sure the pilot is still securely in place; it may be burning properly, but rusted fasteners or poor installation from previous repairs may have left it dangling near the burner tray, but not in close contact with it.
4. Fire the heater: Turn the gas valve control to on. Stand back from the heater (and to one side—not in front of the open door of the heater) in case of flashback. The heater should fire normally (remember that the pump must be running for the heater to fire).
REPAIR/REPLACE A HOT TUBS BURNER TRAY COMPONENTS
RATING: ADVANCED
Rusted out burners or tray components will be obvious to the naked eye. Remove the burner tray assembly and replace any defective burners.
If the pilot fails to light, it may be clogged. If the hot tubs heater "booms" when it lights, it means the pilot is not igniting the gas in the tray soon enough. Is the flame too small because of an obstruction in the pilot? Is the pilot bent or rusted and not positioned close enough to the burner tray? Take it apart, clean it, and reassemble (or replace it if it is damaged).
There are several types of pilot used in various heaters, but once the tray is removed, the disassembly will be obvious. Let's review typical installations and problems with the standing pilot units and the electronic ignition units.
STANDING A HOT TUBS PILOT UNIT
RATING: ADVANCED
Disconnect the wires of the pilot generator from the combination gas valve. Remove the pilot gas tube from the combination gas valve, and remove the entire pilot assembly from the tray.
The pilot generator either clips in place or is held by a threaded ring. Remove the pilot generator. If it is rusted or swollen, replace it.
The pilot itself will further disassemble into two or three sections, depending on the model. Examine each part for obstruction or rust. Blow through one end of the pilot gas tube, and be sure it is also unobstructed.
The pilot can be cleaned by soaking in muriatic acid for 30 to 60 seconds, cleaning thoroughly with fresh water, and blowing dry (do not leave acid or water on the metal parts, which can cause rust, in or on the pilot).
Natural gas is actually odourless, so to make leaks more detectable, the gas supplier adds a perfume. This perfume has been found to attract insects who build nests in pilot assemblies. Insects and rust are the two main enemies of the pilot.
ELECTRONIC IGNITION PILOT UNITS
RATING: PRO
The ignition electricity feeding the pilot is between 10,000 and 20,000 volts, so be sure the power is off before servicing! Remove the high-tension wire that supplies electricity to the pilot. Remove the pilot gas tube from the combination gas valve, and remove the pilot assembly from the burner tray.
The IID senses the pilot by the electricity generated from the heat of the flame—a "reverse" current is generated along the line of 0.00002 amp (2 milliamps), which is so sensitive that any electrical obstruction such as corrosion prevents this "signal" from reaching the IID. I have cleaned and reassembled these units and successfully put them back into service; however, they usually fail again soon. In this case, replace the pilot assembly, including the wire between the IID and the pilot unit.
As described above with standing pilot units, disassemble the pilot assembly and supply tube, and clear any obstructions or rust. Reassemble it the opposite way from how it came apart.
AUTOMATIC COMBINATION GAS VALVES
RATING: ADVANCED
There are no in-the-field repairs that can be made to the automatic combination gas valve. If you determine that it is failing, replace it. The plumbing of the valve is female-threaded and screws directly onto the gas pipe of the burner tray. When replacing it, apply Teflon tape to the male gas pipe of the burner tray. I do not like pipe dope in this case because it can too easily squeeze off the threads and into the opening of the gas valve, obstructing gas flow.
TRICKS OF THE TRADE: HOT TUB HEATER SAFETY
Heaters are unquestionably the most dangerous component of a hot tub equipment group. They combine water under pressure and heat, gas, or other combustible fuel and electricity. The point is simply that whatever care you exercise normally must be doubled when you are working with heaters. Therefore, I have a simple safety checklist for working around hot tub heaters:
•Never bypass a safety control and walk away. Jumping controls is a good way to troubleshoot, but not to operate the unit. Always remove your jumper cables after troubleshooting.
•Never repair a safety control or combination gas valve. Replace it. You will notice that your supply house doesn't even sell parts for gas valves—they should never be repaired, because future failure could be catastrophic.
•Never hit a gas valve it may come on, but it may stay on.
•Keep wiring away from hot areas and sharp metal edges of the heater.
•When you are testing a hot tub heater, especially after a repair, keep your face and body away from the burner tray where flashback might occur. |
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