Hot tub heater parts – a spa heater can be one of the more confusing parts of a spa for homeowners to work on, which is why our spa and hot tub heater parts department is laid out in a step by step fashion. This allows you to start your spa heater troubleshooting with the most common replacement spa heater parts, and progress to the more rare causes of spa heater problems.
Here’s a description of each subcategory of spa heater parts, with information on what functions these various parts perform and how to test or troubleshoot them on your own spa, so you can buy replacement spa heater parts with confidence.
Heater elements are housed inside of the heating chamber, or manifold. The power leads are connected to the element, and when all the stars align, this power will heat up the element, which warms the passing spa water.
Warning: Testing and inspection of spa heater elements should be done carefully to avoid injury. Spa heaters also need to be grounded and GFI protected, before connecting power, to prevent serious injury or even death.
Heating elements can be tested for amperage with an amp meter, or the terminals can be tested for proper input voltage with a volt meter.
In many cases, the heater element itself is not damaged, but it begins to leak water out of the terminals, where the wires connect. If this occurs, replace the element or the entire heater immediately, to prevent electrical shock.
Replace a spa heater element with an exact duplicate, in terms of length, terminal orientation and kilowatts of output. Call for spa tech support if you are having trouble identifying the correct hot tub heater element.
A flow switch is a sensor that tells the heater that there is enough water flowing through the heater element to be able to power the heater element safely. Low flow rates can be caused by a dirty spa filter, low water level or closed valves.
A flow switch has a paddle that dips into the flow of water, to sense the pressure of the passing water. It also has an arrow on the side to indicate the proper flow direction of the water, and commonly has two wires that connect into your control panel.
Problems include a flow switch stuck in the wrong position, closed all the time, or open when it should be closed. Wire shorts or loose connections on the wiring can cause this, as can built up scale in cases of very hard water.
If you suspect your flow switch may be the problem, you may be able to jump it out or isolate it from the circuit. Insufficient heat or no heat is the main symptom of a problem with the hot tub flow switch.
The purpose of a hi limit switch is to shut down a runaway heater. Modern spas use sensors to determine when the water temperature inside the heating chamber is too hot, and older spas will use a mechanical thermodisc, that surface mounts onto the heating chamber or into the control box. Others may use a capillary bulb and wire, with a button that pops out when the hi limit has been tripped, much like a GFI breaker.
A tripping hi limit may be symptomatic of a water flow problem (and the flow sensor or pressure switch), or problems with the spa thermostat. It will have two wires connected, leading to the controller.
Older hi limit switches that are nuisance tripping may be faulty, but it’s more often the case that the hi limit is doing it’s job, protecting you and your spa equipment from dangerous over heating.
Heater unions are the connecting bits on the ends of the heating chamber or manifold. Usually the union nuts are collars, which have a screw on each side to remove it in two halves. If these union nuts become stripped, cracked or broken, you can will find it easier to just replace the collar, and not the union tail nut, or the piece that the union nut threads onto.
We also have available the spa union o-rings and gaskets that always tend to fall off and roll to an unreachable location – or, they get pinched and crimped while tightening up a heater union.
If your spa heater begins to leak at the unions on either end, make a fast parts replacement, to prevent water from contacting sensitive heater terminal connections, dripping or spraying on other spa pack components.
The heater manifold is the housing for the heater element, and may also be home to your hi limit and pressure switch. It’s rare that the heater manifold will fail on it’s own, but it can fall victim to freeze damage, or it can be warped in extreme over heating incidents.
Stainless Steel spa manifolds can sometimes rust or oxidize, and this can indicate that the steel manifold has become energized and possibly dangerous. Plastic manifolds won’t develop rust, but could warp or be melted right through if the element gets too close.
Buy exact replacement manifolds, to fit your element. It may come with complete unions, but it’s easier to not use the supplied union tail nuts, just use the new o-ring and union nuts. Be extra careful to secure the element in snug to prevent leakage.
A spa pressure switch is similar to the flow switch, and in practice their function is the same. When water flow or water pressure is insufficient to adequately absorb the heat from the heater element, a pressure switch will shut down the spa heater, in a bit of self preservation.
We have over 40 different pressure switches to choose from. I guess spa manufacturers like to have their own specific pressure switch, with small differences. They vary in the amperage, the pressure settings, the attachment size and how many poles and throws the switch has. Be sure to replace with an exact duplicate pressure switch.
Pressure switch tripping? It’s probably just doing it’s job, and you may have a flow problem. In some cases, a spa pressure switch can become stuck (open, or stuck closed), or the terminals can become rusty, or it can lose it’s calibration and become more sensitive over time.
Spa sensors are used on today’s newer spas, to replace older hi limit switches and mechanical thermostats. These sensors usually have a wire attached that’s about 3 ft. long, to be able to reach over and plug into the spa pack.
If you receive an error code regarding a spa sensor, check the connections at the spa pack, and inspect the wire carefully for crimps or splits. Remove the sensor itself from the spa plumbing, and inspect the bulb or button for scale or corrosion. If it sits in a dry well, check that the well has not developed pinholes.
Spa sensors for temperature are all factory calibrated and are non-serviceable. If both ends look fine and the cord is intact, double check that you have a sensor error. If you’re having trouble diagnosing a spa sensor, give us a call here at the shop, we’ll be glad to help.
Complete Heater Units
And of course, we have the complete heater units at Hot Tub Works. If there are big problems with your spa heater components, replacing the entire unit may give you more peace of mind, and is definitely an easier installation.
You can order replacement spa heaters such by brand, or according to the type of spa pack that you have. We also list our top ten most popular spa heater, many of which are universal, in that they will fit many different spas.
You can also order new spa heaters by dimensions; refer to our chart of 9 measurements that you can match up to on your existing spa heater, to get one that will line up correctly with all of the spa heater components.
Happy Hot Tubbin’