What does Your Hot Tub Heater Look Like?
There are a few hot tub heaters out there but not so many that you can’t find yours here!
By far the most common spa heater is the Flow Through
This heater is mounted horizontally, usually attached to your spa control. it can be at the top or the bottom and sometimes is placed away from your control in a remote type installation with a cord that runs to your spa control from the heater. The heater manifold often has a threaded hole for a pressure switch. It can also have wells for thermostat and high limit sensors as well. Many manufacturers had custom Flow Through heater manifolds designed for their particular purpose. There are now generic versions available that allow many locations for pressure switch and sensor location, so one is not tied to the original manufactured manifold that may be more expensive than the generic one. The most commons size is 15 inch long by 2inch diameter. There are also manifolds that measure 12, 13, 18, and 19 inches long. There are a few 1.5 inch manifolds as well but they are difficult if not impossible to replace the element.
The element is easily replaced and inexpensive. The heater element is held in place by two large nuts. Smaller nuts hold the wires that energize the elemen
t in place. It is rare that you actually have to replace the entire heater housing, unless it is rusty and corroded, or the plumbing connections are mangled. The element comes right out with a little persuation, and the new one bolts right in. When replacing the wires to the element, its important that the cold pin (the part of the element that carries the current to to the emersed part) is NOT TWISTED during tightning. Most elements have a 1/4 inch nut built in under the nuts the wires attach to, to secure the cold pin when tightening the wires.
The "Brett Aqualine" Style heater was common on many older hot tubs. No manufacturerer is currently using this large boxy style heater with a replaceable bolt in element but there are many in the field. The Box on this heater was so roomy, that some manufacturers used that space to create an actual spa controller. Hydro Quip is one manufacturer who utilized this housing and expanded its functionality to a hot tub control/heater that often mounted right above the pump.The way to tell the difference is that if all component wires plug into this unit, it is a contoller. If only the wires used for the heater and control loop go into this box, then it is functioning as a heater only.
The element is replaceable in either case. However sometimes everything in the box needs to be removed to get to the bolt in heater element. The element in most cases has a threaded hole for pressure switch mounting, a hole to mount a current collector, and studs for the use of a themodisc high limit. If you click on the above image it will take you to SpaPartsNet.com and the element with pressure switch and high limit attached. Its important to always replace the orings that seal the element to the heater housing. The plastic heater housing is also sold separately.
The Brett style heater IS outdated, Today it is manufactured only as a replacement part. the element is more expensive and difficult to replace than the flow though type heater element. If you have the brett style heater, it would not be a bad idea to consider a new spa control with a flow through stainless heater attached. If you are replacing the complete heater assembly (above) its only 20 DOLLARS more.. to go with a complete new spa control system with a flow through heater! The Epak Shown here is 355.00 COMPLETE with heater, topside control, all new circuitry.
Low Flow heaters are popular with many hot tub designers
These heaters are often mounted vertically and utilize a small circulation pump for water flow. There are many styles. If you have this type, click the image and see the complete selection we have at SpaPartsNet.com. These heaters usually have to be replaced in their entirety. An element only replacement is not possible as the element is sealed in the housing. Shown is the Blue Ridge Gatsby heater assembly. Leisure Bay, Hurricane and more have used low flow heater systems.
Watkins, Hot Springs and their sister companies, Tiger River etc, also uses low flow heater assemblies. These are often a bent tube design such as this one: 
Hot Springs has replaced it’s "no fault" heater about 5 times. The latest version will always be compatible with your system. The element only is not replaceable on hot springs heaters.
There are several obsolete heaters that you could find in your hot tub. One is the screw plug style. This is basically a threaded element with a box on the end. In the beginning, they were the only heater so if you have one of these you can consider your hot tub vintage! But when it goes, we reccomend not replacing it at all with a like type.. Now is the time to upgrade your system totally.
Stand Alone Heaters are found commonly on permanent installations they are 240 volt, either 5.5kW or 11kW and are equipped with a thermostat, High limit, pressure switch, contactor and indicator light and are not as dependent on relay logic as portable type systems. They are hard wired to their own breaker. They require flow and temperature demand to fire. Other than that, they still utilize the famous control loop. Manufacturers include: Hayward, RayPak, Teledyne Laars, Comfortzone (Now Hayward) Coates, and others. For outdoor installations this is a great choice.
Gas Heaters: Usually found on permanent spas with remote equipment, have their own special troubleshooting area. However, They still utilize the same control loop. Thermostat, pressure switch, high limits ( at least two) On/Off, and a fusible link ( a little gizmo that should always be closed unless flames have burned it up.) Gas heaters are by far the fastest way to heat a spa. Once you’ve had a gas heater you wouldn’t even consider electric. They provide almost instant heat and properly sized should heat up the water within a half hour in most situations. One thing to remember is that the water coming out of a gas heater is only 7 to 10 above the temp of the water going through it. If it was hotter, it would burn you at the top end of the heating cycle. What you’ll feel is water a “little warmer ” than the surrounding water as it’s heating, but miraculously it will do the job and quickly! !Gas heaters are by far the best way to go for outdoor permanent installs. With a gas heater there is no reason to maintain a temperature in your hot tub because it is sooooo fast! Nothing else comes close! A gas heater is a large appliance located by the equipment. If you own one, we can help you troubleshoot and we do sell replacement parts for gas heaters. They are usually very repairable.
Hopefully you’ve been able to locate your hot tub heater from the above selections and the links to SpaPartsNet.com. IF not? give us a call and we can help you get back in HOT WATER!