Hot Springs Classic F Possible Heater Problem

Model - Classic F (F161072) 1996?
Heater - No Fault 1500W/120V Model # 34798C
Fresh Water II Ozone System

Problem - No Heat

Prelims - Incoming Service Loss. Power outage approx 5 minutes. Approx. 2 hrs later noticed blinking red light on control panel. Reset GFCI and light went off. Did not check anything else. Unit is powered through a 50Amp breaker sub panel fed with 6AWG wiring. A dedicated 30 Amp circuit feeds the heater/jets/light, etc. Later same day noticed significant water temp drop. From normal 102 to 92 in a few hours with ambient near 90. Do not know if temp was dropping prior to power loss. Power has remained on to unit and jets, clean cycle, light is working. Cleaned the 3 filters. Have not observed any air bubbles in tub nor can I detect movement through the circ. pump, but being new to Hot Tub Troubleshooting, not sure how to check. GFCI has not tripped since initial reset at power loss. Heater and circ. pump are cool to touch. We did notice recently a notably loud clicking noise from the tub, but assumed it to be the temp relay activating/de-activating. We had not noticed this in the 2 yrs prior.

I have access to a Laing Model #IHH-6000-NHCW, Laing P/N 6759, Watkins P/N 0927501, 5Kw 25A 240V/1.5Kw 12.5A 120V heater. Would this be an acceptable replacement if my existing heater is bad. Additionally what would be involved in converting to be able to run jets and heater at same time? Electrical power should not be an issue.

Any help/direction is appreciated.

Thanks in advance
Jim

Images attached.

Before jumping in, be sure the heater is actually the problem.
Sounds like it could be a flow issue, or high limit thermistor.... Throwing in a new heater may not solve your problem.
Flashing red led indicates the electronic heater high limit has tripped.... which means the heater is doing exactly what it's supposed to do (get hot)

It also incorporates a flow switch, the heater will not energize if there is not adeqaute flow.

That model is not convertable to 220v, sorry, no heat while pump is on. (By the way, I'd avoid the tri-bend, and go with the PDR heater, Watkins part # 72791) You missed the convertable model by one year... (You have a 1996 Classic, Hot Spring spas moved to 110/220 convertable units in 1997)

Thanks for the informational reply. The more I read on this item, my thinking has been changing to the items you state. I can hear the thermostat clicking as I rotate the heat control. Power is on but heater assembly and circulation pump remain cool to touch and I do not feel any water movement through the circulation pump plumbing lines. Keep in mind that I'm ignorant on most of this and have listed some additional questions.

1) Is the heater flow switch encapsulated in the heater assembly or visible and accessible externally?
2) I have not removed the control box cover yet, (not easily accessible). but will do so this weekend. I presume the high limit thermistor is inside the control box.
3) Am I correct on the following statements?: Flow into heater is the verticle pipe, so output would be at the far end of the heater. The thermocoupling near the verticle pipe is thermostat and the far end thermocoupling is high limit.
4) I cannot feel any flow at circulation pump or water movement in the tub unless clean cycle or jets are on.

Thanks again.

1) it's visible externally, it is a seperate switch. The harness plugs into the control box in the same proximity as the temp sensors. Just follow the leads and eventually, you'll find the flow switch assy.

2)The high limit thermistor is a component that scrws into the heater. There are two thermistors, a high limit thermistor and a control thermistor. Floow ther leads to the side of the control box, they simply plug in the side. You do not need to drop the control box.

3) Flow into the heater is the horizintal pipe. You'll find the circulation pump just to the right of your picture foprcing water into the heater via the horizontal plumbing. The up the vertical pipe, and back into the spa. (It actually routes to the drain in the bottom of the spa. The drain doubles as a drain, and also the circ. pump/heater jet.

Need Help - Hot Springs Classic F Serial # F161072
Control Box Area where Flow Control, Thermostat and High Limit connects.
Am I correct on these locations
Top connection is Thermostat
Center connection is High Limit
Bottom connection is Flow Control.

Any knowledgeable help is appreciated. I've lost my diagram.

If memory serves correct, that sounds right