Hi --

We recently purchased a used 1995 Hotsprings Jetsetter Model J (serial no: J451260, 110V). Upon filling it up and plugging it in, it began heating the water at ~3 to 4 degrees per hour. Around 98 degrees - it stopped heating. The circulation pump continued to run, but the water will not rise any higher in temp. I've made numerous modifications to the tub to try and fix this issue, but with no luck.

Here's what we've done thus far:

** Removed the filters for 24 hours - no results
** Replaced the filters - they were old anyway
** Replaced the heater + replaced plumbing lines to and from the heater
** Replaced the Hi-Limit Thermistor (outlet side of the heater)
** Tested Lo-Limit Thermistor (inlet side of the heater) - ohm readings remain relatively and consistently close to the Hi-Limit Thermistor ohm readings - as temperature rises and falls.

Again, the tub will consistently reach 98 degrees (or so), but will go no higher. When slowly turning the temperature control knob "up" I can hear a "click" as it reaches the current temperature of the water - indicating that it is calling for heat. I have tested this when the water is both cold and hot, and it clicks (calls for heat) at a lower level when the water is cold and a higher level when the water is hot. When the water is around 98 degrees it engages at around 7 (on a scale of 1 to 10) indicating that there is still room for more heat - but I'm not getting any more heat.

The circulation pump on this model quietly runs 24/7 and engages the heater as needed.

I have opened the main control box to run minor tests, but at this point am not finding anything of value, and the insides of the main control box are brilliantly clean (no dust/dirt/mold/moisture...etc). I tested the 2 fuses in the control box and and they are both fine.

I am hoping to be able to fix this myself. Any direction that anyone can give me would be greatly appreciated! If I've forgotten any details, please ask - I'll be glad to post anything I can about this issue.

EDIT: Additional information -- there is a device on the plumbing line, "after" the heater and before the water returns to the spa. This device is not shown in the original owners manual. I do not know what this device does (flow control??)... It may play a roll in my problem - it may not. I'm attaching 2 photos of this device to you to view.

Thanks,
--Kevin

get a good cover on the tub and keep it out of the wind.

I have an excellent cover on the tub, which we keep locked down tight. Wind has not been an issue lately.

Ok do this: Verify the heater is actually on. When you hear the click calling for heat, measure voltage across the terminals of the heater element. If you have line voltage there, disconnect the power and the wires to the element and do a resistance check across the two heater terminals. If you have around 11 ohms resistance.... you have a heat loss problem. If you don't have around 11 ohms (infinit or open) then replace the element.

charger_1 - thank you very much for taking the time to go thru this w/me ... i really appreciate your time...

As my heater is "brand new", I hesitate to take it apart, but can share the following with you. I just tested the voltage and resistance in the control box from the white and black power wires at the end of the heater's power cord:

Voltage: 115.5
Ohms: 9.8

As mentioned, I just replaced the heater (last Wednesday). The ambient temperature outside right now is about 60 degrees during the day and 40 to 50 during the night... What are the odds that both the old heater and the new heater would heat the water to the "exact" same temperature (98 degrees), which is nearly 40 degrees above the warmest air temp during the middle of the day - and both be bad heaters / or / not be turning on at all? Does this (in any way) confirm that we are getting heat - I think it does (but am not even sure of my own name at this point ). Are you thinking that the heater may not be getting full power? It appears to be getting what it needs... What's next?

If your measurements are correct, you are heating. I'm still going to point toward heat loss. 120V spas aren't known for rapid heating, and do have a hard time maintaining 40+ degrees above ambient temp unless they are WELL insulated. Based on your readings, you are pulling 1361.25 Watts for the heater... it's definentally on. As one person put it, you are heating a 300+ gallon tub with a hair drier.

lol - well lucky for me it's a smaller tub - only 205 gallons. i believe this is why it heats so rapidly.

any other ideas of what to check at this point?

Well I would say the t-stat is just fine, since you hear the click at around 7 on the dial and the water temp is at 98 degrees, the spa is calling for heat, and you have room to go on the dial. You have measured voltage at the heater when this temp is at 98 degrees. This means you are heating. You have to be loosing a lot of heat somewhere. Open cabinet door, missing insulation somewhere, poorly fit cover, air getting into the jet venturi's, etc. Make sure your air induction valves are closed... they will cool the tub.

ahh - i should make a correction at this point. i had the spa off for the past few days - as 98 degrees does not make for a "hot tub", just a high electric bill. when i tested it today it was at 81 degrees. i will reheat the spa back to it's top temperature then see if it is feeding volts out to the heater. should be able to report back in the next 24 hours or so.

as for insulation - the tub is really well insulated, and when i remove the panel to the control access compartment, the air in there is "very" warm - meaning - it's staying within the confines of the body of the unit.

tell me more about the air induction valves. are these on the jet lines, or the circ-pump/heat lines? i ask because i've run the jets "very little" and during these tests over the past few weeks, i do not run them at all for days. i just let the circ-pump and heating unit run. i'm not sure where i would find these valves.

while heat loss sounds reasonable - i'll know more after i get the spa back up to temperature and test the heater again.

thanks!