HELP!! I have an older model late 80's earlier 90's, Sunwave/Aquatherm. The model number I think is 12-640 103A. Its wired 220. The water circulates fine. I have no heat on low speed. Heats up fine when high speed jets are on. But because low speed heat doesnt work, temp drops when jets are off. Would be nice to be able to come home and use the tub but it takes a day or so with the jets running to reach soaking temp.
Also the low speed pump runs constantly even after the temp is reached. I can hear the t-stat clicking on and off when I turn the dial and the heat light goes off when the t-stat turned below current temp, but the low speed pump still runs. The timers are turned off and low speed still runs. The only way to turn pump off is to turn off power to whole unit. I have changed the filter. Any Help is greatly appreciated!!
Thanks!!

1st- try taking out your filter. Does it now heat on low speed?

If so, clean your filter.

If that doesn't do it, then ckeck for proper pressure switch operation, adjust or replace as needed.

I have replaced the filter with a new one and still no heat.

I will check on the pressure switch. Do you know is there a low switch and a high switch? Not to sound totally stupid, but since I am new to the hot tub thing, where would I find the pressure switch? Is it located under the black cover plate on the end of the heater?

Do you think this will correct the problem with the low pump running all the time or is suppose to run?

Thanks for you reply!!

The pressure switch detects pressure. On low speed, there's less pressure, so the pressure switch may not close if it's not working properly on low speed, but still be fine on high speed.

I'd try adjusting it first, and if that doesn't work, replace it.

As far as low speed running all the time, after reading your description, does it have a toggle switch marked "24 hr/auto" or something similar?

Also, where is the "heat" light you're reffering that lights up when the heater is energized? IS it on the control box, or topside? How long does it take the spa to heat on high speed (temp F/hr)

Thanks,

~Swine

Swine,

The heat light is located top side.
There is a toggle switch.( on the timer low side) It reads timer, off, over-ride. It is in the off position.

When the jets are running it still takes a bit of time to heat up. But I have noticed that the time might vary. There other day jumped about 25 degrees in probably 24 hours. Like last night, turned them on, temp at the time was 82. Ran all day today temp is now 92. I would say it was pobably about 45 low last night outside and today was probably upper 60's maybe 70 outside. The heater on this tub is burried in the back and I have to take the entire lower control panel out to get the heater out. So if I do, I only really want to do it once, if you know what I mean.

Thanks for your help!!

I'm wondering if the heater is even working. 25 degrees in 24 hours is way too slow on 220v, assuming the spa is covered. With a spa cover- gain about 8 degrees/hr is normal for a 220v heater and 300 gallon spa.

The spa is likely heating on high speed from friction of the water, and the heat generated from the jet pump.

Can you take a pic of the control box? If you want to go further, be sure you know your way around a multi-meter, because troubleshooting is next

I guess maybe it could be heating from the pump. Yes there is a cover.

Here are some pictures to view. I do know my way around a mult-tester, so thats not a problem.

Okay, I took the heater out. I checked the pressure switch with meter and checked out okay. I checked the element with meter and it checked. (not sure what it should be) I even took 110 and wired directly to element and it heated. I replace the unit back in tub and by passed the pressure switch. No heat. When I switch the over ride switch on the heater it pops the GFI at the wall. Is is possible the element is still bad even though it heated on 110 sitting on the work bench? ( its a 220 unit)

Sure, if the bench outlet wasn't GFCI protected. Also, it wasn't full of water that will conduct electricity from the element to the current collector.

In depth troubleshooting on-line on that pack is virtually impossible- it's so old, can't remember the last time I worked on one. I'd have to have it in front of me to properly diagnose. Stick to the simple stuff first- be sure relays are working when the coil is energized.

I also forget to mention. When I re-installed the unit. I left the cover off the end of the heater. (the cover that covers the pressure switch, the wires) (because of the location you can't visibly see directly into that area) When I flipped the heater over ride switch, you can see the glow of a spark and then the GFCI trips.