I have an old hot tub and spa pak (vintage 1991). The spa pak is made by a Canadian co. and is called an "Aqua Spa Pak: Gamma 240". The main electrical connection is 208V and pump/motor/control housing all sit on the ground under the tub. There are no "top side" controls for heat ... the pump on/off switch + thermostat dial + red hi temperature overload button are all mounted on the spa pak control housing.

I've researched various sites on the web and have a pretty good understanding of spa troubleshooting basics ... but am nervous about playing with live electrical connections using ohmeters etc. If power is off to the spa pak I have no problems working with it.

My problem: with the filter removed (i.e. to reduce low water flow possibilities), the pump runs fine, water is circulating, fine bubbles are coming out of the jets, the red high temperature limit switch has not popped out and the gfci in the house has never tripped

... now if I turn up the thermostat dial on the spa pak control housing, I can hear it click when I expect it to turn on, but the indicator light stays dark and I don't get any heat (even after leaving it like this for a few hours).

What I've tried:
1) I've checked 3 fuses it has and they are ok
2) On the Pressure Switch, I've turned the little black control knob completely counter clockwise. I understand this is it's most sensitive setting and should make it switch on (/ and allow the heater to operate) , if the pressure switch is working and it senses the least amount of water pressure coming from the vinyl tube that connects it to the heater jacket. Still no heat.

Based on the above, is there a most likely culprit for my no heat problem. I'm getting ready to buy a new pressure switch and try it (because I think it's the cheapest), but before I do would like to get a second opinion. Obviously I'm trying to avoid the expense of having it serviced by someone that knows what they're doing.

Is the pressure switch a good bet ... or should I first be checking out the heater element itself (by getting a friend who's more comfortable with ohmeters, live circuits etc.).

Is there a 3rd most likely cause that I don't yet see?

Thanks.

You should be able to just jumper the 2 wires from the pressure switch together to rule the switch as the culprit. If the heater comes on and all is well, you need a new switch or the line from heater to switch is plugged. You should also be able to hear the heater relay close when the thermostat is set to heat. If not I would check to see if that relay is being told to turn on. If it has power, then check at the heater leads to determine if it is getting power when it is supposed to. If you have power at the heater and still no heat, then heater is bad.

Thanks James ... just to make sure I understand, I've put "your words" into my words.

"You should be able to just jumper the 2 wires from the pressure switch together to rule the switch as the culprit."

I'm an electical moron, but what you mean would be equivalent to ... turn main power off; remove the 2 wires that are connected to the pressure switch; connect these 2 wires to each other; turn main power back on; try cranking up thermostat again and see if it works ... correct? I could do the same thing if I had a wire with 2 alligator clips (jumper) and attached them to the 2 connections on the pressure switch.

"If the heater comes on and all is well, you need a new switch or the line from heater to switch is plugged."

For the "or the line from heater to switch is plugged." part of your answer, this possibility is that maybe the vinyl tubing from the heater jacket to the pressure switch is plugged ... correct? When I pull the tube off at the pressure switch side, water flows out of the tube fine, so I guess this is not a problem in my case.

"You should also be able to hear the heater relay close when the thermostat is set to heat."

I do hear a "click" as I turn the thermostat from completely off toward completely on ... is this the heater relay closing sound you're referring to?

"If not I would check to see if that relay is being told to turn on."

Since I hear a "click" (= heater relay closing?) can I skip the "check to see if that relay is being told to turn on". (I wouldn't have a clue how to do this anyway)

"If it has power, then check at the heater leads to determine if it is getting power when it is supposed to. If you have power at the heater and still no heat, then heater is bad."

Remember, I'm an electrical moron so ... with power on; pressure switch still shorted out; thermostat in the full on position; if I use a cheap neon light bulb tester and put one lead on each of the heater terminals, I should expect to see the neon light go on ... correct. If not, replace heater element.

Thanks for your help and patience with a moron.

Yes, turn off power and just use a jumper wire with alligator clips and clip onto the terminals or wires of the pressure switch. Restore power, and with switch still bypassed, turn up thermostat and see if heater turns on. If it does, replace switch. There should be 2 clicks when you turn up the thermostat. 1 is the actual thermostat itself. As you turn it up or down, it will click at the current water temp. The other click should be from your heater relay being energized. As long as you DO NOT have a high temp fault, pressure switch is closed, and the thermostat is calling for heat, the relay should energize. But don't worry about measuring to see if relay is energized at this point. You can go right to the heater connections using a test light (rated for proper voltage) to check at the heater connections. Being very careful, place 1 lead on each terminal. You can also check from each terminal to the cabinet ground. If light DOES NOT come on then we have to look elsewhere. If it comes on, then it means that you have power to the heater and it should be on. If still no heat, replace heater.

You can also get some good info if you go to the top of this forum and click on "Spa Babes Inc." They have theory of operation of different components that make up a generic system as well as trouble shooting tips that I may not have suggested.

James - thanks for the extra details.

I removed the pressure switch ... and jumpered the 2 leads that connect it to the rest of the wiring; put power back on; turned thermostat up and heard 1 click ... but red light that normally shows heater is on, stayed dark.

I then tried to check the voltage (expecting to find 208) at the heater element contacts and got nothing (I went out and bought a cheap multimeter to do the check).

I guess I've reached my limit now ... so I'm off to the spa store and will pay them to figure out what needs to be fixed.

Thanks for trying to help.

In response to your question about not heating, I can think of a few thing.

Make sure the heater element is getting voltage, to check this put one meter test lead on each electrical terminal of the element and see if you have full voltage.

Do an AMP check on the heater when you believe it is heating, a 220 element will draw around 20 amps, a 115 element will draw about 10 amps.

Is the spa cycling at all, if you turn the thermostat all the way down does low speed pump turn off, turning up the thermostat does the low speed come on?