Hotsprings Highlift Model K Hot Tub Not Heating

[jkillion]

Hi,

My hottub is not heating. Here is what I have done so far.

1) Verified that control and high limit thermistors are working correctly and reading correctly. Ohm reading across the thermistors compared to chart and current water temperature
2) Verified that the flow switch is working (near 0 ohms when circulating pump is running)
3) Verified that heater is not broken working by checking resistance across two load wires (~9.8 ohms)

Here is the rub. When I check the wires running to the heater I am getting the following readings via multimeter set to 600volts AC (lets assume A and B are the voltage wires and G is the neutral wire)
A-G - 140volts or so
B-G - 57 volts or so
A-B - 59 volts or so

I think it should read more like A-G, B-G being 120 and A-B being 220 or 240.

What causes this type of symptom? I know its not heating because the heater isn't getting the correct amount of juice to do its job. Is it a bad heater relay or something?

Thanks for your help.

Jud

[PreservedSwine]

Most likely, bad heater PCB, but you'll need to confirm source voltage is good from the breaker that is dedicated to the heater circuit.

Ensure you're getting 240v between terminals 1 and 3 on the main terminal block. If you are, replace the heater PCB, assuming you have one.

Also of note, there is no neutral running to your heater if it's 240v. Only two hots and a ground.

[jkillion]

Thanks!

Some additional info. I checked the power from the breaker box to the control unit. 240v.

I checked the power going to the heater relay, 240v. (120 on each side of the relay, combined 240)

The power coming out of the heater relay is messed up as above. I thought relays for the most part were open or closed. Would a heater PCB make it just open on one side and half open on the other?

Is this the part you are talking about for the heater PCB? http://www.backyardplus.com/proddetail.php?prod=71341&cat=258

Thanks,

Jud

[PreservedSwine]

You didn't give your serial number, so I can't confirm that's the one you need, but I can assure you that the part you linked is NOT the part you need. That's an electronic high limit, if it fails, it shuts down the entire spa.

In order to accurately troubleshoot, I need you serial number.

If memory serves correct, they stopped making the highlife in 1996, so lets assume you have a 95 or a 96.

If that's the case, you don't have heater circuit board.

You just have a couple relays. Depending on the serial number, probably 12v dc coil T-92's, part number 34321.

Check voltage to the coil while trying to heat. If it's 12v dc, the relay just needs replacement. Very inexpensive fix

[jkillion]

Yep, its a 1995. To check the voltage, which terminals do I need to test across when it is trying to heat. Lets assume it has a layout as follows for the relay looking down at it:

A B

space

space

C D

E F

The spaces are just dead space (tough to do this in text

Here is the voltages:

C-D 240V

E-F 50 or 60 volts

C - ground 120v

D - ground 120v

E - ground 130v

F - ground 60v

I haven't done anything testing from A-B or either of those to any other terminal.

I will go ahead and grab 34321, but in the mean time if you let me know which terminals to test the 12 volt part that would help!

Thanks,

Jud

[PreservedSwine]

Thanks Doc, as long as we know the year, we're on the same page

A and B are the coil terminals. You should get 12v dc across A and B.

The relay is borked. Once you replace it, the heater will energize, and if it's good, you'll be heating

[mrwrick]

Read this topic because I also have Hot Spring with heater issues. Mine is a Classic F. PS, you have gotten me going on a couple of repairs in the recent. I thank you. Hopefully you can solve my problem again. I have replaced the relay dedicated to my heater. I also did the wiring retrofit recommended for the rectifier that eliminated a diode and converted it from AC to DC , or the other way around. Whatever it was I did it with the kit and instructions, clarified by you. I have also replaced the thermostat and tested the spa and high limit parts. But now I have no heat on starting it up. It is a self priming system and I have good recirculation pressure into the spa after the heater and did a full flush and drain and put in new filters. What can it be? Please help. And thanks, as always for being here and so willing to help us DIYers get it right.