My spa heater does not seem to be heating the water. I adjust the temp until it just turns on and it will continue to run and not cycle on and off as it should. It is drawing current (the cables to the heater get hot to touch) but it does not seem to heat the water. I measured the resistance of the element and calculated the current (based on 1500W - heater power from schematic) and it came to 13 amps, but the element should only be drawing 9 amps (again from schematic). So I think the element is bad.

Incidentally I did have to repair burnt wiring in the control box (yes I double checked everything and all is connected correctly). Everything works except for the heater (which has the correct voltage (120v) across it).

Spa is a

Manufacturer: Gerico
Model: Citation #30
Year: I expect >1984 as that is the copyright year on the control box

Control Unit is a

Manufacturer: Ramco
Description: Spa-Temp Control System
Model: ST-1115A
Year copyrighted: 1984 (so this unit is >1984)

Heater (Specifications from the schematic diagram)
Power: 1.5K Watt
Current: 9 amps
Description of heater: Square box (grey) with single outlet into water flow, ~2" PCV pipe. Small dia Copper tube coming out of box connecting into same water flow tube, but from top (standard copper nipple connection). 2 electrical cable come from unit, one 3 wire (power), one 2 wire (high temp/pressure?). Both have 120v inputs across them. Resistance of 3 wires is 9 ohms (heater power); resistance of 2 wires is infinity (High pressure/temp?). According to the schematic in the control unit the "high pressure” sensor and heater are in one unit. There is a high temp reset on the bottom of the unit. It was tripped but I reset it prior to fixing the wiring and it did not do anything.

Hope this is enough information. I can send a pix of the unit if you need it. I think the element is fried, but don't want to replace it unnecessarily if that is not the problem.

Thanks,
Jim

It's heating.

You're probably just not giving it enough time, or don't have a cover.

Temp gain is approx 2 F per/hour WITH a cover.

Without a cover, expect several days...

btw, if the wires are hot to the touch, are you using large enough wire? All connections tight?

It has a cover (brand new in fact) and ran for 6 hours without a single degree increase in temp. When I repaired the wiring I use the same gage as was originally in the unit. When in doubt I used 12 gage stranded.

I found the heater information
Carlon
Cat# E987N

Hope this helps. Thanks for the reply.

Jim

If the heater is drawing amps, it's heating....period. Are you checking amp draw for the heater only, or perhaps the entire system. Jet pump not runing on high, right? Perhaps a bad thermometer you are using?

Let it run overnight.

Good luck!

~Swine

As you suggested I ran the spa for 4 days. The heater continued to draw current (11 amps measured into the heater). The temp of the spa remained at 72 degrees.

2 points -
The heater is only suppose to draw 9 amps, it is drawing 11 amps instead.
The thermometer that I am using is a standard glass thermometer which has been verified to operate properly.

I think the heater has an internal short. While this failure mechanism is very rare (generally the failure is an open) it can happen.

Are there any other tests you could suggest? If not, I think a new heater will fix it.

Jim

Are you *sure* the heater is drawing 11 amps, and it's not the pump? If the heater is drawing amperage, it's virtually impossible for the electricity to simply vanish.
If the heater has an internal short, it would *not* draw any significant current. It's very simple. That energy is being used, either as heat, light, or in some other form. A heater can't draw that many amps and not get hot.
Where are you taking the Amperage test? Are you sure the Amp meter is working correctly? Are you sure it's reading in F.L.A, and not milli-amps??

A 1.5KW heater at 120v will pull approx 12.5amps and ohm out around 9.6.... (OHMS LAW) as voltage in every home can very as much as 10%, the amperage will always vary as well.... The schematic isn't precise.... You have completed the most accurate test to see if a heater is working....
You can OHM out the heater, of couse, but if it gives you O/L, it is impossible for it to draw any signifigant amperage....

I'm sorry I can't tell you more... if the heater is drawing 13 amps, it's heating.....

I detached one of the wires that connects to the heater element and inserted an ammeter directly into the path. I am an electrical engineer as well as a home hobbyist and have been building and troubleshooting electronics for over 30 years. I did read the meter correctly.

Everything you say is correct, it should be heating. Unfortunately it is not despise the high current flowing into the heater element.

The only explanation I can think of is the element is shorted close to the base and there is not enough actual element surface area to make a difference in heating the water. I was hoping that I had missed something, but it doesn’t look like it.

Thanks again for the suggestions. I will let you know if a new element solves the problem.

Jim

I have to agree w/ Swine on this one, if you are drawing amperage, the heater is heating and you are loosing heat as fast as you are making it. Your description of how you are checking amp draw has me a bit baffled, all the amp meters I have seen, and used clamp around the wire to check for amperage, not to say that there isn't an amp meter that doesn't clamp over a wire, it's just I have never seen one.




Something does not add up.

huh?

You need to keep the heater wired, and energized to check for Amps. When you say "detached one of the wires" you don't mean you disconnected anything, do you? If so, I don't think you are metering it out properly... Maybe you could explain it with a little more detail, or even a pic?

Good luck

http://www.doctronics.co.uk/meter.htm

All of the ammeters I have used are inserted into the circuit in series. My spa time is limited, but cut my teeth (9 years) fixing aircraft avionics systems.