Hello All,

I have a 435 gallon Bullfrog spa with two 2-speed jet pumps. The water temperature keeps rising to 107 degrees, even though the thermostat is set at 98. (Daytime temps have been < 70.)

After some investigation, I discovered that the heater is not turning on at all. However, during the filter cycle, the outer casing of pump #1 gets as hot as 130 degrees, and the temperature at the wet end is 107.

This pump is supposed to have a thermal shutoff, but to my knowledge has never done so. I have three questions that I need a little help with:

(1) Is 130 a typical operating temperature for these pumps?
(2) If not, how concerned should I be?
(3) What could cause the pump to overheat?

The pump is a Vico Ultra Jet with these specs:
model #5KCR48TN2351X
230 volts, 60 Hz, single phase
8.8/3.4 amps (high/low speed - filter cycle runs at low speed)
3450/1725 RPM (high/low speed)

Any thoughts or advice would be appreciated.

-- Brett

130F doesn't sound too hot for the pump casing, especially when running as long as yours is. If the heater isn't energizing, it is indeed the heat generated from the jet pump, combined with the friction of moving water that will continue to heat the spa.... above and beyond 107. All jet pumps incormporate a thermal overload in case the pump motor overheats. This has nothing to do with water temp. There is no indication when the internal thermal overload trips, other than the pump simply not running. You might get a flow error at this point, but no error codes about the pump thermal overload will be displayed on the topside when this happens (OH, HiTemp)

The spa also has it's own high-limit protective devices that may shut down the heating system, or the entire spa, depending on the temp. of the water. When this happens, you will get an error code on the topside. If the spa continues to heat to 107, and the heater is staying off, it sounds as though the pumps are simply running way too much. 107 isn't hot enough to trip the high-limit. If there is a filtration or timed cycle built in, try setting it to run as little as possible, and see if the temp returns to mormal.
What is the ambient temp. in your neck of the woods? Does the spa also have a small, silent 24 hopur circ. pump?

Thank you very much for your response. I'm happy to hear that 130F at the pump casing isn't considered excessive. The high-limit temperature of the spa electronics is fixed at 108F, so quite possibly it is shutting everything down and I simply haven't noticed. But I have never seen any error codes on the display.

The pump runs at low speed during the filter cycle, which is 2 of every 12 hours. This is the shortest filter duration I can set. If I set the spa to standby (no filter cycle) the temp has dropped when I check it the next day. There is no circ pump on this spa.

During summer months it can get quite hot here in North Carolina, but recently the outside temp has been 74F for the daytime high. I don't think that's hot enough to heat the spa to 107F.

Maybe the pump is running more that 2 hours twice a day, but I'm at work all day, so I wouldn't know. Any ideas for how to test this theory?

Thanks again for your help!

-- Brett

I'm wondering if you've had any changes since your last post in May, since all it's done is get hotter.



Hire someone to watch it.



Note: The pump motor's ahem... thermal shut off depends more on excessive current flowing through it (such as that caused by a locked rotor) than ambient temperature. Most of these suckers end up in the 130-160 degree range on the outer case imo. But that's also dependent upon the impeller loading which mfgrs tend to push to the nth degree.

That said, your problem almost sounds normal for an extremely well insulated spa, but considering your outside temp, it seems not...

Your spa got any cabinet vents?
Does your spa have that metallic film insulation inside the walls? (I call it aluminum bubble wrap - sold at home depot to insulate attics).