On Dec 27, 4:10*pm, lesnpat wrote:
My spa is a 2002 Regency Spas, made by National Equipment Mfg. Corp.
The circuitboard system has no mfr. name anywhere. *There are both a
knob thermostat control on the box at the heater and a topside
pushbutton control at tubside. *The heater is electric Vulcan style
(flow-through 2" stainless tube). *Pump is 220v and heater is 110v.

The spa heats normally, but quits short of target because the topside
digital thermometer reads 5 degrees warmer than actual water temp. *Is
there a way to calibrate the digital system to get the reading in sync
with the actual water temperature?

I have a much older NEMCO spa, but the system may be similar. With
mine, the system of measuring and displaying the temp is controlled by
the electronics inside the power pack and it's not meant to be user
adjusted. There are several pots inside the power pack that control
parts of the settings. One of them does what you want. I figured it
out by experimenting years ago, but don't know which one was which
anymore. Plus your power pack is probably different. I couldn't
find any info avail that detailed what's in the power pack or how it
works.

Are you sure it's really a calibration problem? Is it always off by
about 5 deg at all temps?