Hot Tub Supply Spa Depot
Troubleshooting Spa Equipment
Repairing Hot Tubs
 SpaCyclopedia Index Illustrated Repair Glossary Plumbing Diagrams Wiring Parts Catalog
Go to Online Spa Parts Catalog thousands of replacement parts.  Fast, FREE shipping!
CAUTION: Electrical repairs can be dangerous, especially around water. We recommend that repairs be referred to a qualified electrician or spa technician. Regardless of who performs the work, make certain that all electrical power to the hot tub or spa is disconnected prior to making any inspections or repairs. The information  provided here is for educational purposes only.

Return to Troubleshooting Guide

Spa repairs Spa runs, but does not heat; insufficient heat.

Components associated:

  • Flow/Pressure Switch
  • Thermostat
  • Heater Contactor/Relay
  • Heater Element
  • Spa Side Control
  • Filter Cartridge

A) Check incoming power for proper potential (voltage 110 or 220vac). Do not continue until power checks correctly.

B) If installing a new Control System, make sure that the heater is installed after the pump.  The heater's flow/pressure switch will not function correctly if mounted before the pump, i.e. the pressure switch will prevent the heater from being energized.

C) If pump runs, but there is no water flow, and hence no heat, you may have an air-lock in the pump wet end.  Correct this problem by closing the valve on the suction (intake) side of the pump and then loosen the front pump union just enough to allow the trapped air to escape from inside.  Retighten the union,  open valve, and re-energize the system. NOTE: On newer spa packs, a no-flow condition will normally cause the flow switch to cut power to the heater, and/or the hi-limit switch to trip, disconnecting power to all components.  On older systems, the hi-limit may only cut power to the heater element itself, allowing the pump to run in a dry condition, which in turn may damage the pump.

D) Turn thermostat full clockwise (CW) and switch to thermostat mode. If low speed pump engages, check for power at heater element terminals. If power is good but unit still does not show increased temperature within two hours, replace heater element.

E) If power is not correct at heater element, jump out flow/pressure switch connections and recheck power at heater. If power is now correct, flow/pressure switch has failed or is incorrectly adjusted. If power is still incorrect, check heater contactor (110 or 220vac line side contact voltage, 110vac coil voltage, 110 or 220vac load side contact voltage). If line side contact voltage is bad, check line input terminal connections (check also for proper jumper placement if unit is running 110v). If coil voltage is bad and pressure switch is jumped out, this indicates an internal wiring problem. If line input and coil voltages check good but there is no power on load connection or at heater, replace contactor.

F) If the pump does not engage with the thermostat fully CW and the unit in thermostat mode, switch to time clock mode. Rotate timer face clockwise, with some trippers set in and some set out, until low speed engages. If low speed does not engage, go to section on No Low Speed Pump. If low speed does engage with timer, switch back to thermostat mode and jump between terminals on thermostat. If low speed and heat will not engage with thermostat bypassed and previous checks show good, this indicates an internal wiring problem. If low speed/heat engages, pull thermostat bulb from thermo-well and inspect capillary for damage (replace if kinked, crimped or damaged). Let bulb reach air temperature, remove jumper; if low speed/heat engages once bulb cools, either thermostat is out of calibration or flow past the thermostat bulb/manifold is incorrect. Check the valves for restriction or closure, filter element for clogging or reduced flow, etc. If flow is correct, replace thermostat.

G) If the low speed/heat does not engage without the thermostat connections jumped with bulb at air temp and thermostat full CW but will with thermostat connections bypassed, replace the thermostat.

H) If using a spa side control, unplug spa side and attempt to operate using thermostat on control box, if so equipped. If still incorrect and symptoms do not change, follow steps A) through E). If unit heats less or more using control box thermostat than with spa side control,  but still incorrectly, this indicates a water flow problem.

I) If unit works correctly with thermostat on control but incorrectly with spa side, replace spa side control.

Back to Troubleshooting Guide

Illustrated Glossary

spa customers write  Consumer Reviews
EasyPak Spa Controls
"It's just like the name says.  Actually easier to install the new spa pack than I thought it would be.  I appreciated the expert tech support you provided by phone, the new pack arrived promptly, and my spa is up and running again just like new.  Can't thank you enough for the great service and fair prices too."

M. Matson
Fort Benning, GA

Spa Depot, The, Spas & Hot Tubs - Dealers, Olympia, WA

BizRate Customer Certified (GOLD) Site - The Spa Depot Reviews at Bizrate
BizRate Circle of 
Excellence Site – The Spa Depot Reviews at Bizrate