Hot Tub Error Code Guide
No Heat, Hot Tub Not Heating
UrgentThe pump runs but the water won't reach temperature — usually flow, sensors, or a scaled element, not always a dead heater.
Call 385-588-7757 for Fast RepairWhat Does No Heat Mean?
A hot tub that runs but won't heat is the single most common repair call we get, especially November through March across the Wasatch Back and Utah County. The good news: most of the time the heater element itself is fine. Heating is disabled by a long list of protective conditions — low flow, a tripped high-limit, a bad temperature sensor, or scale — and each of those costs far less to fix than a full heater assembly.
The key is to diagnose in the right order instead of guessing. A spa will happily run its jets and pump while heating stays locked out, which fools many owners into thinking the heater is the problem when the real cause is upstream.
Also searched as: spa not heating, hot tub won't heat, water not getting hot, cold hot tub.
Most Common Causes
- A flow problem (dirty filter, airlock after a refill, closed valve, failing circulation pump) that disables the heater — often shown as a FLO/FLC code
- A tripped or failed high-limit sensor after an overheat or scale event
- A failed temperature sensor sending a bad reading to the control pack (SN1/SN2)
- Scale insulating the heater element until it under-performs or trips
- An actual burned-out heater element or corroded heater connections
- A control-board relay that no longer powers the heater circuit
What You Can Safely Check First
- 1
Confirm the set temperature is above the current water temp and the spa isn't in a sleep/economy mode that limits heating
- 2
Remove and rinse (or replace) the filter — a clogged filter is the #1 cause of no-heat calls
- 3
Check the water level; if it's low, the skimmer pulls air and flow drops
- 4
After any recent drain-and-fill, bleed the air from the pump/heater loop to clear an airlock
- 5
Note any error code on the display exactly — FLO, OH, DR, SN1/SN2 each point to a different fix
Brand-Specific Notes
Bullfrog spas often lose heat to JetPak/filter flow restriction or a WellSpring circulation pump. Sundance and other Balboa-based systems commonly show sensor (SN) or flow (FL) codes tied to the circ vs. jet pump. Hot Spring spas can lose heat when the SilentFlo 5000 circulation pump wears out — it hums but moves little water. Brand-specific diagnosis matters because the failing part differs.
How Urgent Is It?
In a Utah winter, treat no-heat as urgent. A spa that isn't heating (and especially one that isn't circulating) can begin freezing in hours at altitude with wind exposure. Keep the cover closed to hold residual warmth and call for service right away.
No Heat FAQs
Does a hot tub not heating always mean a broken heater?
No — most no-heat calls we run in Heber and Park City trace to flow restrictions, a tripped high-limit, or a bad sensor, all cheaper than a heater. We test flow, sensors, and element resistance before quoting so you never pay for guesswork.
How fast can you fix a hot tub that won't heat?
No-heat calls are our top winter priority. Because we run weekly routes across the Wasatch Back and Utah County, we typically diagnose within 24 hours, often same-day in the Heber Valley, and complete most heater repairs in a single visit with parts on the truck.
Still Seeing No Heat?
Send us your spa brand and the code, we'll diagnose the root cause and bring the right parts.
Other Hot Tub Error Codes
No Heat on your display? Let's fix it right.
Owner-operated, CPO Certified repair across the Heber Valley, Summit County, and Utah County. We diagnose the root cause, not just reset the code.