Hot Tub OHS, OH, or OverHeat Error Code
One of the water temperature sensors in the Balboa M7 heater has detected 110°F (43.3°C) incoming water temp and the Balboa spa pack has disabled all hot tub functions. The spa pack will auto reset when water temp is below 108°F (42.2°C) and start to operate again.
If your hot tub has been working fine without any issues and you suddenly find the error code displayed on the hot tubs Balboa topside control display see below:
Possible causes,
Summer time over heat.
It's not uncommon for the hot tub water to reach 110F on a hot summer day if the hot tub is running a filter cycle in the early afternoon when it’s typically the hottest part of the day. Even though the heater is off, the pump that runs for the filtration cycle will typically run close to 120F and when it’s so hot outside the heat from the pump has no where to escape to and the water will absorb it as it’s cooler causing the temperature of the hot tub water to heat up and trigger the error code.
Possible remedy,
Program your hot tub to run the filter cycle at night when it’s much cooler outside.
Clogged jets.
This only pertains to hot tubs that have a separate circulation pump that runs 24/7. If the hot tub is older and has run for many years calcium can form on the heating element and when the build up reaches a certain size chunks can break loose. When they break loose they will either be pushed into the hot tub if small enough to pass through the plumbing or if bigger will get trapped in the plumbing just behind the jets. If enough calcium chunks build up behind the jets it will restrict the flow through the heater below the 25 gallons a minute required for the M7 heater with the sensors. With the flow reduced the heater will still be heating but the water inside the heater tube will start to get hot as it’s not able to flow through quick enough till it eventually reaches 110F inside the heater tube causing the OH code.
Possible remedy,
Identify the jets where the hot water from the heater exits into the hot tub water. With the hot tub running take a coat hanger and gently poke around inside the jet hole to breakdown the calcium deposit, which will be pushed into the hot tub water from the jet pressure. Once all jets are cleaned successfully full flow should be restored and the code should go away.
Malfunctioning Circuit board.
If its cooler outside and your hot tub has a large 2 speed pump that does the filtering and heating on low speed and you’re getting the over heat code without any sensor error code then it is possible that it may be an issue with the firmware on the circuit board’s control chip. Retaining the services of a professional hot tub service person is recommended to diagnose.
Possible remedy,
A qualified hot tub service professional should perform onsite testing and assessment of the hot tubs control system.
Malfunctioning pump.
The pump that pushes the water through the heater may be circulating water at a lower rate then required possibly due to the pump motor’s bearing being dry causing a loud noise, which reduces the pump RPMs. A clogged impeller from debris, which can also reduce the flow rate.
Possible remedy,
Shut down hot tub and have a qualified hot tub technician remove the pump and assess to ensure it’s operating within the pumps specs. Also check the impeller for debris.
Valves.
Gate and ball valves partially closed between the heater and the spa. This only applies to hot tubs that have the shut off valves as not all spa manufacturers install them. If the valve is not fully open it can restrict the water flow from the heater into the hot tub causing the water inside the heater tube to reach 110F and trigger the overheat code.
Possible remedy,
Check to ensure all valves are 100% open and if any valve has been closed and opened recently especially gate or knife valves ensure the gate did not stick and the valve only opened partially.
Sensors.
In Balboa spa packs with the M7 generation of heaters a sensor failure will typically not result in an OH code because the system has separate sensor specific codes that display when a sensor malfunctions.
Jets
If your hot tub is equipped with only 1 - 2 speed pump turning to many jets off will cause severe flow restriction through the heater which can cause over heat error code to appear and shut down the spa. Operating the spa with a couple of jets turned off will not reduce the flow enough to cause issues, however turning more than 1/3 of the jets off will cause flow restriction and error codes.
Possible remedy,
Check all the jets in the hot tub and make sure they are all the way open.
Please note that the topside display cannot produce an over heat code or any error code and replacing it when the code is displayed will not solve this error code or any error that it displays.