Lo only when heating pool

[dhodson]

Wanting to heat pool

I can heat hot tub but when putting it to pool, the heater gives lo code

Why would that be if it heats hot tub fine?

 

[ajw22]

How long does heater run before it gives the LO code?

What temperature does the pool get to?

 

[dhodson]

I was mistaken it does it on hot tub too but less so.

It got to 95 on hot tub then got lo code. A few minutes later started heating again. It’s set for 104.

The pool is around 70 and only heats for a minute

 

[ajw22]

A Hayward LO code is a limit string open error that occurs when any of the safety circuits on your Hayward pool heater opens. This forces the heater to shut down to protect your heater from damage.

Usual reason for the LO code is lack of sufficient flow not closing the Water Pressure Switch. Low water pressure can be due to a filter that needs to be cleaned, low pump RPM if a VS pump, open heater bypass valve, low skimmer water level, or even a stuck weir door.

Also on the Limit String is the Temperature Limit Switch, Exhaust Gas Temperature Limit Switch, and Vent Pressure Switch.

See pages 40-43 in the Universal H-Series Diagnostics Guide.

Hayward H-Series Heaters - Further Reading

www.troublefreepool.com