Question about Pentair Mastertemp Pool & Spa Heater Dual Electronic Ignition 400,000 Btu Lonox Propane 460737

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HLS & Service Heater LEDs

Tested heater for this season (worked well end of last season). Heater ignites and runs from anywhere from 2 minutes to 15 minutes (depending on flow rate or if the universe is happy or not). Burner shuts off. Front panel shows "Service Heater" while rear of panel shows HLS error. After a couple of minutes, heater re-fires and burns for a while and same error LEDs. My flow rate is within the parameters for the heater. I am wondering if my HLS switch has gone bad. The switch is about $40 on Amazon, but not sure how to install (I'm OK with electronics, not so much with plumbing) or if this is the issue. Any advise more than welcome before I call a service tech.

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Hello.... HLS usually means hi limits.... check the connectors at the high limit switches, to make sure they're not rusting off. If they're good, and the heater fires, but turns off after a minute or two, the problem lies usually with the temperature regulator.... it's the round cover with the 4 slits in it between the inlet and outlet. It comes out counter clockwise. It holds a spring with what would be a car thermostat attached to the end of the spring. That thermostat can be malfunctioning, and it will allow the water to get too hot coming out of the heater, which trips the hi limit. A quick fix is to remove the spring with the temperature regulator, and put the cap back in place. You definitely want to get another one to replace it, because the efficiency rating of the heater will go down considerably.... but it will do the job in the meantime with no danger. (Its like running a car with the thermostat removed, it can be done, but the engine runs too cool). They cost about 50 bucks on amazon.

Posted on Jun 21, 2015


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check pressure switch for continuity with pump on

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high limit is open this is due several factors like slow water .pump on low speed or dirty filter, also hard water, or assembly valve not working properly so make sure the filter is clean check the water chemistry an last check the valve assembly. make sure plumbing is correct water in and out from the heater

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