I have an old Hayward H300 natural gas heater. Despite being 21 years old (there is no digital display on the unit for example, that is how old it is), It still ignites faithfully every morning and heats up my pool to the mid 80s without an issue. However, when I switch to spa mode on my Jandy Aqualink, the spa only heats to about 95/96 degrees and then the heater shuts off and cannot be re-ignited for a few minutes. The spa temperature is clearly set at 102 degrees. I suspect that the issue is with a High Limit switch. However, my heater has two high limit switches: one for 135 degrees and another for 160 degrees.
My question is: which one is most likely to be the problem?
Any insight would be much appreciated. Thanks in advance.
My question is: which one is most likely to be the problem?
Any insight would be much appreciated. Thanks in advance.