My Pacfab Minimax Plus 400 heater is short cycling (turning on and off rapidly). The troubleshooting section in the manual suggests the problem/remedy may be one of the following:
1. insufficient water flow/clean filter
2. defective wiring/repair or replace wiring
3. defective flow valve or out of adjustment/call serviceman
4. defective hi-limit and-or thermostat/call serviceman
My question is really how to narrow down the above possibilities (ok, I am sure the problem is not low flow)? Obviously I do not want to call a serviceman again, but I am quite adept with electronics (less so with plumbing).
Here are some thoughts, please tell me if this makes sense:
1. Wiring does not go bad after 15years of operation. So it seems to me #2 above is unlikely
2. Short cycling occurs with switch set to either "pool" or "spa." Since each of those has a separate hi-limit, it is unlikely that both hi-limit shut offs went bad simultaneously. So it must not be the hi-limits.
If this is good logic (is it?) then I have to decide which should be the first step: replacing the thermostat board (easy to do, part is $120) or replacing/adjusting the flow valve (no idea how to do, probably difficult, about same price as thermostat).
Last question: how does one adjust the flow valve?