Question:
Could there be something internal that is overheating and causing it to
properly shut down, or do I have a bad sensor or thermostat? There is a
sensor that is hose-clamped to the output pipe and would therefore be
easy to replace. Could I be that lucky? If so, how do I test it? Can
I just short out the sensor when the heater shuts down and see if it
fires back up?
Answer:
Pool and spa heaters only work when the pump is on and the water is
being circulated, so it isn't a case of stratification. If the heater
USED to stay on until temp was reached, and now isn't, it could be a
problem with a control (thermostat or high limit switch.) More
likely, it is the flow switch.
Pool heaters have a flow switch that is factory set at either 1 or 2
psi, depending on manufacturer. Comfortzone has had both settings in
the past. If you are trying to fire the heater with the low speed of
a two speed pump, you may not have enough pressure to keep the flow
switch closed all the time. A dirty filter, it can cause this same
symptom. Here's why: the filter is installed BEFORE the heater, and
when it gets dirty, it blocks the flow. The pressure guage on the
filter really measures the pressure on the DIRTY side of the water
path, so when the pressure guage rises, you actually have less
pressure downstream of the filter (a good analogy of this is placing
your thumb over the end of a hose . . . the pressure inside the hose
increases, yet you can see the amount of flow coming out the end is
lessened. When you completely close off the flow of water, the
pressure inside the hose is its highest.)
You can reach Hayward's service department at 1-909-594-1600 (Hayward
purchased Comfortzone a few years back when I was still their
Technical Service Manager.)
