Is it ok to shut off water flow to heater?

[Rq120]

Just wondering if it's best to let water flow through pool heater or divert water flow when heater is not is use? We are in FL and have both a solar and electric heater for our pool. The electric heater doesn't get much use as you can imagine but we always have water flowing through it. I guess I was under the impression you don't want to leave the heater "dry".
I see threads on here about chlorine/salt levels and affect on heaters/corrosion so I've always wondered this. Whom better to ask than the experts.

Thanks!

 

[mknauss]

Many pool equipment designs use a bypass around the heater when not in use. Search for heater bypass.

Salt and chlorine at normal levels are not harmful to your heater. Low pH is the biggest threat to your heater.

 

[Rq120]

I can see we can bypass the heater. I just was wondering if we should be bypassing the heater. It sounds like it doesn’t matter either way if you keep chemistry in check?

 

[mknauss]

Correct. Depending on your system you will reduce pressure by bypassing your heater.

 

[Steve_in_C]

However, you may want to cut off your heater while adjusting your chemistry. New fill water may have the wrong pH. Adding borates and then adjusting pH may take a few hours and you don't want a copper heat exchanger exposed to the abnormal pH during these adjustment periods. I always take my heater out of circulation when doing major things with pool chemistry.. My fill water pH is 5.3. I would just prefer a way to bypass the heater. You may need to someday.