Hot water, then cold, then hot, then cold

[VACMAN]

While taking a shower this weekend The water would get hot for about 1 min. the turn cold, another min. go hot again. then no more hot. Could it be: The plastic reservoir tank in rear. It says OASIS..Has a fill line. it is below the fill line. I was told on another thread that I had to fill with a special Boiler Antifreeze. I have not found any of this special antifreeze yet, But do you think this will solve my above mentioned problem?

[Hitchhiker]

I know you'll think it's wacky but if you have an outside shower, check for the hot and cold valves being open. Another place to check would be the winter bypass cross over valve might be opened a tad.

[bill99]

Had same problem with Aquahot system. Fixed it by replacing the thermostat that controls the heater. The heater heats the PG(propylene glycol) solution. The PG solution heats the shower water. With the PG solution hot and the burner off the water is hot until the PG solution cools because of heat transfer to the water. The thermostat is supposed to turn on the heater to heat the PG solution back to temp. My thermostat was not kicking the heater on soon enough so we were getting this hot cold-hot cycle in the shower.

If the level of PG gets too low my system has a low level shut off and the heater will not run period.

Bill99

[VACMAN]

Quote:

Originally Posted by bill99 Had same problem with Aquahot system. Fixed it by replacing the thermostat that controls the heater. The heater heats the PG(propylene glycol) solution. The PG solution heats the shower water. With the PG solution hot and the burner off the water is hot until the PG solution cools because of heat transfer to the water. The thermostat is supposed to turn on the heater to heat the PG solution back to temp. My thermostat was not kicking the heater on soon enough so we were getting this hot cold-hot cycle in the shower. If the level of PG gets too low my system has a low level shut off and the heater will not run period. Bill99

Bill... where is this themostat located, and is it easy to change?

[bill99]

You should have a manual with diagrams, etc. If not contact Aquahot with model no etc. I ordered replacement from Aquahot, had to drain about half the PG solution to get level below thermostat mounting hole. On mine it is about one third of way down side of main tank and screws in/out. I needed a long 7/8 socket and an extension for the wrench to get in the recess.
Bill