Hydro Hot Stir Pump

TClark39 wrote:
I have a Model HHE-500-07M Hydro Hot in my 03 Mountain Aire. We have noticed for a couple of weeks that when showering with the diesel burner on, that we run out of hot water. The following lights have been green: Elec. Heating Element, Hydro Hot Heating Status, Low Temp Cutoff Status, and the Diesel Burner Status. The Stir Pump light is NOT light and the stir pump is NOT running. I have taken a jumper wire from the black wire of the stir pump and jumped it to the Cabinet and the Stir Pump works. For the last couple of showers, I have jumped it to activate the Stir Pump while showering and we have had plenty of hot water. What activates the electronic controller to turn on the Stir pump? Could it be a bad thermostat, or, is the controller possibly bad?
Thanks for any help.
TClark39

shear educated guess on my part would be high limit thermostat or bad control board. as suggested get a manual with the trouble shoot section

http://www.rvtechmag.com/docs/HydroHot_Shop.pdf

Here is the manual if you don't have one. Step 7.9 .
Found this on another forum, seems to be your issue.

There is a thermostat on the incoming (cold) water supply, just before the pipe goes into the boiler tank (low temp cutoff thermostat). As soon as you turn on the hot water in the coach, the pipe cools off, the "Low Temp Cutoff" light on the electronic control board goes out, stir pump starts and interior heat shuts off. Note that the diesel burner switch inside the coach needs to be ON, or the stir pump will not start as designed.

The "stir pump" pumps boiler coolant from bottom front of boiler tank to top back of boiler tank. This "stirs" the hot coolant across the copper coil (that heats the hot water) and across the control thermostat.

If the stir pump is not working correctly, then your Hydro-Hot will not heat water properly. Water will start out hot, then cool off rapidly. There will be several minute delay, before the diesel burner starts, then the hot water will warm up and stay hot.

Moved from Forum Technical Support