Controlling engine water heating temps

[Maerin]

How do you do that?

To limit thread drift, the answer on a separate thread.


I ran into that problem replacing my Raritan 20 gal. It's engine heated, my engine thermostat is 193F because it's keel cooled. The Cummins likes it, but it makes scalding hot water. And, the water heater's electric thermal limiter trips almost every time the engine runs, so open the water heater panel and reset the klixon to get hot water via 120V. I don't think so.



The coolant circuit that feeds the water heater is already valved, so it was a fairly simple matter to pipe in a solenoid valve. https://www.amazon.com/HFS-Electric...pID=51UXtfq-yaL&preST=_SY300_QL70_&dpSrc=srchIt's NC, so it will fail closed. Could as easily be NO. That's a judgement call.



I powered it via a W1209 el cheapo digital thermostat. https://www.amazon.com/HiLetgo-Temp...pID=51A6QActfxL&preST=_SX342_QL70_&dpSrc=srch


Pulled power for the thermostat from the ignition circuit (purple) on the engine. The solenoid is powered from a fused lead connected to the starter (+). Mounted the thermostat in a project box https://www.amazon.com/Plastic-Elec...pID=41Xk9yTvOAL&preST=_SY300_QL70_&dpSrc=srch
and buried the sensor thermistor between the water heater tank and the insulation at the hot water outlet.



It works great. I can now set the temperature to whatever I choose, no more resetting the thermal limiter, and I have a bypass switch to energize the valve manually if the thermostat craps out. (the first one did, no big deal, just swapped it out). I set the temp to about 160F, the W1209 is C only, but easy to convert those values.



The W1029 is very versatile, I adapted another one to control my fridge. WAAY more accurate than the mechanical bulb stat that's on the fridge. It can be programmed for delay, offset, deadband, heating or cooling. All for about 5 bucks.

 

[O C Diver]

Thanks for posting that. I have the same Raritan 20 gallon hot water heater. My John Deere puts out around 180 degrees which is enough to trip the over temperature part of the thermostat. Got tired of removing the thermostat cover to reset the over temp switch. Drilled a 3/16" hole in the cover that lines up with the button. Have a nonconductive 1/8" probe to push the reset switch. Will have to consider your solution


Ted

 

[Maerin]

Thanks for posting that. I have the same Raritan 20 gallon hot water heater. My John Deere puts out around 180 degrees which is enough to trip the over temperature part of the thermostat. Got tired of removing the thermostat cover to reset the over temp switch. Drilled a 3/16" hole in the cover that lines up with the button. Have a nonconductive 1/8" probe to push the reset switch. Will have to consider your solution


Ted

I also considered exactly what you did as an option!

I contacted Raritan to see if they offered any COTS solution, the support guy I spoke with said to throttle the flow with a valve. Anyone with any sense knows that won't work on a storage tank. I looked for some sort of thermostatic valve, no joy. So my solenoid solution, despite being a bit inelegant, does accomplish the objective reliably.

 

[FF]

The commercial folks , think cafe , and farms use HW heaters with higher temperature settings than homes.

We use a Rheem Marathon that has a thermostat which goes to 180F-190F .

If you look at their repair parts perhaps their thermostat will be useful for your unit?

 

[sunchaser]

Nice moves Maerin.

Not a new method, but facilitated by the DeFever's easy ER access, I on some heavy hot water usage days open the on engine water heater valves for about one hour each day of cruising. Then close them for the duration of the day.

Also, the water heater is a great load for the genset, so probably 75% of the Torrid's energy requirements come from that source. As FF is fond of saying, KISS.