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hi oh experts. (real and self appointed)

i actually used the aquahot electric side today for the first time. i have always been where it was hot and needed all the aircons before so would just turn on the diesel side.

i was quite surprised that the electric side heated up as quickly as the diesel side did.

but here is my question. how hot should it get on electric? i turned it off when it got to 215 on the tank temp gauge inside. i took an unhurried shower and it was still at 206 when i got out.

same question on the diesel side. what temp should it reach?



Ashley and I recently replaced both of his electric heating elements, a 1650 watt 120 vac and a 4500 watt 240 vac. Well then the tank temp reading would go above 220 degrees F and the high limit thermostat would open and completely stop electric heating until it was reset.

Ashley replaced the Newel installed relay that the electric switch in the coach turns on/off and problem solved. The relay had failed with the 120 volt element always on (one leg of the two legs) no matter what the control thermostat wanted. So that one element never stopped heating the coolant tank.

The Newell relay is mounted on the front wall of the Aqua Hot compartment near the the door hinges up high near the ceiling of the compartment. It has a silver colored cover.

To diagnose this, turn the electric switch off inside the coach and then look for voltage (120 vac to ground) on each leg of the high limit thermostat. This thermostat is located behind the stainless steel cover just above the burner. It has two legs going to it and has a red reset button. With the inside switch off, both legs should show no voltage. If one does, replace the relay.

Hope this help you.
thanks rudy,

what temp should it be stoppng at?


I do not know the accurate answer but somewhere between 225 and 235 degrees F. Once the high limit opens, it must be manually reset by removing the cover and pushing the red button.

Careful, there can be 120 vac to ground and 240 vac leg to leg on those terminals. You can test with VOM meter first or just unplug the coach if you do not have a non-conduting probe to push on the red button or just want to be certain the terminals are not energize.
I have been researching this issue all morning before I saw Tom's post and Rudy's response. I have been heating electrically this last week and the temperature, like Tom's, jumps up almost as fast as diesel. This morning I noticed the temp. jumped to 235, and a few hours later settled back to 220. I am not sure I can perform the tests Rudy suggests, but I wonder how accurate my gauge is. I would like to find out where to measure the heat at the AquaHot using my infaray heat gun. Rudy, if mine stops at 235 and then settles back somewhat, and assuming that the gauge is accurate, is this OK? Second question, will Roger or Rudy be at Spearfish and will there be parts available? In the meantime, I am going to turn it off until I need shower water and watch for a few days.
Tom, Your unit sounds normal.

When on electric my unit gets up to around 220. When running diesel I think it is closer to 200F. The diesel seems to start heating again when the temp drops to 170-180. I dont really notice when the electric element is on...but when electric is on....I dont usually see a drop in temperature with usage.

Hope this helps.
I know mine is a little older, we use ours often when night temps get in the 50s, but the limit is 199...and stays there until usage. It has always worked this way...maybe an element is not working correctly? or is there a way to set limit?
Never breaks 200. We have alway had enough heat for warming the coach on cold mornings, but for both to shower in cold weather we must light the diesel...
OK, I did some more research and finally read the factory manual. Both AC and Diesel overheat thermostats are designed to shut off power or fuel at 230 degrees. I will open the thermostat metal cover and try to determine if the boiler exceeds 230. My temperature gun may not be accurate enough, so does anyone know what thermostat I should use?
I'm back. Took the cover off of the thermostats, my Ryoai laser temperature gun shows 167 degrees when pointed at the metal adjacent to the thermostats, but my digital gauge in the coach shows a temperature of 227 degrees. Does anyone have an explanation, and should I be concerned?

Both Roger and I will be at Spearfish. I will be there all week to have lots of fun and visits. Roger and his vast part supply will be staying in Sturgis and will visit one or more days. I can assist in getting parts during the week we are there.

Seems your system is operating fine. I do not worry too much about the temp readings because calibration of the sensor varies. But I do worry if the high limit trips. Then I want to know did the temp get too high (control thermostat failed closed) or did the high limit trip early (bad high limit thermostat). A measurement with a contact probe vs IR gun is what Roger and I use to sort it out.

The normal failure mode of the thermostat is fail open.

I do not understand your question about which thermostat to use to measure the temp of your tank. Measure the metal surface around the thermostats that are attached to the outer surface of the tank.

If you want to know which thermostat is 12 vdc or 120 vdc, see me in Spearfish or e-mail me with your phone when you can look at the thermostats and I will be happy to help you sort them out.

Chester, You posted while I was writing and I think the IR gun is not as accurate as a contact probe or the temp sensor in the Newell installed heater that is in the tank. So Please do not worry.
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