We’re here visiting friends and working on vehicles. Tom is building an expedition vehicle and has chosen a 4×4 ambulance as the staring point. More on that later
Tom’s expedition truck and my ’95 Dodge
Tom told me about a trick to save water and propane so I’m going to install that while I’m here.
Plus we’re going to ride Mountain Bikes! How fun is that!?
Tom’s truck is 23′ long, about 10″ tall
First up, the Water Heater:
There is a 10-gallon water heater in my coach that can run on either electricity or propane gas. I suspect it heats water up to about 120/140* F before it shuts itself off. Of course 120/140 is too hot to be comfortable on my skin so I add some cold water to get the temperature just right. Seems simple enough.
There are two issues in my coach about hot water. First is that the shower faucet (mixer valve) has a cruel habit of sending cold water to the shower head when the shower head switch is off. When I switch the shower head on to rinse I get a shot of cold water before the warm comes back. I though it was a back-flow issue so I installed two check valves, one in the hot and one in the cold supply lines to prevent any cold-feeding-to-hot water flow. That did nothing to mitigate the issue so it’s probably a fault with the design of the mixer valve.
Anyway, one solution to the problem is to just run only the hot water and no cold. That saves the shot of cold water going to waste. The way to create just the right temperature of hot water is to put a temperature probe on the water heater tank. I choose a digital thermometer with a wired probe to sense outside air temperature. I inserted the probe between the tank and the insulation at the top (hot water out) connection and mounted the readout nearby.
I turn the water heater on and watch the temperature rise to about 100* F then shut the heater off. The water temperature rises about another 5* after the heater is off. Partly because of sensor lag and partly due to the time it takes water in the tank to mix and stabilize at the same temperature.
The second issue I’m trying to mitigate is propane use. I don’t fancy the idea of heating water up beyond what is useful and wasting propane to do that. By switching the heater off at a lower temperature I save a fair amount of propane. For example, with low temperatures in the 50’s and highs in the 80’s it only takes 5 minutes to heat the water up to 104*. The benefit of this set up is that I save both propane and water – Plus I don’t get zapped with a shot of cold water at bath time!
• Side note: You could use a wireless system and the sensor is going to be much bigger. That requires cutting the insulation away and replacing it over the sensor. Also if the probe is wireless they update about once a minute so there will be a bigger delay in reporting the temperature so it will get hotter after shut-off •