Quote:
Originally Posted by Morich
The concern about a water heater going to pressure so high it blows up is likely totally misplaced in RV that have plastic tubing!
If it totally runs away and steam begins to look for a way out, most RV will have lots of options to fail before the welds on the tank.
Even 1/2 inch PEX is only rated for 80 PSI at 200 F so I feel fine with the tank not blowing up!
Most of us will have far more trouble with something leaking than the water heater blowing up!
|
The design as I see it is to pop the plastic drain plug hopefully before a pex line goes inside the trailer. Far better to have a redundant PRV on the tank outside go than the pex lines. In theory the PRV will leak off excess pressure before the pex pops or the drain plug fails due to overheating of the tank metal past the melting point of the plastic plug. Have not had a plastic plug melt yet but it would be interesting to have a jet of overheated water shoot out of the tank while camped in the bush next to someone with dogs that bark at the squirrels
Here is what happens if someone unscrews a drain plug while the tank still has system pressure in it.
First rule is to shut the thing off and let it cool if any leak starts happening anywhere before even considering draining the system. Poor George obviously forgot to turn on a hot water tap before removing the drain plug. When this happened to me a few years back with our Scamp fiberglass I had remembered to let it cool before winterizing or flushing the hot water tank, I never did find the drain plug...
Yes having to rely upon pex for a hot water system is a bit of a PITA. At least the pex systems of the past 20 years are better than the original polybutylene pipes which caused insurance nightmares for early adopters.
I still think that shutting the system down when not in use is the best way to prevent future troubles with the pex system and along with proper flushing of the hot water tank on an annual basis should greatly prolong the aluminum water bottle as well as the electric heating element. The electronic thermostatic controls and sensor are not as robust as the old school systems that can run from just a propane source but it is really nice not having to hold down a red button to start a pilot light just to have hot water.
That being said if we ever need to replace the tank replacing it with the old school system with a pilot light and gas temperature controls and no logic chips involved at all is not that big a deal. It just means that it adds a step in the process that must be done outside the trailer. When thermocouples fail they fail on the safety side of the equation and that is why a pilot light system is in a great many ways safer than an electric spark gas ignition system.
Sometimes old school is better suited to an application than the latest bells and whistles when it comes to devices like gas hot water heaters.
Important to check pressure relief valve when tank is cold under pressure.
Makes for happy camping and my spouse agrees that waiting for the hot water in the morning is akin to waiting for the morning camp fire to heat up a pot of water to do the dishes after breakfast. The practice makes mornings very pleasant knowing that we are not just glamping it with a portable shack on wheels and will need to use our brains to do things.
Linear Mode
