R Jay wrote:I've seen what happens when a fellow worker at a place where I was employed decided to "leak-test" a drum by plugging one bung and attaching
a fitting with a Chicago fitting to the other bung. From there he ran an air hose to a 90-psi connection....
Within seconds there were two loud pops...and both barrel ends had arched out into a convex shape.
Hot water tank temperature/pressure safety valves are set at 150-psi and a temperature of 212 F
Here is an interesting article on hot water tanks:
It is your choice, of course, if you want to use 55-gal drums in a closed system. The other thing is that, when letting them cool off, if you don't vent them
then the condensation inside will cause a pressure difference. You get to watch your drums fold into a pretzel.
Travis Johnson wrote:I guess I am confused because the whole purpose of using the boiler relief valve is so the make-up water is reduced in pressure from 60 PSI down to the 12 PSI boiler operating pressure. It comes as a kit usually, acting as a vent, and tying into an expansion tank as well.
bob day wrote:I see in the thread starter where you mention valves and such, but don't quite get the need for any pressure at all on your system. I use a small 12v transfer pump on my system and only heat water without pressure. Since I use an old hot water heater there is no problem turning the supply valve and having fully pressurized water when I'm ready for it
If you can position the water storage close to the heat supply a thermosiphon might be possible in which water naturally moves from the heat source to the storage and back, no pumps or thermostats, just keep the system full of water, when this is possible it is my preferred alternative