Northwest Dive Club

I think if you are just opening the lower drain valve the supply line will refill the water heater from the top as you drain off 20 gallons from the bottom. Although I am not a plumber and don't play one on TV...

CaptnJack wrote:I think if you are just opening the lower drain valve the supply line will refill the water heater from the top as you drain off 20 gallons from the bottom. Although I am not a plumber and don't play one on TV...

Yep. As long as you don't turn the valve off. The potential for serious damage happens when you drain the tank. If you don't fill it up before you turn it on, you could be conducting an unplanned test of your temperature and pressure relief valve....and a lot of those aren't installed to code.

thus why my 100w aquarium heater is much cheaper than the 4kw heater in hot water tank... Don't really need 130d+ hot water for my dive gear.

Although in thinking about it, I should spray insulate the sides of my dunk tank....

Joshua Smith wrote: Yep. As long as you don't turn the valve off. The potential for serious damage happens when you drain the tank. If you don't fill it up before you turn it on, you could be conducting an unplanned test of your temperature and pressure relief valve....and a lot of those aren't installed to code.

Yup...one of the things I also did was fix the install... there was no expansion tank, amongst other things... how some things passed inspection the first time around, I will never know.

camerone wrote:

Joshua Smith wrote: Yep. As long as you don't turn the valve off. The potential for serious damage happens when you drain the tank. If you don't fill it up before you turn it on, you could be conducting an unplanned test of your temperature and pressure relief valve....and a lot of those aren't installed to code.

Yup...one of the things I also did was fix the install... there was no expansion tank, amongst other things... how some things passed inspection the first time around, I will never know.

"inspection"

Yeah. Home inspectors are usually highly qualified individuals whose knowledge of the building trades is encyclopedic. OR, someone dropped $85 on a business license, and wrote "home inspection" in the blank space where they ask what you're going to do. That's pretty much all it takes.

Joshua Smith wrote:

CaptnJack wrote:I think if you are just opening the lower drain valve the supply line will refill the water heater from the top as you drain off 20 gallons from the bottom. Although I am not a plumber and don't play one on TV...

Yep. As long as you don't turn the valve off. The potential for serious damage happens when you drain the tank. If you don't fill it up before you turn it on, you could be conducting an unplanned test of your temperature and pressure relief valve....and a lot of those aren't installed to code.

If the tank is electric you won't test your relief valve if you start it up low. The elements will burn out faster than seems possible.

H20doctor wrote:

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Yep, fill it with water, bypass the thermostats and over temp and power it up, its a bomb. Drop the water level below the top element on an unmodified one and the top element burns and that is it. Power never goes to the bottom element if the top of the tank doesn't reach temperature.

http://brainerddispatch.com/stories/072 ... 0011.shtml

just sayin'. Its not something to attempt unless you have some basic knowledge of plumbing, physics, pressure, temperature, etc.

CaptnJack wrote:

camerone wrote:Are there really no chemists here to fix the misinformation in this thread?

Sadly no lol

I'm surprised your hot water tank isn't full of rust and scale like mine

SIDE NOTE: Drain it while you still can, mine just burst and I had to siphon the water out of the top to empty it because it was so full of sludge that I could not drain it from the lower nozzle.

Now back to our regularly scheduled topic...

We rinse our stuff in the shower or on the deck in the summer and we dive in a fresh water lake to get a really good fresh water rinse.


Note: after the story above I changed it to burst which is probably a far better description...

You guys rinse your gear? How quaint.

Q: Why not rip out that tank hot water heater and put in tankless? Advertising says that is cheaper and safer than old fashioned tank heaters.

I have always rinsed my kit twice. Once when I finish at my destination and then, again, when I get home. Almost all my gear looks almost like new. But, after reading this thread I think I may have wasted my water, electricity and effort.

Compare the cost of a new install on a tankless water heater with replacing your old hot water tank and see what the difference is. Then consider that the energy use difference is the heat you feel coming off the metal on your tank. Feel anything? If you do think it is losing much heat put an insulation blanket on it. And remember that the tiny heat loss only is a loss in the summertime. In the wintertime it is heat in your house, what there is of it. And if you are considering replacing an electric tank with a gas or propane instant unit remember that whenever the instant unit is heating, hot air is coming out the exhaust. Your electric tank doesn't have that loss. And if you are considering an electric unit that is capable of raising 60 degree water to 120 degrees at 4 gallons per minute you need 150 amps available in your electrical panel to do that.

Q answered. Thanks.