How to Install a Tankless Water Heater

This week's hack: Install a tankless water heater (aka on-demand or instantaneous water heater)

Shade of green: Verdant pine

Items needed: One on-demand water heater, miscellaneous plumbing bits including copper pipe (1/2" and/or 3/4"), pipe cutter, propane torch, solder

Why this hack: Because you can cut your hot water bill in half. Yes, I said "in half." As in 50%.

Tankless water heaters, like this one from Rinnai, are generally sleek.

Heart of the hack: Ok, folks, this is an advanced hack. If you're not comfy a) handling power tools b) operating flaming torches and c) soldering copper water tubing together, you ought to just call a plumber. Try not to faint when he hands you the bill; it's very rude.

But lets assume you can do all this stuff with one hand tied behind your back whilst juggling a dozen rotten eggs. In which case, you'll first want to shut off water to your current hot water tank (there should be a valve; if there's not, you got problems), drain the tank (there's a spigot on the bottom; you can attach a garden hose and run it out your basement door onto the neighbor's lawn), and tear it out.

What should you do with your old tank? Well, if your day job involves selling used cars or self-improvement videos, you might be able to off load it onto some sucker via Craigslist. Otherwise, you'll probably have to pay someone to take it away.

Installing your new tankless heater is simply a matter of bolting it in place, then installing the vent (it's probably a power vent, whereas your old heater likely had a stack vent, so you're going to need to wire it in. This is a good time to call someone who has experience playing with electricity). Next, run the new water lines. Gosh, doesn't that sound simple?

It is, as plumbing goes. It's just that, you really want to know what you're doing when you're "sweating joints," which sounds like it could land you in the slammer, but is really just plumber speak for joining copper with solder. If you don't have experience with this lost art, it just ain't worth the headache of a leaky hot water system. Lecture over.

The cool (bad pun alert) thing about on-demand hot water heaters is that they heat the water only when asked. Your current "capacity" heater keeps a huge blob of water (probably 30 gallons or more) hot all the time. If you don't draw hot water for, say, the eight hours you sleep each night (you do get at least eight hours of sleep, don't you? You do realize that anything less is detrimental to your health, right?), it don't matter: Your heater is still keeping it warm, just waiting for you to crack the tap. An on-demand heater won't heat the water until you ask it to; when you do, it springs into action with an enormous flame that literally heats the water as it passes through on its way to your shower head.

Got it? Yeah. Get one. It's one of the quickest and easiest energy pay-offs in the modern world.

Editor's note: On-demand water heaters typically come in gas-fired or electric models. Most greens advise for the gas-fired versions, which are more energy-saving overall. Tankless heaters tend to be a bit more expensive than conventional models upfront, but pay for themselves over time. See some brands here.