Niagara 'Titan' N-120 tankless water heater, $5

One very profitable profile you really should take a few minutes to familiarize yourself with is the tankless water heater. You'll run across them from time to time, so be ready!

Instead of holding - and keeping hot - gallons of water in a large tank, as a conventional water heater does, a tankless (also called 'on demand') water heater simply heats the water as it passes through the unit. The tankless water heater has some distinct advantages over its much older relative, the tank-type water heater.

Wherever you look around the modern household, it seems like every appliance and gadget has kept up well with modern technology. Refrigerators, ovens, microwaves, dishwashers - all are regularly improved upon to make the best use of the newest technologies. But when it comes to the lowly, yet very energy-consuming task of heating all of the water for the home, the tank-type water heater, which has been standard in homes and business since the early 1900s, has pretty much been marching in place, in terms of efficiency and dependability.

The tankless, or 'on-demand', water heater is intended to address all of the shortcomings of the tank-type heater, so let's take a closer look at this cool little gadget in the fancy table below.

Conventional Water Heater	Tankless Water Heater
Thermal Heat Loss 20-40% of the energy consumed by a tank-type heater is lost because of radiant heat from the storage tank	Can lower heating costs by up to 50% - Tankless water heaters work completely 'on demand,' when hot water is needed. Because no hot water is actually 'stored,' there's almost no thermal heat loss.
Limited Water Supply Can run out of hot water after a high demand, as in several showers. It is then necessary to wait for the water heater to finish heating the new batch of water.	Tankless heaters cannot run out of hot water - They can run and heat water all day long, and will never stop producing hot water since they heat the water on demand.
Overheating To ensure that they don't run out of hot water, most tank-type heaters are set to keep the water too hot, as in 130 degrees F. Keeping water this hot wastes energy and introduces the risk of scalding, especially for young children and the elderly.	Tankless heaters can be set to keep the outgoing water at a much more reasonable temperature, closer to that which the water will be used at. The US. Department of Energy states that each 10°F reduction in water temperature means a 3%-5% savings in energy costs.
Minerals in Hard Water Scale tend to form when water is heated for long periods. This scale coats the interior parts of the heater, causing a loss of efficiency and shorter life.	Since a tankless heater doesn't store water, it can usually handle hard water minerals and sediments better than a tank-type unit. This means that it's less likely to leak, and can hold its efficiency throughout its entire life cycle.
Short Life / Disposal Tank-type water heaters normally last from six to twelve years in most homes. They are very large, take up lots of space at the landfill and cost a great deal to recycle.	Tankless water heaters can last more than twenty years, and are much smaller and easier to recycle than tank-type heaters.
Large Size Due to the large tanks, tank-type heaters are bulky and space-consuming appliances.	Tankless water heaters are about the size of a briefcase, which means that they save space that can be used for other purposes.

I guess the next thing we really should address is, how the heck do you know if the darned thing even works when you find one? I mean, it's sort of hard to test a tankless water heater that's sitting out in someone's driveway, right? But when you think about it, doesn't this issue really apply to anything that you can't personally test out? In my opinion, there are a couple of ways you can handle this issue, no matter the item.

You can tell your potential bidders that you guarantee the item to work or they get their money back. In the case that your buyer contacts you afterward to tell you that the item doesn't work, you can just refund their cash. I prefer this option whenever I'm pretty certain the item works as advertised, and I have very little money into it (like the Titan tankless water heater in this example.) You stand to get the highest amount of cash this way.

If the particular item is one that is fairly complex and would be relatively difficult or costly to test out completely, especially when I have more than a few dollars in it, I always feel a bit uneasy guaranteeing its performance at all. In such cases, I simply auction the item as-is, with no guarantee of performance and no returns. This way, the buyer is fully aware that the item may not work, and that it's theirs even if it doesn't work. You may get less money for a particular item doing it this way, but it's often worth avoiding any hassles with the buyer.

This Niagara Industries' Titan N-120 tankless water heater sold on eBay for $108.