Tank vs Tankless


Tankless Water Heaters vs Hot Water Tanks

The scientific community is pretty much in agreement, global warming is occurring. We all want to do our part – recycling our waste, smaller vehicles with greater fuel economy, saying ‘no’ to plastic grocery bags at the local market, etc. More and more Americans are become energy conscious when it comes to energy usage in the home, and a significant portion of energy goes into heating our domestic water.
Tankless, instantaneous, on-demand hot water heat has never been more popular. And why shouldn’t it be? Energy efficiency is reported to be in the 80-85% range (95-98% for the condensing units), tankless heaters only heat the water when you turn a tap on, they’re almost silent running, and CO2 emissions are reduced by 900-1000 pounds per year per average household installation! Time to replace your water heater? You’re of course going to want to replace it with a tankless system right? Well – maybe.
Before jumping in with both feet, know what you’re getting into. Tankless may work great for your household dynamic, but it’s not for everybody.

It’s a Tankless Job

Probably the main thing to realize is that a tankless system is just that – tankless. No water storage tank at all. With a tankless system, when you turn on a hot water tap, here’s what happens: Opening the faucet allows water to flow inside pipe and out the faucet. A flow sensor within the tankless system detects this flow usually within a couple of seconds.

Energy Requirements

Tankless heaters have no time to gradually heat the water, it needs to heat the water fast, efficiently and now! This is why a typical gas tankless heater runs at a whopping 199,000 BTU. Thankfully, it only fires on demand, but when the demand is there it FIRES! If you have an 15 minute long shower, its firing for an 15 minutes long. A typical hot water tank relies on its storage (usually 40 to 50 gallons) and an extended recovery time (30 to 40 minute range). In my previous house I installed a quick recovery 50 gallon hot water tank, that recovered quickly enough that even when we had lots of guests staying over, it easily kept our water hot. It was a 50,000 BTU tank.

Energy Efficiency

14% of most home energy is consumed heating water and tankless water heaters are more efficient at heating water than traditional storage tank-type water heaters. Most tankless units are energy efficient within the unit themselves. I mentioned before that typical tankless units run at 80-85% efficiency and the higher end condensing units upwards to 98% energy efficiency rating. What may surprise you is some natural gas hot water tanks have energy efficiency ratings as high as 67%. Modern hot water heaters are much more efficient than they used to be. If you put your hand on the side of a modern hot water tank that’s full of 130 degree hot water, the tank shell isn’t even warm, it will feel cool to the touch, to the now standard use of expanding polyfoam as an insulator to heat loss.

Insulate your hot water lines!

The greatest culprit in heating loss comes not from the heating system used to heat the water, but rather from hot water lines in the house that aren’t insulated. If you have a tankless water heater sending hot water down 50 feet of un-insulated water line, it loses energy the whole way along the line until the pipe is heated up to the same temperature as the water inside it. This is why the water seems to gradually get warmer until finally its hot. The same is true for typical storage hot water tanks. The tank can be as efficient as can be, but if the water lines aren’t insulated, it must waste energy heating those lines up before you finally get the full benefit of the hot water. If you have un-insulated hot water lines in your house that are also part of a recirculation system, the recirc line will actually heat your house, albeit very inefficiently.

Cold Water Sandwich

People investigating tankless systems or who’ve spoken with someone who owns this sort of system will invariably come across the term “cold water sandwich”. What does this mean? With a tankless system, let say your spouse just had a shower so the water lines between the shower and the tankless heater are all hot. Now its your turn for a shower, so you jump in and turn the water on. Immediately, there is hot water coming because the lines are all full of hot water, and you’re in there happily singing at the top of your lungs. But remember, some less expensive tankless systems aren’t truly “instantaneous” – and I love this part – so while the flow sensor is waiting for a ½ gallon of cold water to go through before it decides to come to life and start heating, you’ve got a ½ gallon of cold water barreling down the line toward you while your singing in the shower. “IEee!” Cold water sandwich! Kind of like putting a bucket of cold water above a partly open door.

We only sell quality tankless water heaters that are truly instantaneous at providing hot water on demand, so… never a cold water sandwich.

Final thoughts

The biggest plus that I can give to a tankless system is that is takes up less space. It hangs up very nicely on the wall. When installed correctly, it’s a clean looking unit. When installed correctly, a tankless system can be as efficient as a high efficiency storage tank, but the installation price is certainly higher. Tankless is very trendy right now, and yes we do install them, but you might want to talk to us about high efficiency water storage tanks that will save your pocketbook as well as the environment. If your convinced a tankless system is right for your situation, get a price quote for installing a tankless hot water heater in your home.

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