I’ve researched for hours and am a bit confused with how to decipher the language, lacking context/background knowledge.
Thank you!
(I need a new water heater, wanting to go from tank to tankless. Its currently in the house under the stairs of bottom floor (no basement), 2.5 bathrooms in use (3rd no one uses much), 4 people, 3 story townhome, of any of this info is relevant… not asking for opinion just how it all works)
In: Engineering
Ok, first, you have (3) basic systems –
1) A hot water system that combines a heating chamber with a large storage tank in one unit. These can be (“Direct Fired”) gas (gas can be utility supplied natural gas or a local tank of propane) or electric and might be tied into your home heating system. Direct fired gas systems will corrode over time and eventually leak, one of the most common sources of water damage in a home.
2) A hot water system that has separate heating chambers and water storage systems, since the water storage will get cold you have a loop that circulates the stored water back through the heating chamber periodically. These can be electric or gas and might be tied into your home heating system. These systems are popular since the storage tank is typically fiber glass and won’t degrade or leak, a common problem with aging water heaters.
3) A hot water system that does not have any storage capacity but is integrated directly into the water tap for “on demand” hot water, these are electric. Your home heating system is separate from this. You would need one of these for each tap.
With the first two systems, when you turn on a hot water tap, the water will travel through cold pipes from the storage tank to your faucet and will cool off, which is why it takes a few moments for the water to turn hot. Since the 3rd system is local and ‘on demand’ it heats the water instantly.
For understanding your options you should first understand if you rely on your existing water heater for home heating, that might limit your choices or require you to purchase additional equipment.
In the US central hot water heaters are most common as we typically have the luxury of larger homes with multiple bathrooms and cheap, reliable utilities. From the demands you mention above a central system with a separate tank feels logical. In other parts of the world multiple on-demand electric heaters are more common.
Have you ever cooked pasta in a pot of boiling water?
They work like that.
For conventional tanked version:
There is a heating element(either a flame if the heater is gas powered or an electric coil if the heater is electric powered) at the bottom of the tank(generally heaters in homes are around 50 gallons capacity) and a thermometer linked to a computer that decides whether the water is the right temperature or if the heating element needs to be turned on.
The tank is generally well insulated so once the water is brought to the correct temperature(usually in the 105 degree f range but they can generally be customized) it takes minimal energy to maintain the temperature. The heating element is generally designed to heat the water over a long period so uses less energy but you can “run out” of hot water if you use the full 50 gallons all at once.
Edit: for tankless the heating element is generally much more powerful because it is heating the water as you turn on the tap. This means that, generally, the amount of energy needed to run the heater is inversely proportional to the amount of hot water you use.
A water heater with a tank is a big tank of water with a heating element and a thermostat. It fires the heating element to heat the water, and once the water in the take reaches the target temperature, the element turns off. They have a downside that if you take a really long shower, you’ll use all the hot water in the tank and have to wait for the water to heat back up.
A tankless water heater has a much smaller element in it. The way they work is that water comes in and goes through a coiled pipe over an element. The amount of time they spend in the coiled pipe is long enough for the element to heat the water up to the right temperature. So unlike a tank heater, you can’t run out of water.
The only difference between electric tankless and natural gas tankless is the heat source. I have no idea where you live, but where I live, electricity is 4x as expensive as natural gas – so I have as many gas powered appliances as possible.
A tank water heater holds a certain amount of water in the tank as hot water. Either an electrical element or a gas fed flame is used to heat the water in the tanks. There’s also water heaters that have a heat pump that can draw in heat from outside the tank. Because the water is sitting in a tank the water heater has to periodically heat the water. Even if you don’t use any hot water it will still have to heat the water in the tank because the water slowly cools down. On the side of the water heater on a yelllow it tells you how many gallons of hot water you will get in one hour.
A tankless water heater heats the water as it passes through the water heater. This means it only heats water when you use hot water. These are rated for how much hot water you can get per minute.
When going from a tank water heater to a tankless you have to consider between electric and gas. A tankless electric heater uses a lot of electricity at one time, you might not even be able to get enough electricity to it. A gas tankless water heater might need a bigger gas pipe run to even if there’s already a gas pipe there.
You need to talk to a plumber that installs both systems to know all the gotchas of switching from a tank to a tankless system, and find an honest plumber if you can. Don’t try to install a new water heater yourself.
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