Advantages and disadvantages of the tankless water heater Please,,

We have this system and love it because hot water is instant and always availale. With a tank you run oiut of hot water and have to wait. Our Big bathtubs are both easily filled with hot water, even simultaneously, if you have guests. This is great. No expense to maintaining hot water. It gets hot just as it runs over the coils, just before it comes out of the fawcett. The 220 multi-strand electric wiring is expensive to install, but once that is installed, I think we break even on cost between the two systems. Also no ugly tank to live in your house or to spring a leak.

I have now had one for 6 months. I had a gas water heater before, and it kept going out. I had to remember to turn it down when we went away for more than one day.

Advantages:

not heating water for nothing

We can run a bath and another shower, DW, or wash and dryer at the same time.

It saves a bit on the gas bill.

The water is always hot. Before if we ran the bath, we had to wait 30 minutes before there was enough hot water for anything else.

It takes up a bit less room.

Ours preserves some of the residual heat so it isn't instant cold when you turn it off.

The only disadvantages I see, are that it takes a few extra minutes (about 2) to heat the water initially, so more water wastage. To avoid that, I run the bath or DW or washer and dryer, first to get it going when I can, before taking a shower or running water in the sink for dishes.

Also, although the box is much smaller than the tank, I didn't factor in with the new gas codes that I would have so many big pipes coming out.

Still, I would not go back to a regular heater, and want to put one at my cottage.

Mine didn't work too well. You'd have to keep the water pressure going by turning on the sink faucet while showering just to make sure the hot water wouldn't just decide to stop in the middle of shampoo. Also, it was very difficult even for a pro to install. Must be vented (ours was gas).

The new electric (or gas) hot water heaters are very efficient and way less expensive. They work so well you don't ever have to think about whether or not you'll have hot water.

The tankless water heater is an energy saver and usually pays for itself within the first 3-5 years, but you should do the math for yourself. A good plumber should be able to give you energy costs for the unit you are looking at. If it is sized properly for the family, that is, the plumber takes into account the demands made on it throughout the day, how many bathrooms, kitchen, laundry, etc. that utilize water, it can meet your needs.

The tankless water heater heats the water on demand and if demand is high, it sometimes cannot keep up. When you turn on the tap, depending on when the heated water was last used, you could end up with a slug of cold water before you feel the heated water. I learned to direct the shower head to the wall for a few seconds for each morning shower.

They take up much less space in the basement/closet, but they need special piping for the exhaust and such. You also need to have a large enough gas supply to feed them.

If you are in a hard water area, please know that you will need to regularly flush the system because hard water kills tankless water systems. The deposits can kill the system in as little as 2 years. Flushing is "simple" https://www.youtube.com/watch?v=T4FaqGod3VU or not depending on your point of view. And the manufacturer's warranty doesn't cover the damage done by hard water.

For me, a tankless system was perfect since I was the only person using it and it really did pay for itself it about 3 years versus the tank water I had had before. I moved and am back to a tanked system, but I'm also in hard water heaven and will have to consider that before choosing the tankless heater.

I just had a unit installed in June so my experience is limited. I do know it still takes a minute or so before hot water comes out. But it is very hot and continuous and I've noticed my gas bill is less. My biggest pLus is that I got the water heater out of my house and gained a closet for linens that was lost when a heating/ac unit was installed a number of years ago.