I currently have a standard electric water heater. No problems it works fine. I have been talking to some guys at work that have the on demand gas water heaters and love them. My question for you plumbing experts is would it be worth the change? I would have to get a propane tank installed as natural gas is not ran close enough to me. I could see a space savings, hot water during power outages ( generator big enough for well). So what say you all?

You might look into a Toyotomi while you're at it. Kerosene fired. They're a good unit.

https://www.toyotomiusa.com/factoryOutletStore/OM-128HH-Toyotomi-On-Demand-Hydronic-Heater

I have a renai gas on demand water heater. I love it. Ours is a larger-rated model. I don't know how exactly they're rated, but ours is rated to do 5 things at once, like 2 people taking a shower, dishwasher and cloths washer going, and someone washing their hands, all at the same time (as long as there's enough water pressure and volume of course.) With 5 kids, we love it. Just throw them in the shower one after the other, never have to worry about whether the dishwasher or clothswasher is running, just take as long of a shower as you want. It's saved us money too. And they're tiny, ours is about the size of a 5 gallon bucket, so it frees up space in the basement, if that's important to you. After a while, you get used to it, and it feels strange when you visit somewhere and have to worry about not taking too long of a shower. Ours just plugs in to a standard 110 outlet, so it shouldn't take much of a generator to power it.

I certainly am no expert but have experienced two on demand gas water heaters. I hate them and would never put one in my house. Had to run the faucets way too long before the water turned hot. I usually would wash my hands in cold water because I was impatient.

Thanks for the responses. I can see both pros and cons!!

Put one In my daughters house In Alaska, It just plain sucks.
And I'm pretty sure If the power goes out your not going to have any hot water.

NO good

No I have a generator. I can run the well. The electric water heater pulls the watts though.

This is one drawback. Ours takes about 3 seconds before it kicks on, but then the hot water is good to go. It doesn't really matter for us, our house is two stories with steel water pipes, it took forever to get hot water with the old tank heater too.

Guessing you already have gas in the house for heat?

I have four on demand propane hot water heaters. I have them on cabins and work shop. I love them.
I don't know why they wouldn't work on a whole house application. Mine use two "D" cell batteries for ignition, I replace the batteries once a year before they die, I don't know how long they would actually last. So if your power goes out you still have hot water.
Non stop hot water, you aren't wasting energy by having hot water sitting on standby all the time, and the heaters are fairly cheap.

If you are doing a whole house application get a large heater vs the smaller models.

Here's where I get mine: If you click on the "Propane" link and you'll find the ones I use. Currently I use the Marey 10L for my cabins, and the 5L for a sink in my shop.
https://www.bonterrahomeandgarden.com/tankless-water-heaters

The one I put In has exhaust fan and I'm not sure but I think if the blower isn't operating the tankless water heater Isn't going to lite.

the few ive installed I slaved them to the water heater its preheats the water before entering this boost your capacity of hot water as well as extends the life of old water heater. the electric ones from all ive reasearched cost more to operate. In this day and age efficency is a big deal. Either pay it to supply houses for high efficiency equipment or to your local provider 4 ever. Costs money to save money SADLY!

I think some of you guys are making it sound way too complicated. I'm not a plumber but I figured it out in about ten minutes. Here's a couple of pictures on the one on the outside of my shop. I have it set up so I just screw a garden hose onto it for water supply. the two red values are for draining the system so it doesn't freeze up when not in use.
If you install them indoors just put them on an exterior wall and vent outside, no fans necessary.
I have heard the electric ones are not very efficient.

Waggler-For what it's worth I have not had good luck with those red PCV valves in my house. As they get older and start to stick, the ears tend to break off. Maybe yours are higher quality or different brand, though.

Moosetrot

No, I would have to get a tank from the gas company.
And with our electric heater now, we still have to wait for hot water if the line sets awhile.

Now that you mention it, I think I've had better luck with the blue ones. Hmm.

I’ve been thinking of getting one too, but the delay to get warm water is worrysome. How much longer, on average, do you think it takes vs a regular water heater? Discounting the run from heater to faucet of course. Is it 10 seconds, 2 minutes ...?

I would suggest if you have a electric hot water heater already to save money put a time clock on it to shut off at night and during the middle of the day. Install a insulation blanket. Electric water heaters have inexpensive replacement parts and a much longer life span than any on demand water heater. Plus if you hard water the on demand water coils will plug with lime sediment shortening the units life span. the shorter life span,higher cost need to be thought about as well as higher repair bills. The only reason to replace a electric water heater is if it springs a leak, they can and should be flushed out every six months to remove the limescale before it shorts out the bottom element. Just my opinion. My electric water heater is 26 years old and going strong. Our water is hard lots of limescale. My time clock shuts it off at 8pm on at 4am off at 9am on at 3pm. Even when off I still have 80 gallons of heated water. I would also install a thermal mixing valve and set it to deliver no more than 125 degrees and the tank temperature at 140 so you don't worry about bacteria.

I put one in my cabin and will never even think about using a tank heater again. Mine fires when I open a hot faucet and the only delay is the time it takes to clear the cold from the pipes between the faucet & the heater. That same delay occurs with any hot water heater.