Tankless water heater

Son added a bedroom and bath a couple years ago, electric tankless, don't remember name etc but it draws about 60 amps when on. In winter they were taking cold showers in summer medium warm. Had a water saver shower head. Sink water would get super hot for a half minute or so, then taper off. I'd go gas or forget it.

 

I installed a Rheem 199,000 btu unit last year. You never run out of hot water and the efficiency at 93% is much greater than a tank type. If you have a power vent heater now, there is very little difference in cost between the two. In my case, it also freed up some floor space in the basement because I mounted it on an outside wall.
My neighbor just put one in and he had an interesting observation. They have a front loader washer and he said that his puts a little water in, waits to balance the load, does it again and again. If the washer is set to either warm or hot, the heater does not like that at all because each little pulse of water triggers it to go through the purge cycle.
There is about a 10 second delay from the time water starts flowing to when there is actually hot water but you can get around that by installing a small circulating pump.

 

We just reno-ed our master bath ....step 1 ELECTRIC TANKLESS HEATER!! There are alot if misconceptions printed out there...but the variables MUST be KNOWN
1. What temp is your inlet water?
On a well...this can be quite different than the lil charts they print up... i'm in mid GA.. should be 62+ ..ish degrees.....NOPE..my well water exits the WELL head @ 56 degrees....when it was 90 outside temp (230 ft well), 52 degrees when it was 40 degrees outside.... so with a delta requirement of 54 degrees the GPM is around 2.5 ...far cry from their chart of around 3.5.

Now by the time the water gets to the house..... my cold water at any sink ...is 70-74 degree's..... so if the water is entering the unit at 70 i should have around the 3.7 gpm of 105 degree water.

I have not finished the plumbing YET so all this "theory"...

 

I have a gas fired Rinnai unit for the last 13 years. No issues at all...knock on wood. A guy at work bought a knock-off brand one at Home Depot, and had alot of problems with it. If you run all 3/4 piping, you shouldn't have any flow/restriction issues. The unit keeps up pretty darn good.

 

This is my plan once my tank unit bites the dust. its a few years old now, still in good shape, but i am pretty sure the 50 yr old chimney is starting to come apart inside, so instead of doing a liner, i will abandon that thing for direct vent through the wall, which my heater already is.

 

Only drawback is a tankless gas or elec, will not work during a power outage.

 

True, but neither will a power vent gas heater.

 

Nor will a conventional water heater. (I'm sure the water will stay hot/warm for a little while after power goes out though.)

I'd suggest 3/4" out. The unit can handle it, and then when you split off from there, you won't be out of volume.