Home water heater... tankless?

BigClay

BigClay

Knower of useless ZJ things
Joined
Sep 24, 2008
Location
Winston-Salem
My current water heater was manufactured in March 1990... yes it just turned 29 years old. So it is time for a new one. Should I go tankless?
 
It all depends on your scenario and usage. You just have to do the math, based on realistic numbers, to determine if it's worth it.
In my limited experience and web discussion reading (which is all that really matters, right) it's affordable about 30% of the time.
 
I'm going tank less at my new house. I have 5 naviens at work and they are great so that's what I went with. It cost me right around $1400. Current house has a 40gal electric and if I take a shower within 30 mins of giving my kid a bath I start running out of hot water pretty quick. Kid #2 is otw in July so our hot water usage will continue to increase.
 
92_SquareEye said:
Do you have gas or electric? Do you have kids and do boatloads of laundry? Lots of simultaneous showering? What is your overall demand for hot water?
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High demand for water. At least two showers each morning, that will be increasing very soon as I have three kids approaching morning showing ages. With those three kids is a lot of laundry as well. Simultaneous showering will be a must in a few years.
 
92_SquareEye said:
Lots of simultaneous showering?
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I keep trying to tell my wife that we'll save water if we shower simultaneously...she still doesn't buy it. :lol:
 
But do you have natural gas? Do you have well water or city?

A 50 gallon natural gas water heater will provide something like 90 gallons of water in the first hour, assuming a 120F setpoint. If you up the setpoint, you should be able to get 150 gallons out of it. A great gas water heater costs half of what a tankless does, and costs the same to operate.
 
BigClay said:
High demand for water. At least two showers each morning, that will be increasing very soon as I have three kids approaching morning showing ages. With those three kids is a lot of laundry as well. Simultaneous showering will be a must in a few years.
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If it fits your needs better, do it. It will be more expensive to retrofit to a tankless than just to replace the existing tanked with another tanked unit (especially if your existing unit is electric), and you're probably not ever going to save enough energy to recoup costs to offset it.

So, if it suits your needs better, spend the money and make it happen.
 
Really not looking for the energy cost savings, I really am tired of a cold shower after the kids have had a bath and a load of laundry has been washed.


shawn said:
But do you have natural gas? Do you have well water or city?

A 50 gallon natural gas water heater will provide something like 90 gallons of water in the first hour, assuming a 120F setpoint. If you up the setpoint, you should be able to get 150 gallons out of it. A great gas water heater costs half of what a tankless does, and costs the same to operate.
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City water and I plan to switch to a gas water heater regardless, gas is already there.
 
At the fire department I work at we have the on demand ones at our newer stations. It sees 2-3 showers every morning at the same time an we have no issues with hot water running out. Takes a minute to get hot but it never runs out. Only complaint is the dishwasher. If the waters not hot when the dishwasher starts up, then the dishwasher will shut off. So we just let the sink run for a minute while the dishwasher starts
 
5.5 yrs on a Rinnai running natural gas. Zero complaints. I would do it again.
 
We have one in the new place. It's great.

Laundry kicks in, no effect at all, just know when it happens due to a little blurp in pressure when the washer solenoid valves close.

One reason we put it in is zero gas usage when we travel.

Old house had a 40...even with 2 of us, it was easy to hit bottom. I was always second, so got to finish in cold.

You do have to do some maintenance....annual flush/descaling. Not a big deal. I'd empty and flush the old 40 gallon heater at our old house about once a year or two....17 years and still working fine. Only had to replace one element maybe 5 years ago.

Sent from my SM-G930V using Tapatalk
 
Fabrik8 said:
I figured he knew what the problem is and what his needs are. Probably no reason to not buy one if it suits his needs.
I'm not sure where your head is at, sounds pretty clear cut.
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Well, tankless units have a high upfront cost, not-insignificant yearly maintenance, and you have to size the unit based on an 85F temperature delta at 3.5gpm (city water in the winter).

Tank units cost a lot less, can provide a ton of water to multiple fixtures simultaneously (I did some quick math and estimated two showers simultaneously for 52 minutes cont), and a similar lifespan as a tankless.

Depending on if you have natural gas, a well, and are looking for a lot of simultaneous fixture use or sporadic use throughout the day, the math changes significantly.

And we haven't even talked about venting....
 
shawn said:
Well, tankless units have a high upfront cost, not-insignificant yearly maintenance, and you have to size the unit based on an 85F temperature delta at 3.5gpm (city water in the winter).

Tank units cost a lot less, can provide a ton of water to multiple fixtures simultaneously (I did some quick math and estimated two showers simultaneously for 52 minutes cont), and a similar lifespan as a tankless.

Depending on if you have natural gas, a well, and are looking for a lot of simultaneous fixture use or sporadic use throughout the day, the math changes significantly.

And we haven't even talked about venting....
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Fabrik8 said:
It will be more expensive to retrofit to a tankless than just to replace the existing tanked with another tanked unit (especially if your existing unit is electric), and you're probably not ever going to save enough energy to recoup costs to offset it.
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Should I have expanded my previous post? I really have no clue what your arguing here.
 
This is one of those deals where Shawn has made his mind up for his situation and is so convinced that hes right he cant fathom someone else having a different preference. I love the dude like a brother but its one of his few flaws.

Regarding his last post, I wonder if you quick math takes into account that influx of water and what temp it assumes?

Here is what I can tell you. We switched from electric to gas in a tanked heater, 80 gallons in a climate controlled basement btw, and you can get 1 shower about 35 minutes long and shes cold.
My teenage daughter confirms this nightly. We have the temp set at 8 notches out of 10.

From a pure economical standpoint, a tankless may cost slightly more. Depending on usage patterns. From a happiness and quality of life standpoint....I went tank and wish Id gone tankless. YMMV

Again residential fixtures arent about mathematics solely.
 
I’m using a 18kW Eemax electric tankless unit; I love it. Endless 120F hot water. Requires 80A @ 240V.

My old 50 gallon water heater rusted from the inside out and ruined my floors; I wanted a tankless unit that didn’t have so much potential to ruin my floors to go back in.

Additionally, I have a ton of extra closet space now and changing it out in the future will be very easy and lightweight.
 
BigClay said:
Can two showers run at the same time and have enough hot water?
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Yes. I'm not sure what model we have, but two showers, or one shower and one tub can run wide open with hot water, and it never cools off or runs out.
 
shawn said:
If you up the setpoint, you should be able to get 150 gallons out of it. A great gas water heater costs half of what a tankless does, and costs the same to operate.
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This has been our experience. We have NG and we keep the setpoint up at "A" or whatever 1 over the recommended "safe" level is - it's pretty damn hot, enough that on full on pure hot it is steaming. We have a standard 40 gal tank and I cannot remember ever running out of hot water, even after 3 showers in a row, with one of them being our teenage son who stays in there for what seems like an eternity.
Basically you're drawing a lot less from the tank per shower b/c the standing temp is so high that you naturally dilute it more with cold.
There is no question this costs more in the long run than a lower setting, but if you value hot water over money, then who cares. The cost difference is small.

On this note, I've often wondered if having a small PID controller to adjust the water set temp (switching between "pretty warm" and "really hot" for the time of day would be worthwhile. E.g. if all the action when you're concerned about running out happens at the same time, why not do a small increase then, then let it back off for the rest of the day. For us, showers are the only time we use a lot at once. Everything else is small doses or doesn't really have to be THAT hot.
 
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