DIY Tankless Water Heater

[30WCF]

The reality is, I’ll probably do more homework and kick the can down the road for now. It’s not that big of a deal. The kiddos just wait their turn, and we wait about 30mins between showers. It’s not even that often that everyone needs one at the same time. The kids do night baths, and I’m a morning shower person. I would have just liked to address the complaint if it was easy enough, but not ready for a 200A service upgrade yet.

I probably would have just done it if I could have just added the electric tankless, but the gas one seems like more of a hassle and more expensive. The crawl space is only so tall and I don’t have a spot indoors for a bigger heater.

 

[gthomas785]

Get another 30 gal and gang them together

 

[30WCF]

I think I’d have to pop in a couple thin or tandem breakers for the lights and outlets or something so I can add another double pole. Not a big deal, but the box is getting full.

 

[gthomas785]

Yeah, you can do that. Depending on your panel they make "quad" breakers that give you two double pole breakers in the space of one.
Or, if you're into complexity: plumb them in series, and put them on a single circuit with a lockout relay that gives the second tank priority.

 

[EbS-P]

There are 120v tanked heaters. That would probably be my choice, a 20 gallon 1.5 kw 120v set to something low like 90F.

 

[gthomas785]

lockout relay

Sorry, I meant interlock relay.

 

[all night moe]

Inquiring minds want to know.....and asking those in the know.
What about an electric tankless plumbed in series after the 30gal tanked heater? Set the tankless electric at a lower temp then the output of the 30gal. Say maybe 20* differential. This way the tankless only turns on when temp drops low enough.

Possibly this would be an easier install and electric usage would be close to original demand?

 

[fields_mj]

First, you should be getting more than a 10 min warm shower out of a 40 gal water heater. If you run it at the max recommended setting, you should get at least 30 minutes. Either you have a problem with one of the elements, one of the Tstats, or it's full of scale and not actually holding anywhere near 40 gal.

Second, your dish washer needs water that's at least 120 deg for the detergent to work. If your dishes are spotty when they come out, the water isn't hot enough and you're likely building up undisolved detergent in your drain line. That stuff is rock hard and a genuine PITA to clean out. Especially if it fills the line 90% full for 30 ft... I crank my water heater to max for this very reason. If someone runs scalding hot water on themselves, that's a valuable life lesson. Life's hard; it's harder when you're stupid. Nothing in the real world functions around your personal comfort so learn to behave accordingly. My DW is about 45 ft from my WH which is in my basement. Lines are insulated, but the start-stop nature of the DW makes it hard for the WH to supply constant hot water. I've often thought about plumbing in an On Demand for the kitchen sink/DW, and feeding it from the water heater. It's on my list of things to do.... lol

 

[fields_mj]

Inquiring minds want to know.....and asking those in the know.
What about an electric tankless plumbed in series after the 30gal tanked heater? Set the tankless electric at a lower temp then the output of the 30gal. Say maybe 20* differential. This way the tankless only turns on when temp drops low enough.

Possibly this would be an easier install and electric usage would be close to original demand?

If you're going to do that, I'd drop all the way to a 6 gallon or smaller. The tankless is going to turn on for longer runs like showers or dishes. No way to avoid that. A small 6 gal, or even a 2 gallon should handle everything else.

 

[gthomas785]

I think we established earlier in the thread that an electric tankless WH won't work on the existing electric service unless it's a very small one, sized for e.g. only the shower.
Given OP's electric limitations I really believe a larger storage capacity is the way to go, not smaller.