Tankless water heaters

[SecondAttempt]

Exactly what make/model are you looking at? You must be speaking of a "tankless" model or a tank model in the 80gal range that pulls some serious wattage for the heating elements? I have been speaking to you WRT electric water heaters only - nothing gas related and nothing "tankless".

Whatever you are talking about will not draw 80A from (2) 40a DP breakers. If it did, you would constantly trip the breakers. By NEC code, breakers for specific needs are 'oversized' so as to provide the required max load but also provide some overhead to mitigate breaker tripping and circuit overheating. By code, breakers must be sized at ~125% of the intended max load. So that is to say, at full load on the circuit, the breaker will handle ~25% more electrical load than the water heater requires. So if you are being told you need (2) 40a DP breakers, at max load, the heater will pull ~60a. Codes vary - but this is the general rule.

If you are maxed ~ 100a on your panel, I'd discourage you from installing this device into your mix. Remember, your panel @100a is also intended to provide that same ~25% overhead window - meaning that you really should have no more than ~75a total in-use in your home at any one time. If you drop this 60a max load device into your house, that gives you ~15a for everything else. That's not gonna happen and in actuality, invites IMO, an electrical fire at some point.

All of the info posted is based on my experience & understanding of the NEC circa 2008 - with some changes thru the latest edition. I have read/studied the majority of the ~3" binder. I also spent most of my life in a small town with homes ~ 70-150yrs old where multiple homes burned every Winter because of overloading their 100a (and smaller) panels. Hope this helps.

I appreciate the comments and information. I understand there is overhead so my heater may only draw 0.75*2*40 amps =60 amps and maybe less. But stove plus over, even with derating puts it too close to the main. Maybe not unsafe but approaching the annoying category.

 

[indiajust]

I used to rent rooms in my house to students. they typically drained the entire water heater. so i downsized my tank heater when it failed to save money. i view endless hot water as endless wasted money.

 

[Koolau]

I used to rent rooms in my house to students. they typically drained the entire water heater. so i downsized my tank heater when it failed to save money. i view endless hot water as endless wasted money.

So you had LESS hot water? I guess when the water turned cold, the students ended their showers? Good move. Think of the CO2 you saved.

 

[JoeWras]

Freeze 'em out! Welcome to the real world, students!

 

[ERD50]

So you had LESS hot water? I guess when the water turned cold, the students ended their showers? Good move. Think of the CO2 you saved.

Yep, one of the things that bugs me is the 'greenies' push these as big energy savers, but it seems that 9 out of 10 people brag about how they take long, long showers or fill their soaking tub w/o running out. Really doing some good for the old planet, huh?

-ERD50

 

[mpeirce]

Yep, one of the things that bugs me is the 'greenies' push these as big energy savers, but it seems that 9 out of 10 people brag about how they take long, long showers

We view our tankless as a luxury (well, nice-to-have) product.

It costs more than most tank WHs. With the recirc pump going it uses more energy. We have to descale it every other year.

But we really like it. No, we don't take hour long showers, but we absolutely never run out of hot water. This is really nice when we have a crowd here at the lake house.

Who wants to run out of hot water - ever?

 

[jollystomper]

It looks like we will be making a decision related to this soon. Our 10+ year old water heater just started leaking slightly (not a surprise, before retiring I knew replacing it would be likely be occurring around this time). We are all electric, on well water. We are gong to have our plumber come by (a family friend who has done lots of work for us, including the water heater) and give us the current lay of the land on take vs tankless for our particular situation. It is not really a BTD situation since we knew this replacement would be occurring around this time.

One of my questions would be sizing the tankless. It seems the relatively inexpensive ones are for small dwellings, whereas we have a 3000+ square foot home. Now, it is just the two of us (though we do have family and/or guests over every few months), but we have never had to worry about running multiple things using hot water at the same time (e.g. two baths/showers, dishwasher, washing machine). Have folks noticed any kind of "additional scheduling" of hot water usage they have had to put in place with a tankless heater?

 

[ERD50]

....
Who wants to run out of hot water - ever?

I've never run out of water with our tank unit (a 40 G), even with a family of 5 and/or guests.

But different situations require different solutions. I was just commenting on the environmental advantage (slight in any case) probably being wiped out, if not made worse, by the increased usage of some.

-ERD50

 

[Koolau]

Yep, one of the things that bugs me is the 'greenies' push these as big energy savers, but it seems that 9 out of 10 people brag about how they take long, long showers or fill their soaking tub w/o running out. Really doing some good for the old planet, huh?

-ERD50

With current technology and a commitment to the concept of "less is more," it WOULD be possible to lower carbon foot-print if people were willing to pay the extra money to do that - or expend the extra personal effort.

A simple (and free example - perhaps ever so slightly labor intensive) is to run a tub of water early on a summer morning. By evening it will be ambient temperature (in an un-air-conditioned house) that might be 85 degrees. Then when you take your bath, you only need a small amount of hot water to get to the approximate 100 degrees needed for a comfortable bath temperature - especially since you'll be glad to cool down after a hot day of w*rk and facing a warm house at dinner time.

I mention this "technique" because my mom told me it was SOP in her day. All the "girls" who reported to an office and made $12/week in the early 30s - if they could get a j*b - did it that way. They also wore anklets during their "commute" on the bus or inter-urban and the walk to the office. They changed into stockings when they got to w*rk. It was "hacks" like this that made "modern" life possible back then.

Now - we are energy intensive. We have hot water w*rking against against 55 degree ground water and air conditioning. Instead, we could pre-cool AC with our 55 degree ground water which would pre-warm the water for heating. The waste heat from the AC could increase the "hot water" temp to near a point it would need very little fuel to heat for storage in a tank.

Heating/cooling with a heat pump has now become available and IS much more energy efficient - but it requires much more energy up front for producing the hardware and much better "chip" control of the process as well as dramatically more repairs at $100/hour.

So, for modern life to continue AND still lower carbon foot print, we may have to "approximate" the good old days - but maybe do it in a modern way. Just the musings of someone who - as a non-engineer but fanatic about saving energy (and money) thinks about these things from time to time.

Returning you now....

 

[Music Lover]

Who wants to run out of hot water - ever?

We have a regular tank and ever run out of hot water either. But I believe that a shower should only take 5 or 6 minutes, not 20. If it takes someone 20 minutes they're being wasteful. It's a shower, not a spa.

 

[JoeWras]

A simple (and free example - perhaps ever so slightly labor intensive) is to run a tub of water early on a summer morning. By evening it will be ambient temperature (in an un-air-conditioned house) that might be 85 degrees. Then when you take your bath, you only need a small amount of hot water to get to the approximate 100 degrees needed for a comfortable bath temperature - especially since you'll be glad to cool down after a hot day of w*rk and facing a warm house at dinner time.

Now I just learned showers are the enemy by this technique.

 

[Koolau]

We have a regular tank and ever run out of hot water either. But I believe that a shower should only take 5 or 6 minutes, not 20. If it takes someone 20 minutes they're being wasteful. It's a shower, not a spa.

Military shower, baby, military shower. Take as long as you like, shave your face or your legs if you like, but run water for no more than 2 minutes - tops!

 

[W2R]

I believe that a shower should only take 5 or 6 minutes, not 20. If it takes someone 20 minutes they're being wasteful. It's a shower, not a spa.

When I was growing up, we were supposed to keep it to 3 minutes. If I spent more than 5 minutes even once, my father would refer to me as "the Prima Donna" in a very sneering and mean way (I thought), for probably a week or so. So, I learned to take effective short showers.

Though humiliating, that was actually a good lesson since I was already taking "ship showers" before I ever went out to sea as an oceanographer. I still take 3-5 minute showers since I always have done so.

 

[braumeister]

Though humiliating, that was actually a good lesson since I was already taking "ship showers" before I ever went out to sea as an oceanographer. I still take 3-5 minute showers since I always have done so.

Probably your dad grew up when hot water was a great luxury?

My DW was nearly 12 years old before she got indoor plumbing. Hot water came from the kettle on the stove, nowhere else. She still takes short showers even though it's no longer necessary.

 

[Koolau]

When I was growing up, we were supposed to keep it to 3 minutes. If I spent more than 5 minutes even once, my father would refer to me as "the Prima Donna" in a very sneering and mean way (I thought), for probably a week or so. So, I learned to take effective short showers.

Though humiliating, that was actually a good lesson since I was already taking "ship showers" before I ever went out to sea as an oceanographer. I still take 3-5 minute showers since I always have done so.

I'm a mix of all the things my parents "did" to me (good and bad.) They never understood what an effect they had on their children. I made it a point to NOT do those things that hurt me as a child when we raised our kids. I hope I succeeded somewhat. For the most part, my parents were great - but there are always blind spots. Every once in a while, I find myself in need of forgiving them for not being perfect parents. I hope my kids can do that for me one day - even after I'm gone.

 

[Winemaker]

I didn't read all the posts, put I thik a tankless water heater would be fine since you don't have wide fluctuations in incoming water temps. Don't go solar; we have rented condos with solar water heaters and DW froze in both places. The water was hardly warm, and this was in July.

 

[W2R]

Probably your dad grew up when hot water was a great luxury?

My DW was nearly 12 years old before she got indoor plumbing. Hot water came from the kettle on the stove, nowhere else. She still takes short showers even though it's no longer necessary.

I think that was the case with him, too. He was born in 1910 and grew up in the southern Missouri Ozarks, and IIRC they didn't have indoor plumbing until they moved into Springfield so he could go to school.

I'm a mix of all the things my parents "did" to me (good and bad.) They never understood what an effect they had on their children. I made it a point to NOT do those things that hurt me as a child when we raised our kids. I hope I succeeded somewhat. For the most part, my parents were great - but there are always blind spots. Every once in a while, I find myself in need of forgiving them for not being perfect parents. I hope my kids can do that for me one day - even after I'm gone.

As I think I mentioned, I did not necessarily think that this was an example of "imperfect parenting" or some such thing. Yes, it hurt, but at the same time it got the point across quite distinctly. It made me stronger, and also taught me to take thorough but short showers which was helpful to me later on in my career as a oceanographer. Nobody ever died from taking short showers and I'm fine.

 

[mpeirce]

We have a regular tank and ever run out of hot water either. But I believe that a shower should only take 5 or 6 minutes, not 20. If it takes someone 20 minutes they're being wasteful. It's a shower, not a spa.

That's nice.

We, on the other hand, are encouraging our friends and family to visit us at the lake house whenever they want. Sometimes that entails a small herd of teenagers who do enjoy long showers. Fine with us.

It's all good.

 

[Music Lover]

When I was growing up, we were supposed to keep it to 3 minutes. If I spent more than 5 minutes even once, my father would refer to me as "the Prima Donna" in a very sneering and mean way (I thought), for probably a week or so. So, I learned to take effective short showers.

Though humiliating, that was actually a good lesson since I was already taking "ship showers" before I ever went out to sea as an oceanographer. I still take 3-5 minute showers since I always have done so.

It's unfortunate that your dad corrected you in a mean-spirited way, he could have done so in a nicer way or with (better) humour.

In the grand scheme of things long showers aren't a big deal, but short and fast showers should be the default...especially when someone else is paying for the water and paying to heat the water.

 

[Music Lover]

That's nice.

We, on the other hand, are encouraging our friends and family to visit us at the lake house whenever they want. Sometimes that entails a small herd of teenagers who do enjoy long showers. Fine with us.

It's all good.

We have a lake house and wife's daughter and her friends use it on occasion. They've been told that they can have a shower if they keep it short because we have to pay to have the septic tank emptied.

It's common courtesy to take a short shower when you know that someone else has to pay to have a septic tank emptied.

 

[Badger]

It made me stronger, and also taught me to take thorough but short showers which was helpful to me later on in my career as a oceanographer. Nobody ever died from taking short showers and I'm fine.

Frank Gilbreth (Cheaper by the Dozen) technique could have been helpful at that time.

 

[pb4uski]

We have a Takagi tankless water heater installed when we rebuilt in early 2012. It has been reliable although we did have to replace the core about 6 years ago.

Yesterday it stopped working, something to do with the gas (propane) valve. Cost to fix is about $2k but there are other potential issues in 11-1/2 year old unit. It seems that we are at a precipice where this unit will nickel and dime me to death over the next few years, so I decided to replace it at a cost of $8,444.

The cost may be lower because it is unclear if the 15% discount that I am eligible for was included or not. Meanwhile, we are showering at BIL's house.

 

[NewEnglander]

I'd suggest a tanked but heat-pump water heater. It's the same size and shape as a traditional tanked electric water heater but sometimes slightly taller due to the heat-pump. You most likely can use your existing wiring/breakers. After the applied state rebate (CT) it was the same cost as a traditional water heater but uses less than 1/3 the electricity. I think there are now federal tax rebates from the recently passed IRA? It can run on heat-pump only or along with traditional resistance heat elements. We run our 50 gallon version on heat-pump mode only and have plenty of hot water for our 2 person household.
I will never buy another resistance only water heater.
The only negative can be the place where it's installed will be cooler since the heat-pump will pull heat from that location. Ours is in the basement so there's no issue with it being slightly cooler down there. We've noticed just a few degrees different.
Ours has been trouble free for 3 years so far. No way I'd ever install another resistance heat only electric water heater again.

 

[pb4uski]

^^^ But will the heat-pump water heater work at cold winter temperatures of 20F or lower?

 

[NewEnglander]

^^^ But will the heat-pump water heater work at cold winter temperatures of 20F or lower?

Heat-pump water heaters can't be installed in locations that can freeze , but that's also true of traditional resistance heat models. The heat-pump pulls air from its installed location not outside air.