On demand water heater

johnnyb

johnnyb

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Ok, I’m replacing the flooring in my house and was considering going ahead and replacing my current tank water heater as a bit of preventative maintenance (it’s 17yo). While looking into this, I had the thought of replacing it with an instant water heater, for two reasons; efficiency, and space, as the water heater takes up between 1/3 and 1/2 of the room in our pantry.

Concerns are cost, and the fact that it will need to be electric vs gas since there is no gas line in my area (rural) and I don’t particularly want a large tank in the yard and all that goes with that.

random info that may be helpful:
family of 6 (2 adults and 4 boys ages 14-6)

current water heater is 80G and we rarely, but occasionally do run out of HW

Hot water fixtures are Two Showers, 3 Sinks, dish washer and clothes washer.

Current breakers for the water heater are 30A x 2, not sure if the size of the disconnect for it, can check if this info is needed.

@Armed4defense

and any other experts on here!
 
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Can't help with the electric versions, we went gas on demand. Our reasons were 95% space saving (ours is outdoors in a 20 x 40 footprint home) and 5% due to the fact that this is at our part time residence (on demand VS paying while not used). We love it, but being a frugal nut I cringe every time we use it because of the water that we waste waiting on it to get hot....which isn't that long, just makes me cringe anyway.
 
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One, there is NO WAY you are going to get the hot water you need from a tankless!!!!!!!!! Even if it was gas(which are the only ones that work. Electric is pure sh!!!t. And one more negative- be prepared to change the motherboard every 5-6 years. Manufacturer told me they were designed to fail when I was troubleshooting one. Unless you are constantly using hot water, best thing you can do to save is put it on a timer for energizing certain times of day. And PLEASE have a pan with drain under it!!! Last consideration with gas install and tankless install probably looking at around $3000 at least. If it leaks it's a water line leak. Do you get the idea this plumber doesn't like them?:)
 
Button Pusher said:
Three 30 amp 240 v feeds for the medium size heaters.
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Large one is 36kW. Whole new panel for it alone. Talk about warp speed on a power meter for family of 6. Oh boy.

They sell those tiny units for under sink applications. 20 seconds of warm water. I got asked to troubleshoot one in Charlotte. Walked in turned water on, turned water off, went home. $150.
 
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I have a Rinnai gas at home I love. I put an electric tankless at our Mountain house 6 or so years ago. Main reason is it was located 10 feet from the breaker panel and it cleared up some space in the laundry room. I think it is fed with 50amp breakers and it dims the lights when it comes on. It has worked great up there as it doesn't get that much use. I don't think I would want an electric tankless for everyday use. Plan at some point is to bury a propane tank and change it out.
 
The electric ones (yes even the 220v) will not and cannot replace a tank WH. Sure some have lifetime warranty but you have to show proof you flushed it every year.
 
Great information. I was considering replacing the gas fired tank water heater at the bar with a tankless one to save space, but now I think I'll just stay with what I have.
 
Ok, thanks for the reply guys. What are the thoughts about replacing the existing 80G with another similar? I’d think the existing is nearing EoL and it has to be moved for the flooring install. I’m on a deep well with soft water if that makes a difference.

again
@Armed4defense and anyone else
 
I get guys at my Home Depot who buy the tankless models on Amazon, hire a handy guy to install it, then it don't work right. They run undersized wire to single pole breakers because the panel has only three slots vacant vs the six needed. You can't make this stuff up.
 
Button Pusher said:
I get guys at my Home Depot who buy the tankless models on Amazon, hire a handy guy to install it, then it don't work right. They run undersized wire to single pole breakers because the panel has only three slots vacant vs the six needed. You can't make this stuff up.
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Then bring it back because it doesn’t work.
 
My wife has an electric one in her shop. In winter, it doesn’t make satisfyingly hot water, which it will do when the ground water temp is warmer. I would run away from an electric instant.
 
lowspeed said:
Great information. I was considering replacing the gas fired tank water heater at the bar with a tankless one to save space, but now I think I'll just stay with what I have.
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I'd have no issues replacing a gas tanked with a gas tankless if you have the gas supply capacity. The only problem I know of with tankless vs most tanked is you still need power for hot water. All tankless will need a 120v feed for a blower motor and most gas tanked systems don't need any external power to have hot water.

We rarely loose power at our house in Mint Hill and I'm setup to hookup a generator if needed. I did run our gas tankless a few months ago when we lost power off one of those big battery/inverters for a couple hours as needed.

I'm a super fan of tankless when used in the correct application. I have three teenagers at home so it works well for me and I have never run out of hot water. My gas Bosch tankless at our old house which is now my rental has been running for almost 15 years now with no issues. I installed it myself the day before my youngest came home from the hospital.
 
Armed4defense said:
One, there is NO WAY you are going to get the hot water you need from a tankless!!!!!!!!! Even if it was gas(which are the only ones that work. Electric is pure sh!!!t. And one more negative- be prepared to change the motherboard every 5-6 years. Manufacturer told me they were designed to fail when I was troubleshooting one. Unless you are constantly using hot water, best thing you can do to save is put it on a timer for energizing certain times of day. And PLEASE have a pan with drain under it!!! Last consideration with gas install and tankless install probably looking at around $3000 at least. If it leaks it's a water line leak. Do you get the idea this plumber doesn't like them?:)
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I have a Renai in the apex house that is gas and about 10 years old. I just flushed it for the first time and have had zero issues or maintenance calls so far. We also have one at our cabin in West Jefferson. That one is almost 5 years old with no problems. That one is gas as well.
 
Carolinatlc said:
I'd have no issues replacing a gas tanked with a gas tankless if you have the gas supply capacity. The only problem I know of with tankless vs most tanked is you still need power for hot water. All tankless will need a 120v feed for a blower motor and most gas tanked systems don't need any external power to have hot water.

We rarely loose power at our house in Mint Hill and I'm setup to hookup a generator if needed. I did run our gas tankless a few months ago when we lost power off one of those big battery/inverters for a couple hours as needed.

I'm a super fan of tankless when used in the correct application. I have three teenagers at home so it works well for me and I have never run out of hot water. My gas Bosch tankless at our old house which is now my rental has been running for almost 15 years now with no issues. I installed it myself the day before my youngest came home from the hospital.
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Also, I filled one of those above ground 16' pools when the kids were little from our Bosch hot water heater in February. It was awesome!
 
I’ve had both electric and gas. Electric is fine for a sink in the shop. That’s about all.

My LP Rinnai is great! It’s used in my wife’s veterinary practice. When my gas water heater has to be replaced in my house, it will be replaced with a gas tankless.
 
I swapped out our propane fed 50 gallon heater with a Takagi tankless. It cost me $900, and on top of that OhBummer was giving $300 rebates. I was advised it wouldn't save $ over the tank version with 7 people in the house all day. It saved us 400-500 gal of propane per year. We used it for 10 years until we sold the house. I installed another in our current home over 5 years ago. We've had no issues. I also like not keeping 50 gallons hot all the time when there's only two of us in the house.
 
BlackGun said:
They have them. Rarely bought.
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I've had to wire in probably a few dozen of these whole house electric heaters, and they're popular in the tiny homes too.
90% of them require 3 x 40amp circuits. Yes you read right. 120 amps electrical for the water heater.
If you don't have 200 amp service to your house forget it. And even then you're about to start redlining that 200 amps.
That's 3 #8/2 romex from the main breaker panel to wherever this heater is. Fishing one 15 amp wire through a finished house can be a pita let alone 3 of these bullwhips.
The plumbers bill will seem minuscule compared to what the electrician is gonna charge.

The gas versions of these things work very well. And that is only 1 x 15 amp circuit for electrical, which can often come from a nearby source. But new gas pipe install can be pricey.
Regardless of which version of these insta-hots you go with, you will also likely need to know how to repair sheetrock and paint, or know someone who does.

Recommend replacing the 80 gal when needed, (elec will be the same) and using a water heater timer to shut the thing off from 10pm to 5am.
 
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Those of you that have installed a tankless gas model, did you install it inside the house or on an exterior wall? The reason I ask, talked to the gas company man when he was connecting my tank to my genset and he was talking about putting it on an exterior wall. Not sure if he was giving good advice or getting out of installing in the crawl space which I have about 40” of headroom that he was not familiar with.
 
Read the fine print, you'll probably have this same problem
noway2 said:
My wife has an electric one in her shop. In winter, it doesn’t make satisfyingly hot water, which it will do when the ground water temp is warmer. I would run away from an electric instant.
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Most of the electric ones will only warm 20-40 degrees above the feed temp. so if your water coming in is only 50-60... you'll be lucky to get a 100degree shower. That's warm enough to get by on... but it's not the HOT you sometimes need.
I was looking at electrics too, but that's the thing that stopped me. well, that and the cost...
 
I have an on-demand electric for the wash-tub in my shop. For that, it's fine. The water is comfortably warm (and quickly) for hand-washing and such.
 
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Tatershooter said:
Those of you that have installed a tankless gas model, did you install it inside the house or on an exterior wall? The reason I ask, talked to the gas company man when he was connecting my tank to my genset and he was talking about putting it on an exterior wall. Not sure if he was giving good advice or getting out of installing in the crawl space which I have about 40” of headroom that he was not familiar with.
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I don’t have one but I have run gas piping for them. They can be installed inside or outside. Prefer inside or in dry crawl space.

Gas piping codes are complex. So are exhaust codes. Then you have distances from fixtures to consider. Basically you can’t slam one in just anywhere.
 
Tatershooter said:
Those of you that have installed a tankless gas model, did you install it inside the house or on an exterior wall? The reason I ask, talked to the gas company man when he was connecting my tank to my genset and he was talking about putting it on an exterior wall. Not sure if he was giving good advice or getting out of installing in the crawl space which I have about 40” of headroom that he was not familiar with.
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I installed mine inside the house immediately adjacent to an exterior wall. I felt that it’s longevity would be improved by an inside installation, but wanted to duct exhaust through the wall instead of making a roof penetration.
 
kcult said:
We've been in our house 22 years. Our water heater was here when we got here.

If it ain't broke, don't fix it? Or is there a benefit to replacing it sooner than later?
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When the tank rusts through it will leak all over his nice new flooring.....a much nicer job to do it now if he is removing it anyway.....but if it were me and it didn't have a bunch of sediment in it I'd be tempted to reinstall it.
 
Tatershooter said:
Those of you that have installed a tankless gas model, did you install it inside the house or on an exterior wall? The reason I ask, talked to the gas company man when he was connecting my tank to my genset and he was talking about putting it on an exterior wall. Not sure if he was giving good advice or getting out of installing in the crawl space which I have about 40” of headroom that he was not familiar with.
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In my parents house we put a (propane) Rinai with a circulation pump. Having hot water at the faucet within about 2 seconds is really nice. We mounted it up high on the wall of the basement and it ducts directly outside. The initial GC on the house made the plumber mount it in the crawl space which made both me and the plumber rather nervous. I don’t like the idea of a gas driven ignition source being hidden away in an area that’s not readily accessible. Yes, I said badement and crawlspace; the foundation is one solid pour of concrete with about 2/3 of the house being basement. When I took over as GC, we moved the water heater, but unfortunately I had to get the brick wall fixed where the old penetration was. :mad: You can only go so far before you need a powered exhaust, which I don’t like the sound of.
 
Also the gas ones require a lot of gas. When we installed mine I had to add additional pressure regulators so that we could run full line pressure to the tankless unit and then step down the pressure to 2psi right at the tank, otherwise we would have had to upgrade the line to 3/4" all the way . They pull on the order of 100k BTU that is a lot of gas.
 
Mike79 said:
When the tank rusts through it will leak all over his nice new flooring.....a much nicer job to do it now if he is removing it anyway.....but if it were me and it didn't have a bunch of sediment in it I'd be tempted to reinstall it.
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This (the first part) is my thinking

on that topic, is there a recommended brand or model?
 
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johnnyb said:
This (the first part) is my thinking

on that topic, is there a recommended brand or model?
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I would say Rinnai is the the better on demand water heater.

I want to add to the discussion as mentioned by @TSConver. You cannot simply add any appliance such as a water heater to an existing gas line. There are calculations for line diameter and appliances already on the system. In some cases you can have the gas provider increase the pressure from low pressure up to 2 psi. As stated above it’s a must to then add regulators to every gas fired appliance which is a lot of work with gas fittings.

If you leave it at low pressure which is what most people have then it requires piping size change throughout the structure. The larger water heaters are 199,000 btus. Anything above is considered a true boiler which has new rules. One of those is annual inspections and documentation. That’s why they stay below that threshold. Gas piping is NOT a handyman’s task.
 
BlackGun said:
I would say Rinnai is the the better on demand water heater.

I want to add to the discussion as mentioned by @TSConver. You cannot simply add any appliance such as a water heater to an existing gas line. There are calculations for line diameter and appliances already on the system. In some cases you can have the gas provider increase the pressure from low pressure up to 2 psi. As stated above it’s a must to then add regulators to every gas fired appliance which is a lot of work with gas fittings.

If you leave it at low pressure which is what most people have then it requires piping size change throughout the structure. The larger water heaters are 199,000 btus. Anything above is considered a true boiler which has new rules. One of those is annual inspections and documentation. That’s why they stay below that threshold. Gas piping is NOT a handyman’s task.
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Not gonna do the instant, as no gas availability and the consensus is the electric version sucketh lol. Any opinions on traditional electric water heater brands/models?
 
Disregard, just price checked a replacement 80G electric, the elcheapos start at about $900!!! Mine on the initial install was less than $300! I know it’s been 17 years but dang! I’ll be replacing the pan (current one is cracked) and resetting that one in place lol.
 
johnnyb said:
This (the first part) is my thinking

on that topic, is there a recommended brand or model?
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I have zero idea as it has been 20+ years since I did installs....my wife is a quotations specialist but most of that is more about cost than true worth.
 
johnnyb said:
Disregard, just price checked a replacement 80G electric, the elcheapos start at about $900!!! Mine on the initial install was less than $300! I know it’s been 17 years but dang! I’ll be replacing the pan (current one is cracked) and resetting that one in place lol.
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Not sure you need more than a 60 having boys. Unless they shave their legs a lot. Being a common water heater the price comes way down. Water heaters are cheap now like everything else. I would never buy a big box water heater. I purchased a 60 gallon two years ago for my daughter for $395 from a plumbing supplier. But that was pre damnpanic pricing.

Edit: contractor pricing and relationship pricing on her water heater.
 
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Tatershooter said:
Those of you that have installed a tankless gas model, did you install it inside the house or on an exterior wall? The reason I ask, talked to the gas company man when he was connecting my tank to my genset and he was talking about putting it on an exterior wall. Not sure if he was giving good advice or getting out of installing in the crawl space which I have about 40” of headroom that he was not familiar with.
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My neighbors is in his garage and mine is outside. Both work fine. They did have a larger exterior cabinet at the time for outdoor installations, but my p,umber said it wad unnecessary. So far it seems he was correct. My original tank was in an upstairs closet. Our plumber determined that outside was best due to its proximity to the gas line and plumbing lines. Every application is probably a little different.
 
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