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Tankless water heater tech

Tankless is great. Our house is long, about 110ft and the tank is offset 1/3 of the way. I have a recirc pump that runs off a timer. 6-8a and 6-9p. There is hot water instantly when we often use it, otherwise the kitchen has about a 20s delay and the furthest bathroom about 60s.

I’d never go back to a tank model.
 
For the people with the tankless heaters, just how much water are you going through? Do you routinely take 20 min showers or just have a ton of people that use water constantly or what?

my household is fairly low water usage, and i can not say i have ever had issues with running out of hot water with a 40-60 gal tank.
 
Crimsen said:
For the people with the tankless heaters, just how much water are you going through? Do you routinely take 20 min showers or just have a ton of people that use water constantly or what?

my household is fairly low water usage, and i can not say i have ever had issues with running out of hot water with a 40-60 gal tank.
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just myself and my wife combined average 145 gallons of total water per day.
 
I did a remodel many years ago... I replaced an electric WH with a gas "powered vent" WH. Fucking stupid easy PVC horizontal vent for the win! Hot water recirc pump in my current house is fucking nice. It isn't automatic but is connected to a IOT smart switch that responds to "hey google,; turn on hot water for 90 sec.".
 
Navien is what I have. It’s uses pvc for vent and will run off a 1/2 gas line. We can run 2 showers at the same time etc and never run out of hot water. I would never go back to a tank again. I put it in myself with crimp fittings. 2 years no issues.
 

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Gas tankless for 15 years. Won’t have anything else. 9 gpm at 130F.

The only problem was Miller moths got in the intake once and messed up air flow to the burner.
Screen over the intake now.

A tank of hot water 20 hours a day that isn’t getting used is very inefficient.
 
I had a tankless installed in my last place when I had NG brought in. Rinna outdoor mount with a remote panel installed in the laundry room. I'll be installing another when I build my shop/house this spring. Zero problems other than a little wait for hot water. It was really nice to fill the hot tub up with hot water the couple times I needed to.
 
I regret replacing my old heater with another one instead of going tankless.
Kids have to space out bath/shower time, and while we're on vacation the thing still sucks power and costs me money.
For all you tankless haters, if you want a regular one that's only 2 years old, I'll sell you mine so I have an excuse to go tankless.
Can't wait for this thing to die, but it will likely shit my life for another 15-20 years.
 
Crimsen said:
For the people with the tankless heaters, just how much water are you going through? Do you routinely take 20 min showers or just have a ton of people that use water constantly or what?

my household is fairly low water usage, and i can not say i have ever had issues with running out of hot water with a 40-60 gal tank.
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One shower fixture on each end of the tub to make showering with the girlfriend more enjoyable + showering with the girlfriend takes at least 30min for obvious reasons. :flipoff2:
 
How do recirculation pumps work? I assume you need a return loop? Does everything have to run in series?


All of my lines go though the slab and there are 4 or 5 individual runs to each room/set of fixtures. It's probably also why I have a pretty good lag to get hot water to a fixture. It'd be a major ordeal to modify any of it though.

I'm a little scared of why I'm going to find when I open up that wall and locate the leak. I just have a little dampness coming from under the wall behind the WH. I'm thinking it's just one of the lines going to or from that has a very small weeping leak, but I'm also scared it could be one of the lines that goes in to the slab that's corroded out.
 
Another weird thing, it appears that the house originally had 2 water heaters. There's a second stub out on the propane line and you can see a footprint on the floor where a second tank once sat. I can't make any sense of that. The barn conversion thing was done in '89 and I'm the 4th owner. I'm fairly certain the gas lines and venting are original to '89. Surely the tank isn't that old though. (Haven't peeled off the insulation to look for a date yet, but I'm guessing 15+ years old0

The house is only 3 bed/2 bath. No way you'd need that my hot water.

Could it have been used for some weird heating setup?


UNLESS - The master bath is behind that wall and I know there used to be a whirlpool/jacuzzi tub in there. There's an old breaker for it and the PO told me he removed it when he remodeled that bathroom. I wonder if the original owners that built it really like that tub and wanted to make sure there was enough water on hand to fill it up whenever they wanted.

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That chrome thing sticking out of the wall I believe was a temp regulator or something for the original fixture that fed the tub and whatever shower may have been in there. It's not currently in use and I have not how or even if it was abandoned when the bath was remodeled. It could very well still be live behind the wall. :laughing:

Eventually I'm going to re-remodel that bath and tear all that shit out because the PO did a really shitty job, but I really want to do the other bath first because it's much more original to '89 and if I do that first, I'll have a nice one to use while I'm doing the master.
 
pipe into a concrete slab always seemed like a terrible idea to me.

I know irate hates basements, but it sure was nice to just tear out all the iron pipe in my basement and easily replace it all with pex when it started getting pinholes.
 
18 years with 2 x propane water heaters. Well water. The last 3 years of use, I noticed the propane bill becoming more expensive, not related to price increase, just more use, we could not really pin down.

Replaced with a single Rennai - it has a very small holding tank, about 1.5 gallons, so hot water is always available. If I am outside next to the vent, I can hear it kick on and off. If I am in the laundry right next to the mechanical closet, but separated by a 2x6 wall with insulation, I cannot hear the tankless at all.

There was zero difference in wait time for hot water. Zero. My shower is about the longest distance from the mechanical closet. Takes 60-65 seconds for hot water - no fancy recirc system. Made no difference between HWH and tankless, if anything the tankless water was hotter.

Propane bill in the two years post install was HALF. So please tell me how efficient it was to keep 2 x 60 gallons hot all day, for minimal use.

Cut open one of the hot water heaters I replaced. Originally it was a 60 gallon unit and I had 2x to handle the demand for the upstairs spa bath. The water heater after about 18 years of use held less than 25 gallons, lots and lots of calcification, from the hard well water most likely. (we have a water softener but only on the cold supply line, post water heater - and have not used it for decades as the salt kills wifey's plants). SO basically I had been spending $$$ on propane to keep less than 50 gallons of water, and a whole heat sink of calcium and copper hot. So wasteful.

The tankless needs 120V so if there is a full power failure, and I don't want to fire up the 20kw genset, I can fire up the 500w gas powered genny and still have hot water (at least until the tank for the well runs out (approx 40 gallons)).

I figure the added cost of the tankless took about 39 months to be paid off in reduced propane bills. And that was when propane was half what it costs at the moment, so anyone making the change likely would be break even or ahead even sooner. Gaining extra floor space in the mechanical closet was a bonus.

New shop will have a Rennai, and my favorite plumber tells me he can incorporate that into the slab heating system (in slab heat uses solar to preheat the water, so apparently the tankless only needs to add about 30 degrees or so). Will never go back to the 19th century waste of keeping 120 gallons hot 24/7 for the wife to use the spa bath once a week or so. Tankless has no problem filling 100 plus gallons of scalding hot water on demand.
 
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to be fair, you're comparing propane usage of two fucked EOL tanked water heaters to your new tankless.

I stuck with a regular tanked heater last I did it. the ROI wasn't there for natural gas usage after I figured up all the costs to actually install one with the flue and all that jazz.
only two people and no hot tubs or anything like that, so a 40 gallon water heater provides more than enough.
 
87manche said:
to be fair, you're comparing propane usage of two fucked EOL tanked water heaters to your new tankless.

I stuck with a regular tanked heater last I did it. the ROI wasn't there for natural gas usage after I figured up all the costs to actually install one with the flue and all that jazz.
only two people and no hot tubs or anything like that, so a 40 gallon water heater provides more than enough.
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That's where I'm at.

When I was younger and living with lots of people I would have loved the idea of unlimited hot water, but now there's no point.
 
87manche said:
pipe into a concrete slab always seemed like a terrible idea to me.

I know irate hates basements, but it sure was nice to just tear out all the iron pipe in my basement and easily replace it all with pex when it started getting pinholes.
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Even my last couple houses on pier and beam were fine. And a hell of a lot easier to relocate fixtures or even a toilet.


I get why they did it this way in this place. There really weren't many options. If I were doing it today, I'd probably at least run like 2" or 3" casing and pull pex through it. At least that way you can pull it out and replace it later.

I do have a plan if I ever do have to replace one of the lines, but it's going to mean going overhead along the trusses and making a false "box" to hid the lines through...and then still have to fish them down through walls and whatnot. And it'll add a good bit of length to the line runs....but would also let me run a return to do a recirc. if I wanted to.
 
IGT said:
Please show the class the math and this insulation where we can heat water and it looses no energy/heat after 20 hours?
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Sure, but first you show us where a tankless loses (not "looses") zero energy :homer:

You said "very inefficient", now you're looking for zero loss.

Fuck your moving goalposts :flipoff2:
 
also very happy with mine, it is electric but 3 phase

however, like mentioned already, in the winter sometimes the shower is not as hot as I like it, still acceptable but not burning hot like I like.
 
crispins said:
also very happy with mine, it is electric but 3 phase

however, like mentioned already, in the winter sometimes the shower is not as hot as I like it, still acceptable but not burning hot like I like.
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3 phase? Where? At your store?


From what I remember when I researched them at one of my old houses that didn't have gas....whole house electric tankless is pretty much impossible for anything but high dollar new construction that can start with 400a service.

Just a quick look at HD, this 7gpm one needs 4x40a breakers. 160 amps! I know a lot of smaller older homes around here only have 100a service. And it's rare for even newer stuff to have more than 200.


Gonna be interesting when people realize the bans on gas appliances in CA, NY, etc. mean you're going to need ridiculous power services at 5x the cost.

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bgaidan said:
3 phase? Where? At your store?


From what I remember when I researched them at one of my old houses that didn't have gas....whole house electric tankless is pretty much impossible for anything but high dollar new construction that can start with 400a service.

Just a quick look at HD, this 7gpm one needs 4x40a breakers. 160 amps! I know a lot of smaller older homes around here only have 100a service. And it's rare for even newer stuff to have more than 200.


Gonna be interesting when people realize the bans on gas appliances in CA, NY, etc. mean you're going to need ridiculous power services at 5x the cost.

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Yes at my business.

^^^EDIT^^^ Says is not 3 phase, I do not get how that shit works.

We live here during the winter months and I also use the shower throughout the year when I get sweaty outside but have to work for a while longer.


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18,000 watts, damn that seems like a lot to me!
 
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arse_sidewards said:
I vote replace it with another dumb gas tank style heater.

We all know you have a fucking massive house. It's not like you live in a single wide and are hard up for space.


Having a loop of water going around again and again enough to kick the thing on defeats the entire point of a tankless. :shaking::lmao:
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My system is a smart system that picks up on your shower habits. So, say the wife and myself have a shower around 7-9pm every night, it will preheat the water in the loop around then. Really isnt a big energy draw. Like I said, our energy bill is a fraction of previous houses even with this system in place. I understand wanting to be a contrarian, and that is fine, but I would not put it out there like a water heater running 24 hours a day is any better.
 
crispins said:
Yes at my business.

^^^EDIT^^^ Says is not 3 phase, I do not get how that shit works.

We live here during the winter months and I also use the shower throughout the year when I get sweaty outside but have to work for a while longer.


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18,000 watts, damn that seems like a lot to me!
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2x50 amp feed to it. Yeah, that's a bit.

I'd have to sit down and figure out what the current load is on my panel, but I'd be surprised if I could run that and both A/C zones at the same time.
 
I was at a house years ago with an electric tankless and a decent sized solar setup. Seemed counterproductive. I went back and forth on tankless before deciding to do another 50 gallon electric. If existing w/h was gas I would have went tankless probably Rinnai. I tire of working on the shitty new gas tanked water heaters, they’ve ruined the simplicity and reliability of them for a little added safety.
 
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