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Old 05-28-2015, 12:55 PM
 
Location: Crooklyn, New York
27,623 posts, read 24,832,767 times
Reputation: 11185

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Quote:
Originally Posted by Kefir King View Post
I am assuming that the gas line that was good enough for the OLD water heater will be good enough for the NEW.
It's not about being "good" enough. It's about being "large" enough.

Quote:
Originally Posted by Kefir King View Post
Why make the assumption of a 1/2 inch gas line. Most are bigger than that. I have never seen one so small. Even my apartment's kitchen stove has nominal 3/4 inch iron pipe with a .804" inside diameter (outside diameter of 1 inch.) Every apartment I have had has had the same.
Because that is the standard size for most gas lines, which is why it typically involves an upgrade. Rheem even notes this in their manual.

Quote:
Typically, the gas piping has to be upgraded to support the tankless water heater due to the volume of fuel that is required.
http://snowcrest.net/thriftysupply/p...ping_Facts.pdf

Is there really any more to say here? The problem with anecdotes like "every apartment I've ever had" is that it doesn't reflect what actually happens in most cases. And in most cases, Rheem says an upgrade to a larger gas line is required.

And you can't just look behind your stove and say "Whew, I've got 3/4s of an inch." How would you know what the diameter is at the source or even if there are all types of different sized pipes behind your walls joined together with fittings? It's rarely as simple as "take the old one out and put the tankless in."

Quote:
Originally Posted by Kefir King View Post
An article that might be of actual USE would break that cost down into equipment and labor. How much did the "professional" cost and how much was the water heater?
Given that Navien's most expensive tankless water heater is $1,800, we know that the balance of the job was around $1,800.

I would only advise this type of job if you're doing a full gut job (which is what we did). Installing a tankless heater is a much more involved process than installing a regular water heater. If you have the cash to blow and just want one really badly, I'd say go for it, but even if you have the cash you might not be able to pull it off logistically (you need a professional consultation to know for sure, which you DO NOT need for an ordinary tank). If you're doing it solely to save money, I'd say it's not worth it in 99% of cases.
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Old 05-28-2015, 09:05 PM
 
18,315 posts, read 11,709,355 times
Reputation: 11957
Quote:
Originally Posted by Kefir King View Post
OP is likely tossing out an old tank type hot water heater so the comparison must be the cost of buying and installing tankless, or buying and installing a new 50 gallon tank type.
Since both probably require very similar billing from a plumber, one really must discount labor costs.

And thus the difference in price between tank and tankless cannot ever be anywhere NEAR $4,000,more like <$1,000, perhaps a LOT less.

https://www.google.com/search?q=tank...dress&tbm=shop

KK you are a wonderful person and I am devoted to you; however on this you just are plain wrong.

Instant/demand water heaters have been around since the early 1900's (invented by Mr. Ruud). From the beginning the first thing anyone considering installing such a device be it in a home or whatever use was the gas supply pipes within the structure and mains from the street.

Your average tank water heater, range/stove or even gas heated dryer *does not have nor require the type of piping needed for an instant water heater*, period, end of story, nothing more to see here folks.

This vintage Ruud "side arm" water heater is rated for 200,000 BTU's, you aren't going to get that from a commonly installed gas lines. Antique Ruud Tank water heater

Small electric powered demand water heaters located near say a kitchen sink or bathroom *may* provide enough hot water depending upon the purpose. However once you start moving up to something capable of providing hot water for an entire house or structure including several faucets opened at once you are going to need a *very* powerful gas fired heater, or one that uses *VERY* large amounts of electric.

This is not rocket science; the laws of thermal physics are what they are; that is the required amount of fuel/power to raise water temperature by a certain degree. The more cold water is (such as tap water during the winter in the Northeast), the more energy will be required to get it to anywhere near "hot" within the time frame it passes over/through heated coils.

Consumer Reports and various other professional/commercial media have been saying the same thing for ages about tankless/demand water heaters; basically they are "ok" for new construction and or where the infrastructure within a building already exists to support. However it makes little economic sense to swap out an existing tank water heater to replace with tankless.

Your analogy makes as much sense as someone saying they can replace a 120v electric dryer with a 220v version if they "only" change the outlet. Aaaaak! Wrong. It depends upon the wiring, fuse box/breaker panel and even what is coming from the street. You'd be surprised just how many NYC homes and apartments were wired so long ago they cannot support high demand electric devices.
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Old 05-29-2015, 07:04 AM
 
Location: Manhattan
20,169 posts, read 26,469,688 times
Reputation: 9044
Quote:

Apparently we have 1/4" pipes
Really Liz, quarter inch pipes???? Did you measure them or are you taking the $$$plumber's$$$ word?

Last edited by Kefir King; 05-29-2015 at 07:30 AM..
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Old 05-29-2015, 07:07 AM
 
Location: Manhattan
20,169 posts, read 26,469,688 times
Reputation: 9044
Quote:

However it makes little economic sense to swap out an existing tank water
heater to replace with tankless.
Unless the tank is leaking or about to. This is when most people will do the swap. Of course nobody is going to toss out a new water tank.

Quote:
Your average tank water heater, range/stove or even gas heated dryer *does not
have nor require the type of piping needed for an instant water heater*,
But we are not talking about the piping to an "average tank water heater" we are talking about this average water heater PLUS a whole house heating boiler plus maybe a gas stove and oven. Since piping does not come in micrometer sizing we are probably talking about a gas line that can handle the job.


So instead of babbled conjecture about the size of gas lines, how about asking the OP?
What say you bx? How big is your incoming gas line?

Quote:

And you can't just look behind your stove and say "Whew, I've got 3/4s of an
inch." How would you know what the diameter is at the source
Now really, who in his right mind is going to take a tiny gas line and route it into a large one????? That's talking nonsense.

Real world...my last home was built in 1873, gas line was added in the 1920's for a kitchen stove. A hot water coil was added in the late 1940's followed by a proper hot water tank in the 1950's, and then my parents converted from coal to a gas boiler in the 1960's.
The original piping for the stove was sufficient to heat the water and then the whole house.
That's the real world.

PS...and nobody need 200,000 BTU/hr capacity for heating water, that's 59 THOUSAND Watts.

Last edited by Kefir King; 05-29-2015 at 07:45 AM..
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Old 05-29-2015, 09:34 AM
 
Location: Crooklyn, New York
27,623 posts, read 24,832,767 times
Reputation: 11185
Quote:
Originally Posted by Kefir King View Post
Real world...my last home was built in 1873, gas line was added in the 1920's for a kitchen stove. A hot water coil was added in the late 1940's followed by a proper hot water tank in the 1950's, and then my parents converted from coal to a gas boiler in the 1960's.
The original piping for the stove was sufficient to heat the water and then the whole house.
That's the real world.
The "real world" is a tankless water heater manufacturer stating in its manual that an upgraded gas line is "typically" required. Your single experience does not represent the thousands of people who have or want to have tankless water heaters installed in their homes each year.
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Old 05-29-2015, 10:06 AM
 
1,032 posts, read 995,435 times
Reputation: 781
Quote:
Originally Posted by Kefir King View Post
Really Liz, quarter inch pipes???? Did you measure them or are you taking the $$$plumber's$$$ word?
Could be remembering it wrong, but I believe that's what he said - the house was built in 1912, and it's mostly original plumbing. He's a family friend, so I trust him - it's not my house (mom's house, I am just living there for a bit), so I tend to not get very involved in these things.

I was mostly bummed that i couldn't take an hour long lava-hot shower whenever I wanted to
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Old 05-29-2015, 05:05 PM
 
18,315 posts, read 11,709,355 times
Reputation: 11957
Quote:
Originally Posted by Kefir King View Post
Unless the tank is leaking or about to. This is when most people will do the swap. Of course nobody is going to toss out a new water tank.


But we are not talking about the piping to an "average tank water heater" we are talking about this average water heater PLUS a whole house heating boiler plus maybe a gas stove and oven. Since piping does not come in micrometer sizing we are probably talking about a gas line that can handle the job.


So instead of babbled conjecture about the size of gas lines, how about asking the OP?
What say you bx? How big is your incoming gas line?


Now really, who in his right mind is going to take a tiny gas line and route it into a large one????? That's talking nonsense.

Real world...my last home was built in 1873, gas line was added in the 1920's for a kitchen stove. A hot water coil was added in the late 1940's followed by a proper hot water tank in the 1950's, and then my parents converted from coal to a gas boiler in the 1960's.
The original piping for the stove was sufficient to heat the water and then the whole house.
That's the real world.

PS...and nobody need 200,000 BTU/hr capacity for heating water, that's 59 THOUSAND Watts.
I'm done here, since the whole world obviously is wrong and *YOU* are correct based upon whatever happened in *YOUR* life. This despite the fact a simple Internet search will verify what I and others have stated.

Why you insist that a tank water heater can easily be swapped out for a tankless is just beyond my comprehension. But to each his own.

You stubbornly refuse to acknowledge the two types of units are quite different and have different requirements for installation. Yes, that old Ruud unit was rated for 200k btu and today's offerings aren't much different (120k BTU to 200k for domestic and nearly 400k for commercial). But again am done arguing with you since it seems you either do not know nor care to comprehend the laws of thermo physics. Long story short *YES* that heating power is required to bring cold water anywhere near 120F or above quickly as it passes over coils.
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Old 05-30-2015, 06:11 AM
 
Location: Manhattan
20,169 posts, read 26,469,688 times
Reputation: 9044
Oh for God's sale Bugsy, just go measure your own gas pipe instead of all your silly conjecture.

I am a chem engineer so I know very well the laws of thermodynamics especially as they applies to something as simple as a water heater, and I KNOW that 200,000 BTUs is overkill for a home with a couple residents and a kitchen and a couple bathrooms.

I also know that even the oldest homes had gas inputs larger than 1/2 inch and I know that a home that already has full capability for gas heat, gas hot water, and a gas stove CERTAINLY has the capacity to connect a tankless water heater to replace a water tank without upgrading any gas service lines.

And if the OP has any doubts, he too should just take a pair of calipers to his incoming gas line.
(Alternatively, just tape measure it and divide by pi (3.1416) to get the outside diameter and look for the nominal size here

Schedule 40 & 80 Pipe Dimensions

Shortcut:
3/4 inch pipe has an outside diameter of 1.050 inches.

Last edited by Kefir King; 05-30-2015 at 06:21 AM..
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Old 05-30-2015, 08:48 PM
 
Location: Bronx, NY
94 posts, read 163,110 times
Reputation: 43
Quote:
Originally Posted by LizfromtheBronx View Post
We considered tankless when our water heater started to make noises last year - also in a SFH in the Bronx. Our house is old though, with old pipes, and our plumber didn't recommend it for our pipes. Apparently we have 1/4" pipes, and they recommend 1/2' pipes for tankless. Or something like that. We replaced with another regular tank water heater.
Thx Liz. If you don't mind me asking, how old is your home? I'm buying a 95 y/o home and have a bigger concern with the age of the plumbing in the master bath on the 2nd floor. Because of this, I may just swap the tank and call it a day.
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Old 06-01-2015, 10:02 AM
 
Location: Bronx, NY
94 posts, read 163,110 times
Reputation: 43
Quote:
Originally Posted by Kefir King View Post
Oh for God's sale Bugsy, just go measure your own gas pipe instead of all your silly conjecture.

I am a chem engineer so I know very well the laws of thermodynamics especially as they applies to something as simple as a water heater, and I KNOW that 200,000 BTUs is overkill for a home with a couple residents and a kitchen and a couple bathrooms.

I also know that even the oldest homes had gas inputs larger than 1/2 inch and I know that a home that already has full capability for gas heat, gas hot water, and a gas stove CERTAINLY has the capacity to connect a tankless water heater to replace a water tank without upgrading any gas service lines.

And if the OP has any doubts, he too should just take a pair of calipers to his incoming gas line.
(Alternatively, just tape measure it and divide by pi (3.1416) to get the outside diameter and look for the nominal size here

Schedule 40 & 80 Pipe Dimensions

Shortcut:
3/4 inch pipe has an outside diameter of 1.050 inches.
For the record:

-House built in 1920
-3BR, 1.5BA
-2 Adults, 3 kids
-Gas dryer, stove and oven
-3 yr/o Gas Boiler (if it helps its in determining the gas pipe sizing... Pennco 15B175FV 175k BTU sticker says it has a #31 Gas orifice size).
-Heaters are a mix of cast iron and base board type (hot water)

I do not know the size of the gas piping, maybe the info above helps.
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