Straight Talk About "On-Demand Tankless Water Heaters by A.O. Smith

Users who are viewing this thread

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
The following is some questions and answers about tankless water heaters. I think this will be a great help to all that are considering a tankless unit.
sewerratz-06.jpg
 
Last edited by a moderator:

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
Just a note to those that think A.O. Smith doesn't want to sell you a tankless water heater. That is false, what they want you to do is make an informed choice when you are considering a tankless unit. They want people to realize here in the USA we take the amount of water we use at once for granted, and if you install a single unit in a high demand situation the water will not get hot enough to be satisfactory. Which is why they point out it could be costly to replace your tanked heater with a tankless unit.

For some homes two units are needed to provide you enough hot water for those peak usage times. Below is a pic showing how two units are installed. Just a note if you are just washing your hands only one unit fires up, the only time the second unit will turn on is when you exceed the flow rate of the first unit to get the desired temperature.

tankless-water-heater-4.jpg
 
Last edited by a moderator:

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
Another note about the cost of installing tankless units is gas pipe sizing. Most Tank units only use 1/2" piping due to BTU ratings which the most common is 40,000 BTU's. Tankless units on low flow mode usually draws 25,000 BTU's and full flow mode can go as high as 199,000 BTU's, some units can go higher but they must follow boiler installation codes once they go over 200,000 BTU's. Well in most cases you will need to tap off the main gas supply coming into the home with a 3/4" line to the tankless unit, if you have to install multiple units as this next picture you will see they ran 1 1/4" pipe up to the units then reduced it down to the 3/4" to the units, This insures that when all three units fire up at their 199,000 BTU's they will get enough gas to run at that setting. So this is the other part of the expense that A.O. Smith is talking about.

rinnai_series.jpg
 
Last edited by a moderator:

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
How loud are the tankless units? I don't think I ever found reliable decibel information.

David

They are no louder than a power vent water heater. I never went and measured the decibels. I will try to research this a bit and post it here when I get the answers.
 

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
Here is an interesting read that was a test involving Bradford Whit EverHot tankless units vs. tank type...
It was published in P&M

Ah yes, my local plumbing supply hands that out to homeowners that come in asking about tankless heaters. I am going to make jpgs of them 4 pages and post them here in this thread too. I like to see this thread stay on the facts of tankless heaters instead of a battle ground like the other threads ended up becoming. Thank you Redwood for posting this PDF
 
Last edited by a moderator:

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
Thanks Redwood for the pdf to Bradford Whites testing of Tank Vs Tankless water heaters. Also if you want to view these larger click on the page you want to view. These images where made from the pdf file Redwood posted

TanklessVsTankType_Page_1.jpg


TanklessVsTankType_Page_2.jpg


TanklessVsTankType_Page_3.jpg


TanklessVsTankType_Page_4.jpg
 
Last edited by a moderator:

gregsauls

Homeowner
Messages
56
Reaction score
0
Points
0
Location
Texas
Website
web.me.com
I dunno to possibly save that .15 a week I might be tempted :rolleyes:
I was hoping to see long term test to allow for scale buildup


I'll let you know this August (1st year anniversary) when I do my first descale how hard it was and how bad :rolleyes: the system was hosed up....:eek:
 

Ladiesman271

Homeowner
Messages
220
Reaction score
0
Points
0

Thanks Redwood for the pdf to Bradford Whites testing of Tank Vs Tankless water heaters. Also if you want to view these larger click on the page you want to view. These images where made from the pdf file Redwood posted



I was going to point out how they stacked the deck in that test and have commited a few "code" violations, but those issues have been beaten to death in other threads.

The NG and electric costs are also way out of date!
 
Last edited by a moderator:

SewerRatz

Illinois Licensed Plumber
Messages
1,681
Reaction score
10
Points
38
Location
Chicago, IL
Website
www.a-archer.net
I was going to point out how they stacked the deck in that test and have commited a few "code" violations, but those issues have been beaten to death in other threads.

The NG and electric costs are also way out of date!

That is from 2005 so yes 4 years out of date. But still some information explaining some of the issues.
 

dimprov

New Member
Messages
38
Reaction score
0
Points
0
Location
Austin, Texas
Hi Ladiesman271,

What's the decibel level when measured at 1 meter? That's the usual distance for taking noise measurements.

David
 

gregsauls

Homeowner
Messages
56
Reaction score
0
Points
0
Location
Texas
Website
web.me.com
Hi Ladiesman271,

What's the decibel level when measured at 1 meter? That's the usual distance for taking noise measurements.

David

My Rinai R75lsi is what I would say to be about 50-55db....with 50 db being Normal conversation and 70 db being a Vacuum cleaner.
 

dimprov

New Member
Messages
38
Reaction score
0
Points
0
Location
Austin, Texas
Ladiesman,

Your original post said 10 feet, which is more like 3 meters.

Why not just measure it at 1 meter?

The HVAC guys measure it at greater distances because they're trying to distort reality by saying their unit is, say, 50db, and then asterisk it to say "oh, by the way, it was measured at more than 30 feet away".

Sounds measurements at more than 1 meter are a red flag.

David
 

Sjsmithjr

In the Trades
Messages
314
Reaction score
1
Points
16
Location
Knoxville, Tennessee
To add to what David posted, you should also take your measurements using the Decibel A filter; dbC is typically only used to measure very high SPLs.

FWIW, they even had a discussion of tankless technology on the Sound&Vision forum, where Ladiesman271 is equally well loved...

But wait, Laddiesman271's knowledge base doesn't stop at plumbing and home audio, he also does HVAC. Here's what one professional member had to say about him over on hvac-talk.com: "This loud mouth ain't even a tech and hes giving hvac advice. I checked all his posts and his claim to fame is just putting links to HVAC source information. No solid input of any other kind." It's worth signing up just to check out his posts!

I don't feel so special anymore...
 
Last edited:

Sjsmithjr

In the Trades
Messages
314
Reaction score
1
Points
16
Location
Knoxville, Tennessee
Give me a break.

1. An SPL meter's SPL A scale filters out low frequencies.

If you could demonstrate that you actually know what you're talking about I would.

The A weighting curve approximates human frequency response at low to moderate SPLs. dbC would be appropriate if the SPLs were over 100dB.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks