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

[SewerRatz]

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. Click on the picture to see a larger image.
http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_1.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_1.jpg)

[SewerRatz]

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_2.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_2.jpg)

[SewerRatz]

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_3.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_3.jpg)

[SewerRatz]

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_4.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/prostar_QA_Page_4.jpg)

[Scuba_Dave]

You had me saying "NO" at tankless :D

[SewerRatz]

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.

http://i7.photobucket.com/albums/y292/SewerRatz/Plumbing%20pics/tankless-water-heater-4.jpg

[SewerRatz]

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.

http://i7.photobucket.com/albums/y292/SewerRatz/Plumbing%20pics/rinnai_series.jpg

[dimprov]

How loud are the tankless units? I don't think I ever found reliable decibel information.

David

[SewerRatz]

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.

[Redwood]

How loud are the tankless units? I don't think I ever found reliable decibel information.

David

They are a little quieter than one of these...

http://i44.photobucket.com/albums/f2/Redwood39/saturnv.jpg

Seriously the powervent is a good comparison..

[Redwood]

Here is an interesting read that was a test involving Bradford Whit EverHot tankless units vs. tank type...
It was published in P&M
http://www.bradfordwhite.com/images/shared/pdfs/pressroom/TanklessVsTankType.pdf

[SewerRatz]

Here is an interesting read that was a test involving Bradford Whit EverHot tankless units vs. tank type...
It was published in P&M
http://www.bradfordwhite.com/images/shared/pdfs/pressroom/TanklessVsTankType.pdf

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

[SewerRatz]

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 http://www.bradfordwhite.com/images/shared/pdfs/pressroom/TanklessVsTankType.pdf

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_1.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_1.jpg)

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_2.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_2.jpg)

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_3.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_3.jpg)

http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_4.jpg (http://i7.photobucket.com/albums/y292/SewerRatz/Water%20Heater/TanklessVsTankType_Page_4.jpg)

[Scuba_Dave]

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

[gregsauls]

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]

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 http://www.bradfordwhite.com/images/shared/pdfs/pressroom/TanklessVsTankType.pdf





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!


Link to this "test" - read section called What about tank manufacturers? (http://www.profitableplumbing.com/_wsn/page5.html)


.

[SewerRatz]

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]

Hi Ladiesman271,

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

David

[gregsauls]

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.

[Scuba_Dave]

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

WHAT!! ??

So you mean with better insulation in the tank models recently the gap is even closer!! :D

[dimprov]

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]

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 (http://forums.soundandvisionmag.com/showthread.php?t=351949) 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...

[sjsmithjr]

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.

[dimprov]

I'm sure noise is a "who cares?" topic for most people. Too bad for them. Ignorance isn't always bliss. I care about getting an accurate noise measurement because I care about getting quality sleep. Yes, quality sleep. Ever wake up tired after a full nights sleep? There are many possible reasons, obviously, but one very real possible cause is environmental noise. Now, I know you tough guys will wave this off, but I'm serious. Wikipedia says threshold for noise producing sleep disturbance is 45 dB(A) or lower. You can prove it in a sleep lab. I've seen the video. It's real.

Anyway, that's why this is more than academic to me, especially in a scenario where tankless might be used for hydronic heating. I have a typical 4 bedroom house, and no matter where I put it, it could bother the sleep of someone in one of those bedrooms. Plain-vanilla tanked would be the quietest, but I'm exploring tankless alternatives for unusual reasons that I won't bore you with. I might be able to build a custom muffling enclosure, using soundproofing materials, if I used a zero-clearance closed combustion tankless. However, it's not as easy as it sounds. If you nail or screw the tankless to a framing member (in the attic say), then noise will conduct through the nails/screws, bypassing the soundproofing. You still get some benefit, but not as much as if it were fully isolated. The intake/exhaust vent pipes can also transmit/transfer noise from the tankless--not to mention the water pipes themselves. Has anyone thought this through and arrived at a solution? If necessary I'll re-invent the wheel, but I prefer not to.

David

[sjsmithjr]

You might look into something like "isotrax" for an interior wall. Off the top of my head I haven't got a clue as to how to isolate exhaust noise on an indoor unit.

Outdoor unit mounted using isolation hardware?

You might want to start your own thread to keep your topic out of the weeds.

[Redwood]

I'm sure noise is a "who cares?" topic for most people. Too bad for them. Ignorance isn't always bliss. I care about getting an accurate noise measurement because I care about getting quality sleep. Yes, quality sleep. Ever wake up tired after a full nights sleep? There are many possible reasons, obviously, but one very real possible cause is environmental noise. Now, I know you tough guys will wave this off, but I'm serious. Wikipedia says threshold for noise producing sleep disturbance is 45 dB(A) or lower. You can prove it in a sleep lab. I've seen the video. It's real.

Anyway, that's why this is more than academic to me, especially in a scenario where tankless might be used for hydronic heating. I have a typical 4 bedroom house, and no matter where I put it, it could bother the sleep of someone in one of those bedrooms. Plain-vanilla tanked would be the quietest, but I'm exploring tankless alternatives for unusual reasons that I won't bore you with. I might be able to build a custom muffling enclosure, using soundproofing materials, if I used a zero-clearance closed combustion tankless. However, it's not as easy as it sounds. If you nail or screw the tankless to a framing member (in the attic say), then noise will conduct through the nails/screws, bypassing the soundproofing. You still get some benefit, but not as much as if it were fully isolated. The intake/exhaust vent pipes can also transmit/transfer noise from the tankless--not to mention the water pipes themselves. Has anyone thought this through and arrived at a solution? If necessary I'll re-invent the wheel, but I prefer not to.

David

I have heard comments about the noise from panel mounting being transfered to the frame of the house in other threads on forums. Isolation mounting would be highly desireable for this reason.

I'm convinced that we can't get any subjective statements from either Greg or Laddy Boy on this...
One offers an estimate based on his ear comparison to a vacuum cleaner I think it was and the other was a guy that the airlines would love to have measuring the sound level of their jets taking off at an airport with noise limitations... "It was pretty quiet on the DbZ scale 10 miles away!":eek:

[dimprov]

Thanks for the feedback and suggestions. I think I'll price out a CMU or ICF exterior structure. They look fairly easy to build.

By the way, 60 Minutes did a show sometime in the last year or two on sleep deprivation. A sleep lab used intermittent sound to disrupt the deep sleep of young test subjects. In no time at all the measured health of the test subjects declined dramatically. If I remember correctly, they actually had to halt the experiment early because the health effects were more extreme than anyone had predicted. What was especially interesting is that when interviewed the poor bastards said they thought they were sleeping just fine. The truth wasn't revealed to them until after the experiment.

So just fyi: even if it's killing you, chances are you don't realize it.

Sweet dreams. :D

David

[sjsmithjr]

Best of luck to you on your project David, whatever the heck it is! :D By the way, based on your location, you might want to look into dry stacking with a bonding coat. Send me an IM if you want to discuss it further.