Would love advice on wh gas sizing, brand, and noise

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Squeak

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Existing tank heater is 13 years old. It is not dead yet, but wanting to get my ducks in a row when it does.

Had a plumber come out and talk me through my options, including a tankless system. I am not sold yet due to some concerns -- the biggest one being the size of the gas line. Second concern would be noise from it, as the unit would be in basement below my bedroom, and third is which brand.

1) Gas Line:
We are on a 2lb system here. I have flex gas lines running through out the house. 50' run from the meter to the manifold, and then would be 5' to the water heater. All lines are 1/2".

I have a 95k BTU, 2 stage furnace, and a 65k BTU cooktop. The gas meter outside is rated at 275CFH and 5 psi.

Recommended tankless is a Rheem 199k BTU unit.

When talking with the plumber today, I asked about gas line sizing, and after talking and he asking what I think are the right questions, he said he doesn't believe it will be an issue, but needs to the do calcs back at his office.

He said that with the right regulator at the manifold, and because we are on a 2lb system, he can get about 300-350 CFH to there. That would give me just enough to run the water heater, furnace at stage 2, and the cooktop with all 5 burners going.

Reality is the furnace is usually at stage 1 (65k BTU) given how we heat the house, and cooktop only ever has one burner on (15k BTU) at time opposite when the hot water heater would be on.

Is everything appear to be accurate from what he is saying?

Running a new 3/4" line from the meter will be tough, given that most of the path would be through finished basement ceiling.

If you are only running one shower, and need a 60 degree delta, does the heather still use up all 199k BTU, or only enough to provide that water? When does it actually use all 199k?

2) Noise:

Unit would be installed directly below my first-floor master bedroom in the basement, on the same wall as my headboard. I don't need it 100% quiet to sleep, but the A/C compressor outside my window keeps me up. How loud are these units on both start-up and normal operation? White noise is fine. Pulsating, or scrolling compressors are tougher to deal with.

I am debating insulating the open truss cavities in the basement ceiling with some Roxul between the heater and my bedroom.

3) Brand:

One plumber recommended Rinnai, the other Rheem. Rheem plumber said that Rinnai use to own the market, but the others have caught up and Rheem is just as good (if not better). Is there a material difference in brands at this price point?

Thank you in advance!
 

Reach4

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1) Gas Line:
We are on a 2lb system here.
Nice. That makes putting in an on-demand water heater easier.

However you might reconsider. Any energy savings will likely be overcome by higher initial cost, more frequent failures, and routine maintenance.

For a gas water heater, I would like change the anode and flush the water heater every 5 to 10 years. However they often go 20 or 30 years without doing either of those things. OK, what I really did is to put in a powered anode which has some potential advantage for my well water, gives top protection, and does not get consumed. I would put in a new tank type water heater when your current one starts leaking in another 13 years.

Read the instruction book for your proposed tankless. True, there is no anode to change See they want you to do regular maintenance. See the warranty is easily voided by something simple such as hard water.
 

Dana

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For 2 psi gas regulateddown right at the tankless you won't have a problem with half-inch pipe.

A 2 gpm shower with a 60F rise is about 60,000 BTU/hr of output, or about 62,000 BTU/hr of input. A 1.5gpm low-flow shower would be only 45,000 BTU/hr. So with a 199K tankless you'd have enough capacity to support three simultaneous 2 gpm showers. The tankless modulates the firing rate to match the flow, to deliver the programmed output temp, no matter what the incoming water temp. So with just 1 shower it's cruising along only pulling ~61,000 BTU/hr, give or take. If you're running three showers it'll be pulling more, and if somebody then decides to fill up the washing machine it might peg full-out a 199K.

These things aren't silent, but they're nowhere near as loud as a 3 ton AC condenser. My tankless is in the basement less than 15' from my bed, but I hear the clothes washer at the other end of the house much more clearly than I can the tankless. At night with the bedroom door closed I can hear the refrigerator on the other side of the house at about the same level as the tankless.

How often are you going to be sleeping when someone else is drawing some hot water anyway?

Rinnai is the world's largest vendor of gas-burning appliances- tough to go wrong there. Noritz is another high quality vendor to consider. I have no experience with the Rheem. I'm using a non-condensing~180K Takagi as both a space heating boiler and hot water heater, it's fine.

Who needs more than a 65K furnace? (Surprisingly few, actually!) The design heat loads of the average house in US climate zones 5 & 6 is under 50,000 BTU/hr, and for newer houses it's usually under 35K (except for 5000' McMansions.) You can probably just strap the oversized beast to never bump up to high-fire and still cruise through a Polar Vortex event without giving up ground. The only reason to go higher would be to have reasonable recovery times from deep overnight setbacks, but it usually ends up providing less comfort overall. With a design heat load of 45,000 BTU/hr @ 0F, a 65K condensing furnace would have you covered down to -20F without giving up ANY ground. Almost all gas furnaces in the US are 3x or more oversized for their actual loads. If your low-fire stage is 65K, with a high-fire of 95K, I suspect you're in the ~3x oversized category too.
 

Squeak

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For 2 psi gas regulateddown right at the tankless you won't have a problem with half-inch pipe.

That is good to know! There is a fine line between trusting your plumber explicility, and a little "trust, but verify". Last thing I want to do is put this in, and then find out I have to run a new gas line and/or meter at another $1k.

BTW, Reach4 -- I appreciate your input. Savings is not my number one requirement here -- endless hot water, and not having a tank downstairs would be higher.

A 2 gpm shower with a 60F rise is about 60,000 BTU/hr of output, or about 62,000 BTU/hr of input. A 1.5gpm low-flow shower would be only 45,000 BTU/hr. So with a 199K tankless you'd have enough capacity to support three simultaneous 2 gpm showers. The tankless modulates the firing rate to match the flow, to deliver the programmed output temp, no matter what the incoming water temp. So with just 1 shower it's cruising along only pulling ~61,000 BTU/hr, give or take. If you're running three showers it'll be pulling more, and if somebody then decides to fill up the washing machine it might peg full-out a 199K.

Great information -- that is exactly what I wanted to know. We almost never have more than 1 shower going. Maybe the washing machine as well. But it looks like the majority of my time will be in the <100k BTU/hr range, which gives me a healthy margin of error most times.

These things aren't silent, but they're nowhere near as loud as a 3 ton AC condenser. My tankless is in the basement less than 15' from my bed, but I hear the clothes washer at the other end of the house much more clearly than I can the tankless. At night with the bedroom door closed I can hear the refrigerator on the other side of the house at about the same level as the tankless.

How often are you going to be sleeping when someone else is drawing some hot water anyway?

That is a great question, drives a lot of this as well. Very rare someone would be sleeping and hot water at the same time. But having just been burned on my new A/C compressor, I am gun shy about where I put things. Placement A is right under me, and gives the shortest runs for gas, electricity, and drain line, whereas Placement B is another 15' away (not under me), but complicates everything else. My hope was that between timing and insulation, Placement A would bother me <.5% of the time :D

Rinnai is the world's largest vendor of gas-burning appliances- tough to go wrong there. Noritz is another high quality vendor to consider. I have no experience with the Rheem. I'm using a non-condensing~180K Takagi as both a space heating boiler and hot water heater, it's fine.

Who needs more than a 65K furnace? (Surprisingly few, actually!) The design heat loads of the average house in US climate zones 5 & 6 is under 50,000 BTU/hr, and for newer houses it's usually under 35K (except for 5000' McMansions.) You can probably just strap the oversized beast to never bump up to high-fire and still cruise through a Polar Vortex event without giving up ground. The only reason to go higher would be to have reasonable recovery times from deep overnight setbacks, but it usually ends up providing less comfort overall. With a design heat load of 45,000 BTU/hr @ 0F, a 65K condensing furnace would have you covered down to -20F without giving up ANY ground. Almost all gas furnaces in the US are 3x or more oversized for their actual loads. If your low-fire stage is 65K, with a high-fire of 95K, I suspect you're in the ~3x oversized category too.

You got it. I do have a huge house (3500' above grade with lots of volume, another 1000' finished below). I have a very smart thermostat (Honeywell iAQ), and rarely ever see it go to stage 2 -- except for first thing in the morning if it got reaaaallly cold overnight.

Really appreciate all the insight -- helps me tremendously.
 

Squeak

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Nice. That makes putting in an on-demand water heater easier.

However you might reconsider. Any energy savings will likely be overcome by higher initial cost, more frequent failures, and routine maintenance.

For a gas water heater, I would like change the anode and flush the water heater every 5 to 10 years. However they often go 20 or 30 years without doing either of those things. OK, what I really did is to put in a powered anode which has some potential advantage for my well water, gives top protection, and does not get consumed. I would put in a new tank type water heater when your current one starts leaking in another 13 years.

Read the instruction book for your proposed tankless. True, there is no anode to change See they want you to do regular maintenance. See the warranty is easily voided by something simple such as hard water.

Less concerned about cost, the routine maintenance I think I can handle (I am handy somewhat, and watched videos to give me a sense of the chore).

But, can you tell me more about the more frequent failures?
 

Reach4

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But, can you tell me more about the more frequent failures?
I have no real data. I get the feeling looking at posts from people with problems (what is xx code, etc) combined with what I perceive to be a low penetration. My feeling could be off base.

Your use of wanting to not be able to run a tank out of hot water would seem to make tankless a good fit. I was incorrectly guessing that saving fuel was the prime motivator.
 

Dana

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Lime deposits on the water side of the heat exchanger is #1 in areas with hard water. In some places you'd have to de-scale it annually.

Flame sensor failures are common (across vendors) after 5-10 years of use, sometimes sooner, almost always repairable. Local air pollution can affect how frequently/rapidly this occurs.

The exhaust venting constraints usually limits tankless placement more than the plumbing & power. Check out the installation manuals to see if it'll really go where you think it should be.

Most 3500' code-min new construction houses with 1000' basements would still be running 40-45,000 BTU/hr @ 0F. A tightened-up older house that size might hit 55,000 BTU/hr @ 0F. The 99% outside design temp for Columbus OH is +6F, so knock 10% of those guesstimates. Things like unusually high window area can bump it to 60K, but it would have to be a LOT of window (or missing glass in one or two. :) ) A really leaky 3500' house might hit 75K @ 0F, but that would be a house worth tightening up.

There's not much of an efficiency hit with oversizing condensing hot air furnaces, but there's a comfort hit from the higher cfm and noise. ASHRAE recommends no more than 1.4x oversizing. AFUE testing presumes 1.7x oversizing. You're probably at least 2x oversized at high fire, if not 3x. But at the 65K min-fire stage you could be right in the zone (in which case a 2-stager with a 65-75K high-fire might be more comfortable.)
 

BadgerBoilerMN

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The average tank water heater lasts 10 years, regardless of maintenance. Soft water helps, sometimes. The average tankless water heater, properly installed and maintained, on soft water will likely run for 20 years.

We use Navien, Noritz, Takagi and Rinnai depending on the application and local support. It rarely pays to get less than 200,000 input. The Navien people brag about their 1/2" gas line standard installation.
 

Squeak

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Had another plumber come out today to give me a quote for a Rinnai system. He also said my gas line should not be an issue: he would pull the line for the water heater *before* the regulator at the manifold in my basement, and then put a separate regulator for just the hot water heater.

Quoted me $3800 for the RUC98i and $4100 for the RUR98i, with a tankless vent kit. The idea of the build-in recirc pump with timer control is intriguing, to help offset any "instant" hot water needs my wife has in the kitchen at dinner time.

Also, here is a link to the most recent "quality report" for our municipal water: http://www.delcowater.com/Downloads/2014WaterQualityReport.pdf.

I can't really tell from it if I am going to have similar maintenance issues due to "hard" water.
 

Dana

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See this note on water hardness in the Columbus municipal supply.

Hopefully Del-C0 does similar buffering, but they don't indicate that on their website. You might call and ask what their average water hardness levels are. Anything approaching 10 grains would be a real PITA (Some tankless warranties become void at a water hardness of 11 grains.)
 

Squeak

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Unit has been installed for 2.5 months now, and I am beginning to have buyers remorse! :(

The good things have been the unlimited hot water, and finally being able to use our huge soaker tub. But that doesn't seem to out weigh what have been very real issues:

1) The unit is located in the basement directly under our master bedroom, and the piping makes a lot of noises. For instance, my wife runs the dishwasher as we go to bed, and if I can't get to sleep right away, I get to listen to the tankless "pop" whenever the dishwasher cycles off its solenoid. I thought it was a water hammer (put an arrestor on the dishwasher) but did not fix it. I have gotten use to it where it is just a minor annoyance, but still one.

2) Anytime we draw enough hot water that causes the Rinnai unit to operate on a higher amount of burners, we get this annoying whistling sound at our gas meter. Had the gas company come out, and they replaced the meter with a new one, but didn't fix the problem. They think it is the CCST pipes in the house whistling (and from google searches, looks like this might be legit). What causes it is the washing machine, bathtub, or the right combination of a shower and the furnace running -- all causing the velocity of gas flow through the 1/2" to be too much. UGHH!

I can get it to replicate 100% of the time by having absolutely nothing on using gas, except for the tankless supporting the bathtub at 4gpm. Even if that is at the highest 199k BTU on the unit, the meter is rated for 275 CFH, and the pipes should be fine, but it happens.

Even worse is the gas line is buried in the basement drywall ceiling across 50'. Will not be cost effective to upgrade that pipe. I thought based on conversations here the 1/2" flex pipe at 2lbs would be ok, but appears maybe it is not.

I am at the point that debating chalking it up as sunk cost, seeing if I can sell this unit at 50% loss (maybe get ~$900 for it), and convince the plumber to give me a decent deal on install of a new tank heater.

Sigh.....
 
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Leon82

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An expansion tank may help with the banging. High incoming pressure may also make anything with a selonoid hammer.

Did they regulate the gas near the heater because200k but thru 1/2 csst seems like a stretch.
 

Squeak

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An expansion tank may help with the banging. High incoming pressure may also make anything with a selonoid hammer.

Did they regulate the gas near the heater because200k but thru 1/2 csst seems like a stretch.

Expansion tank already in place and I confirmed it is at 60psi (same as water pressure).

We are on a 2lb system. 1/2" csst from meter running 50-60' to manifold. First slot off that is 3/4" csst running 10' to tankless unit where there is a regulator for it. Manifold also has its own regulator for the rest of the appliances.
 

Phog

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For those curious, this is how the whistling sounds when running the bathtub.


Hi squeak, I know this is over a year later. But I just came across this thread now, and since you haven't had any responses, i thought I'd chime in. I don't have any experience with NG plumbing specifically, but I have heard pressure regulators make sounds similar to this before. Do you know if the gas company replaced the pressure regulator when they upgraded your meter? The regulator is the disc shaped thing bottom/center in your video, to the right of the meter. If only the meter itself got replaced and the pressure regulator is the source of the noise, this would explain why the problem persisted.
 

Master Plumber Mark

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remember that you got 13 years out of the tank type heater an d
you probably have done very little maintaince to this old heater.....

installing another one just the same size or larger is not brain surgery....and
it probably will last you another 10+ years without issues..... Why everyone seems to want to make this
into something more complicated has amazed me for years now

with any tankless heater you decide to buy you will probably never, ever break even on the unit and it could become an albatross around you neck if it does start to constantly give you issues...... that is your risk and gamble...

 

cecil1966

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Sounds like you got some bad advice from installer on gas line. Everything you read about these says to upgrade gas line. I've also read about 2psi mainfold at each point of use, but thats over my head, and this obviously didn't work out. I can't really hear mine in hallway closet if door is closed but maybe could at night if run the dishwasher. I hope you get yours sorted out. Its a shame you paid that much for a professional install and has all those issues. BTW, I also had installers for HVAC tell me underneath bedroom window wouldn't be noise issue, and glad I didn't listen to them. You would have been better off with good advice that half inch gas line could be risky, and just stay with tank. All the problems I read about tankless is someone tying some alternative to gas line or venting, then get really angry when warranty is voided. I think tankless can be very good option that has advantages of saving space, unlimited hot water, and last longer, but also agree that you don't want to take any risk that would void warranty.
 

Jadnashua

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There's a huge difference in capacity of a 1/2# verses 2# gas distribution system...you can get a lot of gas though a 2# system. But, it must move faster. Higher velocity can create some noise. You could not successfully run a 199K device off of a 1/2# system with a 1/2" pipe.
 

Ben_Z

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Why not opt for a tankless water heater ? There are ones with great capacity. Check this guide to pick the most suitable one for your.
 

TraisBB

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Why not opt for a tankless water heater ? There are ones with great capacity. Check this guide to pick the most suitable one for your.
Thanks for this guide.Very useful.
And is there a variety?Thanks in advance.
 
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