Dear Dr., nighttime noise is especially annoying - hope you find something that helps.

If the pros don't respond, google the question, and see if you can find any DIY forums where this is discussed.

Based on things I've seen my husband do, and issues we've had, there could be a loose screw holding the fan in place that causes the vibration.

Is the water heater insulated? Ours has a wooden box built around it, and we've never had a noise issue. I have no idea if that has any bearing on it...

If this was my problem, I would ask my husband if we could wrap the ducts like you wrap pipes to prevent them from freezing. I have no idea if you can do it, but it would be worth looking into. Also, are your ducts held up by metal brackets? If so, there could be a loose screw somewhere that is contributing to the problem.

Google: "water heater noise" as hayleydaniels suggested. Also, contact the manufacturer. As it's in a new build, the heater should still be under warranty -- they will advise on how to arrange for service. Have the serial number of the unit written down as they may require it.

Direct vent water heaters are very noisy. Very noisy. It's the nature of that beast to roar. Since yours is in a basement, you have the possibility of installing a solid door between floors. If the basement is open, consider installing an acoustic ceiling to help to absorb some of the noise. Some noises just resonate worse in some structures. The key to damping that noise is finding out what frequency is being transmitted the most, and choosing materials that dampen that frequency.

I have two power vent water heaters in my basement. I have noise which I recently discovered is being made by one vent pipe rattling against another. I need to add another pipe hanger.

It's not a finished basement, the metal hangers are secure, no loose screws. Had the water heater service guy come out - no problem with the fan. No new insights by web search. The noise seems to amplify through the floor. Thanks, all. I'll try insulation around the ductwork and see if that fixes the problem.

What type of floor upstairs? What does your basement ceiling look like? If this is an unfinished basement it is possible you have created an echo chamber and then added a noise. The noise is then amplified by poor acoust insulation in the basement ceiling/hard flooring choice above (called a floor/ceiling assembly). If you have "nail down" flooring (like hardwood) it is entirely possible the nails/screws are carrying the noise into the upstairs. This is why acoustic insulation cannot be pierced by nails/screws and is almost always "glued" in place...not nailed or stapled.

I've heard of noises doing this in unfinished basements OR basements with polished concrete floors, vaulted ceilings + hardwood floors above...noise abatement as a retro fit can be one of the hardest/most expensive/most frustrating things to deal with. Good luck.

Thanks, Cancork. Yes, my basement is unfinished and my main floor is hardwood. Do you think insulating the duct from the water heater vent will help - A temporary fix until I finish the basement?

Insulating the ducts may or may not solve the problem...it depends on what is making the noise and what is transimitting it. It is a nice place to start...but be aware that you may throw tremendous amounts of money at it and not find the solution until the ceiling is stuffed with acoustic batting, covered with acoustic drywall and you put in something on the floor.

Again, without pinpointing the exact point of "noise" then it is very hard to correct it. It is like trying to remove a tumour while blind folded. You will eventually get it...but at what cost.

An acoustic specialist could help...but that is expensive and the advice they throw at you will be expensive to execute. You mentioned your neighbor has the same layout and same water heater...how does their basement compare to yours? Is theirs IDENTICAL (unfinished without anything but the heater down there)? What are the differences to their set up? Do they have a ceiling hung? Is the water heater encased in its own room?

The differences could tell you where your money would best be spent.

is this a gas hot water heater? might be cheaper to switch out for electric than to start what could be a long hunt for a solution.

I agree with cancork. But here's another idea. The difference between your space and your neighbors may simply be is that your space is unfurnished, i.e. completely empty rooms somehow amplify sound

I see a lot of suggestions on how to stop the transmission of the noise after it exist, but you may want to start by eliminatining or reducing the source of the noise. It sounds like you have a quiet noise made louder by the resonance of the pipe itself. It is likely that you can reduce this resonance simply by changing the length of the pipe. Here is physics 101;

http://www.schoolphysics.co.uk/age16-19/Sound/text/Sound_waves_in_tubes/index.html

Here is something similar that illustrates how a seemingly minor difference between your installation and your neighbor's can make a big difference. Look to see if there is a "T" stubbed off of one or the other exhaust pipes differently for the furnace or future second water heater.

http://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/how-build-exhaust-resonator-tube-eliminate-drone-489463/

Here is something a little more technical

http://www.banksengineering.com/fact_sheet_noise.htm

In this example,
"after adjusting the combustion mix it appears the hum was caused by too lean a mix."
They change the wave lenght of the noise rather than the length of the pipe.


http://diy.stackexchange.com/questions/36885/how-do-i-prevent-harmonic-resonance-hum-in-pvc-vent-of-newly-installed-hot-water

Fred S - fascinating! And makes perfect sense. Fortunately, the basement isn't finished and everything is very accessible, so I am going to experiment a bit.

Update: I measured my exhaust vent, measured the neighbor's vent, did a harmonics analysis, and found that: r x 3.133/4 + (5 rpm + 63/425)/.67 = 72.35 inches, which is the perfect length for my heat vent's harmonics and exactly .627 inches shorter than my heat vent. So the solution will be to add .627 inches of vent! So easy!! LOL

If you read the Banks engineering one, it says that the noise could be coming from one thing and amplified by the burner.......along with the tube.
This is another link on how to fix that, but not necessarily the same type water heater. I think it was on page 15.

http://www.bradfordwhite.com/sites/default/files/product_literature/42036J.pdf

@Fred S- I'm surprised you suggested looking for a Tee in the pipe. That is an absolute no-no(which I found out the hard way when I tied the vents of both of my heaters together initially to save running a new vent. Yes, I'm lazy!) The fumes from the domestic water heater were back-drafting down the vent for the radiant heat water heater.

Fingers crossed. Some of the other "burner" fixes may also help..... along with the earlier sound muffling strategies mentioned earlier.

@River, I didn't say it was legal, or to do it. It was just an example of the little things to look for when comparing the neighbor's system.

I get that. My point is that the Good Doctor has a "new house, new construction" which should mean code compliance(hence, why should there be a Tee) unless she lives in an area where there is no code enforcement.

Exactly. I don't know the situation and can't see it, so I can only present the possibilities. For all I know, someone was thinking just like you were when you installed yours (the first time). Or maybe they ran out of elbows and thought they could get away with a capped off tee. If you have seen all the code violations I have seen that get past the inspector, you wouldn't be questioning why I bring up all the possibilities that happen to be a possible reason for the difference, and not just the code approved ones.

Even one of these screens may effect the system enough to cause or stop resonance. Since the two systems look identical, then it should be obvious that the devil is in the details.

https://pvcventscreens.com/

Here is an example that is more to the point just for you River. Even the installation instructions can get it wrong. They don't show a long sweep in the illustration. If you read the other technical stuff you might understand how this could even cause/ change the resonance.

@River, here is a conversation the Good Doctor and I had back in July on how the nation wide corporate construction companies refuse to follow codes where Doctornancy is building, and get away with it for years pending litigation by the city and gas company.

https://www.houzz.com/discussions/kitchen-ceiling-can-placement-help-please-dsvw-vd~1053606

Ah, yesss. I remember that post. What I find incredibly annoying is that the state governments require licensing for a number of things(West Virginia requires a plumber's licence to change the seats in a faucet I am told) such as HVAC, plumbing and electrical. They are willing to take our money for licensing and permits and to pay for inspectors, but somehow stuff slips through the cracks?
Why would a seasoned plumber/HVAC installer do something so mundane as read instructions?(hint: rhetorical question)

Fred and River - I've got to take a break from this for a bit - you know.... Christmas stuff. FYI: my kitchen cans turned out great. Took an INCREDIBLE amount of persuasion and redos, but my cans are over the counters and centered appropriately on the cabinets. They are perfect. I'll be back after the holiday to sleuth my water heater vent noise. I'll check out the vent configuration - mine and the neighbors and report back. Have a wonderful holiday and thank you so much for your input.

Well, Merry Christmas, Dr. Nancy!

Ok, Christmas was grand, house is cleaned up. Back to that darn heater fan noise!

So, here's the latest. The plumbing company came to look at the fan. They think the fan is okay. The plumber widened the holes in the joists (is it called a ceiling joist in the basement or a floor joist?) that the vent runs through in case it was vibrating against the joist. No change in the noise. Plumber left. So sad.....

Then my boyfriend and I sleuthed it some more today and we thought perhaps the fan noise was being magnified through the metal straps supporting the vent. The metal straps are attached to the joists. So my very sweet boyfriend added some padding around the vent between the vent and the metal bracket. This MAYBE reduced the noise a bit. Still a rumbling on the first floor when the fan kicks on.

Then we went on a field trip to the neighbor's house. They have a very similar vent layout. Their floors are hardwood, mine are engineered - would that make a difference? Their metal straps are attached to the bottom of their joists instead of the top - would that make a difference? What we did discover is that my exhaust vent vibrates more than theirs, so we are thinking that perhaps the fan is just "off balance" and causing extra vibration in the vent and subsequently an amplication of noise to the upstairs. My next plan - to ask the plumber to change out the vent. Think they'll do it??? We'll see. Anymore thoughts from all you brilliant Houzzers?

I guess it depends on your perspective. I call them floor joists no matter my view.

An unbalanced fan was my initial thought. Metal squirrel case fans i have never seen them become unbalanced, but in car heaters the squirrel cage fan is made of plastic and i seen them become unbalanced (they lost their 'prefect' perpendicaruly to the shaft. To dampen the vibration of any motor, put in a rubber gasket where it is bolted down

And also take the acorns out...(I found three in the fan cage of our minivan).

Thx for the excellent update doctornancy

Quote: "Their metal straps are attached to the bottom of their joists instead of the top - would that make a difference? "

I don't know for sure but attaching at bottom of joists instead of at top should help for wood is not that dense (as compared to quartz), i.e. wood is porous and thus should dampen the vibration(s) more before reaching the top floor. Notice also that the best heat insulators are the ones that are porous. Can this idea be applied equally to sound/vibration insulation ?

@River, LOL
Did it sound like a roulette table ?

I didn't look for acorns!

LOL

Hey doc, as a developer I build alot of new homes and if there are any issues with new homes chances are its in the mechanicals. Insist that the plumber change the fan and remove and then reinstall the vents period. I have changed out entire boiler systems because of some mysterious problem that could never be resolved. If push comes to shove call the developer then the new home warranty dealer.

Consider building a small mechanical closet around the water heater. Insulate both the floor joists above and in the walls surrounding the closet. Make sure the doors are tight maybe even add weatherstripping. The doors should be sized appropriately to service the equipment. The closet should be sized to provide proper clearances around the equipment as well.

When people buy new homes they should never have to resort to advice on how to fix a problem that without a doubt falls onto the plumber or builder. They should also never have to shell out a single dime out of their own pockets to resolve a problem that clearly a new home warranty issue. By the way doc, dont let the plumber cut anymore holes in your floor joists, there are tolerances allowed for cutting holes in wood I's (which is what your floor system is) and plumbers, electricians etc. dont know those codes. I looked at the pic you posted and if any of my trades left a mess like that they would be ripping it apart and starting over period.

@Curt D'Onofrio- Worse! It made a horrible screetch. The bad thing is I found the acorns AFTER the mechanic installed the new fan.

This is a side note, but makes for a good story, and Doc, I'm sure you'll enjoy this. We also had a glove box latch problem around that time. The plastic mechanism broke in the handle and the glove box wouldn't open. Soooo...instead of following the recommended instructions, I thought I would fix it the "easy way"(never have a cabinet maker who is not mechanically inclined work on your car). Peering through the clearance around the glove box, I could see that metal loop into which the latch was clipped; Badda Bing! ''l just hacksaw that sucker off and be in there in two shakes of a lamb's tail! I'm sure that little piece just bolts right in." UHHHHHH! WRONG AGAIN! That loop was WELDED to a rather large metal piece held in by five or seven screws, two of which I'm sure were put in before the dash board. It took me DAYS of trial and error to figure out how to get those last screws out, replace the part and refasten it. It's fixed, but I know why I pay to have my vehicles fixed.

Oh, yeah, one other thing: @TMK-That water heater needs to breathe. If the "water closet" gets too tight, there will be other problems.

River, I'll learn from your experience - ie. a doctor probably shouldn't be fixing a fan noise!

TMK, I hope I don't have to build a closet around my NEW water heater in my NEW house - egad!

Curt, I'll reposition the metal brackets attachment to the bottom of the joists (though I seriously doubt this will solve the problem).

Sprucewood, I'm getting on the phone in the morning to give some folks an opportunity to make this right. Thanks, all. I'll update as things develop.

-->"a doctor probably shouldn't be fixing a fan noise! " :)) in the same sense an mechanic shouldn't fix a broken leg.