Q: Our neighbor across the street is complaining about the loud humming sound coming from our water heater exhaust vent and is threatening to report us to the authorities.
We installed a through-the-wall gas water heater about seven years ago (not sure why the sound is bothering the neighbor now). Because of space limitations, we had to vent the exhaust horizontally out to the front of the house using 2-inch PVC ducting.
We have been unplugging the water heater every night because the neighbor said the sound was keeping him awake. Now he says the noise is also bothering him during the day.
Would extending the vent around the front of the house and up to the roof lessen the sound? The only other solution we can think of is trying to build a sound barrier around the vent. Do you think this would be feasible, and should we let a professional handle this or can this be a do-it-yourself project?
A: It’s difficult for us to believe that the noise from the blower on top of the water heater is producing enough sound to irritate, much less keep someone awake — especially if that someone lives across the street.
The water heater you describe exhausts flue gases using a blower assembly that pumps gases directly out of the building. This eliminates the need for conventional chimneys or expensive flue systems.
Your heater is different from conventional gas water heaters that discharge combustion gas by convection. The blower/motor assembly can discharge gas vertically or the unit can be rotated to allow for direct horizontal discharge of exhaust gases.
Don’t try to build a sound barrier around the vent. Obstructing the vent could result in damage to the blower or worse — the backing up of carbon monoxide into the house. We think extending the vent is feasible. And yes, gluing PVC pipe together is a DIY project — just make sure it’s done according to the manufacturer’s specifications.
But you may not have to do anything at all.
First, determine just how noisy the blower is. Most cities have noise ordinances that establish the number of decibels that constitute a nuisance. A decibel is a unit of sound and can be measured by a special meter. We’d be shocked if the noise from your water heater rises to the nuisance level.
Give the city building department a call, explain your problem, and ask the city to send a worker to come out and take a noise measurement. If you’re within the city noise guidelines you can tell the neighbor to get lost. If not, or if peace in the neighborhood is a goal, go to Plan B.
Plan B: Directing the vent pipe around the front of the building to the side, then up, will work. The 2-inch PVC pipe limits you a bit, but our guess is that it’s doable.
Check the spec sheet for your model — for one model we checked a 2-inch PVC vent pipe is limited to a total length of up to 30 feet with three 90-degree elbows.
One elbow will direct the pipe to the side of the building, the second will get the pipe around the corner, and the final elbow will direct the pipe skyward. If you go this route, give a call to the manufacturer or distributor and get the OK for the installation. Finally, get a permit and have the job inspected.