High-efficiency furnaces and water heaters that are becoming a popular option for green-minded homeowners can have a noisy downside.

"They do cause more noise. Your neighbours will hear it. It's quite annoying if it's next to a bedroom window," said Ron Reichart, who installs furnaces in Calgary.

New homes are built closer together than they were in older neighbourhoods, adding to the problem, he said.

Bill Bruce, Calgary's director of bylaw services, said complaints about high-efficiency systems are up, but homeowners can reduce the noise by venting them through their chimneys or adding a muffler.

"One of new phenomenon is, of course, the influx of high-efficiency equipment, whether it be hot water heaters or furnaces. Many of them don't vent up the chimney and up to the sky. Many of them just vent out of a pipe at the side of the house and there is a noise that accompanies that. It's like a low hum or a rumble."

Calgary allows higher levels of noise

Calgary resident Wayne Wegner said vents from a high-efficiency hot water heater and two high-efficiency furnaces that stick out of his neighbour's house are noisy and should never have been put so close to his home.

"It's like pointing a ghetto blaster at someone's house. The sound goes directly at our house and then reverberates between the two bloody things because there is no room between them," he said.

"I don't blame the neighbours. I blame the city of Calgary for allowing this to go on. They should have had a zoning law in place years ago."

Wegner says he has complained to the city, but the noise bylaws on the books make taking action difficult.

Calgary's bylaw allows a higher amount of noise than most other major Canadian cities — 65 decibels during the day and 50 during the evening.

In Victoria and Vancouver, the limit is 55 during the day and 45 at night, while in Toronto the limit is 50 during the day and 45 at night, and in Winnipeg it's 55 during the day and 50 at night.

But Bruce said there is nothing wrong with the city's noise bylaw.

"The bylaw we have was actually produced in consultation with very highly qualified acoustic engineers and you are dealing with a certain ambient noise level anyways."