Would Like a Quieter Furnace

[Steve Kraus]

This is a gas-fired, downflow forced-air furnace situation.

House was built in 1957. Furnace is in a centrally located hall closet with louvered bi-fold doors. My issue is noise.

The original Rheem, with the big long cast iron burners made barely a sigh when the burners came on. More noise, of course, when the blower kicked in.

In the 80's, it was replaced with a new higher efficiency model. It's a Bryant. Spark ignition w/pilot, inducer blower, that sort of thing. The burners are like 4 blow torches. That whole setup is so noisy that you barely even notice the uptick in noise when the blower comes on.

It's time for replacing it. The inducer bearings are going bad (I replaced the inducer maybe 10 years ago). I had to replace the heat switch by the pilot earlier in the year. Seems like it's constantly needing something. Anyway, I'm looking for a replacement.

Looking for recommendations for a brand or general type that would be quieter since this is located right in the middle of living space. I am not necessarily looking at super high efficiency but might pony up for it if they are inherently quieter. A salesman said a variable speed type might be quieter but I think that's only going to affect the blower noise and even with the blower off my present machine is too loud. But that's

80's technology so I don't know how loud or not loud even a regular modern furnace is.

PS: It's 90,000 BTU/H input. I realize greater efficiency would allow downsizing that but I'm concerned about going too small if I keep the same A/C since that's gonna need a certain air flow volume. Have not decided whether to do both but that's another issue entirely. I don't want weak cooling because of undersized air handling capacity of a new, smaller furnace and have them say I "told you so" regarding how I should have replaced both).

[Stormin Mormon]

I put in a York, in my own trailer. Back in 2004, maybe. Can't remember for sure. Anyhow, it's down flow, and reasonably quiet. I can hear it if I'm standing right next to it. Mine is a 90 percenter, PVC vent.

[BenDarrenBach]

We had oil-fired when I 1st moved-in this house...when it came on in the fall it woke everyone in the house! We all thought it was the end! When NG came through our area I installed a Carrier in '95. No problems since and reasonably quiet.

[trader_4]

I have a 120K Rheem upflow, 93% eff, about 3 years old. Rheem/Ruud are made by the same company. I'd say it's quiet and a lot quieter than the 27 year old Ruud it replaced. I'll have to listen to it more closely. IT has a variable speed blower, which I'd recommend for you. Big difference. It ramps up slowly, much quieter, and harder to detect when it comes on. The old one, you always knew.

I'd also recommend two stage. That way most of the time it will fire at the lower output and be even quieter.

[Bill Gill]

My York that I put in around that time isn't very quiet. That is its biggest drawback. It is right next to the bedroom and I can hear it when the inductor kicks on and then when the blower kicks in and really starts sounding off.

Bill

[micky]

What makes the noise? The main fan? Newer furnaces have multiple fan speeds that iiuc change speed when they think it's a good idea, and thus are quieter. But that might just be gossip. I don't own one.

[mike]

Suggest you get the installer to introduce you to a happy user of your selected model and guarantee yours will be as quiet.

I replaced my 40 year old furnace with a high efficiency one in 2010. The fan was so loud I couldn't watch TV when it was on. The installer told me that was the way it was, thanks for your business. Fortunately, It was part of a government low-income deal and THEY forced resolution. They took out the return pipe and put in a flexible one with some bends in it. Solved the fan noise problem. Now, all I hear is air flow. The burners are also way noisier, but they're in the garage, so I don't care.

I wouldn't trust them to tell you the truth. Go listen to one in action. Once they have your house torn apart, you're at their mercy.

[nestork]

Those louvered bifold doors would be a big part of it. They'd stop next to no noise at all.

If it wuz me I would go to your local Habitat ReStore and buy a few sheets of plywood that you can cut to the size of opening to cover the bifold doors. Glue/screw them together and sit that mass of wood in the opening in front of the bifold doors. See if that helps. You can also replace the drywall around the closet with Dow Corning's QuietZone drywall. There are other drywalls that reduce noise, often by simply being heavier than normal drywall, since it's primarily mass that's effective in minimizing noise transmission through walls, floors and ceilings.

Or, at least, I'd focus on containing the noise within the closet as best you can before you start replacing the furnace cuz of the noise.

[FrozenNorth]

That all assumes the bifold doors are not acting as the air return to the furnace.

[Stormin Mormon]

Of course it is a big help to take out one's hearing aids, at bedtime.

[TomR]

Hopefully, you don't mean to actually block the louvered openings in the bi-fold doors since his gas-fired heater apparently sits in a hall closet. It needs enough air intake for good and safe combustion.

Maybe you meant to hang that plywood mass or other barrier between the heater and the louvered doors as a sound barrier or baffle but without blocking any of the air flow through the louvered doors and to the heater.

QuietZone, or QuietRock, or whatever it is called is very expensive and way overrated in my opinion. But the sound barrier/baffle idea that you mentioned before may work.

I agree.

[mike]

There's a lot of technology available for noise cancellation. Wonder if that could be applied. I experimented with it 20 years ago in an attempt to silence the noisy fans on my computer. Wasn't very helpful, but there's been a lot of work done on the technology since.

Noise doesn't like to go around corners. Maybe put a "wall" in front of the furnace with the top foot open. Then some space and a second "wall" with the bottom open. Make the "walls" out of pink rigid foam insulation.

I can't overemphasize the great reduction in noise I got when they replaced the straight metal air return pipe with a flexible one with some bends in it.

[rbowman]

I'm so well trained I can hear the bimetallic strip in the thermostat snap over. Fortunately unless it's very cold a couple of electric space heaters can keep the temp up enough to prevent the beast from awakening in the night.

[(PeteCresswell)]

Per Steve Kraus:

Our NG furnace/AC says "Trane XV80" on the name plate.

It's predecessor was a fifties-era furnace/AC which was quite loud to my ears... and to the wife's.

The Trane has a variable-speed blower and is located about 20 feet from where I do most of my computer work. I would call it "quiet" and I'm kind of neurotic about noise... so it's probably *really* quiet.

Also, the variable-speed blower seems to take less electric. During an outage, with a little 2KW gennie supplying electric through a smart/auto-load-shedding cutover panel, there's no problem running refrigerators, freezers, TV, computers, lights.... and the furnace.

[clare]

We swirched from a 35+ yr old standard gas furnace to a mid efficiency furnace with DC variable speed blower. Our gas bill didn't change a measurable amount, but our electric bill went down. The DC motor is so much more efficient that the gas furnace had to replace the heat not made by the motor - increasing the amount of heat needed by about the same percentage as the efficiency of the burner had improved...

We do run the blower on low speed 24/7 and I think the efiicency of the low speed blower is even better than the high speed blower compared to the old one.

[Mark Lloyd]

I have an XV80 too. It is quiet. I can barely hear it on low (it's a

2-stage furnace).

BTW, this is my first furnace with no pilot light. There's an orange glow when it starts.

[snip]

That is a consideration. We sometimes have power outages during ice storms. My gennie is 2.6KW so it should work.

BTW, my furnace is connected with a cord and plug, making it easy to connect a generator.

Also, there is a blower on the exhaust. I think this is necessary because the furnace is more efficient.

[Steve Kraus]

Actually, the biggest noise is the burner running. So the advantages of a variable speed blower would barely be noticed if the burner makes so much noise.

[Steve Kraus]

Nah, the door vents are not the air intake but they are the combustion air (for the water heater as well). I suppose I can put some insulation on the inside directly opposite the burner area of the furnace to suppress the noise where it is most intense.

But I'm hoping that I can select a new furnace that's not so noisy.

[mike]

Good luck. My old furnace had a gentle flame distributed along long pipes. The new one is more like a flame-thrower with a LOT of turbulence resulting in a LOT of noise.

[Tony Hwang]

Hi, VS DC motor is good when running. When it has trouble on either the motor or control board, it is not easy to fix and cost $$$. Instead I chose X13 DC motor which is less complicated. My furnace is 96% efficient with matching AC unit, came with 10 year P&L warranty.