45k Sterling Unit Annoying Drone

[bmwpowere36m3]

Long story short, got the unit installed w/ separate combustion and horizontal concentric vent. Fired it up and its noisier than I expected, but what make it really annoying is a drone. The level of the drone is dependent on where you stand within garage.

Spoke with Mestek, they thought it might be the fan and I ran some checks. Even installed another fan off first unit (shipped damaged, dropped on corner).

Running the fan "free" (not attached to heater) its fine, no annoying drone. With the fan running, as you bring it towards the rear of the unit, the droning begins. I put a dimmer on the fan to slow it down, that worked to stop the drone... however the HX will overheat.

At this point, I'm thinking its a design of the HX chamber, fan and airflow. I'm really bummed. I'd consider tossing this thing for a Reznor, but I have concerns since the designs are very similar I might have the same issue. Or if my space is playing into these acoustics.

 

[Showkey]

From the description........ Sounds like the cabinet is causing a harmonic. The drone is likely vibration of the panels, pipes or components. Try holding or pushing panels and components especially the pipes. Try using inside air vs outside air.

There’s another heater noise thread.........it’s the nature of the beast. Moving air creates noise, running two motors creates noise and vibration. Not sure the brand will change the problem. Nature of the beast because the home furnace in the basement will make noise and vibration. Some installers and manufactures for to great lengths to isolate the noise and vibration. Garage. Heaters are NOT in the premium class for noise. Maybe the Rinnai is the most quiet and most expensive and limited in BTU sizes.......also not TRUELY a garage heater, more of home supplement heater.

If it’s really that bad or annoying..........build a small room around the heater and duct the air.

Link to the other heater noise post.......where I measured my Beacon Morris ( aka Sterling 45k) witha cell phone sound meter app.

https://www.garagejournal.com/forum/showthread.php?t=466217

 

[bmwpowere36m3]

The fan assembly, running, is pretty smooth when not attached to the case. As I mentioned, when the fan assembly is brought close (not touching) or mounted there is a reverberation/droning. You'll feel vibrations in the cabinet panels, mostly upper and lower and in the middle of the panels.

Holding the panels, doesn't change the tone or volume. I could live with the volume, its the frequency or tone that's annoying. I agree, the longer the unit runs, the less perceived droning there is.

Measuring with the same iPhone app, i'm getting ~70 db 15' in front of the unit (mounted 9' with 14' ceiling). However it is location specific, in "quieter" areas its ~64 db. It shows a peak at 250 Hz, which doesn't align the fan RPM [1650/ 28 Hz] or blade passage freq [4 blades/ 110 Hz]. Even with radio going, it can be heard unless I really turn it up.

I have some dynamat from audio installs, I could put on the cabinet sides. Only concern would be loosing adhesion as the cab gets to 100* in some places.

 

[cadunkle]

I just measured my Sterling 45k at about 15' in front of it I get 58-59 dB. Standing a couple feet in front of it and holding the meter as high as I can reach just outside the air flow it's only 65 dB. I don't consider mine particularly loud, and there's nothing I would describe as a drone. It's more of a soft hum, doesn't bother me at all, can hear music fine when it kicks on, usually playing around 50-60 dB. 70 dB at 15' is ridiculous, something is not right.

The fan guard on mine came with rubber washers to mount it, I lost one and still haven't got around to replacing it. It's mounted directly to a 10' drywall ceiling, OSB walls. B vent exhaust, pulling intake from inside the garage for now. Nothing immediately around the heater that could soak up noise. It sounds like something is loose or vibrating in your unit. I would look at the sort of three finger metal piece on the right side of the unit around the heat exchanger tubes. Maybe either that or the heat exchanger is loose or touching and vibrating against each other when the fan is pushing air through it. If so you can probably bend that piece pretty easily to get it to quiet down.

 

[nadogail]

It might be that the vibration is beating the heater bike a drum. IMHO, try to muffle the drum.

 

[bmwpowere36m3]

The HX isn't loose, the three tubes are secured together with a sheetmetal bracket (right side of unit (but inwards, second loop in from front). On the right side of the unit, the three finger bracket touches the HX where it loops back. However the three finger don't quite line up with the spaces between the HX tubes.

My unit is tucked into the corner of the shop, hung from angle ceiling with unistrut/swivel fittings/all-thread.

I'll get some pics.

 

[p00p]

can you strap a thick rubber band (heavy duty rubber bungee) around the fan assembly?

 

[bmwpowere36m3]

can you strap a thick rubber band (heavy duty rubber bungee) around the fan assembly?

Around the cage? I probably could, though I don't have any flat rubber bungies.

 

[Showkey]

Suggestion: Make a video and post.

Sounds like your concentrated on the blower fan ?
Have you isolated the drone to the blower fan or ruled out the power draft exhaust fan ?

 

[Chevy-SS]

I Dynamat'd my furnace and ductwork. Plus I added TWO layers of Dynamat to the squirrel cage fan housing. It made a huge difference! Got rid of virtually all annoying drone/whine. It's been up for five years, no problems at all. I made sure to thoroughly clean and degrease any areas prior to sticking the Dynamat on there. Plus I use the little roller tool to make sure it's pressed on tightly everywhere.

 

[Showkey]

^^^^^^^^^^^^^^^^^^^^^
Brings back memories of the first generation high efficiency Lennox Pulse.........those were noisy and vibration makers so isolation sleeves on the duct was a must.

 

[Jim greengo]

^^^^^^^^^^^^^^^^^^^^^
Brings back memories of the first generation high efficiency Lennox Pulse.........those were noisy and vibration makers so isolation sleeves on the duct was a must.

What he said,the sledge hammer furnace I used to call them.
I could always tell a pulse furnace or an old york condensing unit as soon as I got out of the van.

 

[Azzkker]

^^^^^^^^^^^^^^^^^^^^^
Brings back memories of the first generation high efficiency Lennox Pulse.........those were noisy and vibration makers so isolation sleeves on the duct was a must.

My house had a functioning pulse furnace when I bought it in 2009. Just replaced it last year. It was still going strong but the main control board was going bad. That thing caused me to insulate all interior wall cavities during a full remodel to quiet it down.

 

[p00p]

Around the cage? I probably could, though I don't have any flat rubber bungies.

an old leather leather belt might work, but you'd need to insulate the buckle with a rag.

 

[bmwpowere36m3]

Here some pics of unit, below. The noise is interesting, the tone is the same, but its intensity changes how long the unit runs when I happen to listen to it.

Noise is only present when blower fan is running, with or without the power vent and combustion. I took a video around the garage, I'll upload it later.

 

[Jackfre]

Get the factory rep out there to determine what is wrong with this unit. If they cannot solve it, get them to replace the unit. Adding belts and bungees and other stuff to fix a new unit is flatly ridiculous. Why would you do that? Should have put in a Rinnai.

 

[ripperd]

I hung mine via springs (with a chain safety 1" looser in case the springs break) to limit vibration to the ceiling. I don't know how much quieter this made it since I did it to start, but mine does not drone at all like that. I have the beacon morris 45kbtu, which I believe is basically a re-badged sterling.

 

[cadunkle]

I wonder if the case or your strut rod mounting setup could be resonating. I'd imagine if you touch or hold the culprit while it's running it should quiet down.

In any event, since I'm in the garage and winter finally appeared today I took a video and pictures. I'd imagine mine sounds like all of them should.

 

[LS6 Tommy]

^^^^^^^^^^^^^^^^^^^^^
Brings back memories of the first generation high efficiency Lennox Pulse.........those were noisy and vibration makers so isolation sleeves on the duct was a must.

What he said,the sledge hammer furnace I used to call them.
I could always tell a pulse furnace or an old york condensing unit as soon as I got out of the van.

My house had a functioning pulse furnace when I bought it in 2009. Just replaced it last year. It was still going strong but the main control board was going bad. That thing caused me to insulate all interior wall cavities during a full remodel to quiet it down.

I used to love changing the spark plugs, err, "ignitors", on those things.
Azzkker, I'm surprised it hadn't rusted out yet.

Tommy