Stopping/blocking low-frequency rumble from pool heater

[Hawthorne]

So I bought a Hayward 250000BTU gas pool heater for my pool, and installed it outside, as per recommendations from pool company and installer. Problem is it produces a low frequency rumble due to the fan-blown air being ignited . The previous pool heater was way quieter as it used "atmospheric draft" to draw air - apparently the fans are used on pool heaters to increase efficiency.

Neighbors are NOT HAPPY - they keep telling me they hear the low rumble in bedroom, office and all around their backyard. I paid $1200 to move it 15 feet further from the 6 ft wooden fence between our properties. Not happy.
I put up another wood "fence" panel, 7ft high by 54 inches (using 1 by 6 inch boards on 2 by 4 s), 14 inches from the heater and between the heater and their property to screen/deflect the sound. Not happy.
I added another fence panel 90 degrees to the previous one to create a "V" shaped wall to try and deflect more sound, and I put in place two large bins worth of earth to build up the ground to try and add mass near the base of the heater's concrete pad. Still Not happy.

Help wanted! Advice wanted! Would adding another layer of plywood to each fence panel help? Foam bass traps?? Bushes? Or is there really no hope due to the low frequency?

Thanks

Hawthorne

 

[Tom.G]

A few possibilities come to mind:

1) Turn off the fan, or reduce the air volume it moves
. . .(replace the blades for less pitch or diameter. install vaariable speed drive for motor)

2) As @dwarde said, reduce the gas pressure by adjusting the pressure regulator, or installing one if absent

3) It could be an resonance of the air flow path induced by turbulent air flow

Cheers,
Tom

p.s. Please keep us updated re success or failure. We like to learn too!

 

[dwarde]

A few possibilities come to mind:

1) Turn off the fan, or reduce the air volume it moves
. . .(replace the blades for less pitch or diameter. install vaariable speed drive for motor)

2) As @dwarde said, reduce the gas pressure by adjusting the pressure regulator, or installing one if absent

3) It could be an resonance of the air flow path induced by turbulent air flow

Cheers,
Tom

p.s. Please keep us updated re success or failure. We like to learn too!

You can't adjust or change the combustion air volume on a gas fired device, because it could cause incomplete combustion. Amazon and others have foam acoustic panels that can reduce sound levels. Build a fence directly around the heater, if possible, and line it with acoustic panels.

 

[Lnewqban]

So I bought a Hayward 250000BTU gas pool heater for my pool, and installed it outside, as per recommendations from pool company and installer. Problem is it produces a low frequency rumble due to the fan-blown air being ignited . The previous pool heater was way quieter as it used "atmospheric draft" to draw air - apparently the fans are used on pool heaters to increase efficiency.

Welcome, Hawthorne!

There should not be any reason for your fan to generate so much noise.

The design is not the best because the weight of the fan is hanging from a sheet metal casing that is poorly supported from a sheet metal body.

If the impeller of the fan is not properly balanced, the vibration will be amplified by the sheet metal surfaces, like a box of an acoustic guitar does.

I would close the gas shut-off valve, open the heater, and observe the fan while working.
Try supporting the motor a little better with something solid but non-combustible.

If you have some, place weights over, or attach some angle, to any vibrating panel that you see.

The above should at least change the frequency and intensity of the noise.

 

[Ranger Mike]

Identify the problem. Your problem as described is noise. Rumble noise indicated vibration of operation but highly doubtful. So we are left with SOUND energy problem.


It took a lot of years and experience to engineer this product. Doubtful the product is defective. This leaves installation as the culprit . Additionally, I assume you are in an out door environment.


Check the air filter on the pump. Mice, leaves, doubtful if it is new. Probably are OK but we have to eliminate potential causes.


The noise level of a swimming pool heat pump is between 45 and 65 dB, depending on the quality of the machine and its power.


If you find the decibel level is too high, send it back or fabricate an exhaust muffler silencing system. You have a noise problem that can not be eliminated. It is there by design.


Right now the exhaust noise is coming straight out of the pump with no direction. I suspect the sound energy is ricocheting against the walls. You can direct the exhaust noise in manner to accommodate the neighbors. If you have the room, fabricate a sheet metal exhaust vent coming from the pump straight out and exiting at 45 degrees and going up then add another 45 degree turn strait up. If possible add another 45 degree point downward so this will care of rain water entering this exhaust system. You can not eliminate sound energy, but you can redirect it to a non offensive direction. Finally, you can build a wood "chimney" to surround the exhaust with sound deadening material to muffle the excess and not impact efficiency of the heat pump if needed. Now you know why some NASCAR sanctioned tracks require their race car have the exhausts to all point to the infield and not the spectator stands.





https://www.troublefreepool.com/threads/hayward-heater-rumbles-vibrates-like-a-harley.181211/



https://www.troublefreepool.com/threads/violent-loud-vibrations-coming-from-heater.174329/

 

[Tom.G]

Or a direct solution could be:
Put a 24 hour timer on the heater so it runs only during "Neighbor Non-Sleep Times."

Such as:
https://www.amazon.com/Intermatic-T101R-Switch-Timer-Mech/dp/B000BVZB3E?tag=pfamazon01-20

Cheers,
Tom