Modine PD 75 making weird noise...

[ol55]

I just installed a used PD 75 75000 btu propane heater. It works fine, but when it first starts up it makes a weird "wooo" noise. It's not the fan, but some kind of harmonic noise. Gas going through the valve? An air mixture problem? The flame looks good, blue with an occasional orange tip. Any ideas, thoughts?

 

[rickairmedic]

Ol55 I am not familliar with that particular heater so I will ask are the flames cone shaped or do the run the length of the heat exchanger if they are more cone shaped then that is your noise and its normal if they run the length of the heat exchanger and go up out of long runners then I am not sure what your noise might be if the heater is solid monted try putting some rubber under the mounts and see if that helps with the noise.

Rick

 

[ol55]

Rick, it has several rows of cone shaped flame that runs along under the heat exchangers. I was trying to get a picture downloaded, but no luck.

 

[rickairmedic]

Ok ol 55 now were getting somewhere . These cone shaped flames are they around 1-2" in diameter and pointed from the back to the front of the unit . I would say if thats the case then thats your noise and its pretty much normal Those type of flames are noisy kinda like a jet hitting the afterburners . I can actually hear my furnace in my basement light off if I am listening on the first floor of the house .

Rick