Is there a product to quiet the loud exhaust sound (outside) from a direct vent furnace (or boiler)? There has been discussion from homeowners of the low “roar” that the high efficiency units emit. In this case,, the unit is a Rheem and the piping I believe is 2″, pitched correctly. I don’t know if the piping can be upsized to reduce flow rate. I assume someone has to manufacture an attenuator or something to disperse the exhaust in such a way as to quiet it significantly. Perhaps someone has made something from PVC caps, elbows, etc? Thanks, Steve
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Check the installation instructions--creating any kind of restriction on the exhaust can cause the pressure switch to sense too much back pressure and shut the furnace down.
Enlarging the exhaust should not adversely affect the operation, but it probably won't help cut down the noise, because the noise is not produced by high velocity air rushing thru the 2" line. You're hearing the burner and combustion blower.
If the manufacturer allows more 90's in the exhaust for the length and diameter of the exhaust, you could add a couple 90's in the line, if there's a practical way to do it. The extra 90's will help deaden the sound.
There are mufflers that are available and legal on SOME furnaces.
But I'd try as suggested and basically LENGTHEN the flue pipe -- likely the run is too short. Lengthen it (according to the mfgr's formula for # of bends, etc) to a third or a half of the legal max.
First, thanks for the replies.
Any idea on who makes a muffler? - I've searched for links online with no luck. I would certainly consider making something myself from PVC, etc.
rdesigns - you are correct, the noise doesn't appear to be from velocity, but rather from the burner itself.
Unfortunately, there are 2-3 90deg. bends and at least 15' of pipe, so I don't think adding to the system would do much good. It is also my understanding now that all condensate that forms in the lines must drain back to the furnace, so that would limit my ability to place a muffler inside the basement (inline in piping).
I will keep searching for a muffler, or try to fabricate something simple, perhaps an offset inlet tube and outlet tube inside a larger diameter pipe to make a muffler? I would of course be sure to minimize back-pressure to avoid a shutdown.
Thanks,
Steve
I may be stating the obvious, but they missed this one on my parent's place:
Make sure the final outlet is pointed down, directing sound toward the ground instead of into your face.
pointing it down may be a bad idea and maybe not allowed by the manufacturer.
>>>pointing it down may be a bad idea and maybe not allowed by the manufacturer.
Ok, good point; then it's back to the mfg. specs as others have stated. If they are silent on the issue I would definitely point it down as long as the bend is counted along with other bends.