carver p4 furnace for isolde - part 4

This is a continuation to a previous post carver p4 furnace for isolde- part 3, and inside propex hs1800 - first look. I dug out a few video clips that I took a month ago of the two furnaces in operation using a Radio Shack sound level meter. The setup is nothing vigorous as would be done in an accurate sound level test (there are a number of specs as to how a vigorous tests should be done which is beyond anyone without access to very expensive test equipment and laboratory). It is a lot better than making a video and recording the sound with a microphone alone.

In the video the Propex HS1800 is installed in my small shop inside a cabinet. The comfort air output is via a circular vent located on the toe kick of the cabinet. Follows the segment of the inside sound level is a segment which I measure the burner exhaust outside.

The Carver P4 is installed in Isolde under the bench seat. The comfort air output is via a circular vent of similar to the one for the Propex. Follows the segment of the inside sound level is a segment which I measure the burner exhaust outside. In the Carver segments, there are at time as if there is no sound at all. It is because the Carver is that quiet, and the Radio Shack meter cannot resolve it. The meter measures down to 50dB. In the video the meter is set to 60dB scale. In the middle of the analog meter face plate is 0. The graduation on the left of 0 is minus while on the right of 0 is plus. At full clockwise deflection of the needle the scale is +6dB. At no deflection of the needle (left most position) is -10dB. It is worth pointing out with no needle deflection is observed at all, one can only infer the meter  has ran out of sensitivity.

I set the meter at about 45-degree from the air ports, and about 3 feet away, though I didn't try to be that accurate since the difference of noise level of the two furnace is day and night.

I set the meter to measure in A-weighted, fast sampling, and at the most sensitive scale of 60dB. Human auditory perception to sound is a very complex science. It is always problematic to describe in relative or absolute layman's terms - like it is twice or three times as loud etc. It is a bit easier to say every 3dB of difference corresponds to 2x difference in energy.

00:00 - 00:27 Propex comfort air sound level
00:27 - 00:38 Propex exhaust sound level

00:38 - 01:11 Carver comfort air sound level
01:12 - 01:33 Carver exhaust sound level



The sound level of the Propex comfort air noise measured between 63dB and 64dB. The sound level of the Propex combustion exhaust noise measured 56dB (60 minus 4).

The sound level of the Carver comfort air noise taxed the meter as can be attested by the almost complete silence recorded by the iPhone. The meter simply do not have the sensitivity. The sound level of the Carver combustion exhaust noise measured also taxed the meter but you can see the small deflection of the needle at about 59dB (60 minus 9).