The Situtation
A few years ago I had the opportunity to explore a GeoThermal Heat Exchanging Pump for my heating and cooling. The plumber I used was a subcontractor and I did not pick out the unit that was used for the job, but simply had the specs outlaid. Once the system was up and running, it worked great at providing heating and cooling functions and seemed to be far less costly than a propane fuel driven heating system. The system was LOUD, 90+db loud. So I scoured the internet and here is what I did to resolve my issue.The Journey
The internet is a fantastic place, and the forums, posts, and expert advice sites out there are very helpful, which is why I am writing this post. After analyzing my system it appeared that the bulk of the noise was coming from my TACO brand flow regulation valve, which was generating a great whooshing sound that accounted for most of the annoying volume of the system. It also generated a jarring swoosh sound when opening as it was taking 40-60psi and releasing it into the open loop drain. So this is where I focused my attention.After wrapping the pipes in pipe insulation and having that reduce the +db level by only a handful, I decided to re-plumb some of the work that the plumber did to provide water to my system. I didn't like the bends and curves that he chose and I wanted a more hidden and direct run to my system. I visited the local hardware and home centers and settled on the Watts Pressure Reducing valve. My hope was that the reduced pressure in the system would allow the TACO flow control valve to keep the 15gpm desired flow rate without having the side effect of controlling the pressure across that valve.
I installed a standard ball valve from the source of my water ingress, 3/4" PEX. I then installed the Watts pressure reducer with some brass PEX adapters on each side to connect to the PEX. I then transitioned to high pressure CPVC which the original plumber had used to continue to my exchanger. I re-energized the system and tried out the GeoThermal unit. Still lots of noise; insert sad face here. But alas, I had not adjusted the pressure reducer yet. So I adjusted the screw nob on the Watts unit and slowly the sound rushing past the TACO flow valve continued to get less and less. I finally got it to be fairly quiet and I used a ball valve that I had after the Taco valve to do some fine adjustments as well. I closed that post value a little bit to apply some back pressure to the TACO valve which got rid of all the noise. The Watts reducer has a small sound however I have to step up on a ladder to hear it.
The Evidence
I started out with some crude measurements using my mobile phone's Decibel meter. It started in the low 90s near the TACO valve. I also want to point out that my TACO valve was foolishly mounted to my cold air return duct, so you can image this sound traveled throughout my house as well. It was hard to have a conversation in the lower level where this unit was, even across the room, but it also caused the TV and conversations to have to be loudened when it turned on. I was able to get the sound down to the high 80s db when I slightly closed the ball valve leading to the unit and insulated the pipes, but that was only able to be done so much before I was over-limiting the 15gpm and the unit would shut off due to low flow. So what did I find after installing the pressure reducer....
After the pressure reducing valve, I now have a Decibel reading of the mid 70s, which is the sound of your dishwasher or refrigerator running. The sound is mostly the compressor running in the Geo unit which has a ton of the sound deadening technology. I want to remind folks too, that the +db scale is not linear, so a reduction from 90 to 70 is very measurable due to the logarithmic nature of measurement. When I close the door, the sound is just like a standard forced air system.
