I'm about to move my exterior wall-mounted tankless gas water heater. It is currently lag-screwed into the wall studs, and I get a fair amount of nuisance fan noise inside, so I'd like to use some vibration isolation mounts when I remount it.
Now the unit weights 48 pounds, is 10" deep, and it is supported via two rear brackets 24" apart vertically, each bracket with two bolts. So I get a load on each of the top bolts of 12 lbs in shear and 5 lbs in tension, and a load on the each of bottom bolts of 12 lbs in shear and 5 lbs in compression. [This assume the center of gravity is in the middle of the unit, which may or may not be true.]
Based on this, I chose some bonded tube mounts, Barry Control 22001. <http://www.barrycontrols.com/defenseandindustrial/productselectionguide/data/22000Series.aspx They are designed to attach to a 3/8" plate through a 3/4" hole. Since the loads are so low, I'm wondering if I could use 3/8" thick redwood? Or if not, 3/8" plywood?
Also, with the unit on flexible mounts, I'll need to use flexible supply connections for gas, water and electricity, right?