In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I built these for some single and two panel systems, short piping runs. The red one is a 4.4 gallon expansion tank, had a bad bladder. I perforated the failed bladder out with a long drill bit, and brazed some nipples in. This will replace a leaky tank at my house that was made from an old freon jug over 20 years ago. Pretty good service for a tank.
The yellow one is an 11 gallon, portable air tank. Harbor freight $36.95. I added the nipples and sight glass. A bit thicker walled tank, compared to the expansion tank.
Although expansion tanks are rated to 150 psi (before the modifications :) This will be a horizontal mount up in the ceiling joist.
I use water heater blankets from the box stores, two wraps around for a 2" fiberglass insulation with a white vinyl covering. Limits heat loss and quiets them down a bit.
A dash of glycol or some Rhomar inhibitor in the system helps protect ferrous metals.
Bob "hot rod" Rohr
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me