MMA zone valves, need distributor information

Richard Daas

I really hope you can help. I have recently been called to
service a boiler system in a church. There are 3 zone valves that are not opening, among other problems. These
are unlike any valves I have encountered before. They bear the letters MMA, are a heat motor type and carry no other
information. The plastic case is approximately 2 inches
square, two-tone gray with the top cover being opaque. The controllers attach to the brass valve body by means of a threaded nut. A plastic lever on the end may be turned
180 degrees from "AUTO" to "ON". It also has an LED indicator. I hope I have given you enough information here.
Do you know who manufactured this valve? and/or parts available. They are in a difficult to replace location and
service parts would be wonderful.

Unknown

http://www.maconcontrols.com/