I have an old Vapor 'Watchman ' boiler (installed c. 1973) for hot water circulating heat on the Milwaukee Road's Dynamometer car. After a lot of effort and help by outside individuals it now works, with one exception, the thermostat. I can not quite figure out the wiring for this goes. When the thermostat "calls for heat" there is a certain startup and shutdown sequence.

-Does anyone have a schematic?
-If you have experience with this, would you willing to private message to discuss?

Here's a picture:
https://millcreeksystem-my.sharepoint.com/personal/warren_millcreeksystems_com/_layouts/15/guestaccess.aspx?docid=0d1f3dc7ad27f4384a1015adc325fce4b&authkey=AceYw2Xgy7mGV4GHJg0nljU&e=bedbe48e48874d81a26b25e1098a6a45

Warren
x-5000.org

The NRM in the UK has an operation and maintenance manual for the 4915-6 in Box 130 of their diesel manuals. Might contact them. www.nrm.org.uk/

Stone-Vapor Watchman
Heater Type 4915-6.
Description, Operating and
Maintenance Instructions

or you could try Vapor http://www.vaporpower.com/

Good luck.

Warren, EMD Maintenance Instruction MI-2109 should have some information on the watchman heaters and might have a wiring schematic for them. If you have a book of 1940s vintage EMD MI's at the museum, please look for that document. If you do not have it, let us know on RYPN and we can see about locating it for you.

Another possibility is EMD MI-2110 for the very small 300 LB/HR Model 4932A1 steam generator, which should have very similar circuitry to the version of the watchman with a motor driven blower.

PC

Warren, I was able to locate a schematic for the very small Vapor 4932-A1 steam generator, which uses an out-fire relay, a control relay, a stack switch, and a solenoid valve along with a temperature limit switch and a pressure switch. While this is not the exact machine you are seeking, it may have some similarities. I have e-mailed it to two friends at IRM to have it forwarded to you.

PC