Not sure if you want to build a 24VDC or 120VAC but I have the 120V Asco Red Hat valves and they are awesome.
Asco Valves - (part # 8214G020 B)
Thermowell (omega.com) - 1/2-260s-u21/2-304ss
Quick Disconnect Thermocouple (omega.com) - CA316ss-14u-12
Round Face Panel Jack (omega.com) - RSJ-K-R...