Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Wow! B&G #72 comfort control regulator

To begin, I only see 1 hydronic to 100 forced airs in my area but in 35 years this is a new control to me. It was abandoned long ago but I did manage to get the complete outdoor unit. It regulated a mixing valve for radiant and had an odd little manifold with two 1/4 inch copper lines at the outdoor section. I have searched and searched for some info on how this control worked and have come up blank.

Does anyone have a link or info on this control?


  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,093
    Is this what you have?

    This one worked off the wind. Early '50s. 
    Retired and loving it.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Interesting system - B&G Comfort Control

    This was an early attempt at outdoor reset control without electronics. The two 1/4 inch lines were connected to the main heating loop and took a sample of the water in the system which was set up for constant circulation. The sampled water was fed to the outdoor sensing part of the control where it heated the exposed end. There was also a thermostat in the outdoor end which activated a mixing valve or the burner directly.

    There was a heat balance between the cold outside air on the outdoor control and the sample of heating water it was also exposed to. So on a really cold day, there was a lot of heat lost to the outside cold air and the internal thermostat would call for heat. The system water temp rose until it heated the outdoor part of the control to the internal thermostat setpoint,  which shutdown the mixing valve or burner.  On a warmer day, less heat was lost from the outdoor sensor and therefore it would shutdown the heat source with a cooler water temperature.

    I have never seen one of these, but there is a complete description of the system in the 1950's B&G engineering handbook.
  • Glenn_16
    Glenn_16 Member Posts: 14
    Solved. :)

    Yep that's it guys! Great call. That explains what the 1/4 copper tubes did that were tapped off a special fitting. I could not see how water was forced to circulate despite having tried to look inside unless it was like some mini mono-flow.

    The wind huh. Who would have guessed. I can't wait to tell the owner one day.


    I was just looking at the outside control here at home.
  • Gordan
    Gordan Member Posts: 891
    This seems like it would work better than today's ODR...

    ODR takes into account only temperature, not wind chill, so I'd expect that it would underestimate the heat loss in high wind situations - even for tight homes, but especially for drafty ones.
  • Karl_Northwind
    Karl_Northwind Member Posts: 139
    newer non electric ODR?

    Does anyone know of a modern answer to this sort of thing? it's exactly what I'm looking for (but not in an antique shop)

    I'd love to have a capillary operated ODR valve. 

    very cool.

This discussion has been closed.