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Old Honeywell Control

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Alan (California Radiant) Forbes
Alan (California Radiant) Forbes Member Posts: 4,699
in THE MAIN WALL
IMG_1360.jpeg

I retired this guy today when we replaced the boiler. There are two capillary sensors. One was in the boiler return and the other was an outdoor sensor. There’s a dial on the right side that was set to 125F. The wires coming in were line voltage that broke power to the boiler.
Early outdoor reset? Boiler protection?

8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab

Comments

  • mattmia2
    mattmia2 Member Posts: 16,455

    probably odr. people have posted systems with a similar control. the minneapolis-honeywell branding stopped by the mid 50's or so.

    PC7060
  • mattmia2
    mattmia2 Member Posts: 16,455

    are there instructions on the inside of the cover?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,084
    edited 3:13AM

    Yes, it is an old outdoor air reset control. The one I was familiar with looked like a Honeywell aquastat. I have seen other old ones like Johnson or Robert Shaw but I never saw a Honeywell that old.

    If I remember you set the temp for the water temp you want at 60 deg outside air (the 125).

    Some had an adjustable ratio and on some it was fixed.

    so a 1-1 ratio as the air temp dropped 1 degree the water went up 1 degree.

    The length of the capillaries limited where you could install them. the two capillaries length (which was usually different) had to exceed the distance from the boiler to the outside air.

  • 109A_5
    109A_5 Member Posts: 3,877

    Did the capillary sensors get cut off ? It would be interesting to map the way it works. Maybe it is just the average of the two sensors.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • retiredguy
    retiredguy Member Posts: 1,089

    White Rodgers made a similar control model 1050-1

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,699

    I cut the capillaries off. It was interesting to see the effort the installer took. The switch box was mounted tight up against the ceiling in a corner of the garage with about 20’ of conduit for the line voltage back to the boiler.

    The outdoor capillary tube ran about 20’ across the garage ceiling to get to the north wall and there was about 20-30’ of extra capillary coiled up.

    Maybe an old Honeywell manual or catalog will have it. @mattmia2 No instructions under the cover. And yes, the house was built in the 50’s.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    HVACNUT

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