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Replacement Room Air Handlers for 1960's Two-Pipe Hydronic Heat/Cool?

I live in a 1960's 15 story building. Apartments heated & cooled with American Standard 'Remotaire' air handlers in each room. Same pipe send hot water in winter, cold water in summer. No thermostats, just a combined on/off-fan speed switch. I'm one of the few residents who have even a vague idea how the system works. Residents have been complaining the units are 'old', 'smell', 'need updating' etc., ad nauseum. As far as I can tell they probably just need a good cleaning (which I do for my units at switchover).

First off, are replacements for these units even made any more? I've looked for a maintenance manual but can't find that. All I seem to find are high tech 4-pipe units with remote controls (!). I'd like to find and price replacement units. But would the ROI (return on investment) be worth it? Am I being naive by assuming since the properties of water haven't changed, there's little to be gained unless the coil itself is no good? Are coils from the 60's so inefficient that it'd be worth it to put in a new one? I suspect not but would need to document it.

I guess what I'm looking for is the hydronic heat/cool equivalent chapter to one on radiators in The Lost Art of Steam Heat, lol.

This site and its members were instrumental in pointing me in the right direction years ago when I 1900's one pipe steam systems to deal with. I know these systems are a bit more obscure, but I hope someone here can point me in the right direction so I can do my own research, the findings of which I'd happily share!

Thanks in advance.


  • retiredguy
    retiredguy Member Posts: 613
    From what I can imagine is that the heating and cooling units you have are what we called "univents" or "fan coils"that are supplied with hot water in the winter and chilled water in the summer from a central plant. If that is the case, the builders of that building were looking for the least expensive installed system since most of these units are either 3 pipe systems or 4 pipe systems. The changeover from heating to cooling is done manually in the equipment room. I am surprised that there is now or never was any type of temperature control for the occupiers of the apartment. That is usually not the case. If that were my place I would install or have the building manager install a thermostat to at least cycle turn the fan on or off to yield some temperature control. Does the fan blow a sufficient amount of air? If not maybe the blades are dirty. Also the filters that should be installed in these units need to kept clean as do the coils that supply the heat and cooling. You can buy replacement univents or fan coils but that may not affect the air temperature from the units. There could be problems with the boilers and/or chillers that provide the heating or cooling. Hope this helps.
    EBEBRATT-Ed Member Posts: 12,131

    I don't know what type of fan coil /air handler you have. But you could look up "Magic Aire" units. They make all types of fan coils and air handlers.

    As far as efficiency a new unit would not be any more efficient. This is assuming the old unit is in like new condition. Dirty coils, dirty fan blades, bent coil fins etc, irt & dust degrade the equipment. You could probably get a unit with a unit mounted thermostat
  • ChicagoCooperator
    ChicagoCooperator Member Posts: 323
    I know that some buildings clean the units at changeover (you are doing the right thing) - the swampy smell might mean the drains (for condensate in summer in particular) are clogged or the pan needs to be cleaned. I lived with something similar in college - I think there was a dial for a "thermostat" and another for off - on/fan speed.
  • bburd
    bburd Member Posts: 338
    edited February 2021
    New fan coils are still available. Although the existing ones are well past their normal service life, there is no reason to replace them unless there is coil / valve leakage or other damage / wear that is not practical to repair. New ones are no more efficient than what is there, except for slightly lower electricity consumption at the fan motors.

    They probably just need a good cleaning of the coils, pans, drains and fan blades, lubrication if the motors have oil cups, and perhaps stripping and repainting of the enclosures. Filters must be kept clean.

    It would not be difficult to retrofit a thermostat to switch the fan, either built in or wall-mounted. A wall-mounted one will control the room temperature much better.

    That said however, nothing lasts forever.  Mechanical piping systems installed when your building was built usually had a design service life of about 50 years. They can last much longer; but before planning to replace those fan coils, it would be wise to have the condition of the dual temperature (heating/cooling)  pipes checked. Replacing them would be a very costly project.

  • mattmia2
    mattmia2 Member Posts: 5,713
    I have seen lots with a hole where someone ripped the thermostat knob off of it.