OLD STYLE COMMON HVAC UNIT SERVICING SEVERAL TOWNHOUSES

**Gene South** · 11-25-2012, 10:44 AM

Tomorrow I am inspecting and older townhouse in Dallas built in1968. The buyer tells me it has a commonheating and cooling for several townhouse units, however the unit he is buyingdoes have some sort of control over their heating and cooling. I don’t know if he means a thermostat or what.I suspect it is much like an apartment complex when I lived in Dallas in1972. The main office decided which timeof year it was necessary to switch from heating to cooling. If I remember right, when spring time came, noone could turn on their AC unit until the Apartment office turned on the mastercontrol. Since that was 45 years ago andI was just a kid, I had no clue how that system worked. Does anyone have any idea or how this HVACsystem would work and what type it is. The buyer told me there is not AC condenser sitting outside his unit. Any help understanding this is appreciated.

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**H.G. Watson, Sr.** · 11-25-2012, 10:58 AM

It appears you are describing a multi-occupancy structure, such as condos, quads, co-ops, row buildings, and not "true" single-family "townhome" structure/s. A "townhome" would have no "common" dwelling unit occupancy system(s), just common wall/s-foundation walls of fire-resistant construction without through-penetrations, separated attics/roof superstructure, possibly common roof decking & roofing, and exterior foundation drainage system(s). The potable, DWV, electrical, gas, ventillation, heating & cooling would be separate and completely independant of each other.

**Gene South** · 11-25-2012, 11:18 AM

H.G., yes, it is a condo, not townhouse. Sorry for the mixup on my description. Any idea how this HVAC system may be set up. Will they have common cool air delivery, (as in some hotels). Does that mean they are pumping HVAC treated air down long ducts up to 75 yards from the main system? How does this work?

**H.G. Watson, Sr.** · 11-25-2012, 11:25 AM

I have no clue from you as to WHAT is present!

Don't recall your having IF there are air handling units IN or devoted to the indivudual units (might be in ceiling space) mentioned duct systems, piping systems, etc.

For example, might be a hydronic system for example...hydro coil AHUs, wherein boiler - hot water is piped through coil (with condensation catch pan below) in winter, and super cooled water (large chiller unit for example) is circulated in the summer. The occupant controls the fan and the circulation to the indivudual coil via thermostat & valve to the hydrocoil with heat/cool switch...

Another example might be baseboard hydronic heat and true AC duct system which the AC isn't "turned on" until the hydronic heating system is shut down, again, thermostat controls IN the individual units required, but limited common elem.

Other example might be heat pumps - possibly dedicated for each unit, with gas backup or electric heats, another possibility might be PTAC units - all electric or gas backups.

The options and possbilities are myriad. With no information whatsoever, who knows unitl you check the listing for data, review the tax statements, or actually visit the property and collect information!

**Bruce Carr** · 11-26-2012, 08:46 AM

Gene,
typically what I've seen around here, and what you seem to be describing, appears to be a 2pipe or 4 pipe boiler/chiller setup. Your boiler will often be in a mechanical room and the chiller and air handler up on the roof, or a high steel stand outside along with the air handler. Each dwelling should have one or more thermostats and air distribution components (don't know the tech term, but similar to a window ac unit) in each large room.

Have fun getting access to the boiler room, and hope it is cleaner than most. It is not a storage room, and they should have no solvents or chemicals in there.

BWC