Wiring multiple thermostats to one unit

[weldon]

Is it possible to wire two thermostats into one unit? Two units at our facility cool the core of the our printiing plant. The also have 10 x 10 branch ducts, 1 each, that cool walled off rooms in the center of the plant. These rooms are not occupied on a regular basis, but at times they require a staff of two for 8 - 10 hours at a time. These rooms have a small heat load in them when they are staffed and need cooling. The problem arises when the plant is operating at the desired temperature and the ac units are not on. The rooms need cooling but the external thermostat is satisfied. Without going to the expense of a zone control system is it possible to wire a thermostat in series with the existing thermostats to cool the room when needed. At the prsent time the thermostat is being turned down as needed but human error leaves the thermostat down for weeks at a time. The extra cooling is of no concern as far as the plant goes but the extra energy used adds up. If a thermostat was set in the rooms and left alone then the extra consumption should be greatly eliminated. Any ideas would be greatly appreciated.

[ralphtheplumber]

Originally posted by weldon
Is it possible to wire two thermostats into one unit?

I wouldn't recommend it.

You can install a special thermostat with remote sensors for each area and assign a priority to each one.

[maxster]

with the returns in the rooms for the common unit...why don't you relocate the exsisting stat to right under 1 of those returns that will control the 2 rooms with no add-ons.how much is the stat controlling now outside the rooms..which has priority as the unit runs.on adding stats you would need to parallel them onto the exsisting subbase or unit 24Vterminal strip.consider the relocating of the exsisting.

[who cares]

if you wire two t'stats in series then both would have to call b efore cooling would come on

[chillerout1]

tstats available that you can hook multiple sensors to so that it will average temps thru area

[markwolf]

Sounds like an ideal location for a mini split to me.we cannot see what you have to deal with listen to your local contractor.

[hvacker]

The way it's done is each t'stat controls a relay that in turn controls the equipment. This way there is no t'stat anticipator problems. Just set the anticipator value to the relay coil.

[BobbyBJr]

Exactly. I have a couple of accounts that have two tstats operating the one system wired that way. I wired the stats to control a relay that in turn controls the unit. Might be crude, but it works.

Bobby

[jayhawker]

you could use a four pole double throw relay to select a location of the thermostat that you want to use at desired time. The thermostat wires from the unit would go to the common terminals of the relay and the N.O. terminals would go to one thermostat and the N.C. terminals would go to another . The coil would be energized to select a location and denergized to select another through a selector switch.This is assuming the unit is a single stage heat and cool unit with a four wire thermostat.

[westsidemech]

One stat two sensors, easy less expensive works great.
Westside Mechanical

Honeywell Vision Pro

[dhwcan]

MARKWOLF, Has the RIGHT answer,let the big boys do the main room & the little ones do the small room. You will save money & have control.

[weldon]

Thanks for all the feed back. Wired thermostats to relay and unit seems to be working fine. I know it's not the best way to solve the problem, but when the company is looking at a 5-10% pay cut across the board to stay open, sometimes you have to make do with what you have on hand. Thanks again