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View Full Version : Large retail - tstat or RAT sensor?


Grawburg
10-14-2010, 11:15 AM
Large retail - 20 ton unit - 2 stage Trane DX split. Currently using RAT sensors to control space temp. Another "HVAC guy" says we should change it to a programmable tstat in the space because it's a truer measure of the temp and the unit will react quicker. I say because its a big open space with racks of groceries, we get a truer sense of the overall comfort by measuring RAT.

Who is right?
just_opinion
10-14-2010, 11:45 AM
Large retail - 20 ton unit - 2 stage Trane DX split. Currently using RAT sensors to control space temp. Another "HVAC guy" says we should change it to a programmable tstat in the space because it's a truer measure of the temp and the unit will react quicker. I say because its a big open space with racks of groceries, we get a truer sense of the overall comfort by measuring RAT.

Who is right?

Why not having a programmable stat AND use its internal sensor and a remote sensor for RAT - Then average them out.

Thus, both of you will be right. ;)
basshound71
10-14-2010, 09:07 PM
Put in a programable tstat with multiple remote sensors on each tstat. It will average the temps but it's still not going to prevent hot or cold areas. Leave the blowers running 24/7 to help keep temps more even also.
jpsmith1cm
10-14-2010, 09:11 PM
Put in a programable tstat with multiple remote sensors on each tstat. It will average the temps but it's still not going to prevent hot or cold areas. Leave the blowers running 24/7 to help keep temps more even also.

Beat me to the punch.

A RAT sensor is only good if the blower is running constantly.

Start cycling the blower and a RA stat is not longer a good read on space temp.
Control Man
10-15-2010, 08:28 AM
Did lots of stores and sports facilities with the OLD Network 8000 and MZIIs , they were nice for this application , had a UTILITY block that changed the input from SPACE to RA.

When occupied and FAN on constantly used the RA when not occuppied controlled off SPACE.
Grawburg
10-15-2010, 09:37 AM
I think I'll go with prog stat. For something as simple as retail, I don't want to complicate things. After we leave I can see the manager fiddling with stuff and messing it up. Thanks all!
jackintheboxtec
10-15-2010, 02:29 PM
Wait until you mount that stat and see all the kid's that fiddle with it and mess it up!! Mgr. you can instruct him how to use it.