I have to control a couple of large fan coil units with
hot water and chilled water valves in a plant where the
chilled water temp is 34 degrees. So modulating valve control is needed. The cust. wants to keep it as simple
as possible. Was looking at Tranes ddc package but its a
bit pricey. Im told the honeywell T7350C prog. stats can
handle this with 2 to 10 vdc outputs. They dont desire set
back. They just want something simple and reliable. I can
choose any control and compatable valves I want. Thanks in
advance for your thoughts
You were considering Trane DDC than went to programmable?
Do you have a budget to work with?
Any consideration in the future for expansion?
There is no economizer,just manual fresh air, future
expansion is unlikley, I have approx $3000 to work with
Tranes zn529 package would work nicley and I was also
going to look into Honeywells XL15 controllers. But if
I could accomplish this with a simple thermostat with a
2 to 10 vdc or 4 to 20ma output to the valves and fan
contacts perhaps I can cut the cost. It was the T7350M1008
stat which has (2) 4 to 20ma outputs for about $270 ea
Location is a consideration. If these come into an occupied mode and the space is warm they could blow SUPER cold for a long time, seriously upsetting anyone near them. With a programmable controller you can put in a supply air sensor and put in a low temp limit plus other things you want.
Perhaps Johnson's System 350 controls will do what you want and save you on the cost at the same time.
Incontrol, I was assuming if this thermostat had 4 to 20ma
outputs then it would have a supply air sensor and modulate
valve so air isnt super cold. They will supply a inspection
area which will be constantly occupied. Norm, Ive only used the 350 series for water loop contrl
staging boilers,towers, didnt know they had modulating
control mods. But the thought of the 15A mounted on the
wall (for s.p. adj) doest sound good
I thought since I dont need communicating and scheduling
capability...why pay for it. They want to keep it simple so
Im not sure they would go for the T7350 since its programmable with 10 buttons etc...
Was looking at some Viconics stuff that might fit the bill
Thanks for the replies
you might consider stats fron tcs basys controls they have stand alone stats with 0-10 outputs and can also be connected to there front end if desired in future. stuff works good
Thanks Bobby,The SZ1060 series controls look good for this
application. Just might be the ticket if the price is right
Have done quite a few setups like this in a local plant. They wanted to control the temperature in mixing rooms , rooms had a constant exshaust.
Used TCS/Basys SZ1143a controller , has (1) 4-20 output , duct sensor on the exshaust duct and controlled KMC VEP series 3 way valves off the ex air temperature.
Also did humidity control in 1 room for them using duct humidity sensor to control dehumidifier with a SZ1143a.
Price was within your noted $ budget with the 3 way valve included.
[Edited by Control Man on 02-13-2005 at 05:16 PM]
I thought you were a Barber Coleman guy, Can't you use a PEM or a Microzone and be under the 3,000.00 limit with a lot more room for adjustments than an off the shelf controller can give you.
After nearly 30 years I am Not MARRIED to any one control / controller I use what is needed to keep my customers happy.
MZII or PEM is higher $ plus you would require PSI and a laptop everytime they need to adjust the setpoint. better off with CP 8161 if it had to be BC.
SZ1143 you use the keypad ( access code )if they want SOFTWARE REV PRO is cheap and readily available.
Plant I put the TCS in has 4 major DDC systems + 5 INDUSTRIAL control systems , plant operators like the TCS for the application its used for.
I guess I assumed that you were or worked for an Invensys dealer, where the cost would then be compatible with the job, there are remote set points that go along with these controls but that also drives the price up.
Sounds you might be looking for something low end like floating control or something, there are several of these to choose from.
My customer wants digital control,they just wanted to avoid
an elaborate sys. that requires a pc to change a set point
or software etc... They dont have a front end, most of the
systems have pnuematic controls. I checkd out the Baysys
SZ1162 (I think) and it is just what Im looking for.
A nonprogrammable digital stat with (2) 4 to 20 m.a. outputs,fan control,and several config. points so I can set limits & setpoints of discharge air,keypadlock etc. My cost for this control is 1/5 of the trane control. I think
its going to work great Thanks alot guys