How good is the-attach graph HVAC control

[jumacao]

How good or bad is the attach temperature and hunidity control?

 

[MintJulep]

Really crappy, or pretty good.

Depends on what the time scale is - which we can't see.

Depends on what it is that you are trying to accomplish - which you haven't told us.

Depends on what is being controlled, and what the controller is - which you haven't told us.

 

[jumacao]

The graph are the results (for one room- 24 hours)of a HVAC system that control temperature and humidity

 

[GregLocock]

As MJ said, you have to define what you are trying to achieve.

Assuming it is for an office for people to work in I'd have thought the temperature swings were a bit on the high side.


Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[MintJulep]

Not so great I would say.

Is this heating or cooling?

A total swing of 4 degrees F is too much during occupied periods.

Why do the upper and lower limits change at different times?

It takes about a hour to pull-down (or up)4 degrees. How did the load in the room during the recording compare to the design load of the room?

There doesn't seem to be any humidity control at all. It looks like the humidity simply follows the DB.

 

[jumacao]

Suppose to maintain temperature and humidity inside manufacturing rooms. The graph is one room example for an actual static test. Controls have two reason protect the product and to have conditions adequate for peoples.

 

[jumacao]

The different high values are probably because return temperature (control is based on that value) are only taken at one point near the AHU unit. The AHU supplies multiple rooms. Graphs is only for one room.

 

[clientsarealwaysrite]

Does the graph meet the manufacturing requirements ... i.e. temperature between 70-80oF and humidity 50%rh.

Looking at the trend of the graph the control appears to be relatively coarse, with no fine control. It appears almost on/off control with no modulation.

Also if the AHU is controlled on a return air probe close to the ahu, using air drawn from multiple rooms, are the other room conditions affecting the supply you need in the manufacturing room.

If the condition in the room need to be tightly controlled either change AHU control to the return from that room or install a local DX heating/cooling a/c unit to acheive fine control. Be aware tho that you could end up the a/c unit fighting the supply air from the AHU.