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Entries in Thermostats (2)

Saturday
Jun222013

HVAC 360 - Episode 068 - Thermostat Operation and Thermal Comfort

Welcome to this week's episdoe of HVAC 360 where we talk about Thermostat Operation and Thermal Comfort, along the lines of ASHRAE Standard 55.  While I have to admit most of you understand proper thermostat operation, you may come up short when describing it to a laymen.  This is where my visual analogy of the operation comes into play.  Hopefully this is something that you can use, but if not I talk a little about Thermal Comfort.  Although I didn't have my ASHRAE Standard 55 handy, I did have my Fundamentals.  Please consider sharing this episode or others that you have found enlightening with your friends and co-workers.

Here are some links that you might find of interest:

ASHRAE Standard 55

The thermal comfort chart

This episode is brought to you with support from our sponsor:

Or if you would like to save this directly to your computer you can Download the Episode Here! Just right-click on the link and save to your desktop.

Sunday
Jan312010

Turn down the heat! I'm melting!

One of the perennial struggles as a commissioning agent is to understand what the owner wants the range on the thermostats to be set at.  One rarely sees it in the specifications of the design engineer and it typically falls to the controls contractor to set up the range. This is where an Owner's Project Requirements (OPR) document should clarify this question, but is all to often omitted.

So what happens in the real world?  Well I have seen +/-10 deg F, so should you elect to hang meat or start a steam shower you have been given the power.  However, I more commonly see that the temperatures are set at +/- 2 to 3 deg F.  This narrow range can still be problematic, as it was for one of my clients.  You see shortly after opening their new building they started getting temperature complaints.  As the building has three identical wings the maintenance staff decided to play around with the systems controls. They took the temperature adjustment control away from one of the wings and a strange thing happened, the complaints stopped from that wing, but still remained in the other wings.  They then removed control from another wing and again the complaints stopped. Now, the entire building has fixed setpoints and everyone seems happy.  If you are confused about why they were happier with less control, let me explain.  First off, the staff doesn't know that they no longer have control, shhhh!  Second, what seemed to be happening is that the staff would be cold in the morning, and turn the thermostat up.  Then, during the day they would get hot and turn the temperature down.  Now at the end of the day would they turn the thermostat back to the normal setpoint? Nope.  They would forget and the temperature the next morning would be cold again, so the cycle continued.

In the end I think that the best bet is to just set it and forget it.  Most higher educational facilities implement this as a policy already and I think one of the best by-products of doing this is truly knowing where your problems lie in your facility and you don't end up covering them up through system manipulation.