Recent content by rogzog

Ziggypump, yes sir you are absolutely right. I had only seen them shortly before I retired. They fail closed on power loss.

Also check with your State or whatever Mechanical Inspector. It would be his call.

IF it has a motor it is a Fire/Smoke damper. The motor is to close the damper when a smoke detector in the system detects smoke and the damper has a fusible link on the inside that will break when the internal air temperature gets too high allowing springs to close the damper independent of the...

Consider going with the recommended CFM requirement but calculate the pad areas in relation to the CFM and keep the air velocity across the pads low enough to not create carry over of the water on the pads. If remember it should be below 500 FPM velocity but you should check that number, it has...

Belt driven is not a problem but you need to check the motors to see if they are compatible with VFD. Not all motors will last with VFD drive.

Get the data / fan curve from the manufacturer of the fan. What ever duct work, dampers etc. that is connected to the fan will determine the static pressure. The velocity of the air in the duct will be determined by the duct size and how much air you are running through it. Higher flow =...

I believe that the make up air system on the hood should match the exhaust air volume.

Perhaps you could fabricate two "Y" fittings to transition from 12" round to two 8" round or smaller, and pass through the beam with two 8" round or less dia. if needed and on the other side go back to a single 12" round.

If there are any strainers on the chilled water lines to the unit make sure they are clean. If the AHU has a bypass damper, make sure it is functioning properly. Check for dirty air filters.

In your picture I see two valves. The main valve and possibly a bypass valve. You may need to check both valves for full closing with their actuators.

It looks like something Graingers might have sold long ago. I have seen similar things and they were soldering station and pc board work station or conformal coat stations. On the top of the hood is the exhaust fan, and inside the hood at the back area you see the filters, possibly with carbon...

Aaaargh! The file didn't show up in my last post, I will try again here.http://files.engineering.com/getfile.aspx?folder=b8dec6b4-51a3-4e6a-9f6c-0e587920a084&file=25_90_00_AHU-VAV-REV4-1.docx

Here is some information on this subject, maybe it could be helpful. It is from Penn State found on a web search. It is quite detailed and covers all situations, I think. Interesting reading. ;p ROGZOG

Yes, it does. ROGZOG

I am trying to understand how the RA fan can control the building pressure instead of the relief/exhaust fan/damper. Lets use a particular condition, say the unit is in economizer mode taking in outside air. As the unit brings in OA the building pressure goes high, the building pressure sensor...