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In order to know what size duct will go with a given CFM you will need to know what velocity you want to work with. For main trunk duct try to keep the velocity around 1000 to 1200 FPM. As you take...

You already have a very good idea of the problems that can be faced with a retrofit VAV system. Don't get me wrong it can be done but you will have to address all of the above. The speed drive is the...

If you use a reheat coil along with the VVT Damper the duct temp sensor will need to be relocated down stream from the coil so you can read duct temp. Then a minimum damper position of (1) is...

In a twinning configuration the return is very important. If one of the units is starved for air it will hit the high limit temp shutting it down and when the fan stops it will spin in reverse from...

System mode demand is by # of callers but can also be influenced by how far a zone is from set point. If you are having problems with this system you will need the literature to set it up properly....

Carrier is still making the VVT control system and is now in the Gen 3 version. I have found it to be a very good system if it is set up correctly. One of my accounts had 175 addresses on 35...

This system would be very hard to control in the spring and fall when it may be summer on the south side and winter on the north side. The only way to save this would sup heat. If using VAV boxes the...

I have toyed with the idea of using a Glycol system using a water coil in the duct supplying the server room and a dry cooler outdoors to reject heat. This would isolate the room from unwanted...

Fabric Duct is cheaper and faster to install and will blend well with open steel structure. Maintenance is a little bit of a problem. The fine screen used in air discharge will collect dirt and plug...

In Cincinnati Ohio. Started in 1964 in a union sheet metal shop. Got in as a 1st year apprentice in 66' took a 2 year vacation in the US Army 66' to 68' and back as a 1st year apprentice in 68'....

It can be easier. The side you are looking at is always the first number.

jmiles when I switched to the service side it was with the same company I was working for. In sheet metal I had experience in all the different phases of the trade. Started working in the fab shop of...

Stay with Mechanical Equipment Service. It will be a well rounded education and cover most all the trades. A good service man is a one call can do it all guy. I spent 22 years in union sheet metal...

cjr7806 stick to the HVAC-R trade. When you get in ask as many questions as the techs will tolerate. I spent 22 years in sheet metal union doing everything from shop, to air balance and finally...

Also on the vibrating damper.If after solving the duct pressure the damper is still vibrating it may be out of adjustment. When it goes to the close position it will try to overdrive ( drive close...

If you check the duct static at the bypass and find it low you need to recalabrate the duct pressure sensor. If you find it won't recalabrate to the value in the duct it is toast. I have changed a...

When the air exits the duct system thru a grill or diffuser it is no longer effected by the static inside the duct.At that point it is just velocity. A vane anemometer or a valometer is just reading...

If you were doing a duct traverse with a pitot tube that formula would be true. The instrument would cancel out the duct static to read the velocity pressure thru a known area to arrive at CFM.

The Alnor hood does not care what the duct static is it is only reading the velocity pressure thru the hood.

You may want to take a look at all the linkage to be sure some or all are not binding in the closed position. If the damper moves easily after the closed point a part of the system may be overdriving.

If the floor tiles are the 2X2 perfs it should be no problem.

That cylinder thing is a solenoid valve. When it is energized (24V ac ) it opens to allow water flow. Check to see if it is getting voltage.

If you think a 42X60 louver is huge why not go to a makeup air fan that is ducted into the room. It can be adjusted to match the air flow of the exhaust.

When I worked in a general sheet metal shop we would use the red and greens to cut 16ga stainless and mild steel.

Remember what a hacksaw looks like? A little slow but works fine.