Recent content by psugreen

Looking for sizing parameters for the higher pressure ductwork upstream of vav between the vav and the air handling unit. Do you look at friction rate and velocity? Or just one of these?

.08-.1" wc / 100 ft on the low pressure side downstream of the vav box correct? What paramaters do you use upstream of the vav box?

When designing duct upstream of vav boxes do you size for both upper limits of velocity and friction per 100' of duct? What limits do you use I.E. Velocity limit of 2500 fpm and friction of .3" per 100'. Or do some size based on just velocity or just friction? (If you sized purely based on...

When sizing a steam line to an AHU coil, should the branch lines going to the ahu coil be the same size as the coil connection size or is it ok to use a smaller size? When using the size charts it looks like a smaller size would be acceptable but I think I remember reading somewhere that...

Application is a typical office building. There must be a range that is used for static or velocity?

What static and velocity do you use when designing vav ductwork upstream of the vav boxes?

2 questions in relation to pump selection: 1. For inline pumps should suction and discharge connections be line size, or is it ok for the pump to have a smaller connection than the pipes it connects too? 2. What is the best speed (rpm) to select pumps at?

In parallel. They would share the same discharge duct only.

This is general exhaust controlled by t-stats (large storage / mechanical / electrical rooms that call for exhaust/makeup to keep temp 10 degrees below ambient). I would put backdraft dampers at the discharge of each fan. They would not necessarily be running in unison. Some could be off...

What are your thoughts on using one discharge duct for several inline exhaust fans? Is this an acceptable practice? Anybody run into problems doing this?

Does anybody have a software program or spreadsheet that they use for calculating pressure loss (ft of head) for hydronic systems to assist in pump selection.

Thanks all for your help. The link for the @air program that UtilityLouie referred to is http://www.techwareeng.com/prodAA.htm. They have a 30 day trial version that I'm going to try out. Imok2, the equation I'm looking for is enthalpy when you have known dry bulb and wet bulb temps which is...

Is there an equation that could be plugged into an excel spreadsheet to calculate enthalpy at a known dry bulb and wet bulb temperature? Or is there a equation for total energy with known entering and leaving dry bulb/wet bulb air temperatures?

I'm working on the hvac design for a new doctor's office. Does anybody know where to find minimum ventilation rates for exam rooms, treatment rooms, x-ray rooms, labs, etc? I don't think ASHRAE 62.1 covers this area.