I'd like to thank everyone for their inputs. One thing is for sure, the motor we have is definitely not the one that we were supposed to have purchased. The motor manufacturer's website has an online selection tool and it has the motor that was specified should be a 9-lead motor. We're...
That is exactly what I am worried about. My tech says the label only says "start" and "run" which is indicative of a wye-delta motor. Usually we see "low voltage" or "high voltage" for multi-voltage motors. The motor was specified to be 208-230 or 460 volts. The range between high and low is...
I'm an HVAC guy here. Ran into one of my pumps that had its bearing fried. Took a closer look and it's a 10hp motor with 6 leads. My service guys typically deal with 9 lead motors. There are 3 diagrams on the motor itself, a "Starting", one named "Delta running". The leads were wired...
As an engineer working for a contractor, i can tell you that installing a duct sock system is not necessarily as easy as installing spiral duct. The reason being is exactly what NCDesign points out; it isn't used much at all. Repetition and familiarity only adds speed and expertise to even...
The reason for positively pressurizing a building is to keep air from infiltrating into doorways, windows, openings and into the building. The plenum is negative with respect to the space and to the environment. The thought is that the building construction is completely tight (or tight...
The only place I have seen that wasn't a good application was VAV systems. The VAV boxes were painted to match the sock but at low loads, there isn't enough air from the VAV box to keep the sock inflated. It looks kind of bad.
If you use a Psychrometric program (PMTherm), you can see that the dewpoint of the plenum air (assuming you're maintaining 22-23C) should be slightly above the supply air dewpoint temperature for most applications.
The duct furnace is rusting because it is vented to the outside. Moist summer air is migrating into the heat exchanger from the outside. It has nothing to do with carryover. Replacing the furnace with a SS exchanger will prevent corrosion but you'll still have condensation problems. What I've...
Here's a bit more info on the problem. It appears that most of the noise is low rumbling from the supply duct. The problem is further compounded because there is no shaft (open to office areas below). Any suggestions on how to dampen the rumble?
ASHRAE Standard 90.1 (the energy standard) has a convenient table that shows when and under what conditions ductwork needs to be insulated. I do know that a cooling only duct, such as a VAV system, installed in a return air plenum does not require insulation. I have seen many installations...
Anybody ever seen any references on how to size gas pressure regulator vents? We have boilers in the bowels of a large building that have regulators that need to be vented. We have medium pressure gas and using about 2500 CFH for each of 3 boilers. Any suggestions?
You should check your local energy code as far as what insulation is required. As far as ASHRAE 90.1 is concerned, a supply ductwork in an "indirectly conditioned space" (aka return plenum with or without exposed roofs) does not need any insulation. I've never come across a sweating...
"Gas piping inside any building shall not be run in or through an air duct, clothes chute, chimney or vent, ventilating duct, dumbwaiter (like there are a lot of these days), elevator shaft or concealed plenum."
