FAQ
5/1/2025-CCB
Q: How did we come up with all of the stub/header sizes for all of the stock heat reclaim coils?
A: We used this chart:
9/3/2021-CCB
Q: What size should the return blower be for a unit with economizer? (assumed from email subject matter)
A: As a reminder, we want to try and select a larger diameter return air blower when possible. I will typically try to make the return air blower the same diameter or one wheel size larger than the supply air blower as a rule of thumb. In general, we want to keep the RPM down to mitigate any sound concerns. With the direct drive, we are typically selecting in the 1,000 to 1,200 RPM range so that we can use a nominal 1200 RPM motor. We want to avoid the use of 1800 RPM motors (for sound), and we also want to avoid the 900 RPM motors due to cost and lead time.
When given the choice, a belt driven plenum usually affords more options for selection. Keep in mind, HOWEVER, that Greenheck does NOT offer a belt driven vertical plenum blower.
Please let me know if you have any questions.
Thanks,
Clay
7/19/2021-VTH
Q: Was asked about the max condenser coil height in 101" tall cabinet with 6" base.
A: You might be able to go with slightly more in certain occurrences, but these are numbers that won't fail you:
Base height = 6” : Unit height – 15” = Max condenser coil height
Base height = 8” : Unit height – 17” = Max condenser coil height
Base height =10” : Unit height – 19” = Max condenser coil height
Ex. 6” base Unit height =101”-15” = 86” of coil, 68.8 - 3/8” tubes, 114.66 - 5mm tubes
6/28/2021-VTH
Q: Was asked about opposed blade and parallel blade dampers and when to use each.
A: S-4 standard control damper uses opposed blades and we should only use parallel blade dampers when required by customer/sales department. Below talks about the difference. Generally we need to leakage to be as low as possible and the opposed blades are better for this.
https://newsstand.mcdlg-hvac.com/parallel-or-opposed-blade-orientation
The Difference Between Parallel and Opposed
While the results may look the same, these two blade orientations have trade offs that make them better suited for certain applications. When opening and closing, parallel blades minimize pressure drop through the damper’s blades. This makes parallel blades the best orientation for maintaining air flow.
In opposed orientation, the movement of the opposing blades can increase pressure drop while opening and closing. This can put undue strain on your HVAC system every time the damper operates. Parallel blade orientation is best for directing airflow in quick bursts.
While they may affect airflow, opposed blades do serve an important role in your HVAC system. The opposed blade action can modulate airflow and provide more torque to the blades while in the closed position. Tighter seals between each blade will minimize air leakage in the process. Opposed blade orientation is best for modulating airflow at different points in the duct.
6/11/2021-VTH
Q: Was asked a question about Surface Treatment dropdown in the condenser tab of the ERP being "ELECTROFIN" instead of the defualt "None" and if it did anything to the weight or performance of the condenser coils.
A: Changing the dropdown to ELECTROFIN does not change performance or weight. It actually doesn't change anything and I would recommend not changing it from the default None.
