There may be some savings in the direct drive since you no longer have losses via the belts. The belt drive assembly must have enough force to spin the motor sheave, belts, and fan sheave, along with attaining the desired speed of the fan or blower wheel to deliver the desired CFM. There is no...
Another caveat is local wet bulb data and the approach temp of your towers. If you lock in 70 degrees entering condenser water temp (ECWT) 24/7, on certain days of the year, the towers may not provide 70 degrees when outdoor wet bulb temps exceed 70 degrees. So your fans run flat out and...
Also, have you thought about not completely unplugging from the chilled water supply of the building's central plant? In other words, if your little 3 ton resi condenser craps out, would you have the ability to switch over to building chilled water to tide you over until the three tonner is...
Two challenges with running a resi/light commercial condenser in low ambient conditions: oil return and head pressure control. Fan cycling wears the condenser fan motors out more quickly. There are single phase controls that can turn the condenser fan into a variable speed, responding to...
How do you plan to circulate the water in the loop with no air handler coils in place? Is there a bypass? If so, is the bypass near the chiller or out in the loop, away from the plant?
Has this chiller also sat a long time? How are its tubes in the condenser and cooler? Sitting a long time can...
>>>>Shophound, I'm not sure I'm reading your critique correctly, but are you suggesting that ducts in general are problematic? >>>>
No. It is where people often choose to place ducts that create problems.
* Ducts in attics = HVAC capacity loss and possible building pressure concerns due to...
Check sheave wear while you're at it. Sheave grooves should be v-shaped, not dished.
Also consider going with cogged belts unless you are already using them.
HVAC Buddy for service techs is good. Allows the user to plug in parameters to obtain target superheat/subcool and target temperature deltas across a cooling coil.
PsychromeTree, available for Apple iOS devices, is also very useful. It's a psychrometric calculator/converter.
Using wall stud cavities for air transfer is most often a BIG mistake. Unless you can guarantee the entire run of that cavity is airtight to anything outside of the conditioned air moving through it, you will encounter building pressurization/depressurization concerns, which often translate to...
I lived in San Diego for eight years, so I'm familiar with So. Cal winters. Not harsh, to speak directly to the point. Less than 20% of the year for heating degree days. Lots of shoulder weather. Pick your climate based on how far you live from the ocean. Further inland, the hotter it becomes...
I also don't quite get the objection toward one air distribution system for both heating and cooling modes. Truth is, do the building envelope right and the need to push air around at high volumes decreases. Comfort levels increase. Comfort is more than just correct temperature of the air. It's...
What temperature do you want to keep the abandoned areas at?
Say you pick 40 degrees to give you a buffer against freezing any pipes running through the abandoned section. From there you can figure how many CFM are required at your winter outdoor design day conditions to hold that space at 40...
KiwiMace also has a good point; some towers with reduced water flow may experience "vortexing" in the sumps (given that pumping capacity is the same but has merely been distributed between more than one tower cell), which is that mini-tornado of water you'd see as a kid when you let the water...
My chillers are Carrier 19XR. The surge prevention algorithm looks at four points: difference between entering and leaving chilled water temp (delta T) along with pressure difference between cooler and condenser at low load (delta P), and the same parameters at max load. When these two plot...
I run my towers the same way, resetting condenser water supply temp via wet bulb approach, ~ seven degrees for our Evapco towers. That said, I have limits on the protocol in place so there is a maximum and minimum setpoint. I've also found I needed to work a buffer into the program to slow...
It depends on how the towers are controlled. If they are controlled by condenser supply water temperature, the protocol may be to stage on/ramp up or stage off/ramp down towers as required to maintain the condenser water supply temperature setpoint.
The setpoint itself could be reset by outdoor...
>>>>>You should likely review ASHRAE 62 and determine if transfering the air reduces the classification of the space. If it is a concern, another option may be to provide a return fan ducted from the south offices to the north plenum, avoiding tranfer through the open office.
If you had a...
