In regards to IMC 403.2.2:
Say you have a building with two spaces; an office and a single bathroom. The bathroom has a single fixture and needs 50 CFM of exhaust; the office space has 5 occupants and is 416 SQ. FT. needing 50 CFM of outside air (5*5+416*0.06 = 50). Does the unit that serves...
Just a thought off the top of my head:
62.1 only requires ventilating spaces that are "occupiable spaces"; the definition of that excluding "those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for...
Thanks for following up! This has been a fun one.
"When return air humidity [...]"
What return air? I thought this was a DOAS + ACB system? If so there is no return air, only supply air from the DOAS and exhaust air.
Even assuming they meant exhaust air humidity, they way that is worded...
dbill74,
System we will tie-in to is on the first floor and goes up to the 7th floor where it is discharge via upblast centrifugal fan. 3025 CFM @ 1.25" w.c. We are literally the second to last branch on the system as the furthest away. Turn this into a fun homework problem and for now assume...
BronYrAur,
That was my gut reaction as well and I showing that the contractor is to provide a balance damper on the discharge side of the booster fan but still upstream of the common node.
Let's run with that thought and make some numbers up with it!
Let's tie-in the branch in question to the...
I am having trouble conceptualizing the following:
I have a piece of equipment that needs to be exhausted. The piece of equipment has a pressure drop through it of 0.25" w.c. at the required flow of 25 CFM.
I would like to tie-in the exhaust to the general building exhaust. Problem is, I am...
Correct. On an evaporator wet coils (in cooling) have much higher pressure drops than dry coils (in heating).
As an example: I am currently looking at the cut sheet for a basic 4 ton nominal goodman residential unitary split DC evaporator (CAPF4860). At 1600 CFM the coil has a dry pressure drop...
If design numbers are as you said (DOAS SAT 55F), then the air will not remove the entire latent load; humidity will rise.
The reason I had come to the conclusion that DOAS SAT was 50F was because the latent load (3450 BTU/hr) closely matched what 360 CFM could remove between 50F DB / 95% RH...
Assume:
Design Space Conditions: 75°F DB / 50% RH
Primary Air Conditions: 50°F DB / 95% RH
Primary Air flow: 360 cfm
Latent load: 30 students * (115 BTU/hr/student) = 3450 BTU/hr
Humidity Ratio in Space = 0.0092 lbw/lb
Humidity Ratio of Primary Air = 0.0072 lbw/lb
[Qlat (BTU/hr)] = [Airflow...
Just a quick double check: in the air system properties, on the sizing data tab, in zone sizing, you have correctly set your zone airflow sizing method and space airflow sizing method?
Secondary pumps should always discharge into secondary circuits away from common piping. Doing so ensures an increase in secondary circuit pressure over that established in the common piping by the primary pump. The common piping can be considered as the compression tank “No pressure change...
Certainly seems doable. If they are budget conscious I would expect they will be OK with HV part of HVAC. I feel like the AC part is gonna kill em. Gut reaction. What region is this building located in the world?
EDIT: Note that in my state if you are doing any new or replacement MEP work in a...
That would be the conservative way to do it. How often do you think those CPUs are computing at 100% load? There is some diversity here.
See "HVAC Equations, Data, and Rules of Thumb" by Bell and Angel.
dbill74,
Tough I cannot answer for afa13's reasoning for switching materials, I have seen many exhaust duct work systems that use aluminum or stainless steel duct work for the showers, then switch galvanized steel once they are comfortable the combined mixed air streams (usually air from a...
cry22,
Understanding your point of view, would you not agree that one could select some of the more modern RTUs that have modulating compressors/ condenser fans and humidity sensors to not only maintain (and match) sensible loads but latent loads as well? Would this marginal cost (from say a...
I agree with urgross, drazen, and composite pro.
So here is an interesting question with an answer based in experience:
If you are pressurizing a room positive (lets say a typical amount is 0.03-0.07" w.c.), how much "less" return air do you return in rooms for balancing?
I have been taught...
