Church AC

Status
Not open for further replies.
J

JaxELectric

Member
Hey everyone, hope everyone is being safe!

-Quick quesiton. Quick backgorund: Recently an estimate for 28 Ductless A/C & Heat Pump combos came across my desk for a Baptist Church in my area. This building is old. This building also has an undersized service. It is 35k sq feet total and has a 400A service.

When sizing the new service I basically used the heat FLA for these units, because in every case it is higher than the A/C, so my question is:
Do I calculate all of them at 100%? In my head I have to, given that they could ALL be cranking ALL the time, as the attached building has the schools, camps, fellowship stuff.
And separating the sanctuary isn't possible because up to 3 days a week, they could be running as well.

Any input is greatly appreciated. Thanks!!

-Shane
 
JaxELectric said:
Hey everyone, hope everyone is being safe!

-Quick quesiton. Quick backgorund: Recently an estimate for 28 Ductless A/C & Heat Pump combos came across my desk for a Baptist Church in my area. This building is old. This building also has an undersized service. It is 35k sq feet total and has a 400A service.

When sizing the new service I basically used the heat FLA for these units, because in every case it is higher than the A/C, so my question is:
Do I calculate all of them at 100%? In my head I have to, given that they could ALL be cranking ALL the time, as the attached building has the schools, camps, fellowship stuff.
And separating the sanctuary isn't possible because up to 3 days a week, they could be running as well.

Any input is greatly appreciated. Thanks!!

-Shane
Click to expand...

Southern California may have a different answer than if you live in North Dakota. Then again probably not because your load will be different. A small neighborhood church here requires every bit of its 225 amp service on cold winter Sundays.
 
probs right

probs right

ptonsparky said:
Southern California may have a different answer than if you live in North Dakota. Then again probably not because your load will be different. A small neighborhood church here requires every bit of its 225 amp service on cold winter Sundays.
Click to expand...

Yeah the more I think about it, the more I am sure I should count every VA. It isn't like an apartment building, or most other commersh spaces in my head. All of those units WILL be cranking on most days it's open.
I mostly want to not over sell a new service. Any way they slice it they need an upgrade tho.
 
JaxELectric said:
Hey everyone, hope everyone is being safe!

-Quick quesiton. Quick backgorund: Recently an estimate for 28 Ductless A/C & Heat Pump combos came across my desk for a Baptist Church in my area. This building is old. This building also has an undersized service. It is 35k sq feet total and has a 400A service.

When sizing the new service I basically used the heat FLA for these units, because in every case it is higher than the A/C, so my question is:
Do I calculate all of them at 100%? In my head I have to, given that they could ALL be cranking ALL the time, as the attached building has the schools, camps, fellowship stuff.
And separating the sanctuary isn't possible because up to 3 days a week, they could be running as well.

Any input is greatly appreciated. Thanks!!

-Shane
Click to expand...

I think you would use the MCA. I dont recall ever seeing different ratings on mini splits for heating and cooling, so not sure really what this FLA number is you speak of. The only problem with adding up all the MCA's is you end up over counting since you are getting that 25% from every unit not just the largest one, so I think you can technically break down a unit's loads into its parts and only count that extra 25% once for all the units.
 
Coppersmith said:
Wow, that's got to be expensive. Wouldn't several large standard A/C units be cheaper even if you had to add ducts?
Click to expand...
Or even a VRF system. Still have multiple indoor units but they all run off one larger compressor or bank of compressors. Such system should run more efficiently than several smaller compressor units as well, and control is easy enough to set up for central control, as well as via eithernet, and still have individual room controls.

One I been around the "system administrator" can set each room from one control point, see what is running, what isn't, current temp at each room, outdoor temp, can give each room an upper and lower setpoint limit - they can set it higher/lower to make them feel good, but it won't go beyond limits administrator has set. Administrator can also set desired temp for an event many months in advance if he wanted.

There are other systems that have many those control features, but this one ties into the basic controls pretty easily, only two wire communications network run to every component in the system.
 
"Jax" is Jacksonville, FL I'm assuming. If so, that certainly plays into the demand factor of A/C.

We've had a pretty hot summer so far and it's still far from over, so even here we have to assume worst case scenarios.
 
Yes

Yes

Most of that is valid, and I have no idea why VRF hasn't been brought in. The HVAC co installing it has a VRF system in their home Church that is probably a multitude more expensive. And as for the ducted systems, they just *don't* have room in the ceilings to add it, as they are adamant about keeping the 1800's ceilings in place. On the third floor they will be using a few mini splits with up to 4 supplies on ea ductless. The Sanctuary has 13 of them going in in that lone space, so really it is 15 in the large building, but it *is* attached. And I do have specs on them, the HVAC guy actually sent the 3 model nums so I have some semblance on what to calculate, because, yeah, they need a new service. And what's more, is the roof on this Church are spires. There isn't a flat roof capable of housing any RTU, and the area of the city is tight on all sides. As long as they give me a design that I can base my calcs on I should be able to get them some prelim numbers. I appreciate all the info and ideas, I wire 80-90 ductless a year in this area, but this one is by far the most wtf of them all yet.
This building is OLD. The good news is the insp in this area is on my advisory board and we get along swimmingly, so at least I have a shot at this one. I will keep this thread posted with progress in case someone stumbles onto WAY too many ductless in the same "building".
-If you saw the size of this place 28 wouldn't sound that ridiculous, but, when I asked to see their switchgear room, they were like "oh you mean the panel? IT is over here"
I laughed out loud. Single 400A disconnect to a single 200A panel. 34,500 sq ft.
:blink:

"Jax" is in reference to my last name which is Jackson. I am in Massachusetts. Our MEC ammendments aren't too crazy here, but like anything else interpretation is everything.
 
drcampbell said:
Could also be Jackson, Michigan or Jacksonville, New Brunswick. (Canada)

Regardless of location, if the mechanical engineers have specified HVAC equipment of an appropriate size, it can be expected to run "continuously" on the hottest summer days and coldest winter nights, and the electrical supply should be sized accordingly.
Click to expand...

Agreed. Evaluation of the existing service per 220.87 should be performed and the new connected loads added. From there you could identify the required service size and quote the upgrade or suggest the Mech Eng re-design to work within the existing service constraints. There are no diversities that I know of for commercial HVAC and must be calculated at 100% of nameplate rating, but perhaps others know of one?

ETA: Is it a single phase system? That limits the splits to 5 tons or less as larger units are nominally 3 phase. Could be a constraint. Hate to suggest mechanical designs, but how about a ducted package unit for the assembly area either concealed under floor or spiral exposed duct?
 
Last edited:
Status
Not open for further replies.
Top