a/c design- off the wall

jim f

i just went to a job we are proposing air conditioning on a very old historic church in bridgeport, ct. i calcuated a rough heat gain on the area (75 x 85 x 31 rough demensions) and was supprised to find 18 tons to cool the building. thats acceptable but the church holds 1000 to 1300 people at sunday mass and the pastor wants it comfortable. well plugging in 1300 people my heat gain jumped to 85 tons. this can not be correct. do you think im missing something. he also wants to condition the lower basement area which i have not even calculated yet. whew.........
any comments much appriciated.
thanks
jim f.
tri-city heating and cooling

Climate Creator

Sure

Use Unico. Go see my friend Mike Stevens at Bell Simons in New Haven on Forbes Ave. He's the best!! Tell em I sent you.

Rich

clammy

church a/c

In the past i,ve done a number of churches and what we did because of limited space was to stage a few (3) 5 ton units off a 2 stage stat 2 units on the 1 st stage and the 3rd unit as a 2 nd stage all units fans cycled at the same time .We use large grills 2 x 2 4 ways in the center and returns on the outside walls in the cieling .It was rough going with a lot of old wire lath cutting a sacofold was real hassle to set up over the pews.As for unico's in a commerical appaclation i believe it's a no go i,ve seen them installed ina few small commerical app. and they did not perform to well and i am a unico fan for older homes but where large volume of areas are concerned i wouldn't put my eggs in that basket and as for decore the standard system with large enough grills to keep the noise level down and attic ventalation to cool the attic are down is amust.The churchin talkiung about was at least 85 years old good luck We also ran a aluimuim trouth ti acept all our line set sure you don't need a electric service up grade we did peace

Tony_8

load

1300 people = 32.5 tons. 300 BTUH ea. Bigger issue is ventilation of CO2. That might be where your larger figure came in if your program adjusts for it automatically. I've used a mix of variable speed air handlers and ductless splits but never done larger than 300 seats. Good luck, you might want to involve an (gasp) engineer.

Kal Row

thats people at rest

in a public forum we use 600btu ea - sorry - i have been in this business to long to blow that – but stage it, so that it its half empty you don’t was energy – the more the merrier

a couple of experience points,
don’t put all you eggs in one basket - calculate the load
and build two independent systems 65% each - independent down to the building electric supply if possible

i cant stress enough the importance and savings of an economizer, I am talking the kind that has temp and moisture sensors, and a an indoor CO2 sensor that only brings in and heats fresh air in the winter, only if it really IS stuffy as indicated by the CO2 sensor

I would go for multiple packaged air/gas heat units with economizer – York now makes the kind of units I am talking about, with high eff scroll compressors and all

Put in the packaged heat with the units even if you already have a heating system, first it’s an alternate, second nothing will warm a cold building faster than scorched air –

And do put in radiant heat If at all possible, you can even do it overhead, since in church peoples bodies are exposed to the ceiling even when sitting down (only hot air rises, radiant heat, ie, infra-red light, can radiate down just as well)

Kal Row

right = i almost forgot

not just noise - but wind chill
ducts’n’registers - ducts’n’registers - ducts’n’registers - you just cant have enough of them to keep it cool enough for the young people and not have the old people complain about the draft - you need to keep the air speeds down - that means - the whole decor is a plenum - that’s why coved ceiling used to be all the rage - it was the only way to get the cool blanket without the wind effect - it was also great for bounce lighting - metal halide lights are great, but no one want them in their eyes – today, there are all sorts of spreading registers and bounce lighting, so coves are no longer a must

John_19

clarifications about assumptions

A space 75' x 85' is about 6,400 sq. ft. If they have 1000 people in that space, that's only 6.4 sq ft per person, which is *tight* -- that's enough for people sitting in place, but doesn't allow for the altar, corridors, etc. I suspect either the measurements are off or, more likely, the church sees a TOTAL of 1000-1300 parishoners each Sunday, but over 2 or 3 services. So the max. attendance at any one time is 300-500 people.

Tony_8

look around

next time you're in church. They ain't dancin' Lots of them is sleepin':) Makeup air is usually more here than people and building load. The farther south you go, the more different it gets.