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Discussion Starter · #1 ·
My heat loss calculations indicated that my theater room may not need much heat if any - in fact I think I will need some cooling/ventillation with more than two people.


The attached floorplan shows the proposed home theater (bottom of floorplan).


The two walls adjacent to the foundation will be normal 2x4 insulated stud walls - R13. The two interior walls will be double walls - R25 (or so). A good amount of the floor is insulated due to stage and riser coverage.


Floor is poured concrete about 4' underground.


New England location (MA). The basement in its current unfinished state is a steady 60 year round.


My heat loss calcs indicate that I will need about 900 BTU/Hr to maintain +10 deg. F. or 70 deg. F. The projector and a single person should generate this (Projector with 250W bulb perhaps 600 BTU/Hr; each human 200-300 BTU/Hr).


Thus, forget a heater for long, with more than two people (and there will be seating for up to 8), we will need cooling or ventillation.


Instead of bona-fide air conditioning, I though perhaps some forced air circulation to the adjacent basement space which will require about 4000 BTU/Hr of heat. I am concerned about defeating the sound isolation with ductwork. I am more concerned about sound to/from upstairs than into the adjacent basement space.


I thought perhaps a 3-500cfm in-line remote blower (bathroom exhaust type) would do the trick. It would suck air from a duct high in the interior partition double wall at the theater front and flex snaked down the wall and out the other side bottom into a closet in the adjacent basement space where the fan will be for noise isolation which will discharge the warm theater air into the adjacent basement space out another of the closet walls into the adjacent space. Same scheme at the other end of the theater for intake air (but no blower - this will be how air from the adjacent basement gets in).


Any other thoughts/tricks? Do my heat calcs seem reasonable?


How do others deal with this issue?


db
 

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Related to heat gain/loss your calculations probably are not too far off. My theater is similar to yours in size and location and have never needed heat though I am a little further south. Generally I need cooling and have been considering putting my projector in a hush box and venting out and/or getting a separate A/C system for the room.


Your idea about putting ducts and in line fans is not a bad idea and I have done this though to a lesser degree. The good news is if your idea does not work it will probably be easier to add the HVAC system later as long as you do the ducts right and the only cost you are out are a couple of duct fans.


I am using one Panasonic in line fan for my equipment closet and it works great.
 

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Your estimates for people are close.

You can assume for one person sitting, total load of 450 btu/h ( 250 btu/h sensible, 200btu/h latent)


What did you use for your calcs?


Even though the theater room has "interior walls", the space on the other side looks to be unconditioned. Did you assume that in your load calcs?


Are you using a program or ASHRAE calculations?



As for your duct idea...just make sure you aren't blowing the air on anyone. That will make them feel cold, even if it is 70 degree air.
 

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Discussion Starter · #4 ·
Here are my calcs - all assume worst case, so even though the adjacent space is heated, it is a basement rec room and the heat could be off yielding an ambient 60 deg. F.


I have ignored heat gain from the ceiling (conditioned living space above) as this is baked into my observed minmum ambient of 60 deg. F. Also, 2x10 joists and insulated so only a small heat gain anyway.


Q total = Q(Wall a,d)+Q(Wall b,d)+Q(Riser)+Q(Stage)+Q(Carpet)


Walls:


Walls A+D are interior double walls, R26, interior

Q(Wall a,d)=(19foot+13foot)*(7.5foot high)*(10 deg.F)/(R26)=92BTU/Hr


Walls B+C are adjacent to exterior foundation, about 2/3 underground

Q(Walls b,c)=(19foot+13foot)*(7.5foot high)*(10 deg.F)/(R23)=184BTU/Hr


Q(Riser)=(6foot)(13foot)(10 DegF)/(R13)=52BTU/Hr

Q(Stage)=(6foot)(4foot)(10 DegF)/(R12)=20BTU/Hr

Q(Carpet)=(13foot)(13foot)(10Deg F)/(R3)=563BTU/Hr


Total Q=911 BTU/Hr


NOTES: I really should measure a wall temperature and a floor temperature as they may differ. Also, I thought about floating the carpet portion of the floor with DriCor to get up to R5, but given my need for cooling, not heating, I will not do this. Can use the extra riser height anyway.


EXPERIMENTAL NOTE: I calculated the raw unfinished basement space to require about 1800BTU/Hr per degree of heat rise. This weekend I ran a 1500watt (5118 btu/hr) heater for a few hours in the space and observed about a 2.2-2.5 degree rise (ran the experiment twice). The 1500 watts should have theoretically produced a 2.8 degree rise. My measurements were rough and the heater is old and might not be making full output. Nonetheless, I am clearly in the ballpark.


db
 

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db


Keep me posted on how your ventilation system works and how you ultimately specd it. I currently use a couple of Whisperline in line duct fans and they work well and are quiet. Plus they are reasonably priced compared to the other brands.


When I build a hushbox for my projector I will probably add more outlets to exchange the air between my basement and my theater as I am not thrilled with the idea of adding another HVAC unit to my house.
 

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Discussion Starter · #6 ·
This discussion has highlighted the likely need for some 'fresh' air in the room. Will likely power the fan off of a relay circuit on the lighting control such that when any scene is ON (including low light watch movie scene), the fan runs.


db
 

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My 14x21x8 Basement Theater boils in the summer and freezes in the winter and I'm in Atlanta. I had to a small portable heater for heat and a mini-split for cooling.


In my new house my main floor theater will be 15x23x12 nad my H&A guy is trying to figure out how to set up the the HVAC system so I don't have to add any supplemental equipment.


Is there a website I can direct him to that will show him how to calculate Heating and Cooling needs.


Thanks

Jim
 
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