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DonKellogg
Joined: 31 May 2006
Posts: 180
Location: Kalamazoo, Mi
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| Posted: Tue Aug 29, 2006 4:46 am Post subject: Relocating Cold Air return Main |
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Has anyone done this? Is this as sensitive a topic as the main feed? I need to move my Cold air return main to the other side of the theater so I can shrink my Soffits from 48" wide down to 20" or smaller.
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Chuck27
Joined: 09 Mar 2006
Posts: 379
Location: Caledon Township, Ontario
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| Posted: Tue Aug 29, 2006 12:43 pm Post subject: |
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As long as your air pickup points remain more or less the same, you won't upset the air balance so relocating the main ought to be fine. It's not as sensitive as the forced air supply, to be sure....the goal is to make sure you don't end up with hot or cold spots in the house and equalize humidity.
Have you considered collecting warm air from around the projector and/or the equipment rack and feeding that into the cold air return? There will be a small amount of suction that will help with heat extraction and pre-warming the air before it goes into the furnace will help with the utility bills. Not a big deal in August but you are on almost exactly the same latitude as I am so it will be a big deal come January. Take it from someone who heats with oil and supplements with wood....I'll take free heat any day!
Chuck
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Chuck
using acreage for sound insulation since 1999
Last edited by Chuck27 on Tue Aug 29, 2006 3:15 pm; edited 1 time in total
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Tue Aug 29, 2006 2:30 pm Post subject: |
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| Chuck27 wrote: | Have you considered collecting warm air from around the projector and/or the equipment rack and feeding that into the cold air return? There will be a small amount of suction that will help with heat extraction and pre-warming the air before it goes into the furnace will help with the untility bills.
Chuck |
jeez that's brilliant. and the planned route for my hush box exhaust goes right past a cold air return.
definately something to think about.
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walk gently. leave a good impression.
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Chuck27
Joined: 09 Mar 2006
Posts: 379
Location: Caledon Township, Ontario
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| Posted: Tue Aug 29, 2006 3:25 pm Post subject: |
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I would like to figure out a way to hook my PJ and my equipment rack to the cold air return in such a manner as to have the furnace fan act as my heat exhaust. I don't think the air velocity is high enough to make a substantial difference but think of how quiet things would be if I could make it work...unless I had to put a 5000 CFM blower on the furnace, which coincidentally is in the next room to the theatre.
I thought you west-coast guys had no need for heating in the winter...doesn't it rarely go below 10C?  
Chuck
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Chuck
using acreage for sound insulation since 1999
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Tue Aug 29, 2006 4:02 pm Post subject: |
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| Chuck27 wrote: |
I thought you west-coast guys had no need for heating in the winter...doesn't it rarely go below 10C?
Chuck |
oh dear me no. it's always cold out here. cold cold cold. in fact there is snow this very August day. snow snow snow. 
actually it depends on elevation. i've driven in snow anywhere from september to june, but that's on the trip from sea level to 1700metres and then back down. nothing like driving in sandals and tee shirt but packing a parka for the sole reason that you know at the toll booth near the peak you're going to need a pee break...
but i did my time. 12 years in ottawa, and then another 12 in london ontario. oh, and some time in the praries as a kid. brrr. nothing quite like a frozen gopher to let you know it's cold.
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walk gently. leave a good impression.
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Chuck27
Joined: 09 Mar 2006
Posts: 379
Location: Caledon Township, Ontario
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| Posted: Tue Aug 29, 2006 4:59 pm Post subject: |
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With that resume, yeah, you do know what cold is....my wife is from Ottawa and she frequently reminds me that Ottawa has more winter than central Ontario....unless you live on top of the Escarpment in which case all bets are off.
I did my time at Syncrude up in Mildred Lake for two winters 1979-1980 and I dare say it gets a wee bit nippy there as well.
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Chuck
using acreage for sound insulation since 1999
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mack1
Joined: 21 Mar 2006
Posts: 494
Location: SARNIA
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| Posted: Wed Aug 30, 2006 10:52 pm Post subject: |
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What if you used a 3"duct and put a bathroom style fan on the far end then plumbed the exaust into the cold air return with another 3" line (like you would have on a dryer--- use the same idea on your electronices.Thats what I'm going to do.Then use the 12 volt trigger on your stereo to turn it on and off as you turn on your sound system using a 12v relay
Last edited by mack1 on Thu Aug 31, 2006 11:37 pm; edited 1 time in total
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Thu Aug 31, 2006 7:05 pm Post subject: |
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| Chuck27 wrote: | As long as your air pickup points remain more or less the same, you won't upset the air balance so relocating the main ought to be fine. It's not as sensitive as the forced air supply, to be sure....the goal is to make sure you don't end up with hot or cold spots in the house and equalize humidity.
Have you considered collecting warm air from around the projector and/or the equipment rack and feeding that into the cold air return? There will be a small amount of suction that will help with heat extraction and pre-warming the air before it goes into the furnace will help with the utility bills. Not a big deal in August but you are on almost exactly the same latitude as I am so it will be a big deal come January. Take it from someone who heats with oil and supplements with wood....I'll take free heat any day!
Chuck |
 Great minds think alike...I JUST got done posting the exact same idea in the CRT forum in the "Building Kal's HushBox" thread... and then wandered in here to find the same thing being discussed. What a coincidunce.
I'm still going to take the active route with mine (24v elongated cage blower in custom built fanbox) except I'm going to pipe the hushbox exhaust heat into the cold air return outside the theater. It should be nice and quiet and will allow me to choke down the heat to the room and divert it to the living quarters. (Looks good on paper anyway!!) 
--Greg--
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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Chuck27
Joined: 09 Mar 2006
Posts: 379
Location: Caledon Township, Ontario
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| Posted: Fri Sep 01, 2006 2:05 pm Post subject: |
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I was surprised how much my projector contributes to the temperature in the room. My theatre is still at the open-joist-and-concrete-floor theatre stage, it's the lowest level in the house and 80% below grade so it ought to be cool, but with the PJ and a full equipment rack running (plus two people and two dogs watching) there is a noticeable temperature rise that I didn't expect.
Now to just get that shunted into the cold air return.....and keep the noise down....
Chuck
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Chuck
using acreage for sound insulation since 1999
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Mon Oct 16, 2006 4:47 pm Post subject: |
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it's been a couple of months, but i'm now at the stage in the HT rebuild that has me hooking up the venting to the bathroom fan exhaust.
i'm still thinking about connecting it to the cold air return, and have been trying to find out if there are any unknown "gotchas" in doing this. the only thing that i have found is this from a company that sells stand along add on furnaces.
| Quote: |
The warm air supply outlet of the NORSEMAN� Furnace may not be connected to the cold air return of the central heating furnace because of the possibility of overheating components of the central furnace and causing it to operate other than it was designed. |
now that is hooking one furnace into another, but still...
can Kal or someone who has a vented hushbox do a check on how hot the the exhaust is from the hushbox? am i going to damage to my furnace by pumping air that is too hot into the system?
i'm hoping not because there is a cold air return by my feet in the HT and i'm looking forward to toasty toes during movies!
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walk gently. leave a good impression.
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Tue Oct 17, 2006 3:36 pm Post subject: |
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| zaphod wrote: | it's been a couple of months, but i'm now at the stage in the HT rebuild that has me hooking up the venting to the bathroom fan exhaust.
i'm still thinking about connecting it to the cold air return, and have been trying to find out if there are any unknown "gotchas" in doing this. the only thing that i have found is this from a company that sells stand along add on furnaces.
? am i going to damage to my furnace by pumping air that is too hot into the system? |
on the off chance that anyone else cares about hooking in their hushbox exhaust into the cold air return...
i talked with one of the HVAC people at work, and called a friend of mine who does commercial furnace installs for a living. neither of them seemed to think that this is a bad idea and were kind of interested in the concept (particularly the scottish one who, like me will squeeze a dime to get nickels and then the nickels to get pennies).
and then i went to home depot...
the fellow there (one of the classic ex-contractor types that HD likes to hire) launched onto me saying that i would be disturbing the balance of the system, that house furnaces are finely tuned (perhaps now, but in '72 when the house was built?) and that i shouldn't try this at all.
i tried to get him to explain what he meant by unbalancing the system and how that might damage my furnace system, but i think he felt i was too dumb to understand. he also dismissed the HVAC people i'd talked to as not knowing anything so i should not trust their advice.
man, i'm back where i started, just don't know what to do on this.
on the up side, in looking for parts yesterday, i learned that "hydroponic" stores are the place to go for ducting parts that are a little bit weed, errrr weird.
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Chuck27
Joined: 09 Mar 2006
Posts: 379
Location: Caledon Township, Ontario
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| Posted: Tue Oct 17, 2006 7:11 pm Post subject: |
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| zaphod wrote: |
on the up side, in looking for parts yesterday, i learned that "hydroponic" stores are the place to go for ducting parts that are a little bit weed, errrr weird. |
Hydroponic stores? In British Colombia? I am aghast! What is our country coming to?
| zaphod wrote: |
and then i went to home depot...
the fellow there (one of the classic ex-contractor types that HD likes to hire) launched onto me saying that i would be disturbing the balance of the system, that house furnaces are finely tuned (perhaps now, but in '72 when the house was built?) and that i shouldn't try this at all.
i tried to get him to explain what he meant by unbalancing the system and how that might damage my furnace system, but i think he felt i was too dumb to understand. he also dismissed the HVAC people i'd talked to as not knowing anything so i should not trust their advice.
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Well, he has a point, but at the risk of offending HVAC people everywhere, his point is a very, very small one. Yes, if you're tinning an entire house for the first time you (might) take the time to go from room to room with a thermocouple or thermometer and adjust the flapper valves (take off a register and reach into a duct and you'll feel one) to maintain similar temperatures in each room or area. It's a comfort thing only, and just like calibrating a CRT, you can do it quickly and less accurately, or you can spend days iterating and getting everything just right, or (unlike a CRT) you can do nothing at all and probably not notice the difference.
He's full of it (pardon my French) when he says it will damage your furnace. Your furnace won't have any idea what you're doing other than slightly pre-warming the incoming flow.....and he has made himself out to be even more of an idiot by implying that the return air system is closed, similar to the supply lines. Furnaces are not particular about from where they suck air, they just act like a man and take the path of least resistance.
My advice, for what little worth it has, is to forge ahead despite what Bozo the Home Depot Heating Contractor tells you, and not worry about the air balance. You're on the right track.
Chuck
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Chuck
using acreage for sound insulation since 1999
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Tue Oct 17, 2006 9:57 pm Post subject: |
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Coming into this a bit late...
| Chuck27 wrote: | | I was surprised how much my projector contributes to the temperature in the room. ... with the PJ and a full equipment rack running (plus two people and two dogs watching) there is a noticeable temperature rise that I didn't expect. |
Ohhhh yes. You'll be amazed how warm a basement room can get in the winter when you add an 800W heater (CRT) and a number of 100W heaters (human bodies, dunno about dogs  ). First night in my theater I invited some friends over. Us & our 2 kids, them & their 2 kids, and that adds up to something like 1600W with the projector. 2/3 through the movie the projector overheated and shut down -- it must have been at least 35-38C on the ceiling!! Now I have an exhaust pulling hot air off the ceiling, but the room still warms up a surprising amount.
Gary
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Tue Oct 17, 2006 11:42 pm Post subject: |
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They don't turn the heat on in this building until mid October. I just come home turn on my 7 mono block amps, Pre amp, 27inch TV in the bedroom, RPTV and projector it'll go from 18C to 28 in about 3 hours. Toasty.
And ditto for what Chuck said. The home depot guy sound very condescending.
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HD done right!
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Wed Oct 18, 2006 12:52 am Post subject: |
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| AnalogRocks wrote: | | They don't turn the heat on in this building until mid October. I just come home turn on my 7 mono block amps, Pre amp, 27inch TV in the bedroom, RPTV and projector it'll go from 18C to 28 in about 3 hours. Toasty. |
well, i still haven't turned on the furnace yet, and it was getting down to 57 in the mornings. now it's shooting about 67 or so. a lot of that has to do with all the tube amps i have upstairs.
| analogrocks wrote: | | And ditto for what Chuck said. The home depot guy sound very condescending. |
it's what it is. i just know not to deal with him. and his manager knows too. i've got lots of acquaintances that will attest to the fact that i'm a "bump it up the food chain" kind of guy. not only is that my job at work, but it seems to work. usually. sometimes not, but usually.
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Wed Oct 25, 2006 7:56 pm Post subject: |
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I'm no HVAC&R or environmental engineer BUT...I have an active solar system in my house and it works exactly like Joe Sawsall said to avoid.
In my system, the solar heat exchanger is in the airbox BEFORE the firebox/heat exchanger for the furnace. Warm water is pumped from the solar collectors on the roof, through a series of pressurizers and holding tanks, and then through the heat exchanger to be mixed with the warm air from the gas fired furnace. Hell, this system is so totally integrated into everything related to hot water in my house that if (ahem, WHEN) the water heater dies it's going to be a nightmare to R&R a new one. (Dumbasses didn't install valves between the water heater and the copper feed lines from the roof mounted collectors).
To my way of thinking...your furnace doesn't give a rats a$$ about taking warm air from one leg out of many cold air returns to feed the output ducts with heated air from the heat exchanger.
The furnace will simply take the preheated air through the cold air return, that air will join into a single input at the furnace, it will be routed through the heat exchanger and heated while the furnace is running, and go out a single effluent to be routed out to the registers in the rooms.
The idea that all the air from every returning cold air duct is the same temp is ludicrous. In every home there are warm rooms and cool-er rooms. It depends on facing direction of the house, window exposure for solar heat transfer (sun shining in a window doesn't do bupkus UNTIL it HITS items in the room, whether it be a couch, bed, carpet, hardwood floor, wall, etc) only then it is felt as radiant heat. If sunlight could be focused and were directed coming in one window, across the house and out another window...the ambient heat change would be minimal at best.
Go for tieing it into your cold air return. In the winter, in an HT with a room full of people and everything running, the WORST thing that can happen is that you'll be able to turn down the thermostat, put the system in Fan On mode...and spread the "free" heat around the house evenly. ('Taint free...yer payin for it. Especially if one of the people in the HT is your mother-in-law)
It's the summer you're going to want to think about. You'll be preheating the air going through the evaporator and loading up the A/C a tad. By then however you'll have had plenty of time to work out how to modify your ducting system for Winter/Summer by installing valving in the ductwork (outside the HT) to enable seasonal switchover, to dump the heat directly to the outside.
Just my ramblings.
And lookee there...here come the Heating Contractors to beat the snot out of me.
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Wed Oct 25, 2006 8:55 pm Post subject: |
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| JustGreg wrote: | I'm no HVAC&R or environmental engineer BUT...I have an active solar system in my house and it works exactly like Joe Sawsall said to avoid.
Go for tieing it into your cold air return. In the winter, in an HT with a room full of people and everything running, the WORST thing that can happen is that you'll be able to turn down the thermostat,
It's the summer you're going to want to think about. You'll be preheating the air going through the evaporator and loading up the A/C a tad. By then however you'll have had plenty of time to work out how to modify your ducting system for Winter/Summer by installing valving in the ductwork (outside the HT) to enable seasonal switchover, to dump the heat directly to the outside. : |
well, at the end of the day, i didn't do it. not because the HD guy said not to, not because i was worried about screwing up my furnace. no, it was for a much simpler reason.
i couldn't fit between the joists to reach the duct.
i knew that it was going to be a tight fit, so i had a friend come over to haul me out incase i got stuck. but when i jammed myself between the joists so that only my legs were sticking out i could not reach the cold air return to cut in the top takeoff.
the plan was to have the fan exhaust into a Y connection with one leg going to the cold air return and one leg to the next room. twice a year i'd open the hushbox and turn the dampers to get the exhaust into the far room or the furnace as i saw fit. but i just could not reach the ducting without going in via the ceiling of the far room. that room is full of HT gear, so cutting into drywall just aint gonna happen.
so i have the exhaust port in the far room. sigh. over the winter i'll be dieting. i'm keeping all the bits so i might end up doing this eventually.
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greg_mitch
Joined: 03 May 2006
Posts: 5320
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| Posted: Thu Oct 26, 2006 3:05 am Post subject: |
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without getting too complicated....
your furnace doesnt run all the time. if you are taking the pains to duct up exhaust from your projector just get a bathroom style fan and shoot it into a storage space. besides you would not want to add that heat during the summer...
I wouldnt 12v trigger it off your equipment either because after you turn off the projector that doesnt mean it instantly cools down...you will want it to run off temperature not use.
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Thu Oct 26, 2006 4:36 am Post subject: |
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| greg_mitch wrote: | without getting too complicated....
your furnace doesnt run all the time. if you are taking the pains to duct up exhaust from your projector just get a bathroom style fan and shoot it into a storage space. besides you would not want to add that heat during the summer...
I wouldnt 12v trigger it off your equipment either because after you turn off the projector that doesnt mean it instantly cools down...you will want it to run off temperature not use. |
yep, check my album to see pictures of the nutone bathroom fan. i also (somewhere in this thread i believe) talk about the snapdisk that i use to turn on the fan at 40C and keep it on until the temp drops below 40C again. i also have wired in a "just run it" switch for the fan in case the snapdisk fails.
but this still doesn't solve the problem of the joists in my house being one size smaller than my hips.
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Mon Oct 30, 2006 10:30 pm Post subject: |
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| zaphod wrote: | | but this still doesn't solve the problem of the joists in my house being one size smaller than my hips. |
I'm sorry I shouldn't laugh but that was hilarious man.
I have the same "limitation". It's strange the things that aren't thought of when planning isn't it. The "Can Do" attitude can quickly turn into an "Oh $hit" problem that's for sure.
Oh well, we were all probably over complicating it anyway. Now you have more time for watching movies.
--Greg--
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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