Newbie - over-garage bedroom HVAC

[kelsner]

I hope you haven't had this question too many times in the past, but we're trying to figure out how to get better heating/cooling in an uninsulated bedroom over an un- air conditioned garage. House is circa 1950. Forced hot air with a leaky duct system and a very long duct run through un-air conditioned space (crawlspace,then through garage up to bedroom). We will eventually have to move our toddler into this room of extreme temperatures...I know kids are oblivious to that kind of thing but we need to do something.

We're leaning towards a booster fan from fantech. Any experience installing these? Results? Is there hope for us without having to rip out the garage ceiling and insulate?

[Shophound]

You are always better off adding the needed insulation and sealing and insulating any leaky ductwork than resorting to a band-aid approach to this problem.

Your kids deserve the best comfort you can give them.

[dash]

Does the room have a return duct and grille?

If not,is there a path ,open doors,to allow air suppiled to the room to flow freely back to the return(s),in the main part of the home.No air out = no air into the room,like blowing into a paper bag.


Insulating is of course worth looking into,thus reducing the air flow needed to condition the room.Garage ceiling ,you could install High -R foam with a white foil skin,wouldn't look bad in the garage,and could be sheetrocked over later on.Walls and attic,depends on the construction.


Fantech is a could product and they will advise contractors on proper sizing,once the cfm required has been determined.Don't just guess at what size to buy.

[majormickey]

Insulation will save heating or cooling costs. After you add insulation, sounds less expensive to have an independent unit for cooling like a window insert or a unit similar to a wall unit you would find in a motel room. Hope that helps.

[classicrock4you]

SIMPLY PUT, AINT GONNA HAPPEN!

Room over garage - 15' X 15' room, 95 degree heat from garage rising thru floor, 2 unventilated knee walls @ 130 degrees each, 2 15 x 10 roof/ceiling sections and a 5' wide unventilated attic peak. The heat gain for this room is
probably from 4 to 6000 btu's.

This room over the garage is one humongous heat sink, and you want to run a duct 20' in the crawl, then up 16' to the peak, then over 15' to the outside wall with your existing system. And no return to boot!

Can you say "how many laws of heat transfer can I violate today"?

see the first line.

[uktra]

Kelsner--the answer can be many fold, but the best solution is to first insulate and then air seal and see if that evens out the temps. Best way to do that is to net and dense pack the garage ceiling with cellulose. A fine mesh net is stapled to the garage ceiling joists. Then small holes are put in each joist bay and cellulose is pumped in under pressure. This will fully insulate and air seal this area. The roof line from the eve to the top of the knee wall should be done in the same manner with the exception of using the foam chutes next to the plywood roof to get air next to the plywood. This should get the heat gain/loss per sq. ft. aprox. the same as other rooms. If it doesn't, you need to look at air flow into and out of the room. The last resort would be to zone the room. The reason you first want to insulate and air seal is that it will save money.

[41gasman]

uktra. Well I don't know the area you live in but around here it is a lot simpler to seal the ducting first then do that insulation thing.When ever I insulate first it takes a lot more duct tape to make the heat stay in that pipe thing.
You know there was a thread here the other day were a guy was haveing no luck getting good air flow to a couple of rooms at the far end of the house from the funace.Well they hired a PRO to come in and they put in a twelve inch dia.ducky booster fan and there problems went away.Maybe you could save a bunch of money by JUST putting one of those twelve inch ones yourself.Worked for them so why pay a pro come in and do all those calulations when someone else already figure it out!!! COOL!
41GASMAN

[rabadger]

Step 1. Run the load calculations for the insulation you can get installed and see where you end up.

Step 2. Insulate and see what happens.

[uktra]

41gasman--you are correct, I needed to mention seal the ducts--that goes without saying. Most duct booster fans I have seen don't work real well and don't save energy. What I suggest will.

rabadger--the problem with doing a load calc on this room is air infiltration with normal fiberglass insulation. This room can have 3 to 4 times the air infiltration of the other rooms. One must air seal as well as insulate--which is done in one step with the method I mentioned.

[classicrock4you]

Gentlemen, I hate to sound like an ass (but I am so good at it, lol) but many of you need to re-read the post carefully and get your facts straight.

Rooms over the garage have 4 exposed sides, roof/ceilings,
unventilated kneewalls, etc. Heat gain per square foot is twice that of downstairs

This is not a garage, it is a a ROOM OVER an unconditioned GARAGE. Ductwork is in crawl, furnace in center of house (he said long run under house)The ROG now has a long run from the trunk, then, 90* turn, then up 16", another 90* turn, then over 15" and come thru ceiling. Talk about going around your elbow to get to your thumb, I bet the equivalent length on the supply line is 60+ feet.

NO RETURN mentioned.

Gentlemen, you can seal the ductwork with r-30 and it wont help this situation. You can install r-60 in the attic and it wont help. You can install a booster fan and it won't solve the problem. The ONLY professional way to solve the problem is to analyse the new situation, get out your tools (manual J and D), rip everything out, and start from scratch and do it the right way.

[uktra]

This is getting fun---Let's take all of our tools that I know each of us has and really do it right. First we will take our duct baster out and pressure check this duct for leakage. Then we will take our flow hood and check for the duct for flow. Then we will take the estimated sealed duct flow and go to our computer and find out if we can add the proper insulation and air infiltration rates that this will match. Then and only then do we need to start over and tear everything apart and charge the customer.

[Edited by uktra on 03-31-2005 at 10:49 PM]

[dash]

Originally posted by classicrock4you
Gentlemen, I hate to sound like an ass (but I am so good at it, lol) but many of you need to re-read the post carefully and get your facts straight.

Rooms over the garage have 4 exposed sides, roof/ceilings,
unventilated kneewalls, etc. Heat gain per square foot is twice that of downstairs

This is not a garage, it is a a ROOM OVER an unconditioned GARAGE. Ductwork is in crawl, furnace in center of house (he said long run under house)The ROG now has a long run from the trunk, then, 90* turn, then up 16", another 90* turn, then over 15" and come thru ceiling. Talk about going around your elbow to get to your thumb, I bet the equivalent length on the supply line is 60+ feet.

NO RETURN mentioned.

Gentlemen, you can seal the ductwork with r-30 and it wont help this situation. You can install r-60 in the attic and it wont help. You can install a booster fan and it won't solve the problem. The ONLY professional way to solve the problem is to analyse the new situation, get out your tools (manual J and D), rip everything out, and start from scratch and do it the right way.

60 feet is not bad,all depends on what cfm is needed and the duct size.

We typically do homes with 500+ "Total Equivalent Feet" of duct.