Gas and Oil Home Heating Furnaces - Return air to heater ???

I have a propane, fan forced type heater in the garage. It shares a sheetrocked pedestal with the water heater and the return duct is between them. The return duct goes into the pedestal and the squirrel cage fan pulls it back into the heater.

The inside of the pedestal isn't finished or insulated and there's no ducting of any kind from the return's entry to the heater's intake.

Wouldn't it be more efficient if there was some sort of conduit for the return air or at least if the pedestal was 'finished' on the inside?

Seems to me that the return air would be cooled further by the exposed garage slab the pedestal sits on and that the extra volume of air inside it (a third of it being under the water heater) would affect it as well.

Should it be ducted or should I at least 'contain' the flow to the heater intake or would it change any kind of HVAC air volumes or something or another in a negative way?

I'm not sure if I read this right, but are you saying that your furnace return is in the garage?

Hank from what I understand, is it's boxed in. The return duct drops into this box, then the furnace pulls it out of o this box back into the system.. sounds like he is from the south with this set up.

C, I really couldn't answer this question since this set up is not done up here in Minnesota. It's all in the basement and ducted. I gather you are from the south, and I don't think it's a big deal to have this as you have it since the air only has a short term expouser. Just make sure the box is air tight so it's not pulling any air from the garage like gas or fresh cut grass from the lawn mower.

I guess I could've worded it a little better ;).

The central return register is in the house. The other end of the return, where the air is fed back to the heating unit, is in the garage - next to the heater.

South New Mexico (Las Cruces) is where I am and I do notice that the newer homes (mine=1999) have the units in a closet or laundry room now out here.

Good point about pulling other, contaminanted air into the system. The box is leaky by nature and I noticed that the backside of the pedestal, that is up against a living area wall is without sheetrock.

So, my thinking was that with all that extra air being pulled from that wall, and I'm sure from the cold garage, that the inherent efficiency level of the unit would suffer in that it has cooler than expected air to reheat.

That, and the fan motor might be not be as efficient with such a big 'leak' and not limited to recirculating what's being returned; an imbalance between pull and push, as it were.

If all things are considered equal, as far as volumetric properties, I think I would be better served if that return conduit was a bit more contained; if only to reduce any 'dirty air' entering the system. but to keep that air a little warmer.

The return should be sealed to the furnace with no leaks, especially in a garage.

So, in other words, this pic shows yet another project in my future?

http://www.cienega32.com/house/heaterped.jpg

By sealed, does that mean I can get away with building an enclosure (wood/sheetrock and sealed) inside, if I can't find any kind of HVAC duct to work?

You don't need to do ductwork, be way too much work for you.

I'd just seal off the open gaps between return box and garage with culking.

I wouldn't worry about losing any sleep about the air temp, you are not in Minnesota where our winter winters are very cold (lows as low at -10 at times)

The best way to go about this is like we do. Get some fiberglass duct board. Take and line the inside of the drywall box all the way from the grill to the where it goes into the furnace. Make all seams fit tight.
Some of the new codes in Florida now call for the furnace out in the garage there now and not in the attic. So you have to line the cold air inside the drywall box with duct board

True - 10 below is tad cooler than what I experience here but inefficiency is still just that and costs money, besides just being inefficient, both of which irk me.

Fiberglass duct board - I'll give that a shot - sounds reasonable and a little easier than knocking some tin.

Last nite, with some 30MPH winds, I had a good, solid breeze coming out of the living area side of the return so I need to do something with it. I pulled the cover off and took a peek into the straight-run duct with flashlite and binoculars (for the far end) and it all "seemed" to be intact. There is quite a breeze inside the pedastal, tho'!

You dont say how big the furnace or AC is there. One other way to go if you have the room in this so called duct is fish a big Di flex pipe from one end to the other????????. If not line it with the ductboard.

ED ;)

My last post about the return duct, I think, may have turned my post into two topics. The return duct is the straight 20' or so return from house to garage that then straight-drops down the 8 or 9 feet into the pedestal I was concerned with.

It's a flat roof southwest type home with no attic or crawl space. I was checking in the main return duct to see if there may have been any signs of seperation and allowing wind in from the soffits but it all 'seemed' to be OK.

As far as that pedestal area - that's only a 2 or 3 foot distance between heater and return but has a small support stud smack in the middle of it.

It's my first winter in this house and it's proving to be an adventure. Today I discovered yet another interesting bit. The swamp cooler is a master cool plus with a 19.75" square down-draft duct, according to the data/docs I received recently for that unit. The Carrier heater's duct is 16x19 or so. Both use insertable dampers. Both dampers are the same size! I haven't confirmed it but I'm assuming there's a 3x19 gap at the end of the cooler damper because of that. That 3x19 "gap" in the cooler damper is probably why I had weak air flow out of most registers with the heater last Feb when I moved in [sarcasm].

Point being that's what made me look closer at the whole system before I fire it up or it gets too cold. There just seemed to be way too much time in heating the house and the weak air flow was another concern as well.

I'm sure, after replacing the cooler damper tomorrow, I'll see the biggest improvement and after closing up the hardware pedestal, I should be good to go.

Oh - one more question - where do I find the fiberglass duct board? Would the Big Box joints have it?

Is the swamp cooler duct tied into the supply duct of the system?

If yes, then that is most likely your problem.

Ductboard is not a common thing up here in MN, so I never seen it at retail stores. You can look and see if they do... But most likley you will have to get them from online or a HVAC dealer.

Yes, they share the duct work. I was pretty relieved to see the size of the cooler damper - sure answered a lot of questions about the heated air flow (I hope). Can't see why it wouldn't be the root of the problem. I'm on my way up the ladder at half-time but I just can't figure how the P.O. would let that go - 3" is a big size difference!

I looked in the Big Box joints but didn't see it so I guess an HVAC place is where I'll look.

After a little snip here and there, I replaced the old, undersized damper in the swamp cooler:

http://www.cienega32.com/house/cooldamp.jpg

It was, as I thought, about 3" too short. It's nice and 'snug' with metal duct tape over the outer seal now. Surprisingly, it didn't make that much of a difference in the airflow from the registers. It does seem to heat up a bit quicker and maintain that level a bit longer but it is still early in the season and the little cold snap is gone tonite.