Heat Exchanger

[Stihl310]

Got a dumb question... the plenum on my furnace is a 16 x 18" going up. What size exchanger do I need to get... I keep finding 16 x 18's but they all say they are for a 16 x 21" plenum... Getting confused and need some help as to what size I need.

Thanks

 

[modn]

Got a dumb question... the plenum on my furnace is a 16 x 18" going up. What size exchanger do I need to get... I keep finding 16 x 18's but they all say they are for a 16 x 21" plenum... Getting confused and need some help as to what size I need.

Thanks

I think the sizes refer to the fin sizing only NOT including the frame. I could be wrong though....it happens.

PS: It's not a dumb question, pretty good one actually.

 

[mtfallsmikey]

is this a cased coil or not?

 

[Stihl310]

I think the sizes refer to the fin sizing only NOT including the frame. I could be wrong though....it happens.

PS: It's not a dumb question, pretty good one actually.

It seems that the sizing includeds the entire frame, but not the copper stubs that stick out... I can fab the sheet metal so the entire copper stub is external, but from reading it, it seems that all that would be encased inside of the plenum... I thought I knew what was going on, but the further I go the more confused I get....

 

[Stihl310]

is this a cased coil or not?

IF your meaning framed all the way around the inner fins, then yes... this is new to me, so I don't always understand all the lingo...

 

[Stihl310]

I guess this is what I'm asking... if it say's a 16 x 18 is for a 21" plenum, then I'm guessing I need to get a 16x21?? Correct, this just doesn't seem to all jive for some reason...

Here is a pic from another thread of what I'm assuming it should look like, am I correct????

 

[mtfallsmikey]

Yes, this would be considered a cased coil, which means coil is in a cabinet like yours, dunno about the damper on the end, that would need to be removed to graft it into ductwork. Duct size would be where the damper fits in, measure the flange each way. If that is the case, 16" x 21" would be the duct size. Now, you can get a tin knocker to make a transition to fit into the existing duct, or go to an HVAC/sheet metal distributor and get a universal plenum, which are separate pieces of metal and make it yourself...good luck, mfm

opcorn: opcorn:

 

[Slick]

Hey that's my heat exchanger That's a 16x16 exchanger in an 18x18 length of old plenum I had after adding AC a few years back. I've done three of these exchangers from KJmotorsports on ebay, all different sized but they are made the same, his dimensions seem to be the same as the freeheat4u guy on ebay. The size listed is the open fin area or exposed heat transfer area if you will. Then the coil has some mounting aluminum flanges on it....top and bottom in that picture aren't much larger, it's only like 1/2" over than the 16" dimension (1/4" each side)...the length or area you can see in that picture is a bit longer, they have a wider aluminum flange to cover and protect the copper turns of the tubes.it's about 1" each side so that took me right out to the 18" of my plenum. Make sense?
So if you have a 16x18" plenum that measures exactly that size...good luck getting a 16" coil in that width..it be 1/2" to tight.