Brand New Rheem RGPS Gas Furnace Short Cycling........ WHY ??

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Originally Posted by Labrat0116

And here some still pics of the setup.

http://katmanduonline.net/albums/NewFurnace/

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Looks like a hack job, duct tape on the vent pipe! I hope you didn't pay much for the install because it needs to be redone by a professional.

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Originally Posted by jmac00

it doesn't look bad, but I have a real problem with the way that duct comes off the backside of the supply plenum. I can't tell if that necessary or not?

I think it would have been cheaper/quicker to install a new plenum and connect directly into the supply at the back, eliminate the down turn short way 90 elbow.

I would also put a supply run in the crawl space

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I guarantee he has enough duct leakage to amount to an 8" supply or two and an 8" return.

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Originally Posted by jtrammel

Looks like a hack job, duct tape on the vent pipe! I hope you didn't pay much for the install because it needs to be redone by a professional.

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Originally Posted by jtrammel

I guarantee he has enough duct leakage to amount to an 8" supply or two and an 8" return.

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I was trying to be nice :cheers: I still want to get a better look at the backside of that supply plenum, something is not right back there

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Originally Posted by Joehvac25

Did he bend it so it sat like the one in the pic? It should have the diaphragm vertical, not horizontal like the pic.

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I'm not clear on what you're asking. ??

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Originally Posted by beenthere

Need full model number of the furnace to tell for sure. Adding another return or enlarging 1 or both of those may be all that is needed.

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RG PN 07 I believe.... I need to find the papers to verify that.

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Originally Posted by jmac00

I was looking at the supply plenum on top of the a/c coil. In Pix 0306, On the back side it appears there is a 6" x ??? that runs about a foot and then goes into (what looks like) 8" x ??? short way elbow. I think you have much to much restriction there.

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You mean in the red box area ? BELOW

This was original duct work from who knows how long ago. ?

Attachment 351351

It's a pretty bizarre setup. That particular run goes into a very large diameter duct (maybe 12" x 12") and runs about 35 feet under the house. Believe it or not, it only feeds to small registers. The air is luke warm by the time it gets to them.

More can be seen here.....

Attachment 351361

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Originally Posted by beenthere

How big is the crawlspace. And what BTU is the furnace again.

A negative pressure in the house will draw in the cold dry outside air. making you heating cost increase, and your house very dry and uncomfortable.

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The crawl space I would guess to be around 5-600 sq ft. ??

The house is rather well insulated. Not drafty at all. It is however, very dry. We keep several small humidifers running most of the time.

Furnace is 75,000 btu 80% efficient.

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Originally Posted by jtrammel

Looks like a hack job, duct tape on the vent pipe! I hope you didn't pay much for the install because it needs to be redone by a professional.

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Are you refering to this pic ?

Attachment 351341

They didn't do that. I taped that about (10) years ago. I saw a gap between the (2) pipes and went to town with the duct tape.

The outer (bigger diameter) pipe appeared to be double-walled. It looked really odd to me so I taped the crap out of it and sealed it tight.

EDITED..... I just found an OLD pic of what it looked like BEFORE I taped it up.

Attachment 351331

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Originally Posted by jtrammel

I guarantee he has enough duct leakage to amount to an 8" supply or two and an 8" return.

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Yea, I was thinking that myself! LMAO!

I should mention also we have (3) CO2 detectors running. One in the crawl space (not far from the furnace), 1st and 2nd floors. None have ever gone off.

Here's some old scary pics of the old furnace setup when we bought the place (17) years ago.

http://katmanduonline.net/pics/ACFURNACEPics/index.html

Note the copper pipe running from the AC condensor to the back corner. No drain pipes available. Talk about a damp, moldy mess! I fabricated a piece of PVC out to a 5 gallon bucket that had a sump pump in it. We would have to empty it every few hours when the AC was running. Crude yes, but it WORKED!

Part of the new install will be to fabricate a new automatic sump pump to the furnace/coil. That will be done when the come back in the springtime to recharge the AC.

BTW, the old duct work that was done on this new install was the 2-12" flexible hose connections and the new plenum before the filter. Nothing else was done to the existing duct work.

why did the not install a filter rack with a door .that job looks low bidder to me and will perform like it .if the reused the coil hope they cleaned it also would want it reconnected and recharged before paying as if they are competent it could be done

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Originally Posted by Labrat0116

You mean in the red box area ? BELOW

This was original duct work from who knows how long ago. ?

Attachment 351351

It's a pretty bizarre setup. That particular run goes into a very large diameter duct (maybe 12" x 12") and runs about 35 feet under the house. Believe it or not, it only feeds to small registers. The air is luke warm by the time it gets to them.

More can be seen here.....

Attachment 351361

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ya, thats completely messed up. jtrammel was right, thats a butcher job, that needs to be changed. It looks like someone took a piece of trunk and laid it in the top of a supply plenum. The company that installed your furnace did not do you any favors by leaving it like that.
They could have done a couple of different things. 1) they could have installed a box plenum that went to the floor joists, come off the back with a start collar into a short way 45, then into a long way 90. or 2) used a radius plenum

either one will make for MUCH better air flow.

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Originally Posted by Joehvac25

Did he bend it so it sat like the one in the pic? It should have the diaphragm vertical, not horizontal like the pic.

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No. It was installed vertically, but it was at such an angle it was touching the outer metal cabinet. The Tech bent it back a bit so it is vertically straight up and down.

That is the ONLY thing the Tech touched and now the furnace appears to be working ok.

I find it very odd that that part touching the cabinet was causing the furnace to not turn ON.

Why would the orientation of the pressure diaphram make any difference to the pressure readings ?