My new furnace plus tankless install with pix!

[beenthere]

I think the fan may be working a bit hard but will compensate. I also think if a restriction exists it's at that return fitting.

That reducing transition is way too short. Causing a lot of turbulence, and then the distance to the ell is too short for the air to stabilize before it enters the ell, causing more PD then there needs to be in the ell.

Vanes will help the ell.

If his A/C only runs at 750 CFM, then he'll be under or right at .65" in cooling mode.

[commerce48]

Guessed at furnace output.

You didn't check CFM, temp rise, and colorimetric value of the gas while using the old furnace, to check what the True BTU output was.

True. Of course, it was just an estimate similar to the Manual J. And no matter what, it wouldn't have changed my furnace choice. I don't think there is any doubt that my heat loss is somewhere in the 20 to 30K range on design day. Every forced air gas furnace is oversized in that range.

They could have installed the air filter in the drop, then they wouldn't have had to reduce the return. Not a big deal. But wold have been better for getting the most usefull life span from the air filter. While maintaining a low ESP. Not a big deal though.

I wish I had thought of that as an option and ran it by them, but I didn't have an opportunity even if I was that smart. I had no idea what the new return drop was going to look like until I saw it already installed on day two (I wasn't even there the second day).

How much would you estimate that a better return design could have lowered static?

Would have been better to transition to the A/C coil, instead of setting it on the furnace and blocking the side of the furnace off. Not a big deal.

Wish I had taken a picture of the top of the furnace prior to installation. The area blocked off was not in the flow path. I'm going to guess that if they included the dead area on both sides of the furnace, that efficiency would drop due to turbulence and added heat transfer through the furnace box.

Overall. looks like they did an above average install.

Thanks, nice to hear from you.

[commerce48]

Would have been better to transition to the A/C coil, instead of setting it on the furnace and blocking the side of the furnace off. Not a big deal.

I found a line drawing on the cover of the owner's manual that will give you an idea of the furnace configuration. The furnace actually arrived unboxed (do they have boxes?) on the company van and there was no top on the furnace at all like the attached drawing. The heat exchanger had an internal box defining the air path, and on both sides of that internal box was dead air space going down to the bottom of the furnace. There really wasn't anything to transition, and it would have just been for looks, so they just squared it off.

The installer said that all the furnaces in this model had a centered air pathway. The larger furnaces had a wider pathway, and I'm guessing that the largest size, a 120K, would take up the entire width. The 60K has a smaller physical size, and a smaller blower too. Strange!

[commerce48]

Obviously. The old duct system was NOT good for 1200 CFM unlike they told him. Or his A/C coil is a lot more restrictive then it should be.

Sorry if my post was confusing. They told me that the 16 x 20 plenum was capable of 1,200 CFM, not that the entire return system was capable of that. That was by way of explaining that even reduced, I still had plenty of return.

Every sales guy that made a duct capability estimate (not many), only measured the supplies, not the returns, to come to an 850 CFM system capability. They all said that the duct design was pretty decent.

These installers said my coil was as clean as any they've ever seen. I asked about cleaning and they said it wasn't necessary, and was usually not part of their install routine unless it was clearly restricted. I believe the coil is what is called an A shape. Looks restrictive as all get out to my untrained eye!

Disregarding turbulence, is a 10 x 20 return drop (the narrowest part of the transition) sufficient for 800 CFM?

[Twilly]

Small furnace, small drain line? It appears to be the right size for the manufacturer provided cut out.

Twilly sayd perhaps but 1/2 lines have a tendency to plug up faster and we always upsize to 3/4

[HVAC Teacher]

Strictly cosmetic but crooked piping (intake & vent) drives me crazy. ( maybe it's the pic)

[commerce48]

Twilly sayd perhaps but 1/2 lines have a tendency to plug up faster and we always upsize to 3/4

Bigger is no doubt better. They did put a pretty good slope on the drain line though. What makes condensate drain lines clog? Does debris get in there, or does something grow in acidic condensate?

[commerce48]

Strictly cosmetic but crooked piping (intake & vent) drives me crazy. ( maybe it's the pic)

I think it is the picture. It is easy to change the perspective and have them look good or bad.

They did tie into existing vents, which slightly limited the options. They did change the routing based on my suggestion (he said it was actually his original thought). Originally they had mocked up (no glue) a route that would not have had the vents paralleling each other out of the furnace, and one vent would have stuck out of the furnace considerably farther for clearance.

I'm happy with the cosmetic appearance. As a non pro, cosmetics is most of what I had to go on to evaluate workmanship. And considering how picky I am, these installers were a good match. I gave my plumber hell for his slopping piping.

[kenney t]

Strictly cosmetic but crooked piping (intake & vent) drives me crazy. ( maybe it's the pic)

his vert piping looks striaght .think it's because the intake is more towards the front of unit. the run up to the 45's is a bit off but,thats the way it is

[hydronicsman]

Nice looking job. The Navien is the internal buffer tank model? Only nit I have is maybe you want to put at least a couple of two hole clamps on the CSST by the chimney in case something snags it and pulls it out. Also, be sure the CSST is bonded to your electrical panel ground. You will have to find an iron section to bond to. We had two fires in town this summer from lightning strikes, one home was bonded, one wasn't.

Inspector said one of the sites had a 6 inch section of CSST pinholed on the high side of the corrugations. Said it looked like a stove burner- flame was actually burning the length of the damage. Funny, but not. They were both LP jobs, whether or not that made a difference.

[commerce48]

Nice looking job. The Navien is the internal buffer tank model? Only nit I have is maybe you want to put at least a couple of two hole clamps on the CSST by the chimney in case something snags it and pulls it out. Also, be sure the CSST is bonded to your electrical panel ground. You will have to find an iron section to bond to. We had two fires in town this summer from lightning strikes, one home was bonded, one wasn't.

Thanks! If I take the acronym CSST correctly, that is not what was installed. It is pure PVC, and permanently bonded.

It is the internal buffer tank model. Do you have experience with it? The really poorly designed stat is my biggest disappointment other than the pump is a bit noisy. But I've worked around the noise issue by turning off internal circulation when I don't need it.

[hydronicsman]

CSST is the yellow gas pipe. Corrugated Stainless Steel Tube. Sorry for the confusion!

[commerce48]

CSST is the yellow gas pipe. Corrugated Stainless Steel Tube. Sorry for the confusion!

Hey, I edited my post as you posted this with additional comments. Oh, you are referring to my gas line, not my vents? The gas line does have a ground on it, but not an additional one just for this install.