Thread: furnace T

This house has two 95% furnaces in the crawl space, the T's that you can see in the foreground are coming from the other furnace and then going to the exterior. I could not find anything in the manual that says you can or can not do this, I have e-mailed the manufacture but I have not heard back from them yet. I think that they should be separate for some reason, any insight would be appreciated.

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Originally Posted by chris mcintyre

I could not find anything in the manual that says you can or can not do this,

Chris,

Probably something in the installation instructions about running the vents "full size" (or similar wording) to the termination?

If so, that precludes reducing its size in any way, which also precludes connecting two together.

Do you have a link to the installation instructions?

Also, I don't know about for that use, but PVC piping needs to be supported every 4 feet in the plumbing code. Also looks like one PVC is supported from the other, and I doubt that is allowed either.

I also see a "running trap", and running traps are not allowed.

Don't see a sediment trap either.

Have you checked to see is those blocks (Styrofoam?) are approved for supporting that unit? Also clearance to combustibles? Tipping over, etc.

Jerry, I looked through the manual that was left on site, I couldn't find the online manual (at least not the complete manual), but this a link to the units being used. Air Conditioners, (A/C), Packaged Heat Pumps and Central Air Conditioning (AC) Units for Home Healing and Cooling Systems. Residential and Commercial Heating and Cooling Equipment by Goodman Manufacturing available in 14 SEER and 13 SEER ratings for

Not sure what a running trap is. HVAC is by far my weakest area (but I learn a little more every day).

No sediment trap, not just on this job, but never on any job. I have always heard of it referred to as a drip leg and since the NG in this area has no moisture it is not necessary, that is from not only the HVAC guys, but the local gas company as well. Only when I became a reader of this site was I made aware of the term sediment trap, another example of a code not being enforced in a particular region.

As far as the blocks, I didn't notice them when I was under the house (there were plenty of other issues to keep me occupied) but in the picture they sure look like styrofoam. I will check on Monday and if they are I will add them to the very long list for the HVAC guy.

Originally Posted by chris mcintyre

I couldn't find the online manual

http://www.acdirect.com/xcart/images...ts/IO-280D.pdf

Not sure what a running trap is.

See attached photo.

No sediment trap, not just on this job, but never on any job. I have always heard of it referred to as a drip leg and since the NG in this area has no moisture it is not necessary, that is from not only the HVAC guys, but the local gas company as well.

Sediment traps and drip legs are two distinctly different things for two distinctly different purposes.

a) Drips legs: As soon as someone says "drip legs are not required because .. " chime in and say "I am not talking about a drip leg. Drip legs are only required for *wet* gas. I am talking about a *sediment trap*."

b) Sediment traps: Sediment traps ARE REQUIRED for all types of gas.

As far as the blocks, I didn't notice them when I was under the house (there were plenty of other issues to keep me occupied) but in the picture they sure look like styrofoam. I will check on Monday and if they are I will add them to the very long list for the HVAC guy.

From the installation instructions: "The minimum clearance information for this furnace is provided on the unit’s clearance label. These clearances must be permanently maintained."

Look under 'Furnace Suspension', there may be supporting problems related to the location of those support blocks too.

Also note 'Drain Trap and Lines', and 'Freeze Protection'.

"Piping must be adequately secured and supported to prohibit sagging, joint separation, and/or detachment from the furnace. Horizontal runs of vent/flue piping must be supported every three feet and must maintain a 1/4 inch per foot downward slope, back towards the furnace"

Read through and see if you can find anything related to routing of the vent. I skimmed through it but have to do something else before reading through more carefully.

Additional information in that installation instructions:

(underlining is mine)
"FURNACE SUSPENSION

If the furnace is installed in a crawl space it must be suspended from the floor joist or supported by a concrete pad."

There are but TWO stated options, neither of which is shown in the photo.

"Never common vent this appliance with another appliance or use a vent which is used by a solid fuel appliance."

And even more:

"Also all vent/flue piping exposed outdoors in excess of the terminations shown in this manual (or in unheated areas) must be insulated with 1/2” thick closed cell foam "

Never common vent this appliance

with another appliance

Found this on page 12, but you beat me to it.

You have given me a lot of other issues to check into, and I will, as always your expertise and willingness to help is greatly appreciated.

Not sure what happened with the font, tried to edit but didn't have any luck, more of my computer skills at work .

Originally Posted by chris mcintyre

Not sure what happened with the font, tried to edit but didn't have any luck, more of my computer skills at work .

When in edit, click on advanced, that will bring all the options up that you have when you first make the post, including font size.

Originally Posted by chris mcintyre

Found this on page 12, but you beat me to it.

You have given me a lot of other issues to check into, and I will, as always your expertise and willingness to help is greatly appreciated.

Not exactly what I was going for, but at least now you can read it .

The common venting is a big time no-no, great catch!

Don't think I've ever seen that before Chris, would you mind if I used the photo in some of my personal classes?

It's a great one.

Originally Posted by DavidR

Don't think I've ever seen that before Chris, would you mind if I used the photo in some of my personal classes?

Not at all, please do.

Besides quoting installation instructions and rules (and yes, they are the CYA we have to use) go back to the basics. If one furnace is operating while the other isn't, a chance exists that the flue gases could be channeled into the other furnace and then into the crawlspace rather than outside. I can see no one ever saying that would be proper installation. Even if approved in the installation instructions, I would call attention to it and recommend that the flues be run separately.

I saw my first running trap last week; and, wasn't sure what it was. And, I certainly did not understand how it worked.
Can you share more info.

The running trap doesn't hold the water basically. They are allowed here in SC on condensation drains.

Originally Posted by Troy Eskew

The running trap doesn't hold the water basically. They are allowed here in SC on condensation drains.

"They are allowed here in SC on condensation drains."

Not really.

Not really ... because I would bet that your code says to install the units in accordance to the manufacturer's installation instructions, and the manufacturer's installation instructions state ... no running traps ... thus running traps are not allowed.

Now, if you said 'That is not enforced here ... ", well, okay, but 'not being enforced' is not the same as 'being allowed'.