Results 1 to 11 of 11
  1. #1
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562

    90% furnace and drain pan

    Getting a 90%+ furnace (no air) and its suggested that a drain pan with drain and alarm be installed in case the furnace's condensate drain or plumbing leaks.

    This is in a crawlspace and the furnace usually sits on blocks the ground. So I guess the furnace would then be sitting on blocks in the drain pain (are drain pans designed for that load?) or would it be best to support the furnace from the joists like they do in attics (I know that's usually done to avoid noise transmission) or some other means?

  2. #2
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by b26440510 View Post
    Getting a 90%+ furnace (no air) and its suggested that a drain pan with drain and alarm be installed in case the furnace's condensate drain or plumbing leaks.

    This is in a crawlspace and the furnace usually sits on blocks the ground. So I guess the furnace would then be sitting on blocks in the drain pain (are drain pans designed for that load?) or would it be best to support the furnace from the joists like they do in attics (I know that's usually done to avoid noise transmission) or some other means?

    Proper installation is suspended from the floor joists with threaded rod, uni-strut w/isolation springs on the threaded rod and rubber isolation pads between the unit and uni-strut.


    I would also make sure that the uni-strut is installed parallel with the unit to prohibit sagging of the cabinet over time.

    Drain pan is always a great idea but I am a bigger fan of a proper float switch over a nuisance alarm.

  3. #3
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Quote Originally Posted by seatonheating View Post
    Proper installation is suspended from the floor joists with threaded rod, uni-strut w/isolation springs on the threaded rod and rubber isolation pads between the unit and uni-strut.

    I would also make sure that the uni-strut is installed parallel with the unit to prohibit sagging of the cabinet over time.

    Drain pan is always a great idea but I am a bigger fan of a proper float switch over a nuisance alarm.
    Been trying to find some examples on the net with little luck. Last installer I spoke with said it sounded like a good idea but they've never mounted them like that it in a crawlspace.

    I'm guessing "unistrut" is what I'd call channelized & slotted bar, like a big brother version of adjustable shelf wall support. I was thinking it would be better to have all four edges supported or at least another horizontal piece down the middle.

    What would your float switch activate?

    Isn't a problem with switches in these situations is that if it is activated the furnace shuts down. For AC, its not a big issue, but if you're away from home and your heat is off that can cause some problems.

  4. #4
    Join Date
    Jul 2010
    Location
    Andalucia
    Posts
    3,238
    Quote Originally Posted by b26440510 View Post
    Been trying to find some examples on the net with little luck. Last installer I spoke with said it sounded like a good idea but they've never mounted them like that it in a crawlspace.

    I'm guessing "unistrut" is what I'd call channelized & slotted bar, like a big brother version of adjustable shelf wall support. I was thinking it would be better to have all four edges supported or at least another horizontal piece down the middle.

    What would your float switch activate?

    Isn't a problem with switches in these situations is that if it is activated the furnace shuts down. For AC, its not a big issue, but if you're away from home and your heat is off that can cause some problems.


    I agree I wouldn't want to lose my heat because of a drainage issue.
    "War is cruelty,and you cannot refine it." Sherman to the leadership of Atlanta prior to burning the city.

    "Common sense is the collection of prejudices acquired by age eighteen."
    Albert Einstein

    Romney campaign: "We're not going to let our campaign be ruled by fact-checkers,"

    Lindsey Graham: “We’re not generating enough angry white guys to stay in business for the long term.”

  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,841
    How the furnace is supported or 'mounted' is more relavent to your location and the installing company. But the issue is that if they're going to put an overflow drip pan under the furnace, the dip pan must be supported over its entire length and width. Otherwise, should if fill with water, that's when it will collapse, dump the water and it was all for naught. One issue in supporting a drain pan can be the limits of the furnace to combustibles. In the past we've used a sheet of plywood under the pan so it has full support. Sometimes this does require raising the furance higher but lately we've used the Goliath heavy gauge drain pans that have stand-offs and rubber donuts all included. They can be purchased with or without a float switch. I believe those are heavy enough to hold the water without buckling.

    As for hanging the furnace, I have issues with that. If done correctly, it's not a problem but too often, in fact, 99% of the time, it's done incorrectly and the vertical hangers are blocking the blower panels, the uni-strut is run across the short side of the furnace allowing it to bow in the middle, making the installation of access panels nearly impossible and the fact that many manufacturer's make access panels that have a flange that goes over the outside of the unit. So if the unit is set directly on the unistrut (that's running across the short side, remember?) then it becomes impossible to install the panels because the side of the unit is now on the strut and the unit needs to be raised to put the panel flange UNDER the unit. Again, the Goliath pan eliminates all of these objections by having elevated contact points that both evenly support the unit and also allow all panels to be removed and reinstalled without interference.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  6. #6
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Thanks for the goliath pan info. Saw they have one for furnaces but its not meant to be hung. Since this is going in a crawlspace it sounds like I would have to level the area then place the pan then place the furnace on the pan. I can see where it would work on basement floors.

    It may be more practical to hang the furnace (which lets me level the furnace easier) and then just place a drip pan on the ground underneath. I'm not too concerned with the pan being level 360 degrees, as long as the pan is pitched toward its drain/sensor it should be sufficient which should be doable with just some leveling sand.

    Believe me, I've already thought about the best ways to run the support rods so the panels (and internals) are fully accessible. I've sen some install drawings where the rods are in front of the panels.

  7. #7
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by b26440510 View Post
    Thanks for the goliath pan info. Saw they have one for furnaces but its not meant to be hung. Since this is going in a crawlspace it sounds like I would have to level the area then place the pan then place the furnace on the pan. I can see where it would work on basement floors.

    It may be more practical to hang the furnace (which lets me level the furnace easier) and then just place a drip pan on the ground underneath. I'm not too concerned with the pan being level 360 degrees, as long as the pan is pitched toward its drain/sensor it should be sufficient which should be doable with just some leveling sand.

    Believe me, I've already thought about the best ways to run the support rods so the panels (and internals) are fully accessible. I've sen some install drawings where the rods are in front of the panels.
    You haven't switched to DIY have you?

  8. #8
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Quote Originally Posted by seatonheating View Post
    You haven't switched to DIY have you?
    Nope, although I know it must seem like it

    I'm too old and fat to work in the crawlspace for any amount of time. Heck, I don't even work on my own car anymore!

    Just gathering some facts and tips so I can have a decent conversation/quote from the next two companies (the last two never returned my calls for over a week now). Seems like I have to be really educated in order to know how all this should fit together so I can judge the installers suggestions, and that's just the physical mechanics of it, not any airflow stuff.

    For some reason I really have a sore spot on getting the furnace mounted correctly. The last two Amana's were just sitting on two concrete blocks and were racked. It wasnt much better with the RGJF install. Its just something about seeing a piece of equipment not sitting on an adequate base.

    I only wish I was able to find some techs like the ones on this board so I could get this installed and over with. I was planning on having it done by June, now I think I'll be lucky if its in before November.

  9. #9
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,761
    nothing wrong with making a platform for pan to sit on then furnace on top of that. that way there is zero chance of noise transfer through joists.

    NEVER kill power to a furnace with a float switch no matter where its installed. better to have a little damage from a condensate leak than to destroy the plumbing in a house from a freeze up.

  10. #10
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    btw, from what I can find on the internet, maybe it was two 10' long pieces of unistrut they had the RGJF furnace sitting on which in turn sat on my two concrete blocks. It looked like some kind of industrial shelving square tubing.

    That was the "appropriate support structure" the last contractor used, and I even had them put that exact phrasing in the quote, and yet they still cut corners.

    It was laughable because as we were working up the quote he was saying how they'd build a nice platform out of pressure treated wood since he also didnt like just the two concrete blocks method.

  11. #11
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    Quote Originally Posted by b26440510 View Post
    btw, from what I can find on the internet, maybe it was two 10' long pieces of unistrut they had the RGJF furnace sitting on which in turn sat on my two concrete blocks. It looked like some kind of industrial shelving square tubing.

    That was the "appropriate support structure" the last contractor used, and I even had them put that exact phrasing in the quote, and yet they still cut corners.

    It was laughable because as we were working up the quote he was saying how they'd build a nice platform out of pressure treated wood since he also didnt like just the two concrete blocks method.

    Sounds like Georgia has a bunch of "good ole boys". No offense to any of you guys on here from Georgia .


    Honestly, why are things like this so difficult for these guys to comprehend?? You want a nice platform, build a nice platform. This is child's play.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event