A set of small HVAC questions

Page 1 of 2  
1) My next door neighbor had a new AC put in and they replaced the cement pad the condenser sat on with a plastic one. Is there any point to removing the cement one if it's in one piece? Later I saw a picture of the underside of a plastic pads and except for some ribs, it's hollow and has no bottom. Doesn't that mean it will slowly sink into the ground and isn't that bad? My own AC condenser unit over the last 31 years has moved 6 or 8 inches to the right, until it hangs off the edge the pad. Was there any way to stop that in the first place? Screw it to the pad? Later on? I was afraid of causing a leak if I pushed it back.
2) When using a gravity feed condensate drain line, Goodman wants a trap in the line. I don't have one now. Is this to seal heated air in the furnace and supply ducts when in heating mode. Or to keep outside air out?
3) Do people really use a secondary drain pan in case the first drain plugs up? Or is it just a secondary drain from the same pan? If a pan, where do they put this pan? (I read that it is required by code some places.) http://www.alpinehomeair.com/related/Goodman%20Coil%20Install.pdf
4) It also says in the url above:
["If the uncased coil is to be installed on top of a gas furnace, allow enough space between the top to the furnace and the bottom of the plastic coil drain pan to have a free flow of air.]
"A minimum of 2.0" distance from the top of the furnace and the bottom of the coil pan is required. The coil should be installed with the line set and drain openings to the front of the furnace."
Does this bit aobut the openings refer only to gas? I don't think so. For oil, is it necessary to have the openings at the front, and why? They're at the side now and work much better there afaic. In the front, the flue will be in the way of the condensate drain pipe and in the way if I want to take off the cover and look inside or clean the evaporator area. But my neighbor with the new furnace/ac has them at the front (with no access door iirc, and her house is the mirror image of mine, so the plastic condensate pipe goes the other direction and doesn't need to pass the hot flue).
Thanks a lot. 5) A cased evaporator is listed as having a "High-quality post-paint cabinet". What does post-paint mean? Googling didn't help.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
?

Seems silly to me. Lots of work for nothing.

I guess that would depend on soil conditions, etc. It is far easier than pouring concrete though, if it works as well. I wonder if it has any anti-vibration qualities built in.

Could have been anchor a few different ways.

Keeps creepy crawly bugs out.

Seems like a good idea to prevent damage. Plugged drains is a common problem and they can cause damage in ceilings, floors, etc. .
I don't know about 4 and 5.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 30 Jan 2011 12:21:19 -0500, "Ed Pawlowski"

I guess they charged him for it and he agreed to it. He doesn't consult with me. :)

I think it would, but I've never heard any noise from the condenser anyhow.

So it won't cause harm to screw it down? If there is no reason not to do it, I think I will put one or two screws in. Otherwise I'll feel stupid when the next one moves too.

Aha. That makes sense. When I take it apart, I'll check if there are any bugs in there. I have spiders in the basement sometimes, but I don't see any cobwebs by the sump, where the AC drain drains.

I get it now.

Thanks a lot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Interesting point. The ribs as I recall are spaced continuosly about 3" apart, forming a checkerboard pattern on the bottom. How easy that can sink into the soil, I don't know for sure, but it seems possible if the soil is loose enough. But, sinkage of pads has been a problem forever, even with a 2" poured concrete one. If you want to really solve it once and for all and you expect to live there a long time, I'd consider getting a couple of small sona tubes, dig footers with a post hole digger, fill with concrete and then set the plastic base on those.

I know in some hurricane prone parts they recommend screwing AC units down, but I think that is more for very exposed units. IF the base stays level, it shouldn't go anywhere. And if the base doesn't, then it's still going to have potential problems, ie sinking, tilting, whether screwed down or not.

I would guess that it's to keep the pressurized, conditioned air in.

I thhink there are 2 seperate things here. A pan can and should be put under the whole furnace or AC handler to catch leaking water if the unit is anywhere that it will cause damage, eg in an attic.
The secondary drain from the coils is one that is slightly higher than the first and is used to route water in case the first one gets clogged. If you use the pan under the furnace, you can run the second drain to it. That's ideal because it's supposed to be routed somewhere where you will eventually see it, realize it's a problem, and fix it. Putting one of those $10 alarms in the pan is a good idea too.


My old coils came out the side too. New ones with the coils already encased come out the front, at least in the ones I've seen. That means the two choices are with the lines coming out the front or turn it around and they come out the back. Of those choices, the most logical in most cases is to have them come out front.

The Rheem one I have that is cased I don't think is meant to be taken apart either. Even if you could take a cover off say one side, the stuff is packed in there so tight now with an N coil that I don't think you have clearance to be able to clean. Better get a decent filter and keep dirt out.
You should be able to route the condensate line without hitting the flue. Why not get a 90%+ and then you only have some 2" PVC to worry about, not to mention the higher efficiency.

No clue there. But in most cases, cased is the way to go. It also takes care of the spacing reqt between coil drain and furnace, etc. You just sit it on top of the furnace and you're done.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 30 Jan 2011 10:09:59 -0800 (PST), snipped-for-privacy@optonline.net wrote:

FWIW, that part of my neighbor's yard is a man-made hill, I think. But by now the dirt should have settled.

Hehehe. Pretty sure my pad hasn't moved or sunk since I've been here.

So there is little or no down-side to screwing it down? If there is no reason not to do it, I think I will put one or two screws in. Otherwise I'll feel stupid when the next one moves too.
Mine has always seemed level to me, but maybe there is tilt I can't see.

Now I understand. I'm okay here.

Do you think that means there is room from a bigger coil that way? I noticed that the coils they have for sale come with adapter plates, to seal the outer perimeter at the bottom in case the coil case is wider than the furnace. Not pretty but maybe I could use that to point the openings sideways.

Currently I only have 13.5 inches between the back and the wall. It might increase an inch or two if the next furnace is smaller, but none of them are much smaller and some might be an inch bigger. At 13.5, I can't even slide myself back there. and if I could, my head couldn't get past the lines, and my face and arms would be too close to see or do anything,

Well, both the Goodman and the Aspen cased coils that alpine sells have panels to the left of the openings that come off. They go top to bottom, about 60% across the face.
I thought all there would be by now are N coils but both of these are still A-coils.
OTOH, the website showed 6 photos of the Goodman cased coil, including from above and below, and it seemed like there was a double wall. But surely they wouldn't call it an access panel if the insulation and second wall didn't come out too.
When I couldn't get the condensate to drain for a couple years I really wanted an access door. I cut a small hole, which I later taped up. I didnt' have nerve enough to make a big hole.** Afraid I would hit the coil.

Okay. But through my small hole, I saw that it was clean when I had that condensate problem. Yesterday I looked in the duct right above the evaporator and it's quite clean, and I'll check what the evap looks like when I take everything apart.

I have no gas available. Only oil.

Good to here. BTW, I recently learned that with an oil furnace one needs a metal pan or a high-temp plastic pan. The Goodman cased coils come with a high temp pan it seems (I will verify that) but the Aspen (which they imply is lower cost ("non-name brand") even though the costs are about the same.), the Aspen don't have that and you have to remember to buy a high-temp pan, (or, conceivably, if they're hard to replace in a cased coil, you just can't use Aspen).
**I've told this story here once before. The condensate had gone down the pvc pipe to the sump very well for 5 or 10 years, whenever I used the AC. One year it started dribbling out the bottom of the furnace. I looked inside and it looked clean. I cut or broke the threaded pvc off, and the hole into the plenum wasn't clogged, as far as my little finger could tell. I blew into the PVC and it didn't seeme clogged. I ran a lot of water throught the PVC, from the laundry sink, and it poured out like there was no obstruction, but I thought, Maybe I flushed something out (even though I didn't really think so).
So I reassembled it and it worked no better! A year or two later I rearranged the PVC. It had come out, gone down an inch or two**, then horizontally to the wall, down the wall to the floor, across the floor, then from the wall to the sump. I changed it to go down about 3 feet instead of 2 inches, and then to the wall, down another foot to the floor and to the sump like before. After that it worked fine again. So you might say, that's how it should have been all along. Then wy did it work fine for the first 10 years!
Thanks a lot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 30 Jan 2011 20:47:04 -0500, "Stormin Mormon"
I won't do that. IIRC, in my current one there are holes in the middle of the "legs", the downward pointing dimples in the bottom of the case, that keep most of the case a little above the pad.
I've drilled holes in car firewalls and the evaporator housing and having punctured anything yet. (although I did cut a place for a receptacle, not noticing there was a 3-gang wall switch on the other side. :) ) But with this I'll be able to see both sides almost at the same time. Probably drill from the inside.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

If you don't have a level buy a cheap one and check it. You should have one to level other things, like appliances. If the unit is already over the pad edge, and you don't want to move it, drive a stake or two in the ground flush with it to stop it from moving further. If you move it and the pad is level, but it still wanders, you could just glue some cleats on the pad to stop it. Don't have to drill or screw.
--Vic
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've seen install instructions for securing them where required for hurricane protection. I never paid any attention to exactly how though, but since it's apparently required by code in some areas and installations, you would think they would all have a means of doing so.
>>using a gravity feed condensate drain line, Goodman wants a

That's the letter of what they wrote.

Unless it says otherwise, it sounds like it only applies to gas. Oil furnaces may have different air flow or design characteristics so that it doesn't matter. But who knows.... You could call the manufacturer, but most of them won't answer install questions from DIY. If you buy an encased coil, this no longer matters.

I still don;t see the need to try to put it together differently than the normal installation. If you have a serious clearance problem then it's one thing. But all I'm hearing so far is the furnace vent and AC condensate drain lines. Every furnace has those issues and they appear to be designed to go together easily, with clearance, etc as built, with the AC lines coming off the front.

What you're describing is a transition kit, or adaptor if you will, for use when you use an encased coil that is larger than the furnace. They are used in cases where you need more AC than heat. You could probably use a similar scheme to allow you to mount it rotated 90 deg. But be aware that there are restrictions on how gradually you have to taper the transition so as to maintain smooth airflow. Depending on your height limitations, that could be a problem.
But it sounds like a lot of work for a reason I'm not clear on. The furnaces are built to go together easily for most applicationsl. And today, that seems to be with the AC lines and drains coming out the front. I don't see why that should present such a problem. Many furnaces also allow the condensate drain lines for the furnace, electric, or gas to be reversed to the other side of the unit too. Should be enough flexibility there to plumb the thing without having to rotate the coils 90deg.

I don't know about that. I looked at mine and it has a panel that appears to come off. But, right behind that is that second panel you talk about. And on the Rheem, from looking at it, it did not appear that the inner panel came off. It appeared to be attached to and part of the coils. I'd look at the documentation for the coils and see if it says anything about how the access panel, cleaning, etc. Or google for cleaning... And even if that panel came off, if you have dust stuck to the coils it's not clear to me how well you could clean it with access that is still going to be very limited.

Seems odd they would include an overflow drain pan that has to go under the whole furnace with the coils. Are you sure what you're reading isn't talking about the regular drain pans that are part of every coil?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks, Vic. I do have a level, but it's always looked so level I never checked. This week it's been under 6 inches of snow so I can't check now.
On Mon, 31 Jan 2011 00:41:21 -0800 (PST), snipped-for-privacy@optonline.net wrote:

Great. No hurricanes here but I'll do something to keep it from moving.

Well, I'll try, and I'll make a greater effort to see neighbors' new furnaces.

Maybe this is why I'm still single. Maybe an objective opinion would be that I'm increcredibly picky, but it always seems reasonable to me. :=)

Good to know.

Height is a problem. That's a big reason why I can only install the smallest simplest non-electric humidifier.
There is an I-beam over part of the furnace that requires a shift several inches to the right as the duct goes up. That piece starts about 10 inches above the coil.

That would help. I'll look into that.

I guess part of this is wanting to feel the installation will be comparitively quick and easy, since I'm still a little scared of doing most of it myself. I can probably buy my way out of any problems by paying the guy who will be finishing it to do more, but that's no comfort now.
I won't be doing this until April or May, but I'll try to let you know how this part and the rest of it goes then. .........

ROTFLOL. You're right. The access panel might just give "access" to another panel. I'm glad you warned me so I don't get surprised when I get it. IIRC, the first model of the Apollo space ship was like that, and that's why they only circled the moon instead of landing.

I'll do that.

A vacuum cleaner with the round bristly attachment?
What do people do now when the drain is clogged? If they just go in through the drain hole, then my drain was never clogged. :)

Yes, the regular drain pan. What I meant here was that there was a pan right under the coil included in the cased coil. With Goodman it seems they are all high-temp. With Aspen, it seems none of them are. Elsewhere on a different subpate it said to buy a high-temp pan if you use oil, to replace the pan that is included in a cased coil.
It made no exception for Goodman, but maybe it is better for them to be safe than for me to be sorry. In case Goodman would change the kind of pan it included and they didn't find this one isolated paragraph and change it.
Thanks again.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then I don't see the problem with mounting a humidifier on the coil box.... The box alone is a lot larger than typical humidifiers. And you usually can mount it starting a few inches above the bottom, no? All you need is room to be able to make the cut in the sheet metal without hitting the evaporator coils and to know what's located near where your're cutting. By cutting it before install, you'll know exactly.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Over the years, Aprilaire has been consistently recommended as one of the best humidifiers. The 700 is self powered, so no additional bypass duct is needed. I have one of those and it doesn't enter the coil box at all. I've seen a Honeywell that uses the same media, but is a bypass and it too does not extend at all into the box/plenum. I would think the Aprilaire bypass ones are similar. So, you have choices in a humidifier that doesn't extend into the coil box. In fact, I'm having a hard time imaging why you would design one that way, or if you could even sell it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 1 Feb 2011 07:28:57 -0800 (PST), snipped-for-privacy@optonline.net wrote:

It's designed that way becuase it depends on the hot air from the furnace (and not from a humidifier fan) blowing by the wet fiberglass pads, so the pads have to be in the duct, in the original airflow. So the pan is in there too, of course. So it's small and needs no electricity.
They've been selling the one I have for 25 years that I know about.
It says "General Filters, Inc. [that is, Arthur Redner] founded in 1937, developed the implementation of the wool-felt fiber element for cleaning home heating oil. The General Brand Fuel Oil Filter allows residential and commercial oil furnaces to run more effectively and efficiently. The General Fuel Oil Filter set the industry standard across North America and leads the pack for reliability and dependability today.
1940s GFI won a government contract, delivering an engine-driven portable filter device to military aircraft ground support during WW II. GFI introduces new technology, using wool filter elements to clean lubricating oils. www.generaloilfilters.com "
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Doesn't sound like a good idea to design it that way because if you have AC coils you can't install it, as you discovered, or if you can, it's problematic. And with those AC coils, the last thing you want is something sticking into the coil box, further restricting the air flow.
There are plenty of humidifier choices that don't extend into the coil box, including bypass models that require no power. Check out Aprilaire, problem solved.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 30 Jan 2011 10:09:59 -0800 (PST), snipped-for-privacy@optonline.net wrote:

They used a plastic pad when they put mine in. About 8 years in I noticed a corner had dropped a couple inches. A pry bar and some gravel fixed that. The problem was bad drainage making the ground soft there. Fixed that too. Nothing wrong with plastic pads IME. I don't think my unit weighs more than a couple hundred pounds, if that. Have to be pretty heavy before I'd go with footings.
--Vic
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 30 Jan 2011 20:57:09 -0600, Vic Smith

I don't think so either. I just want to know there is no reason to take out my cement and put in plastic, like they did for my neighbor.

LOL
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mm wrote:

The original concrete pad may not have been big enough for the new unit.

In all the installations I've seen - and admittedly not that many - the secondary drain is used as a fail-safe in case the first drain becomes clogged (it almost always will). This second drain is connected to a pan located UNDER the base unit. When the first drain becomes clogged, condensate will overflow to the second pan and drain to somewhere it can be seen, often to the house's soffit.

Sounds like mumbo-jumbo. On its face it says the cabinet went on after the paint. Call 'em and ask; the rest of us would like to know too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

No, it was plenty big. While it was under the original warranty, the original owner had some leak they coudln't fix, so 25 more years ago, they put in an extra-large compressor. What a large comparessor has to do with a leak I don't know, but that's what the owner told me. That fit on the original pad and this one is smaller than that.

Now that you mention it, I have seen that, at my brother's old house I bet.
Of course my furnace is in the basement. The AC condensate just ran through the pvc to the sump for years, but for a year or two, the few days I used it, it dribbled out the bottom of the furnace. One of those times, the water heater started to leak but I thought the other water just hadn't dried yet!

Yeah, it does. :)

What are the odds I could find someone who knows! Very small.
Thanks alot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mm wrote:

Ah! Okay. Put a big pan under the whole installation and equip it with a water alarm (less than $25).

No, the telephone operator might very well be the one who coined the phrase. Or the receptionist. Or the janitor.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Good idea. I remember now. The water heater just dribbled for a few days. If I'd realized it was leaking I coudl have turned off the hot water, before it all poured out, wetting all my cardboard boxes on the floor, etc.

LOL.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I'll screw it to the pad then, unless you think that will harm something. (And you don't seem to think that.)
Thanks a lot.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.