On 5/30/2011 7:30 PM, DerbyDad03 wrote:
On May 30, 8:03 pm, The Daring
wrote:
On 5/30/2011 3:12 PM, DerbyDad03 wrote:

On May 30, 2:19 pm, wrote:
On May 30, 8:51 am,
wrote:

On May 29, 11:39 pm, wrote:

On May 29, 10:07 am, wrote:

On 5/29/2011 9:01 AM, wrote:

On May 29, 2:25 am, wrote:
On May 29, 1:05 am, The Daring
wrote:

On 5/28/2011 8:17 PM, DerbyDad03 wrote:

I have a Conquest 90 Max gas furnace with central air.

I also have a bunch of questions:

1 - The internal coils have not been clean since it was installed 5
years ago, so I decided to take a look and see if they needed
cleaning. Problem is, I'm not sure how to access them.

I removed the screws from the panel where the condensate and
refrigerant pipes are, but as you can see from this picture, I can't
remove the panel because of the vent pipe.

http://imageshack.us/photo/my-images/62/furnacef.jpg/

If I could tilt the top or bottom of the panel outwards, I could
remove it, but the vent pipe prevents any significant tilting.

There is no other panel that I can remove. The other 3 sides that
surround the coils are a single piece which has the duct work on top
of it. The duct work would have to go up in order for the 3-sided
surround to come off.

How do I get to the coils?

2 - Through the limited opening, I can see into the coil area with a
flashlight. I see 2 tee-pee sets of coils and as far as I can tell
they are perfectly clean, at least on the surfaces that I can see with
the panel open as shown. Should I just close it up and forget about it
or are there areas I should check - assuming I can gain better access?

3 - When I removed the panel I saw 2 stickers, both of which raised
questions in my mind:

3.1 - One sticker has a picture of a "condensate drain trap" made from
a piece of flexible tubing attached to the drain output pipe. As you
can see from the picture, I don't have a trap. At the bottom of the
PVC pipe seen behind the gas line is the condensate pump.

The pump sends the condensate up a flexible tube and across the
ceiling to the utility sink.

I don't need a trap with that set up, do I?

3.2 - The other sticker says: "Coil is shipped with a low pressure (5
-10 psi) charge of dry nitrogen. Evacuate system before charging with
refrigerant."

Would the unit work (i.e. cool) if the system was not evacuated/
charged when it was installed?

I'm not saying that it wasn't evacuated/charged because I don't
remember if the installer did it or not, so I'm just curious.

Thanks!

Are you sure you can't get the PVC vent loose and swing it aside?
Me and my bud I do AC work with never install a 3/4 PVC drain without
a union so we can service the drain if it clogs up. You can cut the
3/4 drain line and install a coupling without glue so you can get it
loose. I always use unions anyway. With the 3/4 drain out of the way,
you could easily remove the cover. Big box stores have the unions.

http://www.grainger.com/Grainger/Union-1WKD7

TDD

@TDD:

That vent pipe is for the flue gasses from the burner in that high
efficiency direct vent furnace... I wouldn't cut into that for any
reason EVER, as if you don't glue it up perfectly when you put
it back you will have issues with carbon monoxide leaking into
your home from the exhaust products during heating season...

While I would not cut the vent pipe unless it was really
necessary, the notion that you can't do it "EVER" because
it's dangerous is pure nonsense. It's just glued together
using regular PVC cement and if you can glue a piece of PVC,
it's no big deal. IF you think that is high risk, explain how all
the furnaces, hot water heaters, etc, prior to high efficiency
used simple galvanized sheet metal pipe that just got shoved
together and secured with sheet metal screws. The seal
there was far worse than what you get today with PVC pipe.

The older systems that you could simply slap together as you described
were natural draft. High efficiency designs use induced draft and the
flue is pressurized because of it.

The better solution here is to have the OP cut the sheet metal
panel which can not clear the obstacles and obtain a piece of
flat stock which he could install so he could screw it back into
one piece when he is closing the coil compartment on the
main trunk duct back up again... The joint the OP cuts in the
cover panel and the screw heads can be sealed up with foil
duct sealing tape...

~~ Evan- Hide quoted text -

I'd like to know how he's going to cut that piece of sheet metal
when the access is so limited. For sure I'd cut the exhaust
pipe before I did that. I'd also check to see what the exhaust
is or isn't connected to inside the furnace. There is a small
chance it could be disconnected from inside.

But, if the coils appear clean, I'd just put it back together and
save a lot of trouble. The real problem here is that the eqpt
manufacturers typically don't provide a means to clean the
coils. Nor do installers take that into account when doing
the install. On the other hand, if you have a decent filter,
I've seen systems that went 25 years and the coils were
still fine.

Yes, that and you can have a slightly imperfect glue joint on
a length of PVC drain pipe and never find out about it until
the line clogs and the entire pipe fills up with water...

With a high efficiency condensing boiler exhaust pipe,
there is an induced draft in the flue pipe and it is
under pressure, any imperfection in the PVC glue
joints in a flue pipe on such a boiler would allow
dangerous carbon monoxide gas to leak into the
house...

~~ Evan- Hide quoted text -

- Show quoted text -

What exactly do you think the typical HVAC guy does
with regard to that PVC exhaust pipe that is so
different from what a guy like DerbyCad could do?
Do they use some secret solvent or glue? No
Do they use some special skills, different from
gluing ordinary PVC pipe? No
Do they presssure test it for leaks? No

You jump into things you don't understand and
issue all kinds of nonsensical advice. Some
recent examples:

Code says metal eletrical conduit can't touch
metal HVAC ducts or any other metal

Nitrogen is recovered from an HVAC system

I would not cut that PVC exhaust pipe to clean
the coils, because he's looked at them and said
they are clean. But if Derby wants to cut it, for whatever
reason it can be put back in place with a simple PVC
coupling.

Also, there is no dangerous amount of CO to
leak back into the building unless the furnace
is operating improperly. And even then, it would
have to a significant, leak, not a small pinhole
leak.. Yeah, there is slight pressure in that
PVC exhaust pipe, but it's minimal.
It's not a 50PSI pipe.

This is a homerepair newgroup, isn't it? Explain
how gluing a simple PVC coupling into a furnace
exhaust is any more dangerous than a homeowner
replacing a gas stove or dryer. Or wiring up
their own hot tub or dozens of other things that
they do every day.

You are right, there are dozens of things that homeowners
do every day that they absolutely shouldn't be doing because
they are not properly trained in how to do them...

Because they are lucky and manage to get the thing done
without injuring themselves or burning their house down today
doesn't mean that the repair or improvement will stand the
test of time...

As far as a PVC vent pipe for a high efficiency burner being
involved in some repair -- no way, not unless the homeowner
in question has experience gluing PVC and can create
consistent air-tight joints...

The problem that _this_ OP has is a sheet metal problem,
not a vent pipe, drain line or refrigeration line issue...

The sheet metal panel is too large to manipulate it around
the obstructions near its installation -- so either someone
would have to remove the obstructions EVERY TIME they
wished to access the main trunk ducting panel OR make
the panel so that it can be removed around the barriers
by cutting it into smaller pieces which are attached to eachother
in the same way the outer edge of the panel is affixed to a gasket...

For all the "common sense" you offer, I haven't seen too many
threads where you have offered your wisdom where no less
than 5 other people hadn't offered it first...

I came up with the answer in this thread that seems to be
something the OP might actually consider doing if he actually
wants to open up the duct work and inspect/clean his coils...

~~ Evan

As it turns out I was able to remove the panel without cutting
anything.

It's hard to tell from the picture, but the PVC vent pipe has putty
around it where it enter the exhaust port on the furnace.

http://imageshack.us/photo/my-images/62/furnacef.jpg/

Once I removed the putty I was able to lift the vent out of the port
and move it (with some effort) to the side just enough to be able to
swing the bottom of the panel out enough to rotate it around the other
obstructions and out.

Unfortunately, I think it was all for naught. I don't have much more
access to the coils than I did before.

Behind the exterior panel there was another panel whose purpose is to
keep the condensate from soaking into the insulation on the back side
of the exterior panel. Once that was panel was removed I found this:

http://imageshack.us/photo/my-images/703/acoils.jpg/

I can't get to the coils anyway. There's barely a 1 1/2" opening at
the largest point along the top near the bar code label. Unless I'm
missing something, the only thing I can do is inspect the coils
because there's no room for a coil brush to reach anymore than a very,
very limited area of the coils.

Oh cool! You have a W coil. No joke, that's what it's called. If you
remove the 3/4" PVC drain and put it back with a union you may actually
be able to (with some help) slide the W coil out of the housing with the
refrigerant lines still connected. You can set it on top of a large
trash barrel next to the furnace and with great care, get some
evaporator cleaner and a water hose (hot water works best) and clean it
up to like new condition. Of course a shop vac is another useful tool to
bring to the party. I slide coils out all the time to clean them
but if I can't set it to one side with the lines still connected, I have
the knowledge, tools and equipment to pump the system down and
remove the evaporator coil for an outdoor cleanup. The first picture
you posted looks like there would be enough room to slide the W coil
out with the lines attached for a good cleaning. :-)

TDD

Feel free to stop over when you're in the area 'cuz this DIY'er ain't
sliding nothing out of any housing! :-)

If it gets to a point where I think it needs cleaning, I drop the big
bucks and have a professional do it.

In the immortal words of Dirty Harry, "A man's got to know his
limitations."

Thanks anyway!

Well, it's an advanced DIY project but you may still be able to lift it
up to inspect it by looking underneath. :-)

TDD