OK to cut humidifier in side of A-coil box?

[N8N]

Subject says all... it's been unuually cold for the area here (DC-land, single digits at night) and I stayed last night at my girlfriend's place while she was out of town. A while back I'd brought over a little weather station thing for several reasons, and had always noticed that it was very dry in the wintertime. We've disconnected the dryer vent in an attempt to mitigate this (I know you're not supposed to do that but desperate times etc.) Last night it got down to single digits and the hygrometer was measuring 20% RH when I got up this morning. I guess the combo of only one person in the house and cold temps just dry everything out.

The house has an updraft natural gas furnace with a whole house A/C sitting on top of it. There's no room to install a typical humidifier like I'm used to seeing e.g. Aprilaire 700 between the A-coil and the ceiling. Would it be acceptable to just cut it right into the side of the A-coil box itself? This seems to be literally the only way to make this happen.

Or are there any other ideas for humidification (besides leaving a teapot on all the time...)

Oddly, my place does have a humidifier that I serviced when I moved in, and never finished hooking back up (hack job by previous residents) and it never gets this dry...

thanks...

nate

[trader_4]

Typically today they are being installed on the cold air side
with a duct running over to the hot side to bypass some air across
it. That avoids the problem you describe. I had a relatively new
Aprilaire powered model (760 I think) that doesn't used bypass air
and it was mounted on the hot side of my old furnace. When I replaced the
furnace, I put it back on the hot side. Not sure if I'd do that
again. With the coil and plenum assembly sitting on the floor,
it was possible to see where there was clearance and cut it. But
today the plenum part is double
walled with insulation in between. And instead of A coils the
higher efficiency ones today, at least mine, had an N coil, ie
an additional section. The humidifier will still fit, but
without having it sitting, open, pre-install on the floor, I
would not have attempted to cut a hole because there isn't much
clearance, IDK if you could even figure it out, because once it's
on the furnace, lines connected, not so easy to tell. Bottom line,
much easier to put a bypass model on the cold side. Then you just
need a hole anywhere on the hot side for the bypass duct. It
can be up higher or over, etc where there is no coil to worry about.

Also, with it in the single digits, that 20% humidity isn't too
far off. You want the humidity backed down as the outside temps
decline. About 40% when it's 50F out, down to mabye 25% when
it's in the single digits. Otherwise you can get condensation
around windows, ceilings with recessed lights that damages paint,
etc. When it'r real cold like that, better to err a little on the
low side instead of getting it too high. I'd recommend getting one
with an outdoor sensor that automatically does the adjustment. Highly
recommend Aprilaire.

[Tony Hwang]

Hi,
700 model is pretty big in capacity, No need to over sizing it. Our
house has 600 model. I'd stay clear of evaporator coil for maintenance
reason.

[trader_4]

On Saturday, February 14, 2015 at 9:20:28 AM UTC-5, trader_4 wrote:

Just to add to what I previously posted, if it's really an A
coil, one layer of metal to cut through, then I'd probably put
it on the hot side. That's what I did with my old furnace.
Recent experience is with an N coil, double thickness, insulation
in the middle plenum.

If it;s single wall, A coil and you can visually verify where
the coil is at or alternatively drill some small, very limited depth
holes to probe and figure it out, then that's OK too.

[Stormin Mormon]

On 2/14/2015 6:33 PM, trader_4 wrote:
>
> If it;s single wall, A coil and you can visually verify where
> the coil is at or alternatively drill some small, very limited depth
> holes to probe and figure it out, then that's OK too.
>

I'd not want to drill holes into an AC coil.
Too easy to nick a refrigerant line, and
let out the "freon".

To the OP, I think others have mentioned
the hum typically goes on the return side.
I'm not there to see the setup. But, cutting
into an AC cased coil is a poor decision.

In my trailer, I've got a floor model humidifier,
which takes about two gal of water per day.
It's a bit of work, but easier than try to
modify my duct work.

-
.
Christopher A. Young
learn more about Jesus
. www.lds.org
.
.

[N8N]

I've honestly never seen a humidifier on the cold side, only on the hot side above the A-coil (if present.) Will that actually get enough water into the air to make a noticeable difference? One would think that air in the high 60s F will be less likely to draw in moisture than the output of a running furnace...

nate

[Stormin Mormon]

On 2/19/2015 7:49 PM, N8N wrote:
>
> I've honestly never seen a humidifier on the
cold side, only on the hot side above the A-coil
(if present.) Will that actually get enough water
into the air to make a noticeable difference?
One would think that air in the high 60s F will
be less likely to draw in moisture than the output
of a running furnace...
>
> nate
>

I used to install them. There is a six inch round
duct that goes from the hot air to the humidifier.
Some air pumps in circles, but most of it goes into
the structure. Yes, it works. There is a damper that
needs to be closed for summer, open for winter.

[N8N]

On Thursday, February 19, 2015 at 8:24:56 PM UTC-5, Stormin Mormon wrote:
> On 2/19/2015 7:49 PM, N8N wrote:
> >
> > I've honestly never seen a humidifier on the
> cold side, only on the hot side above the A-coil
> (if present.) Will that actually get enough water
> into the air to make a noticeable difference?
> One would think that air in the high 60s F will
> be less likely to draw in moisture than the output
> of a running furnace...
> >
> > nate
> >
>
> I used to install them. There is a six inch round
> duct that goes from the hot air to the humidifier.
> Some air pumps in circles, but most of it goes into
> the structure. Yes, it works. There is a damper that
> needs to be closed for summer, open for winter.
>

Ah, OK, after some more searching and that idea in my head I see what you mean now.

But then I still have the same issue; the only accessable point on the hot side to install the duct flange is the A-coil box...

nate

[trader_4]

No other hot side duct area near the furnace is accessible for a 6" round
duct connection? That would be very strange. And you certainly can cut
a hole in the section with the coil, as long as you ascertain where the coil
is and isn't and make sure there is no way to hit it.

[Stormin Mormon]

Might have to. I'd reccomend to open the cover
of the A coil, so you can see what's inside. They
usually have 1/4 inch or so of fiberglass inside
the sheet metal. I'd want to be super sure not to
damage the coil. Also to be sure a future tech
could get the coil out for service and cleaning.

[N8N]

Nope. Is very strange. Very tall updraft furnace, A-coil on top of it, then there's maybe 6" of flex bellows and the duct disappears into the ceiling. The ceiling in the mech. area is very low, probably hiding more ductwork and plumbing, but I'm loath to cut into it as then that would turn into a Major Project(tm) and I've already done tons of stuff that'll never give any payback except to the actual owners... (but was kind of necessary, like fixing the arsed up handrails, replacing completely toasted receptacles, etc.)

nate

[D F Bonnett]

On Sat, 14 Feb 2015 06:06:09 -0800 (PST), N8N <n8n...@gmail.com>
wrote:

>Would it be acceptable to just cut it right into the side of the A-coil box itself?

That's how mine was when we moved in and how the new furnace was done
later on. So far, so good