Is there an Alternative to Roof Air?

[heinz wittenbecher]

One of my pet peeves is the noise of the roof air unit. I have a Dometic
15000BTU with the heat pump and unfortunately it only has 2 fan speeds but
even my previous one was 'noisy'.

I know that air has to circulate, etc, etc but isn't there an alternative
even for a coach our size?

I suppose one gets used to the noise (does one?), but as I live in the more
temperate area of the Northwest (actually Southwest of CanuckLand) I get
spoiled by not having to run the AC all the time. Then when I hit CA or
Texas it's 24hour GenSet/AC. Nothing like the roar of the AC unit to kill
the serene settings of nature.

BTW, any chance someone out there has the same unit and managed to 'quieten
it down some'?

Of course the real breakthrough I'm waiting for is a tractor beam on the
highway that the GMC can lock onto, i.e. a real autopilot.

Oh well, AC first...
Thanks in advance for any suggestions.

Heinz
sweatin' it out in CA.

 

[donald w. miller]

Heinz,

I agree with you about the Roof A/C noise. I have had roof air for 30 years
and never adjusted to it although I don't mind it when asleep.

I hope my Alternative to Roof Air works OK, otherwise I am going to be
really stuck in the deep stuff this time.

As part of our refurbishment I have already replaced both roof A/C units
with some nice quiet ventilators.

My alternative is to greatly enhance the Dash Air output and make it our
only A/C.

With the 455 engine idling, the oem compressor pumps enough freon to out
perform my two roof air units. Unfortunately, other areas of the dash air
system are lacking and do need some upgrading.

Jim Bounds gave me a thought provoking response on 6/25/98 and Jim, I am
looking forward to discussing this further with you on the phone soon.

Jim has installed a second evaporator under the refrigerator which operates
from the dash compressor and he says with it, the dash air can cool the
coach very well. This setup is similar to the dual air units often seen in
Suburbans and Vans.

I recently modified my dash air box for enhanced air flow. I need to do
some further testing before I would want to recommend my modification to
anyone else but it looks promising so far.

Once my modified dash system with a second evaporator are performing well,
my next step will be to add 120 volt shore power capability to the Dash
Air.

This will involve either adding a 120v compressor up front or driving the
oem compressor with a 120v motor and a belt. I am still pondering the
tradeoffs but leaning toward the belt driven scheme.

Two 14" 12 volt fans will cool the A/C condenser in front of the radiator.
They will cycle with the compressor.

By eliminating the roof air I eliminated our largest genset loads so our
Onan is being replaced by a high output 12 volt alternator and a 2500 watt
sine wave inverter.

When boondocking the idling 455 engine will make enough electricity and it
idles quieter than the Onan. During quiet hours AC is available from the
inverter and house batteries.

The idling 455 also heats the hot water, and heats or cools the interior as
needed.

For electricity I am using a large frame Leece Neville 12v alternator as
they are very dependable and produce well over 100 amps with the engine
idling. The inverter is a Statpower unit.

For me the most troublesome factor to overcome is the idea of letting an
engine idle for long periods of time.

With leaded fuel and older engines there can be some problems, but the
experts tell me not to worry about this engine with unleaded fuel.

For you weight watchers, it now looks like this one is going to have lost
over 1500 lbs. when finished.

My GMC mods are now on hold until mid September. Getting the 1970 Twin
Comanche ready to fly out to Victoria, B.C. in a couple of weeks for some
fun and frolics.

Don

- -----Original Message-----
From: Heinz Wittenbecher
Date: Monday, August 17, 1998 21:56
Subject: GMC: Is there an Alternative to Roof Air?

>One of my pet peeves is the noise of the roof air unit. I have a Dometic
>15000BTU with the heat pump and unfortunately it only has 2 fan speeds but
>even my previous one was 'noisy'.
>
>I know that air has to circulate, etc, etc but isn't there an alternative
>even for a coach our size?
>
>I suppose one gets used to the noise (does one?), but as I live in the more
>temperate area of the Northwest (actually Southwest of CanuckLand) I get
>spoiled by not having to run the AC all the time. Then when I hit CA or
>Texas it's 24hour GenSet/AC. Nothing like the roar of the AC unit to kill
>the serene settings of nature.
>
>BTW, any chance someone out there has the same unit and managed to 'quieten
>it down some'?
>
>Of course the real breakthrough I'm waiting for is a tractor beam on the
>highway that the GMC can lock onto, i.e. a real autopilot.
>
>Oh well, AC first...
>Thanks in advance for any suggestions.
>
>Heinz
>sweatin' it out in CA.
>
>

 

[heinz wittenbecher]

Wow... and I thought I was ambitious (at times

Nice going Don.

>
> For me the most troublesome factor to overcome is the idea of letting an
> engine idle for long periods of time.
>
> With leaded fuel and older engines there can be some problems, but the
> experts tell me not to worry about this engine with unleaded fuel.

Do you believe the experts? I assume so as your project is built on that
being so. Does this mean that it's really true that it's better to leave
then 455 idling than turning if off for 10 or 15 minutes even? or in your
case even longer. No hesitation to leave it idle all day in fact?

I sure hope you're going to track your activity and successes on the 'net
for all of us to follow. ( I say successes as all failures are shortlived,
especially on the 'net ).

>
> Getting the 1970 Twin
> Comanche ready to fly out to Victoria, B.C. in a couple of weeks for some
> fun and frolics.

Now that brings back memories... took my Multi/IFR in one.

Enjoy Victoria.

Heinz

 

[tipton eric]

I installed a second evaporator running off the engine compressor under
the sofa on the driver's side. This is an aftermarket unit I purchased
at a large auto A/C shop. I mounted the unit & snaked the lines to the
front. The A/C shop then installed compression fit tee's in the
original line. It puts out significantly more cold air than the dash
air.

I am interested in any modifications which increase dash air efficiency.
I have considered either removing the glovebox & adding a second unit
for my lovely copilot, or installing a small unit in the metal box under
her seat. I would be much more interested in simply increasing airflow
in the stock unit. I completely went through the system several years
ago plugging all leaks.

An innovative idea I saw at the beach last week was a wind generator
providing shore power for an sob. With the constant sea breeze this
worked well. In the outback of Western Washington where we live, there
isn't the constant source of wind.

Eric Tipton

-----Original Message-----
From: Donald W. Miller [SMTP:millerdw]
Sent: Tuesday, August 18, 1998 4:04 AM
To: gmcmotorhome
Subject: Re: GMC: Is there an Alternative to Roof Air?

Jim has installed a second evaporator under the refrigerator
which operates
from the dash compressor and he says with it, the dash air can
cool the
coach very well. This setup is similar to the dual air units
often seen in
Suburbans and Vans.

I recently modified my dash air box for enhanced air flow. I
need to do
some further testing before I would want to recommend my
modification to
anyone else but it looks promising so far.

When boondocking the idling 455 engine will make enough
electricity and it
idles quieter than the Onan. During quiet hours AC is available
from the
inverter and house batteries.