REFLECTOR: Cabin Heating

[Chuck Jensen]

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of jack davis
Sent: Wednesday, January 28, 2004 10:08 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR: Cabin Heating


I have done exactly this (i.e., fabricated a flapper valve that directs all
incoming air into the cabin).  You get very good heat when the engine is
running at 65% power or above and when the outside temperatures are above
about 15 degrees F.  Below that temperature, it is a bit cool in the cabin.
I also place a strip of duct tape across the front side of the oil cooler
(as Duane Swing suggests).

Jack
----- Original Message -----
From: "Jim Sower" <canarder@frontiernet.net>
To: <reflector@tvbf.org>
Sent: Wednesday, January 28, 2004 4:01 PM
Subject: Re: REFLECTOR: Cabin Heating


> It sounds like most of what we need is already in place.  My 173FG has the
front oil
> cooler in a plenum.  The input to the plenum is the NACA in the nose, and
it exhausts
> out the bottom of the plenum.  I have a 2" duct out the back of the plenum
going to
> the cabin foot warmers (could be larger and go to more places).  As it
stands now,
> only the (tiny bit of) exhaust from the oil cooler that doesn't go
overboard goes into
> the heat system.  I aim going to make a flapper valve that can cover
either the outlet
> to the cabin completely or the overboard opening completely or anything in
between.
>
> If it's really cold, I'll block the overboard vent and the only air that
passes
> through the oil cooler will be whatever the outlet to the cabin will
permit.  Air flow
> will be much reduced and therefore much hotter.  If I don't need that much
heat, I can
> crack the overboard vent which will increase flow through the cooler but
reduce flow
> into the cabin (the rest going over the side).  I can keep venting the
overboard vent
> more and more until I have the cabin vent blocked and all the air the
cooler will pass
> going over the side.  One flapper valve, a plenum that's already there, no
additional
> oil coolers.  I may have to make a new plenum so the flapper will fit
between the
> cooler and cabin outlet bulkhead and be big enough to cover the overboard
vent, but
> that's not rocket science.
>
> Limiting air flow to the hot air I need should make for enough delta-T to
heat the
> cabin, and increasing air flow as my heating requirements go down will
tend to match
> increased oil cooling requirements.
>
> Just a theory ... Jim S.
>
> Dave Black wrote:
>
> > Scott,
> >
> > > I think if you had the nose oil radiator and an inside one for cabin
> > > heating you could easily run them in series, much easier plumbing.
> > >
> > > Then close off the cabin heat outlets on the oil cooler duct.  If your
oil
> > > is too cool just close the flap(that used to direct the air into the
cabin)
> > > a bit thus reducing the flow through the radiator and raising the oil
> > > temps, good for the engine and for the passengers too.
> >
> > You may be on to something! It would be stone simple plumbing. And I
believe
> > it would be a huge improvement over the standard nose cooler only
> > installation.
> >
> > I see two drawbacks:
> >
> > 1) The total length of the oil line. The longer the line, the more
'congealed
> > oil plug' effect you have in cold weather. But now that I think of it,
with
> > this system, there'd be absolutely no need to leave the original cooler
in the
> > nose. Rather, it should be relocated to the engine compartment. Hence
the
> > total plumbing could be MUCH shorter than the standard system.
> >
> > 2) The cabin heater would always be hot, even in summer. However I'm
certain
> > that with some clever design, most of the unwanted heat from the cabin
heater
> > during the summer can be contained, blocked from entering the cabin, or
ported
> > overboard. Heck, if the unwanted heat can be eliminated efficiently, the
cabin
> > heater could even be used during summer as an auxiliary oil cooler.
There are
> > certainly times when that would be a good thing.
> >
> > All-in-all, I believe two coolers in series with no valves is a big
> > improvement over the standard system. Certainly it'd be a very simple to
> > plumb, and cabin temperature control becomes a matter of controlling a
blower
> > motor and flapper(s).
> >
> > I guess a flapper valve located in the cabin floor could direct hot air
either
> > back into the cabin or overboard. It needs to work quite effectively to
keep
> > the cabin from getting hot in summer. But I'll bet it could be done. On
the
> > other hand, putting a bypass valve around the cabin heater would keep
the heat
> > out too.
> >
> > Hmmm...
> >
> > Dave Black
> > Shortwing RG
>
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