IN search of a COACH FURNACE that is good on power

S

slc

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Jan 24, 2017
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In looking for a furnace that has a discharge to the outside for the burnt gasses and recircs the air to heat it,
I keep my eye open on the video RVing channels.

This unit has popped up recently.
Best I can figure, cost is about $250 to 350.
Runs on a separate Diesel tank.

Power consumption, including the fan is UNDER 1 AMP.

Any thoughts ?????

https://www.youtube.com/watch?v=iyB70MplFo0
--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
If my head is working correctly this morning the 5 KW unit is equal to about 15,000 BTU or 1/2 the capacity of a normal GMC furnace. That might
work.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Should you find one, I would love to get info on it

On Sun, Feb 24, 2019 at 5:22 AM Ken Burton via Gmclist <

> If my head is working correctly this morning the 5 KW unit is equal to
> about 15,000 BTU or 1/2 the capacity of a normal GMC furnace. That might
> work.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Jim
My message has about 5 links to vids about the furnace and one that goes directly to Amazon where it has a current price of $150
There is quite a bit of info on it there as well as the guys talking about installing and running it in the vids.

It is made in China, but for the most part, the people that have installed it, for what it is worth, have said it works and uses very little power
after it is started.

Now all we need is a propane version.

Wonder why the RV suppliers can't design something like this?? It has to take CHINA to come up with it! ! !

--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
As I mentioned in a previous thread, I found my Suburban's duct work system to be very restrictive. There are no blockages or sharp turns in the
ducts, just turbulent airflow I guess.

In an effort to please my wife one cold morning, I opened the front panel of the Suburban and left the access door open. The amount of hot air the
furnace can now deliver is almost overwhelming! It quickly heats the coach and shuts down. I's say before it would run for 50% of the time or more.
Now I would say it runs for maybe 1/4 of that... maybe 10% of the time. So therefore less duty cycle, less power drain.

Just what I did.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
> As I mentioned in a previous thread, I found my Suburban's duct work system to be very restrictive. There are no blockages or sharp turns in the
> ducts, just turbulent airflow I guess.
>
> In an effort to please my wife one cold morning, I opened the front panel of the Suburban and left the access door open. The amount of hot air the
> furnace can now deliver is almost overwhelming! It quickly heats the coach and shuts down. I's say before it would run for 50% of the time or more.
> Now I would say it runs for maybe 1/4 of that... maybe 10% of the time. So therefore less duty cycle, less power drain.
>
> Just what I did.
>

I am certainly not an authority on coach heating (I received the
original OEM Suburban heater with my MH but it was 'loose in the box' so
to speak) but examining the heater it seemed to have two heated air
outlets but no return air provision. The heater case was contoured to
butt up against the outside skin and there was no way the circulating
fan could get any air (other than what leaks past the edges) to blow
through the heater core, thusly making heat output a mystery.

So when Bruce opened the front it became the 'return air' source and
things started cooking as they should.

I will eventually have to install a new heater with electronic ignition
since the firebox of the one I received was used by a family of mice as
their family RV for a while. Very stinky operation once I got it to
light at all. :)

Regarding these diesel heaters, remember the BTU rating is 'input BTU'
(or how much heat energy is in the diesel it burns) and what actually
heats the coach is the input multiplied by the efficiency which I am
guessing is pretty low for these little crackerboxes with small blowers.

Just a guess though, I'd never even seen one until this thread popped up.

Stu

'The only time you have too much fuel is when you're on fire.'
 
> As I mentioned in a previous thread, I found my Suburban's duct work system to be very restrictive. There are no blockages or sharp turns in the
> ducts, just turbulent airflow I guess.
>
> In an effort to please my wife one cold morning, I opened the front panel of the Suburban and left the access door open. The amount of hot air
> the furnace can now deliver is almost overwhelming! It quickly heats the coach and shuts down. I's say before it would run for 50% of the time or
> more. Now I would say it runs for maybe 1/4 of that... maybe 10% of the time. So therefore less duty cycle, less power drain.
>
> Just what I did.

***** *****

Interesting but that problem is not unique to just one coach. Just about every coach that has the furnace system for heat has the same problem. It's
a bad design that has never been corrected.

I have never taken any load readings from the fan running, just know that with a new battery, by morning if on battery power, the battery would be
down by morning.
My coach has 3 duct outlets, 2 of them open almost right from the furnace as the furnace panel is against the cabinet wall. 1 duct opening goes
through ductwork toward the bedroom.
So the two duct openings have no flexy duct at all, just an opening to the living area.
The run to the rear bedroom is all flexy duct so must be a huge amount of "tension" or resistance to the airflow to move air to the rear of the coach.
In my coaches case, it is difficult to know if the duct is clear and open or if it has kinks in it because the friggin PO had replaced all that duct
run when he made changes to the interior of the coach. I'll certainly look into the chance that a panel may be able to be removed to lessen the air
tension (load) on the fan. Be nice if it could drop the run time and or drop the power load the fan requires.

The whole reason for this thread is because of the high amps that the fan draws and the battery not lasting overnight. The match is not good.
The OEM coach had a single 12v battery. Later owners updated to the 2 6v batteries as they were using the coach to overnight. The trend now is to
change your lighting to LED which cuts power usage. The last power hog is the coach furnace. The popular fix is to use the Buddy heater, or a heater
that uses propane and does not require power. Most of these are ventless which brings up the exhaust concern and carbon monoxide.
But, as I have noted in some postings, the BUDDY heater and similar heaters, are built with aluminum tubing and connections, making them somewhat
fragile. After My heater went ablaze while running, and it was just sitting there and had been running for awhile, I got concerned. I could have
lost my coach to that incident. There were at least two UTube vids that illustrated the same problem and similar conditions. And I did post a
warning about the event. Many campers use those heaters, to save power on the battery, when heating the coach without land power.
It seems the coach furnace is the last obstacle to power hungry systems.

There is a lot to think about with this information about moding the furnace cabinet.
It would be nice to know what the furnace fan load was before you open the furnace door, relieving the fan of the power load to push air through the
duct system, and then compare the load after you open that furnace door. If that loading on the fan drops, that can make a big difference.
The time length of the fan running is a big determining factor also, as you illustrate.

If it resulted in less power drain to run the fan and a cut in the length of time the fan runs ( load on battery ), then that could be a big factor in
the problem.

But, some of the installs will not allow the furnace to be opened to let the duct air pressure to be relieved. Mine is in a tight spot under the
kitchen sink so I'd have to look at it and see if the panel could even be opened.

Another attempt could be to add more duct openings?????

But the fan power load readings would need to be taken to get an idea if it would even help to make a modification.
Also to consider is the old style of furnace, which is a high, boxy looking design, square pretty much, and the newish compact design, which is a
lower design made to fit in smaller spaces. The same act, to open the furnace panel to relieve the air pressure, for one design may not work for the
other..

Thanks for the information, it is something to play with.

I found the cheap furnace in a Utube vid and posted it here to be scrutinzed. The PRICE of this has dropped. The first vid said it was $350, the
next vid said it was $250 and now there is one, (it may be on sale or a sell out) on Amazon for $150. It is half the size of a compact furnace for
the coach and comes with everything to install including the controller.

The only thing left would be to test one and find space to install one, at least in a GMC. The friggin PO removed what little storage space my coach
had and I have been trying to get some of it back ever since purchase.

This little furnace is available in two fuels, one is diesel fuel which is what most of the Utube vids show running and they run well. There is also
a GASOLINE version, I only saw one vid for this unit and he said it ran better on diesel than gasoline. Could be an install problem, but it is an
option. If they come up with a propane version, we'd be good.

If I remember right, the start up was about 10-12 amps and after it was running and making heat, that power use dropped to under 1 amp, I want to say
.5 amp but check the vids and Amazon site.

It was luck that this heater was found, good or bad, that is to be determined. Happy to pass the info along.

s
--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
I think you're kind of missing/glossing over the key point.
The coach is not holding heat.

The problem isn't that the heater is pulling too much power, it's that it's running too much. (really a combination of the two)
Single pane windows are a huge heat sink and we have lots of them.

That tiny heater likely wouldn't even keep up with the losses through the windows.

If your heater pulls 12 amps for 5 minutes to warm the coach, then turns off for an hour, then does it again it's not an issue.

If your heater pulls 12 amps for 5 minutes to warm the coach, then turns off for 5 minutes, then does it again you're in for a dead battery pretty
quickly.

--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
 
Stu,
It sounds like my Suburban furnace is different than yours. Mine has a very coarse grill at the back of the furnace for admitting return air. My mine
coach is a Palm Beach, so it has louvers in the door, plus air access from under the side couch for return air. Return air has never been a problem.

There are four flexible ducts going to vents plus a smaller one going around to the bath module.

It just never seemed to move much air out the vents along the floor. All the ducts are open and no sharp turns, but they are ridged with an internal
spring to keep their shape. I believe its just the turbulence of the air along with the ridged ducts that is causing too much resistance to air flow.
Previously I could hear what was likely the hi-limit switch kick out and the burner would shut down, but the fan would keep going. After a few
minutes, the furnace would re-light. It would cycle like this until the thermostat temperature was reached.

Now, there is so much heat from the furnace, we sometimes need to manually shut it down, because with the thermostat in the back, it takes a while for
the heat to reach it. We get overheated in the front. I've talked to one of my sheet metal Clients about making a smooth duct to use the existing
vents. Maybe someday...

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
I can attempt to get a fan current measurement with the furnace cover ON and OFF.

Justin's point is well taken, our coaches are poorly insulated at the best.

However, with poor air flow from the furnace, if the fan is running much of the time trying to get the heat out of the furnace, the motor is running
much more than it should. If we can get the available heat out of the furnace easily, then the fan duty cycle will go way down and the battery power
requirement will drop accordingly.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
"""""""I think you're kind of missing/glossing over the key point.
The coach is not holding heat.""""""""

I'm not missing this point at all, but it certainly is a big consideration in the formula to a warm coach.

The booners, and some GMC'ers, put insulation over the windows in deep cold weather and voice improvement.

The GMC has pretty miserable insulation for its original cost, but that was GM.
The huge windows are a benefit, in the summer, lol, In the winter, its a bit more of
a concern.

But I added a heater core in the rear of my GMC, it uses 4 whisper fans to pass air
through to blow heat out at half speed. It is by far not a large heating system and I used it
in some pretty cold weather and the interior would get quite comfortable. Those fans use
minimal power but the heat source is the engine.

Stopping air infiltration into the GMC is a huge concern.

I am looking at the alternatives to heating the coach and not using enough power to
keep the lights on in Washington DC to do it.

The BUDDY type heaters are extremely popular but I found they have a fault that
needs to be known, they can flame up. You have to be extremely aware when using
that BUDDY type heater.

I thought the coach furnace was well designed but the comments coming in tell me
they are not the well designed furnace that I thought it was.

I suggest sitting back and watching the comments.

There are some interesting results, to what owners have tried and some of them
have had positive results, on top of the large glass windows and very poor insulation
quality.

After all the comments roll in, we may have a direction to go to attempt a retro fit
for these furnaces or even a different heat source.

""""""""That tiny heater likely wouldn't even keep up with the losses through the windows."""""""""

TRUE, the heater is more like a toy, however, it has been installed in a van in 10 degree weather and it did well.
So I thought it was worth mentioning as we have many out there that like to experiment.

"""""""If your heater pulls 12 amps for 5 minutes to warm the coach,
then turns off for an hour, then does it again it's not an issue.""""""""""

This is very true, DOESN"T HAPPEN IN MY COACH, mostly runs.

-- STU --

My furnace may be different and I also have the thermostat in the rear of the coach. Seems a silly place to put it but
I'd have to hear what GM designers had in mind to place it there. I have a Glacier so GM did the design.

I don't totally buy in on the duct problem for my coach because 2 of my ducts actually blow directly into the vents. no ducting at all.

But the point of the thread is the power usage of the furnace. It's power usage is high, and my unit continues to run even if the propane runs out
and the thermo is calling for heat. That is a plan for a dead battery.

I mentioned the diesel heater because one of the illustrations was installed in a van, and they have less insulation than the GMC does, if any at all,
and the owner said it could heat the unit up. I am aware that temp difference when the test was done is a big difference, one test was done at 10
degrees F. All results of the "owners tests" were said to be good which is why I brought it to notice here.

There are so many variations of install, vehicle insulation, windows, flooring, heat source, that it is almost a individual basis. There are very few
original GMC's out there and most have had mods done of one type or another. So any ideas to keep em warm is a huge plus IF you plan to use the GMC
in the cold weather. I plan to chase 70 deg's when on the road.

Next..... we can talk about the Watt Buster roof Air conditioner, LOL.. I have a thought to share, LOL .

Thank you all
s

--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
I replaced the flex tubing under the couch with PVC. I added a T and an
outlet, then went from that to an ell into the existing outlet nearest
the driver.

ron

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II
 
I would really be interested in installing one of these:

https://www.truma.com/int/en/products/truma-heater/truma-combi-6.html

I don't think they are available in the aftermarket in the US at this time, but are used as originall equipment on some of the newer class B motor
homes.

It seems to me this would be the ideal solution to heating both the air and the water in our coaches and would eliminate the issues some of us have
with having just an electric water heater as well.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
These diesel fired furnaces are common in trucks, busses and newer RVs. Most are configured as diesel boilers which heat water And pump it to heat exchangers throughout the coach. While they are produced by different manufacturers, most use a burner and boiler unit made by Webasto. On trucks it is common to see them as air heaters to keep the sleeper warm at night. Any large RV show will feature several manufacturers and two to four people who claim to know how to diagnose issues and perform annual maintenance. Some do and some don’t.

It looks like these Chinese units are copies of the Webasto air heater designs. Like the cheap generators they likely will blow a lot of hot air but who knows for how long.

Were I to do another GMC I would stick with the Suburban units and reengineer the air ducting much like others have suggested. The major design flaw appears to me to be the right angle bend the air takes when exiting the heat exchanger. I think some careful work making that a less radical transition would pay great dividends. Do as one poster said and remove the front cover to discover just how much heat these things actually put out. Plenty for our application.

Jerry Work
Kerby, OR
 
Furnace current measurements.

I have a Victron BMV-712 battery monitor in my coach. It had been sitting on charge for several months through the multistage converter/charger. I had
unplugged the coach yesterday morning because of a wind storm that was causing power fluctuations and was still unplugged when I made these
measurements. The Victron was reading 12.95V battery voltage and the temperature in the shop was 16C.

Before starting the furnace the Victron read 0.00Amps. Upon turning ON the thermostat the reading increased to 0.52Amp before the fan came on. This
would be the control board current.
Fan ON blowing through ducts: 5.8Amp
Fan ON cover removed, access door open: 6.1Amp
Voltage under load 12.84 at the battery (where Victron measures battery voltage at the shunt)

My furnace is a Suburban SF30 I believe.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
I was just reading the Suburban manual. On the topic of the furnace continuing to run after running out of propane, the manual says basically.
-The control board monitors the flame. If the flame goes out or fails to start, it cuts off the gas and purges the burner for 30 seconds
-It will then attempt a second re-light. If it fails to light, it again cuts off the gas and purges the burner.
-It will then attempt a third relight. If it fails for the third time, it purges the burner for 3 minutes, then locks out the system until reset
(power cycle)

For exact wording, check the manual.

So it should not run all night with no propane.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Here is the Chinese heater and steps of disassembly.....

This fellow placed some boxes or some item in front of the air intake and it sooted up.
He disassembled it to clean it out.

So this is how it is made and what it looks like inside.

https://www.youtube.com/watch?v=KEFT2DVvOfI
--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
When I replaced to sol aire in our coach, I found that the original ducting had debris within, that almost blocked the air flow completely. I replaced it complete and it helped some, but when I put a vent screen into the area that the furnace is located in, it made a HUGE difference. It does not run as long, and it seems to use a lot less fuel. That being said, it sounds like an open hearth furnace lighting off! Just another situation to ponder.......

>
>
> As I mentioned in a previous thread, I found my Suburban's duct work system to be very restrictive. There are no blockages or sharp turns in the
> ducts, just turbulent airflow I guess.
>
> In an effort to please my wife one cold morning, I opened the front panel of the Suburban and left the access door open. The amount of hot air the
> furnace can now deliver is almost overwhelming! It quickly heats the coach and shuts down. I's say before it would run for 50% of the time or more.
> Now I would say it runs for maybe 1/4 of that... maybe 10% of the time. So therefore less duty cycle, less power drain.
>
> Just what I did.
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
> Here is the Chinese heater and steps of disassembly.....
>
> This fellow placed some boxes or some item in front of the air intake and it sooted up.
> He disassembled it to clean it out.
>
> So this is how it is made and what it looks like inside.
>
> https://www.youtube.com/watch?v=KEFT2DVvOfI

**** ****

Here is a fellow that is testing the heater.

He also measures the current.

with the glow plug energized it goes to 9 - 10 amps.

Now one of the vids, someone said the current drops when the glow plug de-energizes.
This is true but they said it drops to under 1 amp when running,
the vid actually shows the amps at around 3-4 amps. He only let it run for awhile
so I don't know if it is supposed to drop more amps or this is the normal running current.

Here is the vid

https://www.youtube.com/watch?v=H8AYsRL8jds

--
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO -
UBUNTU VOYAGER - Berzin Auto Center
 
Having the thermostat in the back is good and bad I guess, good in that's where you are so that's where you want the heat maintained, but bad in that
there are not ducts (other than that little tiny useless one going to the bedroom). I bet the front of the coach where the ducts are is 15 degrees
warmer than the back when the thermostat turns off.

Some sort of oil filled radiator would be ideal, no fans so no power draw.
We heat our hose with a wood stove, but we have a couple 120v oil radiators in various rooms for when it's truly cold and they put out an amazing
amount of heat. I actually leave on e in the GMC sometimes when I don't feel like winterizing it and the temps getting into the teens.
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
 
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