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Author Topic: On board heat  (Read 4640 times)
buswarrior
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'75 MC8 8V71 HT740




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« Reply #15 on: May 10, 2011, 07:44:02 PM »

Hello hanks69chevy,

If you choose, it is possible to remove the coach heat and the parts, and keep the driver's heat/defrost.

But, being from New York State, you may want to keep the coach heat, whether you distribute the heated air via the stock duct work,or another solution you devise, is a choice you may make.

Remove the duct work for cleaning, keep track of which panel goes where, and when it is apart, once you see how it works, you can change your design ideas, otherwise, put it all back together nice and clean, and carry on.

If you remove the coach heater core (and coach AC equipment to open up that space) just cap the lines when you remove the coach heater core at the heater core, do not disturb the lines deeper than the core.

The maintenance manual will show you how it is plumbed, and these words will make more sense.

FWIW, I still have all my stock coach HVAC parts installed and available for use.

happy coaching!
buswarrior
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gus
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« Reply #16 on: May 10, 2011, 08:06:59 PM »

I forgot to mention that you don't want to use the original blower when parked because it is huge and uses a lot of battery power.
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PD4107-152
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Ash Flat, AR
buswarrior
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« Reply #17 on: May 14, 2011, 06:21:04 AM »

I can engage the coach blowers on my MC8 by way of a bypass switch, the Trace draws 10-11 amps of 120V shore power to make then run....

happy coaching!
buswarrior

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« Reply #18 on: May 14, 2011, 08:20:53 AM »

I forgot to mention that you don't want to use the original blower when parked because it is huge and uses a lot of battery power.

  Im considering installing two radial ducted fans in front of the cores (plain old radiator coolng fans, blowing through), and removing the centrifugal fan unit. My thinking is the flat fans are (or can be) more efficient, and if they draw less current while providing enough airflow, even if its less airflow, perhaps equal to the airflow the current fans provide on low now, that will greatly reduce electrical loads. The centrifugal blower fan in an MCI9 is a 1.5 HP 24V motor that draws over 53 running amps.

  I guess as long as I dont destroy anything I can always put it all back like it is again if it dont work?
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travelingfools
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« Reply #19 on: May 14, 2011, 10:00:18 AM »

We are keeping the otr heat but are planning to change out the blowers. The originals push way to much air without the original duct work...
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John P, Lewiston NY   1987 MC 9 ...ex NJT
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« Reply #20 on: May 14, 2011, 10:31:34 AM »

  I plan to keep the duct work, but rework it to fit within the needs and constraints of the conversion. Insulated and freeflowing behind cabinets, etc. Think about the tiny lil pos fan they stuff into a 30,000 BTU Suburban gas furnace in an RV. They expect that stupid thing to heat a 30 foot RV, and it actually sorta does. Or consider the tiny fans in roof AC units. We could reduce the fan power considerably in a Bus and still be quite comfortable, IMHO.

  Moving a large volume of air slowly, is always more efficient (and a heckuvalot quieter) than moving a small volume or air rapidly. They needed all that air flow when the Bus was crammed full of 47 breathers. In an RV we likley dont need 1/10 that flow rate.
  
  Edit: Has anyone ever considered hot water baseboard heat?
« Last Edit: May 14, 2011, 10:43:16 AM by artvonne » Logged
buswarrior
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« Reply #21 on: May 14, 2011, 11:27:56 AM »

There have been transit coaches that used baseboard radiant heat with some success.

A number of busnuts have too.

Costs of firing a coolant boiler (Webasto/Espar/Aquahot/Proheat) versus other options versus your anticipated length of use are all part of the mix.

Coolant boilers make lots of hot water, but waste a lot of heat out the exhaust, and require some messing around to design a system of sufficient volume and controls to get the burn cycles from being too short, and the temp in the coach not to fluctuate.

Deep cold isn't the challenge, 45 - 65 degrees is the trick!

happy coaching!
buswarrior
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gus
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« Reply #22 on: May 14, 2011, 02:09:43 PM »

Paul,

I plan to something like that eventually, the original blower is way overkill for a conversion.

Now I have to turn it off and on every few minutes since the original thermostat is long ago failed or disconnected.
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PD4107-152
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« Reply #23 on: May 14, 2011, 07:53:48 PM »


Deep cold isn't the challenge, 45 - 65 degrees is the trick!

happy coaching!
buswarrior

  Not in the Bounder. With no insulation in the floor, and almost none around the cab, its a cold sob. 35F is about the limit, and to really be tolerable when driving in colder waether ive had to run an electric heater up front. Parked its not so bad, I believe weve gone through a zero night a time or two. Its when its moving. Brrrrrr. I always meant to fix that part of it, but once I decided I wanted a Bus I thought I would just leave well enough alone. I did put foam all around the firewall to block air and try to retain some heat, but I never noticed much difference, maybe a little less cold blowing on me. I should probably stop carping about it, someone will google "Bounder" and read all my negative comments, lol. I'll just say I will be glad when im able to Bus it.
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buswarrior
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« Reply #24 on: May 15, 2011, 07:22:00 AM »

I thought we were talking about designing a heating system for a converted coach?

Air infiltration is your big enemy, both camping and driving, but much more so when driving.

No doubt, besides having insufficient heating capacity, the Bounder likely leaked air like a sieve going down the road.

As I was alluding to, it is a much bigger challenge to get your home made heating solution to cycle properly and maintain the temperature in the coach in cool weather 45-65 degrees, than to do so in cold weather, where the heating solution is closer to running continuously.

Baseboard radiant heat is one of those systems that has some complexity in design in exchange for the silence of operation.

There's an article here: http://www.busnut.com/bbs/messages/12262/34237.html?1267457597 that might help with your research.

A common man's forced air RV furnace does have its advantages!

happy coaching!
buswarrior
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TomC
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« Reply #25 on: May 15, 2011, 08:13:59 AM »

I removed the OTR A/C and heat under the floor-I needed the space for my gray and black tanks.  I had the heater core tested (a big thing-like 5ft long and 18" wide) and remounted it inside under my cabinets in the hallway powered by 2-14" electric radiator fans.  It is not ducted, but has 4 vents aimed forward.  When it kicks on, I can count to 10 and feel heat in the drivers seat.  Very powerful and effective.  I have a manual ball valve to cut off the water to it in summer, but have T's in the line so my front defroster can always work (it too has a ball valve that I can control from the drivers seat).  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
hanks69chevy
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« Reply #26 on: May 15, 2011, 03:35:51 PM »

Thank you all for the info. Gives me a lot to think about. I will definitely keep the OTR heat. I'll just have to figure out how I want run it.
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pvcces
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« Reply #27 on: May 15, 2011, 09:56:46 PM »

That OTR heat is a couple hundred thousand BTU of free heat when it is cold outside.

If you want to ditch the fancy control system, you can get a 110 volt line thermostat and use it to turn on and off the underfloor fan's relay. They take a few degrees to switch from on to off. We have one fan left, and it is plenty for OTR use.

Tom Caffrey
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Tom Caffrey PD4106-2576
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Jriddle
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« Reply #28 on: May 16, 2011, 12:50:20 PM »

We kept both. The A/C was converted to 134a and I didn't need what little space that would be gained by removing it.
I have to say the factory thermostat that controls the temperature is a pain. I only had the return air coming from the front till now. I cut a hole in the floor in the bedroom to allow for return air there. I have not hit the road since I made this change. I hope that will help on the thermostat situation. The sensor for the water valve is in the return air duct.

John
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If It Can't Be Grown Then It Has To Be Mined
John Riddle
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1984 MC9
Oonrahnjay
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« Reply #29 on: May 17, 2011, 01:11:33 PM »

  (snip)   Im considering installing two radial ducted fans in front of the cores (plain old radiator coolng fans, blowing through), and removing the centrifugal fan unit. (snip) 

Paul, you might want to look at all the factors in this.  My vehicle HVAC experience came in small doses but they were intense doses -- our Golden Rule for fans is that the centrif/"squirrel cage" fans were almost always better for a given amp draw.  One of their greatest advantages is that "flat blade fans" can't build pressure; if you try to run them in a situation that needs pressure, the back pressure just sort of loads up against the blades and the air flow chokes out.  The centrif fans will build pressure.  And if you're talking about moving air through most any configuration of ducting (particularly if you have long lengths and/or bends), you're going to need pressure to move that air efficiently.

In a plain air, unobstructed situation, those radiator-type fans will blow a lot of air but if you're doing any "air handling". you may want to look at current draw and air flow specs for centrifugal fans of the same or lower current draw.  And "more air" @ "lower current draw" is the most basic definition of better efficiency.
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
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