Radiant heat vs heat exchangers and fans what do you think

[makemineatwostroke]

Guys I have radiant on both sides of my coach does anyone have a idea if the diesel fired system runs longer with that type compaerd to the exchangers and fans.I know the radiant makes a very comfortable heat with no noise, but I seem to use a lot of diesel fuel for a well insulated coach staying warm and making hot water for showers.The 6 grandkids during ski season may be my problem.      have a great day

[TomC]

While I have no experience with radiant heat, other than in homes, I know that temperature control is much more difficult with radiant heat-hence the possibility for more fuel usage.  I personally would use fan powered heat exchangers.  Then you'd have exact heat control and my guess, the heater actually running less than radiant.  Using 4 heat exchangers throughout the bus I would think would be enough.  Good Luck, TomC

[skipn]

MMa2S
  With as many variables on efficiency it is hard to say definitively
  Assumptions
   1. you are running both sides as a single zone.
   2. you are not running a radiator under the toe kick of the cabinets.
   3. probably have a radiator under the windows

   A couple of things to concider...
     1. plumb a heat exchanger/fan by the entry door to move the cold air to a warm state quicker.
     2. If the window shades have an air gap to the window either close the air gap or install a deflector.
     3. re-plumb the supply and return pipes with factory insulated piping.(if not already done)

   Hope this helps
Skip

[Ednj]

I have both in my coach and the heat exchanger with the fan definitely cools the heating media faster then the radiant.
The diesel fired system coolant will cool off quicker with air blowing through the heat exchanger rather then just the heated coolant circulating through the radiant.

In my case anyhow

[Nick Badame Refrig/ACC]

MMA2S,

By far radiant heat is more efficient. With that said, Is there a chance you have a heat transfer issue between

your heat source and the radiant heaters? In other words, does your first loop get as hot as the heat source?

Alot of parameters to eliminate.
Nick-

[rusty]

Two Stroke,  I have heat exchangers in my 05 they work well. The one thing to think of is the drain on your batteries. I have to run my generator every day when I am in heat mode. I have 6 L 16,s.

Good luck Wayne

[buswarrior]

I'd be thinking the BTU needs won't change, all things being equal, between radiant and fan forced, to keep the interior warm.

Engineers?

To what temp are you maintaining? ie: Takes a lot more fuel to reach 80 than to reach 70.

Is all piping and the unit itself wrapped in some kind of insulation? Every warm surface outside the living area is fuel gone overboard.

Air intrusion?  Stock HVAC air vents in sides closed up?  Front of coach isolated from the rest? A curtain works well just aft of the stairwell, tucked in at the bottom is more important than a gap at the top, to keep the breezes contained up front. Heating cold air and letting your warm air get outside is a HUGE drain on consumption. Of course, we need some air exchange, but the coach does have a lot of stock "holes" in it.

Perhaps adding a rad in the stairwell down low will moderate the transitions?

To keep the coach warm all weekend at the ski slope, I'd vote radiant heat, less power draw, even heat.

To warm the coach up quickly, fan forced will distribute the BTU's into the interior more quickly than "lazy air".

The marine folks have some neat fuel fired things:  http://www.dickinsonmarine.com/
Those diesel fired cooking stoves are well known in the sailing crowd.

happy coaching!
buswarrior

[Lee Bradley]

Making hot water for showers is spendy no matter what; water takes a lot of energy to heat and then you throw it out.  If you use a lot of hot water this way, you might look into a heat exchanger to preheat the water going into the heater with the waste water.

The problem with radiant heat is that it is slow to transfer heat into the living area but is comfortable heat but the whole system is releasing heat at about the same rate, unheated area a little faster. So if you have 2 gallons of coolant in the boiler and 1 gallon in the radiators most of the heat will be released in the unheated area. Not to mention the heat you lose out the exhaust while the boiler is running. With forced air, you extract more heat from the coolant in the radiators for a given time but you have a lot of hot air mixing with cool air in the living area but you get more heat out of the system into the living area. Because you are transferring more heat into the living area you should get less run time on the boiler and less heat loss through the exhaust. Insulating the piping in the unheated areas will help but I'm not sure how much you can insulate the boiler itself.
I plan on radiate heat in my bus, borrowing greatly from gumpy's design, with a 20 or 30 gallon electric water heater as a heat sink for the system. The diesel boilers put out a lot of heat very quickly so I plan on heating the 20/30 gallons in a well insulated tank and using that water to supply the radiate system. This heat sink should keep the boiler from cycling as often. When there is 50 amp power available the electric water heater will supply the hot water. In the summer, I figure I have 20/30 gallons cool coolant to meter into the Detroit on hills

[makemineatwostroke]

Guys; I got some answers today about the fuel consumption on my heat I am not that bad according to Hurricane, Aqua Hot and Webasto with the figures they gave me.At 32 degrees they will cycle 33% of the time and will use .5 g/p/h of fuel that comes out to be almost 8hrs in 24hrs using about 4 gals of fuel a day also at higher altitude and colder temperature fuel useage will increase with longer cycles. I have installed a Flo-Scan on my unit and will have a exact reading after Christmas for you guys I will post.FWIW the 3 manufactures all agree the radiant system is far more efficient than the exchangers but cost more and you lose some wall space around the floor.They agreed that 4 to 5 gals per day with the grandkids is not that bad,man am I glad fuel is lower in price this season   have a great evening

[VanTare]

MM, I own a 45 foot bus with a Aqua Hot 600D 56,000 BTU rating 5 zone with heat exchangers spending 3 days and nights in Mason City Iowa this week where the temperature was  in the 20's down to 0 at night the best I can figure ( using the SliverLeaf for the engine) on the fuel running the heat and the generator to charge the batteries I am at 10 gallons every 24 hours, your 4 or 5 gallons sounds good to me.         

David

[NewbeeMC9]

If you put some hx with fans inline in a couple places down low, they will be radiant when fan not running but will help heat quickly when the fan is running.  So at least you would have some options if you added a couple.

[JackConrad]

If you put some hx with fans inline in a couple places down low, they will be radiant when fan not running but will help heat quickly when the fan is running.  So at least you would have some options if you added a couple.

When we installed out ProHeat, we installed switches on the heat exchanger fans so we have options avallable (3 fan speed or no fans).  We have found that usually we end up leaving the fans running on low.  Jack

[pickpaul]

Is it crazy to think you could use a waste motor oil furnace or boiler to produce free heat for the bus. These guys look interesting...

http://www.cleanburn.com

Not sure they make anything small enough but that boiler would make plenty of hot water for radiant or heat exchanger right?

Cheers, Paul.

[JohnEd]

Paul,

You are not crazy in the least.  These things are all over the place and doing very well.  I haven't found any that are of a small enuf capacity to be possible in a bus.  The thing about them is their variance from the straight Dino burners.  The WMO needs to be heated to compensate for it viscosity.  There are lots of tank heaters on the market and the "heater head" that is riight next to the burner head is a special item available in the oil furnace industry.  Then comes the problem of air pressure to "suck" the oil out of the head supply tube.  Have to keep the pressure in the oil supply tube exactly at zero or neg or positive but always the same.  Low pressure air for the burner and a design of fins to provide the proper "swirl" to the charge.  Finally a hi voltage supply to keep that spark going is the electrodes that sit right under the vaporized oil mist.  Finally the flame must reach the boiler at the tip of the flame where it is hotest so that carbon won't build up on the boiler so quickly.  Sounds loke it is too hard to do doesn't it?  Well those Wabesto folks have already been there done that.  So has all the rest of the mfr.s  Now you try to go using some other type of fuel and you then have to redo all that design to some degree and that is a mouth full.  The WMO furnaces will also get by on straight diesel or trans fluid or differential oil and that amazes me with as little as I know.  To my thinking there should be a modification kit for the Webasto to convert them.  Those little devil of a preheater blocks do eat electricity but there should be a way around that.  My thoughts or better daydreams but at 20 or $40 a day some industrious tinkerer should be burning the midnight oil....no pun intended.

Keep searching on that waste oil burner topic as there are oodels of other manufactures out there.  If UI were heating a shop in cold country or a bus barn anywhere I think I would be on this like a chicken on a June bug.

John

[pickpaul]

That's great news John. I just found these guys who even have a veggie oil powered A/C unit!

http://www.econoheat.com/index.html#