Diesel Heater

[cadillackid]

parallel flow is how I set the system up.. the heaters all have an in / out so you can pipe them in however you like.. but the bus design is typically either parallel or series..



in a series system, the hot coolant leaves the engine, goes in one heater core.. and out the other side.. then goes into the next one in the line, and out.. once the coolant goes through the last heater core it makes the lon g return trip back to the engone to be heated again.. that last heater core under heavy load conditions (all the bus heaters on high and engine idling).. the l;ast heater wont be very hot..



blue bird tends to build all their busses in this manner..



a parallel flow system is one where you have 2 main trunk lines.. so coolant comes out of the engine and flows down the main line to to the end..

each heater has a 'T' connection into the main supply line and then the other side of the heater core, 'T's into the return line.

the last heater often has smaller lines or has a restrictor device in it so to keep a pressure differential going between supply and return, facilitating flow..



in high load.. engine idle situations.. all of the heaters tend to blow a little less hot air rather than having any of them blow cold..





so now in a series system is you close a valve to the engine.. you lose all flow through all the heaters.. its in / out and you cut off the main supply...



in a parallel system if you close one valve.. all the flow stops also.. EXCEPT you can put in a pump.. I put mine in the end at the rear heater.. the flow reverses through the heater cores as the return line now becomes the supply.. you pipe in your diesel coolant heater in parallel.. or you can send all the coolant from the main supply line into it in series.. if you clkose the engine heater valve (just one not 2). and you turn your coolant heater on.. its pump circulates coolant within your closed-loop of the inside of the bus.. it pushes coolant into the trunk line.. creates a pressure differential and that flows coolant through the bus heater cores...



if you open the engine heater valve now some coolant is going to flow intop the bus engine.. (it doesnt take a lot of flow to warm the engine).. and coolant still flows through the heater cores (yes you use a pretty strong pump)...


that said i tested mine.. so overnight it was minus 12f, I did a cold start of my engine (it doesnt have glow plugs).. and it started hard!!..


I left it sit all day.. the highest it got today was minus 5.and has been windy.. so I started the coolant heater with the engine valves open.. and left it run for about an hour.. I came back to the bus and it started like summertime...



tomorrow morning is supposed to be minus 20f, I wont even try to start it without first preheating.. so ill preheat for at least an hour or more before trying to start.. its only 830 at night and its already down to minus 12 here..



because its so cold.. I will drive with the coolant heater on.. and of course all SEVEN bus heaters on high.. once I get to the freeway im guessing Ill be able to shut off the coolant heater..

 

[CompLexxx]

parallel flow is how I set the system up.. the heaters all have an in / out so you can pipe them in however you like.. but the bus design is typically either parallel or series..



in a series system, the hot coolant leaves the engine, goes in one heater core.. and out the other side.. then goes into the next one in the line, and out.. once the coolant goes through the last heater core it makes the lon g return trip back to the engone to be heated again.. that last heater core under heavy load conditions (all the bus heaters on high and engine idling).. the l;ast heater wont be very hot..



blue bird tends to build all their busses in this manner..



a parallel flow system is one where you have 2 main trunk lines.. so coolant comes out of the engine and flows down the main line to to the end..

each heater has a 'T' connection into the main supply line and then the other side of the heater core, 'T's into the return line.

the last heater often has smaller lines or has a restrictor device in it so to keep a pressure differential going between supply and return, facilitating flow..



in high load.. engine idle situations.. all of the heaters tend to blow a little less hot air rather than having any of them blow cold..





so now in a series system is you close a valve to the engine.. you lose all flow through all the heaters.. its in / out and you cut off the main supply...



in a parallel system if you close one valve.. all the flow stops also.. EXCEPT you can put in a pump.. I put mine in the end at the rear heater.. the flow reverses through the heater cores as the return line now becomes the supply.. you pipe in your diesel coolant heater in parallel.. or you can send all the coolant from the main supply line into it in series.. if you clkose the engine heater valve (just one not 2). and you turn your coolant heater on.. its pump circulates coolant within your closed-loop of the inside of the bus.. it pushes coolant into the trunk line.. creates a pressure differential and that flows coolant through the bus heater cores...



if you open the engine heater valve now some coolant is going to flow intop the bus engine.. (it doesnt take a lot of flow to warm the engine).. and coolant still flows through the heater cores (yes you use a pretty strong pump)...


that said i tested mine.. so overnight it was minus 12f, I did a cold start of my engine (it doesnt have glow plugs).. and it started hard!!..


I left it sit all day.. the highest it got today was minus 5.and has been windy.. so I started the coolant heater with the engine valves open.. and left it run for about an hour.. I came back to the bus and it started like summertime...



tomorrow morning is supposed to be minus 20f, I wont even try to start it without first preheating.. so ill preheat for at least an hour or more before trying to start.. its only 830 at night and its already down to minus 12 here..



because its so cold.. I will drive with the coolant heater on.. and of course all SEVEN bus heaters on high.. once I get to the freeway im guessing Ill be able to shut off the coolant heater..

Would the coolant heater not be able to replace the bus heaters to save weight/things to repair? How much diesel does it usually drink in a week in winter when heating the inside? Also know of any diagrams that show the layout? Thanks so much this is great info!

 

[DrDanger]

Buying a heater from a reputable company is a good idea. It's not the way I'm going, but I understand and appreciate where you're coming from. But... if you plan to ever be in sub-freezing temps, relying on any single heat source is asking for trouble. Make sure you have a backup plan, even if that means plugging in and having some electric space heaters on hand. I'm sure you already thought this through, but it's worth saying just in case.

A hearty amen to that. We have a Webasto, Tiny Wood Stove, minisplit with heat, and electric blankets. Also, baking with our oven or cooking on the stove does a good job of heating up the bus but tends to raise the humidity and requires venting.

 

[magnakansas]

complexxx

might be able to answer questions in addition to Cadillac.

the coolant heater does not replace the heaters in the bus.... the engine is a coolant heater.... the running engine heats up coolant and you use the heated coolant to make heat inside the bus with the heaters.

with a coolant heater, you burn diesel fuel to heat the coolant, you pump the coolant along the same hoses the engine uses, it uses the same engine coolant. You dont replace the heaters in side the bus, you use the same heaters to pull heat from the coolant.

I have one of the big webasto brand coolant heaters, supposed to burn a little more than .5 gallons of diesel per hour at full tilt boogie. I do not have it in the bus but looks like I will be installing it in a different bus. I have three buses now.

This big webasto unit weighs about 150lbs total. about three feet long one foot high and two feet deep. goes under the bus.

In colder temperatures, diesels dont make a lot of heat when you are running a bunch of heaters, and it takes a while to get heat coming out of the heaters. I will preheat the bus before starting just like cadillac does.

my little 25 foot bus, 1994 TC FE 2000 has all the heaters up front, under the driver, and one in the rear that I replaced with a bigger heater. I carry five or six kids most of the time. Kids not comfortable sucks during road trips. also, if I screw up and get stuck, I should have enough fuel on board most of the time to run that heater for a week 40 to 80 gallons of fuel on board.

as for diagrams, go hunt up webasto heaters for school buses - the big ones. You should find plenty of pictures and diagrams

william

 

[CompLexxx]

might be able to answer questions in addition to Cadillac.

the coolant heater does not replace the heaters in the bus.... the engine is a coolant heater.... the running engine heats up coolant and you use the heated coolant to make heat inside the bus with the heaters.

with a coolant heater, you burn diesel fuel to heat the coolant, you pump the coolant along the same hoses the engine uses, it uses the same engine coolant. You dont replace the heaters in side the bus, you use the same heaters to pull heat from the coolant.

I have one of the big webasto brand coolant heaters, supposed to burn a little more than .5 gallons of diesel per hour at full tilt boogie. I do not have it in the bus but looks like I will be installing it in a different bus. I have three buses now.

This big webasto unit weighs about 150lbs total. about three feet long one foot high and two feet deep. goes under the bus.

In colder temperatures, diesels dont make a lot of heat when you are running a bunch of heaters, and it takes a while to get heat coming out of the heaters. I will preheat the bus before starting just like cadillac does.

my little 25 foot bus, 1994 TC FE 2000 has all the heaters up front, under the driver, and one in the rear that I replaced with a bigger heater. I carry five or six kids most of the time. Kids not comfortable sucks during road trips. also, if I screw up and get stuck, I should have enough fuel on board most of the time to run that heater for a week 40 to 80 gallons of fuel on board.

as for diagrams, go hunt up webasto heaters for school buses - the big ones. You should find plenty of pictures and diagrams

william

Ok I understand the difference between the heaters now, one creates the heat and the others blow it out.

I'm guessing you have the big DBW 2010? It is massive. Someone was saying they have a 16k coolant heater that would do their whole 40 foot bus. But you have a 45k in a 25 foot. Is this necessary? We will be living in a 40 with raised roof full time here in Canada so it has to be able to deal with occasional extreme conditions.

 

[magnakansas]

complexxx

you asked if the 45 btu is necessary? well If I get the kids out in 0 degree weather or colder.... I would like them to be able to go for the ride, not all bundled up. I want all of to be comfortable when we stop for lunch or sight seeing or what ever. And if I screw up and get us in a dumb situation, I want us to be able to wait out the cold the long enough to out of a dumb situation.

The bus is a giant metal box with heat leaking windows.... Is it over kill? Yes. I can always turn heat down, cant turn it up. I can add a loop for the fuel tanks to warm the fuel in extreme low temps

I've only been around buses for three years. In that three years there are many stories I have been a part of where cold cold and more cold and not enough heat in a bus.

I am not burning wood in stove. I dont want that kind of heat where little hands can get to it, I dont want to run a wood burning while running down the road. My buses are more for going places, getting to and from than about living in them. I think tents are going to be a big part of this, along with hotel rooms. having a place to prepare food, drinks, a toilet, shower are part of making life livable for half a dozen kids and two or three adults in one go.

Yes I do not think I fall in the "most people" category when it comes to the heater. I have kept all my blue bird heaters. The rear heater in the '94 tc2000 was about 14" long and that got swapped out for one that is about 24" long.

I really really think Cadillackid is a smart person. I copy as much as I can when he talks about heating and cooling in his busses. I will do a heater system install like his so that I can heat the inside without sending hot water out to the radiator when we are parked.

I dont want to mess with gasoline generators propane cook tops diesel engines and wood stoves..... too many fuels to deal with.

I am on the look out some lithium batteries and another good sine wave inverter.

I charge from engine alternators, not solar. The engine is running and being used. I dont feel the need for solar or generators. If I did a generator it would be diesel.

I have four air conditioners on board. I bought the bus that way. Two engine driven ac systems - The bus was used as a transit bus in Houston parking lots. Hot, humid summer days on paved concrete jungle. and two roof top mounted RV a/c systems that run on 110 volt. Those are a shor power kind of set up.

okay enough running at the mouth.

If you take your time. Read, read and read some more. Look for all stories you find that are along the lines - cant keep warm. then do the same for the all the yea plenty warm.

Keep this in mind - folks that are doing good dont usually make a post about how every thing is just fine. more of the "this sucks" "can you help?" stuff.

I just see and have been a part of other peoples buses that arent warm enough to live in.

Cadillac is not like me, I am over weight and have body fat, keeps me warmer. He is a lean machine kind of guy. He also works in his buses and uses them like most folks use a toyota corolla. I totally understand his atmosphere control inside his bus.

I think, if you are living in this bus, better plan for a two week at -25F kind of conditions. cold gets into places and freezes stuff up. Diesel fuel in the wrong conditions looks more like meat jello than a liquid fuel. batteries have to be kept warm. water and some times even waste pipes... drains frozen become blocked and drain backups in freezing temperatures are very slow to undo....

It is not matter of heating a space. It is a matter more of heat loss. You not only have to heat the space, but have to keep making heat for the all the heat that goes into the skin of bus, window, air leaks, engine covers, doors,


Go talk to others living in motor homes and travel trailers, find out how big the heaters are, are they keeping the place warm enough. heat loss numbers through laminated glass. Heat conduction loss through metal.

also, if you do find out that you dont have enough heat... you change what or how you are heating......

I do hope this helps you.

william

 

[CompLexxx]

Thanks for the info! I definitely prefer to stick to slightly bigger than slightly too small in this case. I'll look around to get a better idea of what people are saying. I understand that insulation is going to probably be the more important equation and will make sure to have that done well. Considering the DBW 2010 heats up to a 48ft boat and I have a 40 foot but with a raised roof that will probably be the right choice for us unless someone knows or I find a better option for the price. Appreciate it!

 

[cadillackid]

so I just returned from a road trip to the FROZEN TUNDRA!!.. minnesota..

the DBW2010 is the most common diesel coolant heater.. its definitely not 150 lbs.. (i just parted one out).. the one magna has is probably the model above it..



I am using a D&E (chinese) brand unit that is Much more compact and is 16kw (essentially 45k BTU)...



remember my bus is bone stock 30+ years old.. tall windows, original inside metal and original floors.. original doors..



my D&E heater started up with ease multiple times that I tried it.. i was staying at a fun hotel and rode the train everywhere i needed to go so the bus was a play-toy on the trip.. (for those diesel geeks out there ill be posting my "cold start" videos in my DEV random thread..).. anyway at 0f, starting from a bone cold bus and letting the D&E along with 3 inside heaters run for an hour it got to be decently warm inside.. I felt warm air blowing around and the interior was workably comfortable as a mobile office...



at minus 18f that wasnt the case.. I left the D&E start with a cold bus and after an hour you wouldnt freeze to death ionside by any means but i wouldnt wear shorts inside.. 3 bus heater fans on high kept the D&E busy (meaning coolant temperature never made shutoff temp.. it ran 100% duty cycle).



that was with the engine out of the Circuit (heating just the interior)...



later that morning after I let the system completely cool down, I used the D&E to preheat the engine for an hour... the engine started like summer.. then I took off to drive..


driving at minus 18 I didnt need the diesel heater firing when on the freeway. the bus engine made enough heat to keep the coolant around 72C or so.. as soon as the bus interior warmed up more then the coolant temp went to 80C.. my bus has an automatic winter-front (air powerred shutters) which stayed closed for the first 2 hours of my trip.. till the sun came out and I started turning down the bus heaters.. then the shutters cycled open and closed to maintain about 80-85C coolant temp.. (dash gauge 180-190).


I stopped for coffee and it was still minus 15 and clouds had returned.. parked with an already warm bus the D&E heater kept the inside toasty warm.. (short sleeves).. I ran the same 3 bus heaters.. my D&E cycled off for a very short time and then right back on.. cycles out at 75C coolant and in at 60C.. by the time the startup sequence gets the heater to full tilt the coolant temp had dropped to 55C and i notice a tinge of chill in the bus but soon it was toasty right again..



there was very little wind..



I like my bus basicially being a fishbowl of windows so covering up the windows is not an option for me.. i hate caves... I like bright and cheery..



so now if the debacle of last season is not repeated I can rewcommend that D&E hesater to others.. the first one I had broke in early october after having been installed in march and used very little.. so far so good its been good the new one and ive used it quite a bit..



my BRAND NEW MP-100 circulator pump leaks though when the coolant is cold.. ill get that resolved.. that pump is an extra, it didnt come with the D&E heater. its pump is fine.


whether it matters or not i was running a pretty heavy dose of Power-Service anti-gel / Cetane boost additive to my fuel.. I had NO issues with fuel gelling..


my bus has fresh batteries.


thats my real-world findings..
-Christopher

 

[magnakansas]

Cadillac

Thanks. For the fill in.

 

[Bon Voyage]

I went with a Rv propane forced air furnace. Suburban brand. 35,000 BTU works beautifully to heat my 40 foot roof raised spray foamed bus. As far as I’m concerned it’s the best way to go.

 

[cadillackid]

I went with a Rv propane forced air furnace. Suburban brand. 35,000 BTU works beautifully to heat my 40 foot roof raised spray foamed bus. As far as I’m concerned it’s the best way to go.

RV furnaces are tried and true for a long time.. the only thing ill say is make sure you have a spare control board.. RV furnace parts seem to go obsolete rather quickly.. recently diagnosed a control board bad in a buddy's 9 year old camper that has a suburban furnace.. the board was obsolete.. luckily i was able to find a white-rogers board with nearly the same spec's.. just had to change the flame sense rod with it.. but 9 years and gone? yeah there's a spare white-rogers board for his now in his collection...



that furnace in his camper never had an issue till the board died so it is a good unit and always keeps it warm..

 

[CompLexxx]

Consider coolant heaters also heater the engine I'll be going with that unless I find 2 separate systems dirt cheap! Great info in here!

 

[cadillackid]

Consider coolant heaters also heater the engine I'll be going with that unless I find 2 separate systems dirt cheap! Great info in here!

thats why I went with coolant heater.. at minus 18 and an engine which has noi glowplugs (yes its designed that way).. there was no way I was going to start it.. at minus 10 it BARELY made it. the diesel coolant heater lit right off and then the engine started with ease


depending on a person's build it can be the difference of whether you need to carry another fuel or not.. if you are already carrying propane for hot water, cooking, etc then an RV furnace on propane is no big deal.. but if you are not needing to carry it for other reasons then a diesel heater which uses existing diesel fuel avoids carrying a second fuel.



propane heat is also cleaner from an odor standpoint outside.. diesel fumes are noticeable from the diesel heaters if parked in an area where air stagnates..



my 16kw unit makes some noise when it runs too.. putting the unit in a box would greatly reduce the inducer-motor fan noise and a muffler on the exhaust works well to reduce exhaust noise..



probably a non issue if you arent camping in quiet-zone campgrounds.. if you are in a suburban parking lot or are in the middle of nowhere noise really means nothing unless it bothers you yourself..



RV furnaces resemble the noise inside and out of a Home heating system

 

[CompLexxx]

thats why I went with coolant heater.. at minus 18 and an engine which has noi glowplugs (yes its designed that way).. there was no way I was going to start it.. at minus 10 it BARELY made it. the diesel coolant heater lit right off and then the engine started with ease


depending on a person's build it can be the difference of whether you need to carry another fuel or not.. if you are already carrying propane for hot water, cooking, etc then an RV furnace on propane is no big deal.. but if you are not needing to carry it for other reasons then a diesel heater which uses existing diesel fuel avoids carrying a second fuel.



propane heat is also cleaner from an odor standpoint outside.. diesel fumes are noticeable from the diesel heaters if parked in an area where air stagnates..



my 16kw unit makes some noise when it runs too.. putting the unit in a box would greatly reduce the inducer-motor fan noise and a muffler on the exhaust works well to reduce exhaust noise..



probably a non issue if you arent camping in quiet-zone campgrounds.. if you are in a suburban parking lot or are in the middle of nowhere noise really means nothing unless it bothers you yourself..



RV furnaces resemble the noise inside and out of a Home heating system

Do you happen to know on similar size heaters which of the two are more efficient? With approx daily costs in winter?

 

[cadillackid]

Most RV furnaces are 60-70% efficient . It’s done this way because RV Often are heated from a dead cold state and they want to avoid the possibility of cendensation in heat exchangers.. since many RV drop at or below freezing when parked high efficiency condensing furnaces would add a whole other layer of winterization requirements and procedures .. high heat exchanger temps (low efficiency ) mitigate the condensation issues

 

[CompLexxx]

Most RV furnaces are 60-70% efficient . It’s done this way because RV Often are heated from a dead cold state and they want to avoid the possibility of cendensation in heat exchangers.. since many RV drop at or below freezing when parked high efficiency condensing furnaces would add a whole other layer of winterization requirements and procedures .. high heat exchanger temps (low efficiency ) mitigate the condensation issues

I think I should have said more cost efficient (initial investment/fuel/maintenance)

 

[cadillackid]

RV furnaces once installed require little maintenance.. like any furnace you clean / replace the filter, clean the burners if needed.. inspect heat exchanger by use of a CO meter if you suspect issues.. otherwise they geberally just go.



diesel heaters can generally run well with longecity also if you use good quality fuel and keep the fuel filter clean. old or dirty fuel will mess up a diesel heater just like it will a fuel oil home furnace..



again a lot of the cost comes down to whether you already have propane on board or not.. if you do its minimal to connect as propane furnace in.. if your bus is diesel its pretty easy to tap into the main bus fuel tank for fuel.


if your diesel heater is easily accesible you can take it down to disassemble it should it break.. if you buy chinese units look for replacement parts for it before purchase so you know if you can get a good array of parts should it die.. (glowplug, ignition screen, fuel pump, fan motor)..



RV furnaces can be bought that are on slide-out trays so the whole furnace literally slides out for servicing..

 

[Peabus]

Being a truck in the northern climate we use wabasto heater for our cabs and sleepers when stopped have never been cold and can actually be to hot sometimes as for fuel consumption depending on space and size of heater should be between 0.2 to 0.5 litres per hrs of run time maybe little more on how hot you set it

 

[CompLexxx]

Being a truck in the northern climate we use wabasto heater for our cabs and sleepers when stopped have never been cold and can actually be to hot sometimes as for fuel consumption depending on space and size of heater should be between 0.2 to 0.5 litres per hrs of run time maybe little more on how hot you set it

Truck as in the small cabin of an 18 wheeler?

 

[Peabus]

Small maybe not but they will heat an 82 inch sleeper + can space so maybe 12 feet in my experience but know of others that heat the large 130 inch plus sleepers with them so for heat a bus I believe yes can be done depending on length of your bus go with 2 heaters with thermostat and on there own batteries to power them