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Old 05-25-2024, 03:16 PM   #1
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Year: 2004
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Engine: Cat C7
Question Bus Heater & coolant tubes

Greetings,
We are currently in the demo phase of a rear engine Thomas bus with a Cat C7 Engine. We have 4 heater fans with coolant tubes going to each of them, we want to remove them. However, we are worried that the tubes also lead to the window defrosters. Do we remove them, install new defrosters?

Idea 1: remove the fans and connect the tubes together for window defroster

idea 2: remove everything and loop the lines together in the back

any ideas or insight anyone has would be most appreciated. I have included some pictures of what I am looking at.
Attached Thumbnails
Skoolie Heaters.png   20240525_124625.jpg   20240525_124637.jpg  

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Old 05-25-2024, 03:24 PM   #2
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yes those tubes feed your defrosters.. idea 2 is technically against the law. you can remove your windshield defrosters...



you can remove the bus heaters that were under the seats and just bypass them with line fittings.. or get new lines if you want continuous fresh lines from the back to the front.. or if you remove the lines you'll have to get creative with how you are goingto have heated defrost and driver heat.. little 5kw diesel heaters wont cut it.. you'd have to install a 12 or 16kw diesel coolant heater, expansion tank, reservoire and lines to your front heaters to have the defrost..


you could also run heater lines inside some type of semi-rigid conduit from front to back under the bus to get the defroster fed.. (you dont want the bare lines just run under the bus.. too much risk of failure .. you probably could run #12 Air conditioning hose under the bus for the heater lines as it is much stronger and designed for such mounting.. you would need a booster pump probably up front since the line size is a little smaller..
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Old 05-25-2024, 06:02 PM   #3
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People with Rear Engine buses should just get used to framing over the lines, and should be our advice going forward. Re-routing them under the bus isn't good cause it cools them down making the defroster not work.

If you buy an RE bus, expect to build around the coolant lines.
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Old 05-25-2024, 06:37 PM   #4
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Quote:
Originally Posted by nikitis View Post
People with Rear Engine buses should just get used to framing over the lines, and should be our advice going forward. Re-routing them under the bus isn't good cause it cools them down making the defroster not work.

If you buy an RE bus, expect to build around the coolant lines.



thats why I mentioned a Booster Pump.. with enough flow the temperature drop is minimal... also using A/C hose, while its not as big around is multi-layer and better insulated.. again to be used with a booster pump..



you have to think about it that even inside the bus the lines shed some heat but they also are running the front heating / defrosting,. driver heater and most often a midship and rear unbderseat heater as well.. a booster pump is typically equipped on all RE busses
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Old 05-25-2024, 07:48 PM   #5
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I just saw a post somewhere where someone ran insulated hard coolant lines underneath the floor from the rear to their front defrosters. Just another idea.
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Old 05-27-2024, 01:57 PM   #6
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Quote:
Originally Posted by cadillackid View Post
yes those tubes feed your defrosters.. idea 2 is technically against the law. you can remove your windshield defrosters...



you can remove the bus heaters that were under the seats and just bypass them with line fittings.. or get new lines if you want continuous fresh lines from the back to the front.. or if you remove the lines you'll have to get creative with how you are goingto have heated defrost and driver heat.. little 5kw diesel heaters wont cut it.. you'd have to install a 12 or 16kw diesel coolant heater, expansion tank, reservoire and lines to your front heaters to have the defrost..


you could also run heater lines inside some type of semi-rigid conduit from front to back under the bus to get the defroster fed.. (you dont want the bare lines just run under the bus.. too much risk of failure .. you probably could run #12 Air conditioning hose under the bus for the heater lines as it is much stronger and designed for such mounting.. you would need a booster pump probably up front since the line size is a little smaller..
Thank you for this, I might go with removing the two heaters in the back and keeping the two upfront including the defrosters, are you aware of how one would go about doing this? I am a visual learner
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Old 05-27-2024, 04:07 PM   #7
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each heater has an in and an out... if the hose connections are right close together (they have been on my busses).. you might be able to just get away with something here..


https://www.tacbusparts.com/Heat-Def...ose-Connectors


constant tension spring clamps
https://hpsperformanceproducts.com/p...45870325432572






its most likel;y 1" heater hose.. dont buy plastic.. get metal..


of course the ideal would be that you replace that run of hose which has been chopped for the heaters wit ha brand new continuous run to minimize the possibility of a future leak.. would suck if you buried the hose in your conversion and had a clamp come loose..
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Old 05-27-2024, 04:16 PM   #8
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4 heaters plus defrost. Dang.

I live up North in freaking cold Canada and mine only came with 2 heaters.

I pitched the mid heater. Kept it for parts. Kept the rear heater. Belt a shroud and ran ducting to the rear room and bathroom.

My foot well heater ducts I turned and pointed toward the living area plus I have the driver heater and defrost.

I don't plan driving in mid winter..
.-30c but the one time I drove it at -5c it was pretty warm still.

Bus is factory insulated so guess that helps plus all the damn wood I put in it seems too make a difference from the day I gutted it till near end of build while heating with my wood stove.
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Old 05-28-2024, 12:16 AM   #9
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Quote:
Originally Posted by dbsoundman View Post
I just saw a post somewhere where someone ran insulated hard coolant lines underneath the floor from the rear to their front defrosters. Just another idea.
All Crowns came from the factory with a pair of 1" galvanized pipes running all the way to the front to supply the front heater/defroster and any other heaters. Last year I found out that my original coolant booster pump wasn't working, but the front heater was getting plenty hot even without it. I bought a Groco CP25 bronze pump to replace the old seized-up POS pump, and now it's even hotter in the front. In really cold weather the slight heat from the uninsulated pipes will keep the underfloor storage bays from getting too cold.

John
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Old 05-28-2024, 06:52 AM   #10
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Quote:
Originally Posted by Iceni John View Post
All Crowns came from the factory with a pair of 1" galvanized pipes running all the way to the front to supply the front heater/defroster and any other heaters. Last year I found out that my original coolant booster pump wasn't working, but the front heater was getting plenty hot even without it. I bought a Groco CP25 bronze pump to replace the old seized-up POS pump, and now it's even hotter in the front. In really cold weather the slight heat from the uninsulated pipes will keep the underfloor storage bays from getting too cold.

John

wow thats neat crown came with galvanized pipes rather than hose!. most regular school busses come with Bergstrom booster pumps which are notorious for the plastic manifold cracking and then they leak.. or the bearings go and they squeal not pumping anything..then just die or leak at the shaft seal.



the real webasto DBW2010 and scholastic model diesel coolant heaters came with MP-100 pumps which are all metal and move a ton of water.. however their downfall is if they are ever run dry for any reason the seal will melt and fail... and theres not a seal kit sold ...



my go to are Davies-Craig magnetically driven pumps.. no shaft seal, less current pull and they seem to last well.. they come in different sizes, the 3/4" line size ones are easily adaptable from thye school bus 1" and have a solid head pressure.. like most they arent self priming, but they dont ruin themselves if run dry by accident. and they dont crack...



they are australian but are easily obtainable in the states... are popular for hotrodders to use for liquid intercoolers or for engine off cooling on street cars being run at the track..


https://daviescraig.com.au/electric-...hoC8uwQAvD_BwE
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