Original Heat Exchangers

[lornaschinske]

I've used the search function and still can't find what I'm looking for (I did not go thru all 86 pages). We have a BlueBird All American FE. Is the heat exchangers on a separate loop from the engine cooling system or does it intersect? On our Eagle the DD engine had a "preheat" loop thru the engine that was independent from the engine cooling system. Would the BB have a similar setup? We were told at the time of purchase our BB is supposed to have a DD in it. But I ran the VIN and it came back as a GM 8.2TA Gas (we fill up with diesel). I want to use the existing heat exchangers for heat and add a dedicated LP water heater into the loop to heat the coolant.

 

[SHORTS]

the gm8.2 was built by detroit diesel, which is now owned by daimler benz, it's not the same as the DD's used in big trucks but still a decent engine.
I,m assuming that you are refering to the heaters in the bus, they are/should be plumbed into the coolant bypass loop along with the defrosters, that allows coolant to circulate thru the engine before the thermostat opens and allows coolant into the radiator to cool the engine. you might want to look at Webasto heaters, they are diesel fired and specifically designed as coolant heaters for trucks, etc.

 

[lornaschinske]

I don't want to use diesel fuel to heat with. We will be living full-time in the bus. I would rather heat with propane since we will also be using propane to cook, heat water and run a blue flame wall heater (built into an antique fireplace mantle we have). We will have diesel to run a generator. I do not want to have to either move the bus or haul in cans for diesel to refuel the heating system. I want to reuse the original heat exchangers (with a little modification) and I would like it if we could have the over the road engine heat for the heat exchanger while driving AND still use the heat exchangers while parked. Also I can buy an RV AC/LP water heater for far less $$ than a Webasto.

 

[SHORTS]

a properly sized lp water heater should work along with a couple of circulating pumps and a liquid/liquid heat exchanger if you want to use the same heater for both heat and potable water. look at household radiant heat for schematics and ideas, just replace the heat loops with the heaters.

 

[lornaschinske]

I will want to use a dedicated heater for the hydronic system. Someplace (probably packed into my stuff stored in NM) I have a breakdown on the Aquahot heating systems that I got several years ago. I can't seem to find the same thing online anymore. It listed every part, fitting, etc involved with the Aquahot system and how it was all put together. I had used it to figure out how to put a similar system together (it was all off the shelf parts in the early days). That combined with the DIY radient flooring heat info that I accumulated resulted in cost estimates of 1/4 the $$ they wanted for a similar sized Aquahot system. This was all planned for our Eagle (which we no longer have). I don't want to use an RV furnace (we've got one in the Class C and it's a bit noisy) mostly because of they tend to be energy hogs (either eats up the propane or the fans suck electric). Since we never, ever, ever plan on being in snow again, we are opting for the hydronic heat and a solar air heater like the http://www.motherearthnews.com/Do-It-Yourself/1977-09-01/Mothers-Heat-Grabber.aspx(plans are here http://greenterrafirma.com/solar-air-heating.html ) . We will probably just remove the back heat exchanger from the current loop and reset it up as a fan forced ducted system using energy efficient fans. That way we keep the front heating system for over the road use. I really just needed to know how the engine preheat loop was set up. Thanks

 

[busdriver_phil]

I'd look at the Webasto heater, they're offered as original equipment on every school bus. Espar is another one, but Webastos seem more popular. Some of the buses I drive at work have them, and there's a noticeable difference in heat first thing in the morning. They also help preheat the engine for cold weather starting.

Most school buses don't have a separate loop for the heaters. The hoses are plumbed right in to the engine cooling system. Webastos are installed under the bus in the cooling system, and run on diesel from the fuel tank. Nothing inside the bus, no separate fuel supply - just turn the switch on and they start heating with a quiet hum.

 

[lornaschinske]

I don't think we have a Webasto in our bus. Of course I can't look because the bus is in NM and we're in Corpus. But the bus was titled out of SC. So they may not have ever had a Webasto in it. The front heat exchanger says "Hurri-Hot" on it. And I can't find any info on the internet. I guess I will wait until we pop-up there to pick up some tools to have a look under the bus. I have been under it and didn't see anything that looked like a heater but I wasn't looking for a heater at the time. And there is nothing with any vents/air intakes down the side of the bus so it would have to be near the engine.

 

[busdriver_phil]

Most school bus heaters are made by an outside supplier such as Hurri-Hot. They run hot coolant through the heater core (similar to a radiator core) and use fans to blow air across it. Most of them don't need a separate air intake, they just draw air in from around the heater and filter it right before the fans. All of the heaters and defrosters should work on the same principal.

Webastos weren't common in the 80s. They're becoming popular now, depending on your budget you might want to consider a retrofit. If you can find a good way to heat the coolant lines with propane it would be effective too.