Extra Boost to a Hot Box?

BlueBliss

BlueBliss

New member
I'm curious about running my engine exhaust through my hot box to add a little extra heat rise...why waste the heat?

We have operated out of enclosed trailers, vans, and box trucks for some time. We have solved exhaust problems in many different ways. I recently saw a picture from someone on this board (or another) that had piped their engine exhaust to their heater exhaust duct. It's so simple, yet the idea had previously evaded me. Seeing that made me think about it. It seems that the engine exhaust is rarely conveniently placed with this in mind. A new (used) machine I recently acquired has an exhaust pipe that can be easily adjusted (aimed) in many different directions. It is also positioned pretty well beneath the heater that a simple straight, vertical pipe would easily connect the exhaust to any duct work we already need. But, why enter at the duct work? Why not enter at the other side of the heater? Would a 30hp kohler (or in my case a 3cylinder diesel) increase the water temperature at all? What if there were also a 13hp engine for a vacuum? How much effect would this have on combustion in the heater when the burner actually starts? Or, could the blower supply enough circulation? Is there any merit to this? I would imagine this would greatly reduce the noise as well.

Any thoughts?
 
This is what most carpet cleaners use as a water heating source, called heat exchanger. It is basically a coil inside a exhaust pipe. I have a 18hp briggs engine, which the exhaust is connected to the heat exchanger and usually get temp close to 200 degreees. My pump is a hypro, 4gpm if i remember correctly, using it at 400 psi most of the times. It works good for this, but it might slack at higher flows and pressure. My opinion is that it might help get it to certain temp and keep it there, but hardly to help it rise temp.
 
I'm familar w/ the heat exchangers, but I think PSI is their choke point. They seem to be very efficient, but they normally max out at 1200psi or so. It would be nice to produce 8gpm at 3kpsi up around 140F w/ just exhaust. I just need to pipe it into the coils next to the burner.
My concern it that the O2 level would interfere w/ the burner ignition.
 
BlueBliss said:
I'm curious about running my engine exhaust through my hot box to add a little extra heat rise...why waste the heat?

We have operated out of enclosed trailers, vans, and box trucks for some time. We have solved exhaust problems in many different ways. I recently saw a picture from someone on this board (or another) that had piped their engine exhaust to their heater exhaust duct. It's so simple, yet the idea had previously evaded me. Seeing that made me think about it. It seems that the engine exhaust is rarely conveniently placed with this in mind. A new (used) machine I recently acquired has an exhaust pipe that can be easily adjusted (aimed) in many different directions. It is also positioned pretty well beneath the heater that a simple straight, vertical pipe would easily connect the exhaust to any duct work we already need. But, why enter at the duct work? Why not enter at the other side of the heater? Would a 30hp kohler (or in my case a 3cylinder diesel) increase the water temperature at all? What if there were also a 13hp engine for a vacuum? How much effect would this have on combustion in the heater when the burner actually starts? Or, could the blower supply enough circulation? Is there any merit to this? I would imagine this would greatly reduce the noise as well.

Any thoughts?
Click to expand...

Good thinking on exhaust heat (I had a few post about this before,and I guess landa had the ecos trailer in the pipeline too),

But you answered you own question in your design thought, with the O2, and possibly the velocity of the engine exhaust will add a turbulence factor to the boiler exhaust and flame pattern.

I think that one solution would be to preheat the water to the pump up to 140F, with better seals you may be able to go higher temps, the cons are you would have to put in place controls to monitor this temp and install a engine kill activated by over temp. Or better yet heat down stream

Once you go down stream of the pump and want to use waste heat you now have to deal with higher pressures, and most of the carpet cleaner heat exchanges I have seen utilize 3/8 tubing (which could be a significant psi killer in an efficient long tube exchanger,... 200-300ft) and what about the cost to make...... vs keeping the preheating to the inlet side of the pump (the exchanger need not be high psi rated). A positive of downstream heating is, not limited by pump seal temps, once you introduce it after the unloader.

However if you introduce preheating after the unloader and the trigger is not pulled for while then the water will get super heated, so you would need to have an activated exhaust bypass to the exchanger. (kind of like an unloader, but for the exhaust)

Truly I believe the best way is drive an independent low pressure piggy back pump.
 
You must log in or register to reply here.
Back
Top