Aqua/Hydro Hot Smell Cure

[Windward]

I've gone to great lengths optimizing the operation of the diesel fired Hydro Hot in our rig. I've replaced several parts and have it running like a watch. It's quite an ingenious piece of equipment however, there is no way you can completely eliminate the diesel smell.

Everyone has different tolerances to the odor but I don't like to share my stink with the neighboring campers. I connect a Genturi when parked which works great to push the odor above the roof line and disperse the stink.

We just returned from a week on the Oregon coast spent in State Parks. When we walked the campground returning to our rig you could pick up the diesel smell a couple camps away. I was the only Class A there so the only diesel burner running. The limited capacity of the electric element won't space heat much so if its cold your running the diesel.

When we got home I looked for a high flow muffler to help the roar of the burner. Looking through my salvage parts I came across a catalytic converter off a 4 cylinder 2004 Toyota Tacoma. It had 2" inlet/outlets, an oval chamber about 5" x 8" and about 12" long. After blowing it out I could see through the internal element. I temporarily put it on the end of the Hydro Hot exhaust pipe and fired it up. Wow no more diesel stink. There is a slight acrid smell similar to a car exhaust but a huge reduction in smell. Not much different than a propane furnace exhaust.

I cut the pipe and inserted the converter just after the iron pipe discharge of the Hydro Hot. I put a heat shield on top of it and verified it prevents the underfloor from getting too hot on a long firing. Unlike a car that is flowing a lot of hot gases for long periods, the Hydro Hot doesn't run for hours per cycle so it should have limited heat generation. It also has good air flow so I'm not worried about restricting the exhaust. No smoke on start up and no diesel smell when running. Like in a car it finishes burning the exhaust and cleans it up.

I will monitor it's operation over the next few trips and post the results.

[BrianGlenn]

Originally Posted by Windward

I've gone to great lengths optimizing the operation of the diesel fired Hydro Hot in our rig. I've replaced several parts and have it running like a watch. It's quite an ingenious piece of equipment however, there is no way you can completely eliminate the diesel smell.



Everyone has different tolerances to the odor but I don't like to share my stink with the neighboring campers. I connect a Genturi when parked which works great to push the odor above the roof line and disperse the stink.



We just returned from a week on the Oregon coast spent in State Parks. When we walked the campground returning to our rig you could pick up the diesel smell a couple camps away. I was the only Class A there so the only diesel burner running. The limited capacity of the electric element won't space heat much so if its cold your running the diesel.



When we got home I looked for a high flow muffler to help the roar of the burner. Looking through my salvage parts I came across a catalytic converter off a 4 cylinder 2004 Toyota Tacoma. It had 2" inlet/outlets, an oval chamber about 5" x 8" and about 12" long. After blowing it out I could see through the internal element. I temporarily put it on the end of the Hydro Hot exhaust pipe and fired it up. Wow no more diesel stink. There is a slight acrid smell similar to a car exhaust but a huge reduction in smell. Not much different than a propane furnace exhaust.



I cut the pipe and inserted the converter just after the iron pipe discharge of the Hydro Hot. I put a heat shield on top of it and verified it prevents the underfloor from getting too hot on a long firing. Unlike a car that is flowing a lot of hot gases for long periods, the Hydro Hot doesn't run for hours per cycle so it should have limited heat generation. It also has good air flow so I'm not worried about restricting the exhaust. No smoke on start up and no diesel smell when running. Like in a car it finishes burning the exhaust and cleans it up.



I will monitor it's operation over the next few trips and post the results.

Very cool. Keep an eye on back pressure as the diesel soot may plug the cat catalyst.

Brian

[Windward]

Good point about back pressure. I thought about that when locating and that's why I it's as close as possible to heat source to maximize heat to catalytic core for max burn up of soot.

To monitor back pressure I added a 1/8" pipe port bent to point to the core. I can remove brass pipe cap, add fitting and blow the core out with air or monitor back pressure when it is running.

After installing the port today I ran the burner with the space heat and engine pre heat on for a long burn cycle. No back pressure on start up or running. After it ran for over 30 minutes, it was hot at the iron pipe 90 deg discharge of the burner but the catalytic was running cooler. Heat shield appears to work good shielding the under floor. Coach was inside my shop with the side door open while running and I could tell it was burning but no diesel odor.

Waiting for 2" band clamp to finish install up.

So far I'm impressed!

[Windward]

Went out for a quick overnight trip. Put 3 hours on the heater and was really happy with the exhaust smell or lack thereof but I think I have a little too much back pressure for the combustion blower. It started making a different sound while running I didn't like. No problem heating but didn't sound right.

Got home and pulled the catalytic off and ran the burner with a much better blower sound and volume of exhaust. I took a 1/4" drill bit and put holes in the catalytic core, blew it out then put it back on. Still didn't like the sound or volume coming out of the pipe vs: no catalytic. Pulled it off again and used a 1/2" drill bit again blew it out and out it back on. Much better sound of the blower and better volume out the pipe. It appears to still be burning the exhaust up but due to large holes in the core it is not quite as acrid as compared to the fine holes of the original catalytic core.

Need to get some hours on the drilled out catalytic to see if it behaves. I am packing a pipe with me that I can put on in the field if I don't think it is working right.

Stay tuned!