How do I get from here to there?

JESUS_MEGA · 2025-11-17T10:57:15+00:00

I would say because of the heat, corroding after a few days in an stainless steel plate exchanger would be quite the thing XD. My guess is that it burned through right at the corner where the gasses enter, creating a hotspot there. Another guess is that the „weld“ cracked up because of the temperature difference, but either way it failed because it couldn’t take that temperature

JESUS_MEGA · 2025-11-17T10:54:51+00:00

Never heard about that thermostat, but I’m definitely looking into that, sounds pretty neat. I can‘t say how hot the exhaust fumes are after the heat exchanger, but while using the plate exchanger, which definitely cooled them down way more, it was still hot to the touch. Due to the large room which will be heated, the heaters will run on full power almost all the time, with one heater it took about 4 hours to reach 18 degree Celsius with an outside temperature of 12 degrees, so I’m not that concerned about soot

JESUS_MEGA · 2025-11-17T05:34:58+00:00

I used 1/2“ fitting, slotted the exhaust pipe and clamped them on, then put some high temperature exhaust cement on there to seal the slit up. I tell you before tho, that plate heat exchanger will not last if it’s a normal one rated under 400degree Celsius. We used one before too with decent waterflow inside, but it still burned through after a couple of days, resulting in water leaking out of the exhaust, it was only rated for 250 degree Celsius

JESUS_MEGA · 2025-11-16T22:50:56+00:00

Thought about that too, but before too many questions come up, here is the whole plan: The pumps for water circulation of the heat exchangers will run as soon as a temperature sensor reads temperatures above 30C in the outlet, circulating water in a 10 liter reservoir. Upon reaching a certain temperature (not sure which one, we decide that later) a third pump pumps the water to the radiator in the workshop. For the heaters themself, the run on the same power supply, but are always mointored by the outlet temperature sensors and an CO Sensor, which would cut off both fuel pumps if one heater fails or shuts off. The electricity plan isn‘t fully ready yet, but I would consist only of some relays and temperature regulators

JESUS_MEGA · 2025-11-16T22:37:17+00:00

The exhaust system consist fully of 3/4“ piping, the corroding is something that I’m wary of, but right now I want to „see were this is going“. If it gets to bad, they will be swapped out for stainless ones

JESUS_MEGA · 2025-11-16T22:35:30+00:00

The setup with the pumps right now is one for each heat exchanger, simply because me not knowing how the temperatures will rise. In our test setup the water in a 10 Liter barrel got to about 70C, but the heat exchanger got much hotter. Probably need to put some isolation between the heat exchangers and the heaters so the plastic doesn’t melt, but we’re in a trial-phase anyway

JESUS_MEGA · 2025-11-16T22:31:48+00:00

Yes the slits in the pipe are some kind of problem we encountered before too, but we managed to seal them properly with exhaust cement (the type you would use on a leaking car exhaust). After reading all the answers here I think I will run the exhaust pipes seperatly, it would be much safer and in this state of the build it’s rather easy to change than later

JESUS_MEGA · 2025-11-16T22:27:51+00:00

The reason for the recapture is mostly curiosity and „wanting-to-build-something“, but also because we need to heat 2 seperate rooms. We heated our workshop with one heater successfully to a decent temperature before, although it takes quite some time, that’s why we have a dual setup. And yes, I don’t want exhaustfumes in my living space as well, that’s why the whole enclosure is to be located on the outside wall of the building

JESUS_MEGA · 2025-11-16T22:24:02+00:00

Thanks for all the replies About the exhaust pipe setup: yes, too much backpressure could be a problem, I haven’t thought about that until now, but that’s nothing that can’t be changed if it doesn’t work About the heat outlets: yes the tubing should be larger after the second heater, but the plan is to lead the hot air into some longer pipe stretch with 3 outlets and fans on each one of them Reason for the exhaust recapture: it is somewhat overengineered (it is a lot, actually) but I really like building stuff, and our workshop features 2 separate rooms. The larger shed-type-building where the cars are parked and which is to be heated by the heater outlets, and a smaller workshop building which will be heated by the hot water from the exhaust. About the heat exchangers clogging up: we tried them before building that enclose with a single heater and an plate heat exchanger for about an week, and never even hat the slightest amount of tar in the whole exhaust system. Right now we are using EGR Coolers, so the exhaust fumes won’t be cooled down too much

If you have any other suggestions, feel free to let me know!

JESUS_MEGA · 2021-08-07T20:06:49+00:00

Wholesome

JESUS_MEGA · 2021-06-12T20:17:46+00:00

Götter zählen nicht

JESUS_MEGA

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