Diesel Heater Project

[Delta Riverat]

In the for what it's worth column. I have an Hcalory 8KW heater in my shop. I know the exhaust gets hot. This thread got me curious so I broke out the General Tools infrared thermometer. Right at the exhaust pipe I saw 253 F. That seemed to me to be too low. I know these don't work well when sensing the temperature of a shiny reflective object, and it is an el cheapo. So I took a bit of carpenter's shim and lay it on top of the exhaust tube. In just a few minutes, I'd say less than 2, it started to char the wood.

And, 8KW Chinese Diesel heater. Ummm, no, I don't think so. They seem to be a copy of the much lower output originals. And I have an Espar 8KW in the boat. There is no comparison. The Espar puts out a lot more heat.

Hehe, yeah, I know it does too, I've seen it glowing red hot in the videos. But generally in open still air. That thin SS tubing doesn't have a lot of thermal mass and with no dissipation, yeah, gets hot. The wood on the pipe proves it also.

But if there was constant air over the dissipation would go way up and so the temperature would go way down. I am concerned about radiant heat close to the wood and thus my air spaced heat shield plan. I'm also going to relieve the wood around the though hull fitting. I kept it small to locate the drill holes so I could orient the angle correctly. Next trip I'll use a much bigger hole saw to remove a lot more wood and secure the fitting to the fiberglass only. There is a bout a 1.25 inch gap between the wood wall and the outer fiberglass shell. That SS backing plate will go away.

 

[MVCalypso]

A thought about the elec feed to the heater - I put a circuit breaker cover over the breaker that runs the heater. Except in a true emergency, you don't want the circuit to open while the heater is running. Crew may think that shutting of the power is how to turn the heater off. When power is interrupted the control can't run the cool down cycle that's part of shut off & the usual result is that the control PCB (inside the heater, under the top cover) electronics get fried. It often requires a new control before you can get the heater running again.

 

[Delta Riverat]

I agree. The cool down cycle must be observed.

 

[Bmarler]

Please reconsider putting lagging on the exhaust. It’s not expensive, and makes a big difference.

Exhaust Insulation Sock, white (by the foot)

Marine HVAC Solutions

www.nwmarineair.com

 

[more]

for insulation i use https://www.amazon.com/exhaust-insulation-wrap/s?k=exhaust+insulation+wrap

after this 2-3 layer temperature drop under 100°C then use standard thick 1-inch pipe glass insulation if need temperature under 100°C

 

[more]

this guy messure

 

[Delta Riverat]

Ok guys, I ordered up the exhaust pipe insulation.

 

[Delta Riverat]

Progress, today's work;

Got the heater output to the microwave compartment. Don't think this is weird, look close to the bottom right and see the AC output coming up from the fridge compartment. There is a nice wood louvered vent that exceeds the area of a 3" circle right on top of the microwave. And yes, with AC on cold air comes out that vent. Soon, warm air will be coming out also -

The inside of the heater cab;

All the angles are coming together nicely. The stars are aligning in the cosmos -

Next some marking for the fuel lines and electrical connections (which will require much mods) as the harness they supply is way too long just like the exhaust pipe.

 

[Bmarler]

So the microwave box is sort of a plenum box for the ac and heater outputs? If it’s a pressurized box and the treated air comes out from the louvered door you might want to go around the corners with some caulking. There’s some good sized cracks there that will leak a lot of air.
I’ve never seen anyone do it that way before, especially with the microwave in there too.

 

[Delta Riverat]

Yeah Baby!

These old boats...

That pic is a good one, shows the steps down which the scaffold spans and yeah, that top cabinet is right behind the microwave cabinet -

 

[Delta Riverat]

I’ve never seen anyone do it that way before, especially with the microwave in there too.

Cool, I'm an innovator -

 

[luna]

And there I thought hot air rises. What warms your toes?

 

[Delta Riverat]

Whisky

 

[Bmarler]

While there’s no doubt that warm air will come out the vent, I have to wonder about the efficiency. Ac air handlers and Chinese diesel heaters use entirely different fan types. The cage fan in an ac air handler can withstand higher static pressures and still deliver air quantity. The diesel heater fan can’t handle back pressure well. They need shorter, more free flowing ductwork.
It will be interesting to see how it performs in this setup.

 

[luna]

With the heater's output (as show in the You Tube video upthread) running at around 214º F, I would be concerned about the operational limits of the microwave.

There could also be an unintended feature in that you may be able on a cold winters day to reheat your coffee in the nuker without even turning it on!

 

[Delta Riverat]

While there’s no doubt that warm air will come out the vent, I have to wonder about the efficiency. Ac air handlers and Chinese diesel heaters use entirely different fan types. The cage fan in an ac air handler can withstand higher static pressures and still deliver air quantity. The diesel heater fan can’t handle back pressure well. They need shorter, more free flowing ductwork.
It will be interesting to see how it performs in this setup.

The diesel heater uses a slant blade centrifugal blower designed for high pressure. I has to blow air through the small space between the housing and the exchanger fins. My 3 inch outlet is going to less than a foot long blowing into a large plenum and then out the louver vent that has more open area than a 3" pipe. The return air is also not throttled as I have (2) 3 inch inlets.

 

[Delta Riverat]

Got the wood around the exhaust fitting relived and the wiring harness for the heater installed. Didn't need to shorten anything -

Trying to keep that middle shelf as clean as possible because storage space is precious on a boat eh?

Next trip will be fitting the 4 pipes for length and position.

 

[Delta Riverat]

Three pipes fitted;

Had to locate the unit first with one pipe and mark it on the shelf and then it all seemed to fall together;

Now on to the fuel line.

 

[luna]

Before you move on, let's see. Three hoses, Combustion Air Supply, Exhaust, and Conditioned Air to the Cabin, all fitted.

But not a hose clamp in sight! What could possibly go wrong? With the risks so large would you want to save the $15+/- for some clamps?

Once the clamps are installed do yourself a favor, heavily insulate the Exhaust and the Conditioned Air lines.

 

[Delta Riverat]

Oh yeah, no problem.

Right now, still fit up time. No sealant, no clamps, no holes drilled for hold downs either. No fuel, no electric, still lots to do.

 

[Delta Riverat]

Got me a SS fuel tank for the heater and painted it white. Changed out the sight tube to Tygon.

This is going on the outside of the boat on the same wall as those through hulls are on. Measured carefully and drilled the hole today for the fuel line pass through. Plan is coming together nicely.

 

[MVCalypso]

I've always tapped my (diesel) heaters off the fuel manifold from my tanks. Figure I'm unlikely to run out of heating fuel that way.
I'm curious - What's your thinking re a separate tank for the heater?

 

[Delta Riverat]

Line from engine room would be long, well over 2 meters and running it would be a nasty job. Also not going to need it much as winter time is used to work on the boat and we do not live aboard.

 

[Portage_Bay]

Got me a SS fuel tank for the heater and painted it white. Changed out the sight tube to Tygon.

This is going on the outside of the boat on the same wall as those through hulls are on. Measured carefully and drilled the hole today for the fuel line pass through. Plan is coming together nicely.

Where did you get the tank?

 

[Lepke]

I have 2 Chinese heaters I use in mild weather when I don't need the main system. I ran a fuel line from my main fuel manifold with a small lift pump and a pressure regulator. The heaters are about 2 decks above the tank outlet. I set the regulator so the fuel doesn't overpower the heater's pump. And then I don't have tanks I have to fill and maybe spill diesel.

I would insulate the exhaust inside the cabinet.

 

[Delta Riverat]

Where did you get the tank?

Amazon

 

[Mac2]

I got this and have been very happy with it.

 

[Bmarler]

Got me a SS fuel tank for the heater and painted it white. Changed out the sight tube to Tygon.

This is going on the outside of the boat on the same wall as those through hulls are on. Measured carefully and drilled the hole today for the fuel line pass through. Plan is coming together nicely.

That’s a nice little day tank. A fill up on that should last several days of off and on use.
It’s amazing what you can gat on Amazon, I haven’t seen those before.

 

[CaptTom]

I'm curious - What's your thinking re a separate tank for the heater?

For me, it was the fact that I want to be able to run kerosene when I'm not using it regularly. Supposedly that cuts way down on soot buildup and improves reliability.

 

[Delta Riverat]

I plan to mount the tank behind the steps up to the fly bridge so it will be protected from much contact.

And now you know why I painted it white -