Robin RGD3300 Diesel Genset

Re: Robin RGD3300 Diesel Genset

Tony - yes, I'm going to try to seal around the bottom where they can get in by laying down a green-treated 2 x 6 under the bottom of the glass batts and then seal the raised corrugations in the steel outside walls near the ground with bag-crete.

NorthGuy - the insulation I bought is fire-retardant type. I got it at Menards. I will kind of melt in a direct flame from a torch but if you take the flame away it doesn't continue burning or melting. They don't call it fire-proof, just fire resistant, made from non-combustible fibers. I think that is required now by most building codes to help prevent spread of a fire inside the walls in a building.

That is sort of one reason I prefer to use the onboard fuel tank for liquid fueled generators. They ARE a fire hazard and if one would catch fire it's generally better to have a limited amount of fuel there (6 gallons) to fuel the fire instead of a large tank nearby. It would require a fuel transfer pump to have a large fuel tank a safe distance away for fire purposes, and that's not really practical for a small genset either. And nowadays you can't even set a stationary fuel tank anymore for a generator unless it has spill containment (concrete dike). It won't pass the building inspector. For a large diesel genset it's worth it to go thru the hassle. But for a small generator that will run for a whole year on 100 gallons of fuel, it's easier to just fuel it from a can.
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Chris

Re: Robin RGD3300 Diesel Genset

Well, decided two things different tonight - I'm going to put a gravel floor in the powerhouse instead of a floating treated plywood floor. I like gravel - it's really hard to get it to burn.

And I decided to re-arrange the furniture a bit from what I had originally planned. The Robin diesel will set where I show it in the photo with the exhaust routed thru the wall to the right. The Honda will set along the right wall with the control panel facing the room and the exhaust routed directly thru the wall like it is in the present gen house. Electrical panels will go in the corner to the left of the door. Fresh air will enter thru the wall on the left in the photo (forced in by ventilation fan) and ventilation exhaust air will exit thru the wall to the right.
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Chris

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Re: Robin RGD3300 Diesel Genset

I'm not sure about the toxicity of it. But it won't burn. If you hold the point of the flame from a propane torch to it, it takes about five minutes to burn a hole thru it. And it never does catch on fire, nor is there any smoke from it. So I wouldn't call it fire proof (like concrete or steel). But it's definitely fire-retardant material.

It's got a listing of code compliance and ASTM numbers on it longer than my arm.
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Chris

Re: Robin RGD3300 Diesel Genset

Ralph - it does that now in the little enclosure using Relay #3 in the AGS as a preheat would be for a diesel. It runs the fan for one minute before cranking. After the initial startup, then the fan is thermostatically controlled so it normally stays running after the genset shuts down until the temp in the enclosure falls below the stat setting.

I've changed that whole setup since I first built it, and after we put in the XW inverter. The XW-AGS operates three pilot relays in the gen house and the pilot relays handle ignition/ECU, crank, and fan control. I also added a fourth relay that sends switched B+ back to the XW-AGS, with the relay coil activated by the genset's battery charging alternator, so it knows when the gen has started so it can halt the crank signal. That wasn't required with the SW+ GSM.
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Chris

Re: Robin RGD3300 Diesel Genset

mike95490 wrote: »

Be careful with crankcase breather fumes and the insulation capturing the oil mist, in a couple years, you can accumulate enough oil to make a rockwool wick burn nicely.

The crankcase breathers on both the Honda and Robin are re-combustor type that circulates the breather gases back into the intake. So no problems with that.
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Chris

Re: Robin RGD3300 Diesel Genset

Skip - the present smaller gen house for the Honda has a gravel floor and dust has never been a problem in there. So I don't think it will be a problem. But if it dries out from the heat and dust gets kicked up I'll just dump a couple five gallon pails full of water on the floor. The area where I build the powerhouse is a low area that gets all the rain runoff from the shop roof, so I think the ground is going to stay pretty wet under that gravel, though.

Tony - yep, I think I'm going to have to go a version of that system that Onan used. I sat in the powerhouse on my upside down five gallon pail studying the situation last night and that was the exact conclusion I came to - I need to duct the ventilation intake air directly towards the diesel generator. That will give it fresh cool air. And when it's not running the fresh air will flow around the diesel and over to the Honda where it can use it. Then put a forced air exhaust fan where I got that warm air exhaust vent, and make the exhaust vent larger. That will prevent the air from going directly across the room and out the warm air exhaust vent, without picking up the heat off the generators like it is now.

The only thing is, an axial fan does not work that good for ducted air. So I'm going to try to find a centrifugal furnace blower fan for the intake side. I'll try the axial fan first, but I suspect the back pressure from the ducting will reduce the airflow too much.
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Chris

Re: Robin RGD3300 Diesel Genset

Bill, that's why I put that warm air exhaust vent up by the ceiling. I figured that the heat would naturally rise and the air flowing across the room would carry it out. But there must me some turbulence issues there so the air doesn't mix properly and carry the warm out out like it should. Standing in the room with the Robin running there was a nice cool blast of air flowing directly across and out the vent. The vent air was warmer than the intake air, but not warm enough. But it was trapping hot air down by the generator. I think I need to introduce a "swirl" in there by ducting it so the ventilation air picks up the hot air and carries it out.

For noise, you have to have the ventilation openings away from the generator so the sound has to go around corners to make it outside. If you put the ventilation opening right by the gen, then it's really loud right thru the hole.

This is NOT my area of expertise, so I'm just experimenting
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Chris

Re: Robin RGD3300 Diesel Genset

I put the muffler in the room because I wanted to use it for heat in the winter so I can get it up to about 60-70F in there for those air-cooled engines. The muffler, however, doesn't put out anywhere near the heat that the engine cooling system puts out. The silver insulation, which is only about 6" from the muffler, barely gets warm to the touch with the generator running at full load for an extended period. That's a pretty big muffler for a little 265cc engine, so it just doesn't get that hot.

I really think the ducting idea you came up with will work good, and use both forced intake and forced exhaust to improve the airflow thru the thing for summer. I found a little 1/3 hp axial fan that has special blades on it with an actual airfoil on the blades - it moves a LOT of air. I'm going to build a air box around the ventilation exhaust, mount that fan on the air box and try it again, using a temporary deflector of some sort to deflect the incoming cool air right over the genset.
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Chris

Re: Robin RGD3300 Diesel Genset

I found out that this setup barely gets the room above ambient temp. For whatever reason, blowing the fan right on the genset gets the heat away from the generator, it goes around the back wall and right up to the exhaust fan. I ran the little Robin for 24 hours straight from 6:00 PM yesterday to 6:00 PM today. Halfway thru the test run today I pulled that makeshift air deflector down and made a flap that covers the air intake hole. Then placed the fan so it's blowing right on the gen. It dropped the temp in the powerhouse by 5 degrees. 77 degrees outside 84 degrees in the powerhouse.

The little diesel burned 5.3 gallons of fuel and our consumption was 36 kWh. But several times during the test run the load exceeded what the little thing can put out so the XW assisted it from RE power. So the 36 kWh all didn't all come from the little generator. But most of it did - better than 30 kWh.

This is what it looks like the way I have it set up now.



The room is so air-tight that the exhaust fan pulls that foam insulation flap I made open about a foot. So I'm thinking that in the winter I'll just set the window fan on the floor and have it run all the time when either generator is running to circulate air in the room and eliminate "hot spots". And let the Duct Stat control the exhaust fan. The flap will go shut by itself when the exhaust fan isn't operating and help keep the cold air out when it's 30 below and the generators aren't running.

This is my theory on this:
With the price of diesel fuel crashing recently, and it's now cheaper than gasoline (which hasn't happened for 5 years) - and off-road #2 being 60 cents a gallon cheaper than gasoline right now, I can run this thing around the clock for about $15 a day. That's pretty darn cheap off-grid prime power when I take into account that a week of bad RE conditions in the dead of winter can be easily handled without charging the batteries even once with the generator. In fact, the batteries can float for the whole week, we can use all the freaking power we want and live in style, and the fuel bill in that little diesel generator will only be about $105 running 24 hours a day for 7 days.

As it is now, on those bad days when we only get 3 kWh (if we're lucky) the Honda starts on low battery voltage and charges up the batteries. And we only got about 20 gallons of hot water in the heaters because the only element that heats is the top one in the primary heater unless we get sufficient RE power. With this little diesel going I can heat water 24 hours a day if I want during those times, just to keep it busy - and not have to conserve a single watt in the house or shop.

So the way I got it figured is that the net difference between having to charge batteries with the Honda and heat water with it (inefficient) vs running the little diesel for week, not cycling the batteries at all, and having all the power we want on tap ("borrowing" from the little bit of RE we get for Gen Support on the big loads) is about nil. It costs money to cycle batteries and charge them with an inverter charger. My theory is that the long term total cost of off-grid power will be cheaper by using the prime power genset and putting some fuel in it than it will by working the snot out of the batteries and the Honda for that week (or two).

We'll see how all this pans out. But after my 24 hour test run, she's lookin' good.

Now I have to get the Honda moved to the new powerhouse so it can live with its new companion. Also, preheat for that diesel for winter time starting is neatly solved. I can heat the Honda's head and carb with the heat lamp like I did last year and it'll start in any weather. The Honda runs several times a day in the winter, even during excellent RE generating times, for peak load support. As well insulated as this new powerhouse is, just the fact that the Honda runs an hour or two every every day will keep the diesel warm without having to preheat it at all.
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Chris