Solar Power Shed Project

[mwood]

3RRL - Sounds like you've got everything covered! I'm sure you'll enjoy this for years to come! Hopefully, a few years down he road, you'll look back and feel proud of all the hard work and planning you put into this to make it work just as planned!

 

[patrick_g]

Pat, need I remind you that the light bulb is a hardware issue and you should not be involved.

Guilty your honor but with an explanation. For a span of years prior to finding TRUE RELIGION (Software Engineering) I labored in service of false gods in tasks such as Electronic Hardware Design and consulting in same. I confess I designed medical electronic equipment that had no microprocessors nor any computational ability beyone simple analog (excuse me for using the "A" word) scaling. Deprivation was rampant, all math functions such as taking the log base 10 of the ratio of a reference current to a object current and displaying this on (oh goody) a digital display.

I have since successfully completed a 12 step program (5 times (recidivism is a *****) and only occasionally when with bad company do I do much design of analog circuits. I have honestly tried to quit and have managed to cut back a lot but getting this monkey off my back is not easy.

Pat

 

[Highbeam]

It would seem that if you have a sealed room and a sealed duct through which your engine fan is sucking outside air, that an open vent of the same size and located high in the room would exhaust the hot air at the same rate that it is being pulled into the room. It will get warm in there if you suck with the fan which is why I would recommend a pusher fan like on a bulldozer. Maybe cummins offers a pusher fan which would allow you to force air from the room through the radiator and out through the sealed duct with replacement air sucked in through (filtered) vents. Any vacuum that the room feels won't matter so long as all parts of the generator are exposed to the vacuum equally.

I wouldn't even worry too much about filtering the makup air since the genset was made to be operated outside.

 

[patrick_g]

Highbeam, Sorry, it just doesn't work that way. From your description,during a long run the room air would be all exhaust. Of course at equilibrium the same amount of heat would leave the bld as the engine produced but at equilibrium the inside temp of the room and the delicate electronics would get too close to the temp of the air coming off the hot radiator.

Reconsider the milk in the bottom of the glass example as it illustrates the exponential mixing problem very well.

A really good solution would be to use a reverse fan (pusher like you mention) and put a good fitting shroud/duct system to direct the hot air off the radiator out of the bld and not let it mix with the air in the bld. Then the fresh air coming in would dominate the interior temp.

Lowe's sells temp regulating vents for venting the crawl space of a house. Above a certain temp they are fully open. Below another temp they are fully closed. In between those tow temps they are intermediate. You could put a couple of those (were $9.00 each) or similar in the system and divert some of the warm air to the inside of the bld for winter heat but not to exceed a reeasonable temp.

If it were me I'd probably remote the radiator to a box on the wall and use a thermostatically controlled fan like so many cars use. By directing the hot air out fo the bld, fresh air would come in through the supplied vents. As to not needing filiters on the vents... They were not for the engine because as you say the engine and associated generator were designed for outside use. The vents are to reduce the ingress of excessive dirt and dust which will build up on the electronics. Filters are cheap and easier to change than to dust and clean the electronics.

Pat

Purposely filling the entire space, delicate electronics and all with the hot air off the radiator is not a good idea.

Pat

 

[RavensRoost]

3RRL (Rob):
I have been following this thread for sometime now and enjoy it. I guess I missed the post where it said your Onan PULLED air in the radiator vs. PUSHING is out. Is this for sure? I would have predicted it is a "pusher".

I have a weekend offgrid place and installed an 8KW diesel in an insulated "doghouse" (enclosure) on a slab inside a shed for noise treatment reasons as much as anything. Diesels aren't the quietest things around! The direction of airflow is in via fresh air louver to the generator end past the engine and OUT the radiator/2x louvers.

I ended up having to fab a shroud to duct radiator hot air to the louvers at side of shed. Later, I discovered the shroud itself was rejecting so much heat (in summer which is when it gets the most use: think A/C) that I had to insulate the shroud as well as add a large box fan in front of the air inlet louver to force as much of the heat out of the shed as I could (fan is wired/fused to genset outlet so it only runs when genset is running.)

RavensRoost

 

[RavensRoost]

Rob, I forgot to say box fan is blowing outside air into shed: pressurizing if you will.

RavensRoost

 

[patrick_g]

Bruce, If Rob's genset is a "PUSHER" we sure wasted a lot of internet bandwidth. If it is a pusher then duplicating your design would be a good alternative. Roger the insulation on the ductwork! The little fireplace/wood stove I had on my sailboat put as much or more heat into the boat via the stove pipe as from the stove itself. Likewise the wood stoves you make out of 55 gal drums by adding a cast iron door and flue pipe.

Pat

 

[Highbeam]

I would shy away from a non mechanical fan. There is something to be said for the dependability of a fan that pumps cooling air anytime the engine is running. Simple and reliable for a system that will run unattended.

Air must leave the room at the same rate at which it enters. Getting the hot air to leave is superior, as is pulling nonheated air over the engine and genset guts.

So does your fan suck or blow?

 

[patrick_g]

Highbeam, If it is a pusher it is a slam dunk. If not... well There sure are a lot of cars on the road with electric fans and a pretty low failure rate. I agree the pusher fan, engine driven, is a good thing but if it is not a pusher the hassle of trying to plug up the hot air leaks would probably f=drive me to a remote radiator and an electric fan. I suppose you could extend a mechanical shaft from the current fan mount to a bearing and a remote fan instead of an electric fan and retain the mechanical reliability. I agree on how nice it is that if the engine runs and needs cooling the fan turns for sure. It just matters what you would go through to avoid the small probability of an electric fan failure.

Pat

 

[3RRL]

3RRL (Rob):
I have been following this thread for sometime now and enjoy it. I guess I missed the post where it said your Onan PULLED air in the radiator vs. PUSHING is out. Is this for sure? I would have predicted it is a "pusher".

I have a weekend offgrid place and installed an 8KW diesel in an insulated "doghouse" (enclosure) on a slab inside a shed for noise treatment reasons as much as anything. Diesels aren't the quietest things around! The direction of airflow is in via fresh air louver to the generator end past the engine and OUT the radiator/2x louvers.

I ended up having to fab a shroud to duct radiator hot air to the louvers at side of shed. Later, I discovered the shroud itself was rejecting so much heat (in summer which is when it gets the most use: think A/C) that I had to insulate the shroud as well as add a large box fan in front of the air inlet louver to force as much of the heat out of the shed as I could (fan is wired/fused to genset outlet so it only runs when genset is running.)

RavensRoost

RavensRoost,
After reading the suggestions about having an exit for the radiator fan, I took it for granted that it was sucking air in, through the radiator from the outside. Much like a car or tractor radiator would.

I just looked at the schematic my solar contractor made and it is indeed a "pusher" as drawn. So the air is being exhausted through that opening. I have not been to my property for several weeks and have not seen the generator run myself, only from what the contractor told me. I am going up at New years and will confirm after the final walk through.

But for now, according to the schematic, consider it a pusher fan ... directly exhausting to the outside through that opening in the photo.