# Generator shed question



## Bear (Dec 28, 2021)

Hi, I just purchased a Westinghouse 9,500/12,500-Watt Dual Fuel Portable Generator. I am going to build a sound-reducing storage shed for the generator. I am fairly handy with woodworking, so feel confident in building the shed. I of course will be installing a fan for adequate airflow (with a separate exhaust pipe going well above and away from the tanks). I was considering the propane tank freezing issue in the winter. My idea is to build a well-ventilated box at the end of the shed to store the tanks. The box would be completely removable for reloading tanks and for use in the summer months. But the idea I am having is to allow the warm air from the generator to flow over the tanks in the ventilated box in the winter. What do you guys think? One thing I am also thinking is maybe a bit of a deflector, so it flows around the tanks, but not directly onto the tanks, so maintain a warmer ambient temperature, but not apply direct heat of any kind to the tanks themselves. I assume if I can just keep the area well ventilated and nom direct heat source, it would be perfect to keep the propane tanks from freezing. Also, during the summer months if needed I would completely redirect all warm air away from tanks. What might I be missing? Thanks for your thoughts!


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## FlyFisher (Jun 30, 2018)

Bear said:


> What might I be missing?


Have you done fuel usage calculations to see what kind of run time you are going to have from the tanks you have on-hand? 

Are you running solely propane? Or do you have other fuel options? 

From the sounds of it your propane supply appears to be what you have in tanks, and not a large tank on your property such as would be used for primary heat for a season like what you see out in the country. 

The reason I bring this up is I came up with a ballpark number of fuel consumption for my 15kw on propane that is about 4lbs of propane per hour. That equates to, with a 100lb propane tank, 25hrs of run time. However, what that calculation does not take in to consideration is the pressure/flow loss as the tank nears its depletion. If you can only take the tank down to, say, 20% capacity before the propane in the tank can't meet the demand of the generator that means only 80lb of the 100lb tank is usable and that gets the 25hr run time down to 20 hours. 

As far as I know - places that fill portable propane tanks generally max out at the 100lb tank size. 

Your generator likely will burn less propane, it is a smaller generator. However, the same question is there - and is there with any size generator. How far can you go on the fuel supply you have? How many 100lb tanks are you planning to have on-hand and store in your "shed"? 

As far as the heating question - there are electric heated blankets you can get for propane tanks. That might be an option for ya. There again, how many tanks do you need and how many blankets do you need? What is the power requirement for the blankets and what is it going to take to get a power circuit out to the shed that can supply enough wattage/amperage to the blankets? The more current demand the larger the wire gauge to keep the voltage drop from being too large. So run your numbers and plan accordingly.

Running power to the shed would also allow you to put a battery maintainer on a starter battery if you have an electric start gen.


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## Bear (Dec 28, 2021)

FlyFisher said:


> Have you done fuel usage calculations to see what kind of run time you are going to have from the tanks you have on-hand?
> 
> Are you running solely propane? Or do you have other fuel options?
> 
> ...


Thanks for the reply! I will be most likely will use 40LB tanks. Easier to handle. I plan on have tanks in storage. I will have electricity for charging installed. A single 110 plug will be installed by my buddy the electrician. I have not run a live test yet of course, but the specs say 7 hours on a 20 lb tank at 50%. I plan on using an auto regulator switch to have two 40 pound tanks connected. I would do 100 lb tanks, but they are so much harder to transport in my pickup... It would be ok if you could lay them down, but I have read that is a no-no. As for the power blankets, well, if I could use the free heat from the airflow off of the generator, then why would I spend 5-6 hundred on those [ower blankets? Not to mention the power the blankets would use reducing my available power to the house. Efficiency is key.


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## Bear (Dec 28, 2021)

Bear said:


> Thanks for the reply! I will be most likely will use 40LB tanks. Easier to handle. I plan on have tanks in storage. I will have electricity for charging installed. A single 110 plug will be installed by my buddy the electrician. I have not run a live test yet of course, but the specs say 7 hours on a 20 lb tank at 50%. I plan on using an auto regulator switch to have two 40 pound tanks connected. I would do 100 lb tanks, but they are so much harder to transport in my pickup... It would be ok if you could lay them down, but I have read that is a no-no. As for the power blankets, well, if I could use the free heat from the airflow off of the generator, then why would I spend 5-6 hundred on those [ower blankets? Not to mention the power the blankets would use reducing my available power to the house. Efficiency is key.


I plan on having 6 to 8 tanks in storage...


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## FlyFisher (Jun 30, 2018)

Bear said:


> As for the power blankets, well, if I could use the free heat from the airflow off of the generator, then why would I spend 5-6 hundred on those [ower blankets? Not to mention the power the blankets would use reducing my available power to the house. Efficiency is key.


How are you going to keep the tanks warm so they are ready for when you DO need to run the generator?

If the blankets are on and running the tanks are always at the ready. 

If you are not heating the tanks and they are cold to start with - how are you going to warm them up in order to get the generator going when the power goes out?


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## Bear (Dec 28, 2021)

They would be in a storage box. 


FlyFisher said:


> How are you going to keep the tanks warm so they are ready for when you DO need to run the generator?
> 
> If the blankets are on and running the tanks are always at the ready.
> 
> If you are not heating the tanks and they are cold to start with - how are you going to warm them up in order to get the generator going when the power goes out?


They would be in a storage box or area. So they would not be stored outside in the weather. I believe the issue is not that they will freeze before you sue them, but during use when you get somewhere around 50% empty... So by that time, the generator should be blowing warm air.


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## Bluwolf (Nov 8, 2020)

There is some good info on this page at US Carb. If you scroll down the info is broken down on size of generator and size of tanks. There is also a vaporization chart for different size tanks at different temperatures. I'm in SW Florida so I didn't pay much attention to the temperature chart  

I'm doing the same as you with auto-switch and I'm using 40, 30, and 20 lb tanks.

Propane Consumption Rate - Motorsnorkel by US Carburetion


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## iowagold (Jan 22, 2020)

Bear said:


> They would be in a storage box.
> 
> They would be in a storage box or area. So they would not be stored outside in the weather. I believe the issue is not that they will freeze before you use them, but during use when you get somewhere around 50% empty... So by that time, the generator should be blowing warm air.


i second the tank blankets...
the tanks get cool when they let out fuel as well as cold to start with...
the tank blankets would have the LP pre heated to get a good start up and keep the fuel warmer for better fuel ratio...
or a better run.
also think on crankcase heater if you are in super cold temps like 10 deg F or colder.
LP and NG both need warm to work the best...


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## drmerdp (Apr 10, 2018)

Tank blankets can always be a functional improvement at a later date. It’s a solid tool for having adequate vaporization rates. But… it’s entirely feasible to carefully utilize generator heat to bump vaporization rates at low temperatures. Though there is a tipping point where the generator may not start or run long enough to achieving enough warming.
Here is another chart for propane tank run times based on size. It’s specific to Honda generators but may be of some use. 


https://genconnexdirect.net/Liturature/Technotes/GenConneX_Technote_Propane_Tank_Runtimes.pdf



Keep us in the loop as you start to build and configure.


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## iowagold (Jan 22, 2020)

drmerdp said:


> Tank blankets can always be a functional improvement at a later date. It’s a solid tool for having adequate vaporization rates. But… it’s entirely feasible to carefully utilize generator heat to bump vaporization rates at low temperatures. Though there is a tipping point where the generator may not start or run long enough to achieving enough warming.
> Here is another chart for propane tank run times based on size. It’s specific to Honda generators but may be of some use.
> 
> 
> ...


yea if you are above 10 deg f...
but if the temps are lower you need to get ahead of the vapor rate temp drop you will get as soon as you start drawing LP from the tanks.
small tanks the temps drop fast and so does the pressure.
i would do some sort of warmer in the shed to keep it above lets say at least 40 deg F as a min temp..
a balmy 50-60 deg f would be nice.

it take a long time to warm up a small 30-40 lb tank of LP from 0 deg F...

if you had the larger 100 lb tanks it would not be an issue.
at least down to -10F
on a small single cyl gen set.


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## tabora (Sep 6, 2018)

I place my 40lb tank(s) right outside the exhaust shutter for my shed in cold weather, and near the intake shutter in hot weather. Keeps them temperate at all times...


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## Bluwolf (Nov 8, 2020)

There's probably something wrong with this idea but... I understand the part about needing to pre-heat the generator and the tanks before you even start it. What about a small space heater in the shed? He said he was going to run power out to the shed anyway. It could keep the the shed and everything in it, in a constant state of ready warmth.


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## OrlyP (Oct 19, 2021)

I'm curious... How about combining two 40lb tanks to get twice the surface area for vaporization? Then put a two-stage regulator at the outlet side of this Y-adapter:



https://www.amazon.com/MOFLAME-Y-Splitter-Converter-Conversion-Appliance-POL/dp/B09BKND3TQ/ref=sr_1_3?crid=1XAYHLAGHLXTG&keywords=MOFLAME+Y-Splitter&qid=1640782511&sprefix=moflame+y-splitter%2Caps%2C331&sr=8-3



In particularly cold days, I would place the tanks about a foot away from the side of the generator shed to capture most of the heat from the exhaust pipe and fan.


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## Bear (Dec 28, 2021)

tabora said:


> I place my 40lb tank(s) right outside the exhaust shutter for my shed in cold weather, and near the intake shutter in hot weather. Keeps them temperate at all times...


Great, thanks, this is just what I was planning for.


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## Bear (Dec 28, 2021)

iowagold said:


> yea if you are above 10 deg f...
> but if the temps are lower you need to get ahead of the vapor rate temp drop you will get as soon as you start drawing LP from the tanks.
> small tanks the temps drop fast and so does the pressure.
> i would do some sort of warmer in the shed to keep it above lets say at least 40 deg F as a min temp..
> ...


I live in the North Central Texas area just north of Dallas. I am hoping we never have another great blackout, but I am sure it is possible, thus the generator. LOL, Lived here for 30 years before we ever had an issue, but suddenly we are having power issues in Texas... Anyway, It is extremely rare to drop into the single digits, and historically rare to drop below zero. If it does drop too low for the propane initially, then I was thinking I could run a tank of gasoline to get the gen and gen box warm, then switch back to propane. Does this make sense?


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## drmerdp (Apr 10, 2018)

Bear said:


> I live in the North Central Texas area just north of Dallas. I am hoping we never have another great blackout, but I am sure it is possible, thus the generator. LOL, Lived here for 30 years before we ever had an issue, but suddenly we are having power issues in Texas... Anyway, It is extremely rare to drop into the single digits, and historically rare to drop below zero. If it does drop too low for the propane initially, then I was thinking I could run a tank of gasoline to get the gen and gen box warm, then switch back to propane. Does this make sense?


Yes, makes sense. Your generator is dual fuel. If temps arent conducive for starting on propane, gasoline will have you covered. Just be careful with leaving fuel in the system, and the potential for carbs gumming up.


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## Bear (Dec 28, 2021)

Bluwolf said:


> There's probably something wrong with this idea but... I understand the part about needing to pre-heat the generator and the tanks before you even start it. What about a small space heater in the shed? He said he was going to run power out to the shed anyway. It could keep the the shed and everything in it, in a constant state of ready warmth.


I thought about this, and maybe this would be a good idea if extreme cold weather is coming in. I could prepare by running a small heater in the shed with the propane shut down to ensure no danger. This would result in the generator already being warm and the tanks would also be warmer. The shed will be very insulated, as I am also going to make sure it has soundproofing. This also made me think of what I did for a cat house and this would be perfect I think just to keep it from freezing in the shed. while having high safety. https://www.amazon.com/Hound-Heater...aWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1


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## Bear (Dec 28, 2021)

drmerdp said:


> Yes, makes sense. Your generator is dual fuel. If temps arent conducive for starting on propane, gasoline will have you covered. Just be careful with leaving fuel in the system, and the potential for carbs gumming up.


Yes. I really hope to never run gas through it. But I will also make sure it is real gas and treated.


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## Bluwolf (Nov 8, 2020)

Bear said:


> I thought about this, and maybe this would be a good idea if extreme cold weather is coming in. I could prepare by running a small heater in the shed with the propane shut down to ensure no danger. This would result in the generator already being warm and the tanks would also be warmer. The shed will be very insulated, as I am also going to make sure it has soundproofing. This also made me think of what I did for a cat house and this would be perfect I think just to keep it from freezing in the shed. while having high safety. https://www.amazon.com/Hound-Heater-Protector-Mounting-Template/dp/B00II71C72/ref=sr_1_51_sspa?crid=1BG3UAAZGL31U&keywords=dog+house+heater+with+fan&qid=1640786722&sprefix=dog+house+heater+with+fan,aps,86&sr=8-51-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFRU1hZNjkzOFkyN1EmZW5jcnlwdGVkSWQ9QTAzMzYzNjQyUEVCMjFEME5QOERQJmVuY3J5cHRlZEFkSWQ9QTA4OTcwNzQxWjdROEs1RUFJRDRBJndpZGdldE5hbWU9c3BfYXRmX25leHQmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1


I didn't even realize there was such a thing as a dog house heater. In hind sight it makes perfect sense. The way you say you would prepare for, and use it is exactly what I was thinking. Obviously not something that would run 24/7. Only when you felt it was appropriate. Hopefully this would keep you from having to run gas through it at all.


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## Bluwolf (Nov 8, 2020)

OrlyP said:


> I'm curious... How about combining two 40lb tanks to get twice the surface area for vaporization? Then put a two-stage regulator at the outlet side of this Y-adapter:
> 
> 
> 
> ...


The two tanks being Tee'd together is a good way to help the vaporization rate. But, unless I'm missing something, doesn't that leave out the auto-switch set up? I mentioned that I've got the same set up. I like the idea of knowing when the tank is really empty instead of having to guess and being able to swap it out while the gen is running. And not running the risk of the gen shutting down under power. Which we know is not good for the gen or the house.

Maybe you included the auto-switch in your description and I just didn't understand how.


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## OrlyP (Oct 19, 2021)

Bluwolf said:


> The two tanks being Tee'd together is a good way to help the vaporization rate. But, unless I'm missing something, doesn't that leave out the auto-switch set up? I mentioned that I've got the same set up. I like the idea of knowing when the tank is really empty instead of having to guess and being able to swap it out while the gen is running. And not running the risk of the gen shutting down under power. Which we know is not good for the gen or the house.
> 
> Maybe you included the auto-switch in your description and I just didn't understand how.


That's true, my post was about solving the vaporization in cold weather issue. But you can scale this up to include an auto-switch by using two banks of two 40lb tanks in a T.. (total of 4x tanks).

Bank 1 has Tank 1 and Tank 2 on the 1st T
Bank 2 has Tank 3 and Tank 4 on the 2nd T

The outlets from Bank 1 and Bank 2 feeds into the two inlets of the auto-switch. You'll now be able to switch between Bank 1 or Bank 2.

Once the tanks within the same bank are turned on, they'll eventually reach equilibrium and should run out virtually at the same time.


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## drmerdp (Apr 10, 2018)

OrlyP said:


> That's true, my post was about solving the vaporization in cold weather issue. But you can scale this up to include an auto-switch by using two banks of two 40lb tanks in a T.. (total of 4x tanks).
> 
> Bank 1 has Tank 1 and Tank 2 on the 1st T
> Bank 2 has Tank 3 and Tank 4 on the 2nd T
> ...


Since the generator and tank enclosures are going to be custom built anyway. Sizing things to accommodate banks of cylinders attached the changeover valve is a neat idea. Pairs of 40lbs cylinders tied together absolutely will improve vaporization rates in cold temps. And will provide nice long runtimes. The guy lives in Texas, so much of the priority for preheating the cylinders may be misplaced. Also considering gasoline is always still on the table.


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## Bluwolf (Nov 8, 2020)

OrlyP said:


> That's true, my post was about solving the vaporization in cold weather issue. But you can scale this up to include an auto-switch by using two banks of two 40lb tanks in a T.. (total of 4x tanks).
> 
> Bank 1 has Tank 1 and Tank 2 on the 1st T
> Bank 2 has Tank 3 and Tank 4 on the 2nd T
> ...





drmerdp said:


> Since the generator and tank enclosures are going to be custom built anyway. Sizing things to accommodate banks of cylinders attached the changeover valve is a neat idea. Pairs of 40lbs cylinders tied together absolutely will improve vaporization rates in cold temps. And will provide nice long runtimes. The guy lives in Texas, so much of the priority for preheating the cylinders may be misplaced. Also considering gasoline is always still on the table.


These two posts pretty much summed up where I was going with this. The only way to use OrlyP's idea and retain the auto switch is to go the 4 tank route. If I had the room that's the way I would go. Bear said he was building a custom shed so the fit is not a problem unless he says it is. And he has to store the tanks somewhere, why not in the shed.

Would that eliminate the need for the heater on the propane? Then he could just have one to warm up the generator.


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## OrlyP (Oct 19, 2021)

Bluwolf said:


> These two posts pretty much summed up where I was going with this. The only way to use OrlyP's idea and retain the auto switch is to go the 4 tank route. If I had the room that's the way I would go. Bear said he was building a custom shed so the fit is not a problem unless he says it is. And he has to store the tanks somewhere, why not in the shed.
> 
> Would that eliminate the need for the heater on the propane? Then he could just have one to warm up the generator.


Bank 1 and Bank 2 does not need to be identical. You can have two 40lbs on one bank and a single 20lb on the other bank and it should still work. In this example, you just need three tanks... Tank 1 and Tank 2 in a T, while Tank 3 goes straight to the 2nd inlet of the auto-switch (2nd T is not used, in this case). In fact, I don't see any reason it wouldn't work with any tank size combinations....from 5 to 40lbs.


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## drmerdp (Apr 10, 2018)

It should technically work with 100lb tanks as well. Just need to change the hose whips from QCC1 ends to hoses with POL ends. 100lb tanks only come with POL valve ends.


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## Bear (Dec 28, 2021)

OrlyP said:


> Bank 1 and Bank 2 does not need to be identical. You can have two 40lbs on one bank and a single 20lb on the other bank and it should still work. In this example, you just need three tanks... Tank 1 and Tank 2 in a T, while Tank 3 goes straight to the 2nd inlet of the auto-switch (2nd T is not used, in this case). In fact, I don't see any reason it wouldn't work with any tank size combinations....from 5 to 40lbs.


So if I am reading this right you have 4 tanks total. using tee's you tie two tanks together, then the 2 sets of two are connected via the auto-switch, resulting in a 4 tank system?


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## Bear (Dec 28, 2021)

OrlyP said:


> I'm curious... How about combining two 40lb tanks to get twice the surface area for vaporization? Then put a two-stage regulator at the outlet side of this Y-adapter:
> 
> 
> 
> ...


Thanks for that link. This y-connector is exactly what I was looking for. it makes sense to do this and attach to use to create two banks fo 40 lb tanks, that are connected to a single auto-switch regulator!


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## OrlyP (Oct 19, 2021)

Bear said:


> So if I am reading this right you have 4 tanks total. using tee's you tie two tanks together, then the 2 sets of two are connected via the auto-switch, resulting in a 4 tank system?


Exactly. With that setup, you effectively have two 80lb switchable tanks.


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## Bluwolf (Nov 8, 2020)

OrlyP said:


> Bank 1 and Bank 2 does not need to be identical. You can have two 40lbs on one bank and a single 20lb on the other bank and it should still work. In this example, you just need three tanks... Tank 1 and Tank 2 in a T, while Tank 3 goes straight to the 2nd inlet of the auto-switch (2nd T is not used, in this case). In fact, I don't see any reason it wouldn't work with any tank size combinations....from 5 to 40lbs.


No, you're right there wouldn't have to be identical twin set ups. But he said he has quite a few 40 lb tanks. So as long as he was going to the trouble of doing a T set up with the auto switch over, why not not two T set ups?

I was still thinking about having to warm them too. This would have 4 tanks warming up at the same time. Even if he had more tanks somewhere cold, he'd be swapping out empty tanks and the fresh, cold ones would be warm by the time they switched back over.


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## Bear (Dec 28, 2021)

I will definitely give pictures and plans of what I end of with.


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## Bulldogger (Feb 19, 2021)

Bear said:


> As for the power blankets, well, if I could use the free heat from the airflow off of the generator, then why would I spend 5-6 hundred on those [ower blankets? Not to mention the power the blankets would use reducing my available power to the house. Efficiency is key.


 Check Ebay for blankets. I got an open box Powerblanket for my 420pound tank for $129. You can tell it's never been used. Might be a harder challenge to find for a 40-pound tank. If you can get one at a great price, it wouldn't hurt to have in your "tool box."


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## Bear (Dec 28, 2021)

I have started building my shed. here is what it looks like. will hold 4 40lb tanks (2 tanks per bank, each bank attached to high-flow auto-switch regulator) and my Westinghouse gen. Building the floor this weekend and getting it on pads and leveled this weekend. next weekend the back wall. Start working on the side and compartment separator walls. All three of these will need to be built with the vents and fans' attachments, so going to take my time to get it right. Then I think I will do the lids. Doing one for each compartment, so I can open them separately. Also, the end cap for the propane section will be removable so that the whole compartment can be completely opened if running in the summer and make it easy to replace the rear tanks. The floor will be constructed of 4x4 and 3/4 marine plywood, with a foam mat covering. 4x4 floor will be approx 15/16 inch on center. I want to make sure that there is a brace running under the compartment separator wall, so will be splitting the difference.


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## GenKnot (Dec 20, 2021)

Looks like a really nice plan. I live in far north Dallas area, so I certainly understand why you are doing this. I am putting my gen in my existing shed and hooking up to NG. Hope our NG doesn't get turned off or have low pressure.

My shed has a concrete floor. Have you considered concrete? It would take about 12 bags to do a 3.5 inch slab (41 x 82), so about $70 there. Some rebar or 6X6 wire reinforcement...a few more bucks. Concrete is a lot of work if only using a wheelbarrow for mixing. I just installed new concrete steps (10 bags) out front using wheelbarrow, and it wore me out! I probably should have rented a mixer at my age!

With concrete you wouldn't have to worry about rotted flooring down the road, or critters living under the shed either. I was just thinking about water getting under the foam mat and eventually damaging the plywood.


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## Bear (Dec 28, 2021)

GenKnot said:


> Looks like a really nice plan. I live in far north Dallas area, so I certainly understand why you are doing this. I am putting my gen in my existing shed and hooking up to NG. Hope our NG doesn't get turned off or have low pressure.
> 
> My shed has a concrete floor. Have you considered concrete? It would take about 12 bags to do a 3.5 inch slab (41 x 82), so about $70 there. Some rebar or 6X6 wire reinforcement...a few more bucks. Concrete is a lot of work if only using a wheelbarrow for mixing. I just installed new concrete steps (10 bags) out front using wheelbarrow, and it wore me out! I probably should have rented a mixer at my age!
> 
> With concrete, you wouldn't have to worry about rotted flooring down the road, or critters living under the shed either. I was just thinking about water getting under the foam mat and eventually damaging the plywood.


Yes, I did consider the concrete pad. But I wanted to make sure it was completely portable, shed and all. in case it needs to be moved. I am using treated wood on the entire shed, with 3/4 treated plywood on the floor with the treated 4x4s. So very heavy duty so to speak, I am also going to paint it. it should last many more years than I would ever need it... LOL... Also, I will set it off the ground with prefab concrete pads. as far as critters go, well I live on acreage, so critters are just part of it - LOL I am hoping we will never need it, but I figure worse case I have it, best case don;lt need it but adds to the value of the home. I don't have NG supply, so going the next best thing with the propane on a dual-fuel generator and putting in large propane tanks just for the generator makes little sense to me for the cost, as I have an all-electric house. 6 x 40 pounders will last about 3 days, I am going to add at least 2 more to have well over 3 days supply, never goes bad, and is easy to refill if I run out of propane, I can scrounge up another 1/2-1 day worth of gasoline... And I could also extend using some of my 20Lb's I have. I have camping stoves and heaters that use the 2/3 lp tanks and make sure to have several of those around in case of emergency. It was those 1-2 pounders that saved the day last year...


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## drmerdp (Apr 10, 2018)

Bear said:


> View attachment 10929
> I have started building my shed. here is what it looks like. will hold 4 40lb tanks (2 tanks per bank, each bank attached to high-flow auto-switch regulator) and my Westinghouse gen. Building the floor this weekend and getting it on pads and leveled this weekend. next weekend the back wall. Start working on the side and compartment separator walls. All three of these will need to be built with the vents and fans' attachments, so going to take my time to get it right. Then I think I will do the lids. Doing one for each compartment, so I can open them separately. Also, the end cap for the propane section will be removable so that the whole compartment can be completely opened if running in the summer and make it easy to replace the rear tanks. The floor will be constructed of 4x4 and 3/4 marine plywood, with a foam mat covering. 4x4 floor will be approx 15/16 inch on center. I want to make sure that there is a brace running under the compartment separator wall, so will be splitting the difference.


 Drawing up a plan is always a smart way to start. I like the idea of a wooden deck. It keeps it moveable if needed. Never hurts to keep things flexible. 

The generator is configured with the engine on the left and alternator on the right. To best utilize airflow I would switch the propane tanks from the left side of the enclosure to the right side. The exhaust fan should also be moved to the right side. 15” fan… are you thinking attic fan with a thermostat?

A two compartment structure with a centered exhaust fan is an interesting idea. It’s a bit safer from a propane perspective but might hinder airflow and cooling for Texas summers unless using large enough intake and exhaust openings. Attic fans are around 1500-1900cfm which feels too small for Texas’ warm climate. I’d say a 20” fan minimum and more square inches on the openings for both ends.

Its not likely to scale but too much deflector around the tanks might defeat the point of using cooling air to keep the tanks warm and may hurt airflow as well.

Will you be lining the interior with something cement board, foam or another type of shielding?


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## GenKnot (Dec 20, 2021)

@drmerdp When I was looking at the drawing, I was wondering if exhaust would be drawn into the shed. OP did not mention if exhaust is turned up or just going straight out.

Would turning gen around and exhaust out the front work? That would put controls at the back, but maybe there is enough height to the shed to not matter that much.


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## drmerdp (Apr 10, 2018)

A vertical exhaust would be effective for the build either way, but turning the generator has the doors facing the back of the generator. If you flip the doors, effectively I think it’s the same as moving the propane tanks, fan and dividing wall to the right hand side.


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## GenKnot (Dec 20, 2021)

Okay, I follow that. Thanks.


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## OrlyP (Oct 19, 2021)

Yeah, solid plan except that the airflow needs to be improved.

On such generator, the side where the recoil and airbox are located is the cold side. This is where the generator pulls cool air and push it out, hot, towards the right side. On the other hand, the power head is cooled by pulling air from the end cap and hot air expelled out the vents where the engine and power head mates. But that said, the majority of the airflow goes from left to right. The fan will be fighting this natural airflow so I tend to agree that the tanks should be on the right while the exhaust pipe is rerouted to the back.


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## Bear (Dec 28, 2021)

OrlyP said:


> Yeah, solid plan except that the airflow needs to be improved.
> 
> On such a generator, the side where the recoil and airbox are located in the cold side. This is where the generator pulls cool air and pushes it out, hot, towards the right side. On the other hand, the powerhead is cooled by pulling air from the end cap and hot air is expelled out the vents where the engine and powerhead mate. But that said, the majority of the airflow goes from left to right. The fan will be fighting this natural airflow so I tend to agree that the tanks should be on the right while the exhaust pipe is rerouted to the back.


On my generator, the engine is on the left side the generator is on the right when facing the control panel, I think this is kind of a standard layout, so you got me thinking. So the generator pulls or pushes cool air in from the end cap, after your comments I am assuming it pushes air through the end cap? Now the problem, due to where this shed will be and access/maintenance and other factors, I really think it best to maintain the current generator control panel direction. So there is the one choice to switch the tanks to the other end, this makes sense, just complicate the exhaust issue to the rear of the box with a vertical pipe to go above the enclosure. 

The other approach I was thinking about was using a baffle, that would push the air movement around the powerhead end cap. Basic physics says, if done right, this would actually create a bit of a vacuum in the baffled area, thus helping pull air through the end cap. Anyway, thank you! I am going to go this morning and take a look at the situation and think through the best approach. Also, I have a support request out to Westinghouse to see if they have an opinion on the matter. Anyway, will let you guys know the ultimate direction I go with.


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## OrlyP (Oct 19, 2021)

Some visualizations might be helpful...

This is the airflow of the engine.... It pulls air through the recoil side, through the blower, metal cowling, and diverts the air over the cylinder head.










At the same time, the stator pulls cool air from the end cap, over the windings, stator blower, which then expels the hot air down to the ground through the steel vents between the engine and the power head.










But for all intents and purposes, most of the heat is generated by the engine and it flows from LEFT to RIGHT, when looking at the control panel. If you intend to use a fan to warm up the propane tanks, it will be better that it works with this airflow rather than fight it. That means, it's batter to have the tanks on the right.


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## GenKnot (Dec 20, 2021)

Just a wild idea, what about putting tanks at rear of shed? No diffuser, use reversible fan for summer/winter use. I like the inside fan idea between 2 compartments...it is protected from rain, etc. Two doors to access tanks. Flow across tanks should be better maybe. Vent sizes could be smaller since using 4 vents. I have not designed a gen shed before, so keep that in mind.


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## GenKnot (Dec 20, 2021)

Two more thoughts. First, with side flow air, there wouldn't be a fight against the two different directional flows from engine and alternator. Second, summer air might be slightly cooled by the tanks before going to engine compartment.


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## OrlyP (Oct 19, 2021)

GenKnot said:


> Two more thoughts. First, with side flow air, there wouldn't be a fight against the two different directional flows from engine and alternator...


Not sure if that was addressed to me(?) but, I was referring to the added fan in the middle, between the tanks and the generator that the OP is planning to put in. That fan will be fighting the genset and it's not going to be the best way to do it.


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## GenKnot (Dec 20, 2021)

@OrlyP No, I wasn't addressing that to anyone in particular. I'm just thinking out loud.


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## Bear (Dec 28, 2021)

GenKnot said:


> Two more thoughts. First, with side flow air, there wouldn't be a fight against the two different directional flows from engine and alternator. Second, summer air might be slightly cooled by the tanks before going to engine compartment.


The main intent of my design is to use the heat from the generator to marginally keep the tanks warmer during very cold weather and use the shed to protect the tanks from year-round weather. So I need the warm airflow to go through the tank compartment during the cold months. During summer use I would open the tank compartment so that the flow would not overheat the tanks. I wonder if during the cold freezing weather, overheating the gen would not really be an issue, no matter the direction of the flow. So now the reversible fan begins to make sense.  during cold weather, the flow of warm air is over the tanks, and reverse the flow in warm weather to then create the maximum value flow for the generator. Also, another design consideration; what if I had a smaller vent on the generator side in the lid and a smaller vent on the opposite wall? In theory, this might create a swirling effect.

Another idea is to run two 10 inch fans one facing left, the other right. Plug in the appropriate fan for the appropriate weather outside... What do guys think?


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## drmerdp (Apr 10, 2018)

To under engineer the ventilation system means doors open for summer use and doors closed in winter. Do you want the enclosure to provide sound attenuation?

You need to decide if you are building a warm box for winter use, or a closed door operating enclosure suitable for summer use...


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## GenKnot (Dec 20, 2021)

@Bear Just in case you haven't looked for fans yet, there are a number of multispeed reversible fans on Amazon. I don't know if you are looking for a more "industrial" fan (mucho $$), or if you are trying to go with more economical fans as you would probably not be using the gen that often. It would be helpful if you had an idea of the CFM needed if someone could weigh in on that. Pushing too much CFM would just waste electricity (which means wasted fuel), and too little CFM would not get the job done.

Here are just some examples of economical fans.

3-speed reversible...








Amazon.com: Air King 9166F 20" Whole House Window Fan , Gray : Home & Kitchen


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Flip over to reverse direction...








Amazon.com: OEMTOOLS OEM24895 18 Inch Workstation Fan, 3853 CFM Max. Industrial Wall Fan, 360 Degree Rotating 18 Inch Wall Mount Fan, Barn Fans for Livestock : Home & Kitchen


Buy OEMTOOLS OEM24895 18 Inch Workstation Fan, 3853 CFM Max. Industrial Wall Fan, 360 Degree Rotating 18 Inch Wall Mount Fan, Barn Fans for Livestock: Table Fans - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



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This could be mounted vertically if needed and has a remote...








Amazon.com: KEN BROWN 9 Inch Twin Window Fan With Remote, 3-Speed Reversible Air Quiet Flow and Thermostat Control,ETL Safety Listed : Home & Kitchen


Buy KEN BROWN 9 Inch Twin Window Fan With Remote, 3-Speed Reversible Air Quiet Flow and Thermostat Control,ETL Safety Listed: Window Fans - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



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