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Here you go!
I’d agree with the post above. Move the top 2 breakers down to free up the space for a generator breaker then use a mechanical interlock. You’ll have full access to any of the circuits you want on with the generator ( on the main panel or sud panel). Though you will have to manually manage the breakers you want on so you’re not overloading your generator. . From a load perspective you’re not adding any load to your system with the generator breaker so can’t see why you’d have to change the panel.
cheers.
 

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Discussion Starter · #22 ·
Thanks for your response as well as responses by everyone else. It is clear to me that I should move the top 2 breakers on the right side down to the bottom. I have been reading alot about interlock vs transfer switch and it does seem like interlock is the way to go. Most of the circuits I want to run are on the main panel but I am adding central air which is being wired to the subpanel due to the lack of slots on the main panel. Another reason why the interlock sounds like the way to go. I was concerned with overloading the generator but it sounds like I need to manage this by managing the load, flipping off some circuits and worst case the breaker on the generator will trip if overpowered. I am planning on buying a Firman tri-fuel generator with the following specs:

OUTPUT
Running Watts8000(Gas) 7250(LPG) 5500(NG)
Starting Watts10000(Gas) 9050(LPG) 6900(NG)

I plan to hook it up to my natural gas line that is going to my gas grille. The supported wattage is alot less than gasoline so I will need to be more careful when running with natural gas. Maybe I will run gasoline during the day when usage is higher and natural gas at night. If anyone has any comments, let me know.
 

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Thanks for your response as well as responses by everyone else. It is clear to me that I should move the top 2 breakers on the right side down to the bottom. I have been reading alot about interlock vs transfer switch and it does seem like interlock is the way to go. Most of the circuits I want to run are on the main panel but I am adding central air which is being wired to the subpanel due to the lack of slots on the main panel. Another reason why the interlock sounds like the way to go. I was concerned with overloading the generator but it sounds like I need to manage this by managing the load, flipping off some circuits and worst case the breaker on the generator will trip if overpowered. I am planning on buying a Firman tri-fuel generator with the following specs:

OUTPUT
Running Watts8000(Gas) 7250(LPG) 5500(NG)
Starting Watts10000(Gas) 9050(LPG) 6900(NG)

I plan to hook it up to my natural gas line that is going to my gas grille. The supported wattage is alot less than gasoline so I will need to be more careful when running with natural gas. Maybe I will run gasoline during the day when usage is higher and natural gas at night. If anyone has any comments, let me know.
My neighbor runs his generator in a similar fashion. Gas during the day when it’s easier to fill up. Nat gas at night so he doesn’t have to get out of bed!
If you’re willing to spend a little extra, reliance sell a wattage meter that you can install near the panel. Uses a small toroid that you pass each hot leg of the cable from the panel to the inlet box. There are also tons of cheap Chinese options on wattage meters that work the same way but you need to power most of them where as the reliance one is passive. But to the point. If you install a wattage meter you can get a good feel for what you can safely have on so you’re not overloading the gen set.
cheers.
 

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Thanks for your response as well as responses by everyone else. It is clear to me that I should move the top 2 breakers on the right side down to the bottom. I have been reading alot about interlock vs transfer switch and it does seem like interlock is the way to go. Most of the circuits I want to run are on the main panel but I am adding central air which is being wired to the subpanel due to the lack of slots on the main panel. Another reason why the interlock sounds like the way to go. I was concerned with overloading the generator but it sounds like I need to manage this by managing the load, flipping off some circuits and worst case the breaker on the generator will trip if overpowered. I am planning on buying a Firman tri-fuel generator with the following specs:

OUTPUT
Running Watts8000(Gas) 7250(LPG) 5500(NG)
Starting Watts10000(Gas) 9050(LPG) 6900(NG)

I plan to hook it up to my natural gas line that is going to my gas grille. The supported wattage is alot less than gasoline so I will need to be more careful when running with natural gas. Maybe I will run gasoline during the day when usage is higher and natural gas at night. If anyone has any comments, let me know.
what is the btu rating on that gen set?
make sure the line is large enough for the gen set.
that is the cc's on the engine?
i like 1 inch on NG feed to medium gens.
then size down to 1/2 couplers and use 3/4 id hose.
 

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Discussion Starter · #27 ·
what is the btu rating on that gen set?
make sure the line is large enough for the gen set.
that is the cc's on the engine?
i like 1 inch on NG feed to medium gens.
then size down to 1/2 couplers and use 3/4 id hose.
Yes, I have been reading about the issues with gas pressure and line size. Attached are the specs for the generator and a picture of my gas line. I have no idea what the gas specs mean. Firman told me they require a 1/2" gas line to regulate the gas pressure. In the photo of my gas line, I have a clamp controlling my shutoff. The shutoff says 1/2", but then it seems to get reduced. I couldn't see any labeling on the hose to my grille. The gas line comes out of the house about 10 feet away and the gas coming into the house is about 30 feet away if that matters. Any advice would be appreciated.
 

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most gens need 150k btu min.
a gas grill needs 30-80k btu depending on how large the grill is.
3/4 would be the bare min.
so on the 1/2 line what is the total feet from the T from the larger line and the size on the larger line
and how many 90 deg fittings? each 90deg fitting is a minus 5 feet from the size chart.
 

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Discussion Starter · #31 ·
most gens need 150k btu min.
a gas grill needs 30-80k btu depending on how large the grill is.
3/4 would be the bare min.
so on the 1/2 line what is the total feet from the T from the larger line and the size on the larger line
and how many 90 deg fittings? each 90deg fitting is a minus 5 feet from the size chart.
Thanks for your reply. I attached two photos of my indoor gas line. The photo that is titled 3/4 to 1/2 inch (the one with the red water shutoff), you can see where I think it goes from 3/4" (could be 1") to 1/2". From the tee moving to the right is what the next photo shows. The 1/2" inch gas line from the previous photo continues on in this photo where the red hook on the left is. The distance from the 3/4" to 1/2" fitting to the red hook is about 3 feet. As you can see, there is an elbow that runs to the tee on the right. That is about 2 feet. From there, it's about 12 feet outside to an elbow and another foot to the shutoff valve that I showed you in my last post. I attached the shutoff valve photo again. What I am going to try to do is attach a 1/2 gas hose from my generator to the quick connect on the shutoff valve but I am not sure if the pressure is reduced there and won't give me enough pressure. Firman told me that a 1/2" hose should be used to regulate the pressure to the generator. Any thoughts and advice would be appreciated.
 

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how far are you from the meter to the gen set?
can you get a 1 inch direct from the meter to the gen area?
they make pipe unions that help with system pipes that are already in place.

if you had 1 inch to the gen area, then you could do a mini manifold with 2 shuts offs and valves outside so you could run the grill and the gen at the same time.
neck down to 3/4 valves and 1/2 couplers at the point of use.
that is nice for when you are on extended outage to be able to boil water outside for drinking or for grilling some dinner.

that outside pipe needs replaced any way.
make sure to use good rust proof primer and rust proof paint.
they make the pro cans of pain these days with high solids.
a can goes a long ways!
pm if you need links.
 

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This site has alot of good info on pipe sizing.

My suggestion is to draw a pipe map with lengths and diameters For us to see And for your own experience. Your system looks to be 3/4 and 1/2 in those pictures. I can almost guarantee that you don’t have enough volume tapping into your existing system. A home run from the meter would be the best move.

Your generators 439cc engine is approximately 14-15hp. A safe rule of thumb is 10,000btu per HP, so 150,000 btu of supply volume will guarantee proper fuel Quantity. In all likely hood you’ll need far less supply during normal operation with the generator mildly loaded but that leaves zero reserve for when other NG appliances are operating. Inadequate supply can cause the generator to bog and send voltages and frequency tumbling. It’s not worth damaging your devices and appliances.
 

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yup in the case of NG to a gen bigger is better on the pipe dia.
so for standard port gens.
i like 1 inch to the gen location with valves on both ends.
at the feed and at the point of use for safety shut off just in case you want to work on it or of you get a leak.

and if you are in earth quake areas ( almost all of the usa now ) make sure to have the new earth quake whole house shut off units put on for the new gas regulations.
they help keep you safe...

we had another bit of bumps last month here... a 2.xx rumble ...
and that is Iowa! lol!

they say those valves work for storm damage if you get a lot of building shaking.
and might be a good idea for storm areas!
 

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Discussion Starter · #35 ·
This site has alot of good info on pipe sizing.

My suggestion is to draw a pipe map with lengths and diameters For us to see And for your own experience. Your system looks to be 3/4 and 1/2 in those pictures. I can almost guarantee that you don’t have enough volume tapping into your existing system. A home run from the meter would be the best move.

Your generators 439cc engine is approximately 14-15hp. A safe rule of thumb is 10,000btu per HP, so 150,000 btu of supply volume will guarantee proper fuel Quantity. In all likely hood you’ll need far less supply during normal operation with the generator mildly loaded but that leaves zero reserve for when other NG appliances are operating. Inadequate supply can cause the generator to bog and send voltages and frequency tumbling. It’s not worth damaging your devices and appliances.
Well I had alot of fun after Thanksgiving dinner lol! Thank you so much for the information and the link to the generator pipe size page. Incredibly helpful! Attached is the pipe layout for my house as well as the calculations I came up with. I am pretty sure I have 1" and 1/2" pipes. I measured the circumference of each and used a pipe size chart I found and it looks like those are the pipe sizes. I don't believe I have any 3/4" pipes. In addition to the 2 notes in the diagram, there were several BTU numbers on my gas boiler so I included 2 of them. Note that the boiler is 30 years old. Here are some comments on my calculations. I realize this is new to me and I may be way off on my assumptions:
  • I used the 14.5 horsepower number you provided and the 145 CFH full load number that was derived from the horsepower. One thing I wondered about was that the generator specs have the generator running natural gas at 69% of the wattage compared to gasoline. I was wondering why that is and whether the CFH full load number with natural gas is also 69% which would be around 100 CFH.
  • The only thing off of legs I, J, K and L is the gas grill. If it is not used during an outage, that seems to give me 73 CFH which seems to get me close to the 100 CFH number but pretty far away from 145 CFH.
  • If I was to tap off of Leg G, that should give me 180 CFH (286 - 106) which would get me to both numbers but where does that leave the gas stove when that needs to be used? The 55,000 BTUs is if all 4 burners + oven are used at 100%, but at 2 burners + oven that would be fine if we are trying to get through a power outage. Seems like that would fit within the available CFH.
It seems like tapping off of Leg G (before the gas stove) is the way to go. It's certainly doable because it should be fairly easy to tap in there and run a line to the outside wall. It would be close to where I was planning on locating the generator as well. Of course, that would require a plumber and extra expense. I'd love to be able to run it off of the existing 1/2" line but that may not work if 73 CFH is not enough. Let me know your thoughts on all this. If anyone else wants to chime in, please do.

Finally, what did you mean in your last post by "A home run from the meter would be the best move. ". Thanks again!
 

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Well I had alot of fun after Thanksgiving dinner lol! Thank you so much for the information and the link to the generator pipe size page. Incredibly helpful! Attached is the pipe layout for my house as well as the calculations I came up with. I am pretty sure I have 1" and 1/2" pipes. I measured the circumference of each and used a pipe size chart I found and it looks like those are the pipe sizes. I don't believe I have any 3/4" pipes. In addition to the 2 notes in the diagram, there were several BTU numbers on my gas boiler so I included 2 of them. Note that the boiler is 30 years old. Here are some comments on my calculations. I realize this is new to me and I may be way off on my assumptions:
  • I used the 14.5 horsepower number you provided and the 145 CFH full load number that was derived from the horsepower. One thing I wondered about was that the generator specs have the generator running natural gas at 69% of the wattage compared to gasoline. I was wondering why that is and whether the CFH full load number with natural gas is also 69% which would be around 100 CFH.
  • The only thing off of legs I, J, K and L is the gas grill. If it is not used during an outage, that seems to give me 73 CFH which seems to get me close to the 100 CFH number but pretty far away from 145 CFH.
  • If I was to tap off of Leg G, that should give me 180 CFH (286 - 106) which would get me to both numbers but where does that leave the gas stove when that needs to be used? The 55,000 BTUs is if all 4 burners + oven are used at 100%, but at 2 burners + oven that would be fine if we are trying to get through a power outage. Seems like that would fit within the available CFH.
It seems like tapping off of Leg G (before the gas stove) is the way to go. It's certainly doable because it should be fairly easy to tap in there and run a line to the outside wall. It would be close to where I was planning on locating the generator as well. Of course, that would require a plumber and extra expense. I'd love to be able to run it off of the existing 1/2" line but that may not work if 73 CFH is not enough. Let me know your thoughts on all this. If anyone else wants to chime in, please do.

Finally, what did you mean in your last post by "A home run from the meter would be the best move. ". Thanks again!
Nicely done. The pipe map really clears things up. I agree tapping off of G should be satisfactory. The 1” x 1/2” x1” tee can be replaced with a 1”x1”x1” and keep 1” all the way to the end necking down to the right sized quick disconnect.

The only limiting factor to your system is the gas meter itself. Most are rated for 250cfh. A buddy of mine that works for the gas company tells me that there is more wiggle room to that number as long as the distribution lines in the street are under pressure. Essentially if you have a pressure regulator before your meter.

“home run” meaning a dedicated pipe from at the meter to the generators location. Since your trunk line is 1” you should be ok. If the trunk line was 3/4 tapping off of it would not have been sufficient.
 

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Discussion Starter · #38 ·
Nicely done. The pipe map really clears things up. I agree tapping off of G should be satisfactory. The 1” x 1/2” x1” tee can be replaced with a 1”x1”x1” and keep 1” all the way to the end necking down to the right sized quick disconnect.

”home run” meaning a dedicated pipe from the meter right to the generators location. If your existing trunk line was 3/4 this would have been absolutely necessary.

The only limiting factor to your system is the gas meter itself. Most are rated for 250cfh. A buddy of mine that works for the gas company tells me that there is more wiggle room to that number as long as the distribution lines in the street are under pressure. Essentially if you have a pressure regulator before your meter.

“home run” meaning a dedicated pipe from at the meter to the generators location. Since your trunk line is 1” you should be ok. If the trunk line was 3/4 tapping off of it would not have been sufficient.
Thanks for the explanation around the home run pipe. It is a possibility but would mean I would need to locate the generator further to the front of my house which is not preferable. I'll probably go with tapping in at the end of the 1" pipe as discussed. Do you think there is any chance the existing 1/2" connection would work? Firman said they require a 1/2 inch hose to regulate the pressure so there seems to be an expectation for a 1/2" connection.
 

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1/2 pipe has a steep drop off as it get longer. A few feet is one thing but a total of ~30ft including restrictions from elbows and quick connects cannot support enough gas volume.

just remember the gas pipe size is the inside diameter.
This is a good point, 3/4” black pipe has a ~1” outer diameter. Make sure you have your measurements correct.

Nominal size [inches]Outside diameter [inches]Outside diameter [mm]Wall thickness [inches]Wall thickness [mm]Weight [lb/ft]Weight [kg/m]
1/8 inches0.405 inches10.3 MM0.068 inches1.73 MM0.24 lb/ft0.37 kg/m
1/4 inches0.540 inches13.7 MM0.088 inches2.24 MM0.42 lb/ft0.84 kg/m
1/2 inches0.840 inches21.3 MM0.109 inches2.77 MM0.85 lb/ft1.27 kg/m
3/4 inches1.050 inches26.7 MM0.113 inches2.87 MM1.13 lb/ft1.69 kg/m
1 inches1.315 inches33.4 MM0.133 inches3.38 MM1.68 lb/ft2.50 kg/m
1 1/4 inches1.660
 
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