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02-18-2019, 03:28 PM
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#1
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Senior Member
Join Date: Jul 2018
Location: Dallas, TX
Posts: 198
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LPG for coach, and generator, or both...
Have a new fiver, five tanks. This is the basic setup that I can see:
About to install a new Onan LPG genset.
Comments I've heard: "You can run anything else when you're running the generator, there's not enough gas".
Onan recommends going at the start of the chain for the same reason, and kind of hints at turning everything else off hard in case the gas being consumed starves something else out.
Another post here mentioned having a dedicated LP system for the generator.
So, I thought of this:
Seems like with a couple of Y valves I could dedicate one take to generator and the rest to coach, vice versa, or almost anything. Is is a Bad Idea, or even hard?
Thanks, all!
__________________
2020 Ford F-350 6.7l 4x4 SRW LB
2019 Palomino Columbus 289RL
2003 Thor Jazz 2780BH (sold)
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02-18-2019, 06:11 PM
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#2
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: May 2016
Location: Kamloops, BC, 60 miles from the Center of the Universe according to the Rinpoche, of the SF monks.
Posts: 7,305
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Most likely your regulator is not made to flow enough for the genset and other loads. Talk to a propane shop about getting one with higher flow, not higher pressure.
Happy Glamping.
__________________
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!
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02-18-2019, 10:30 PM
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#3
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Senior Member
Join Date: Nov 2015
Posts: 26,643
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Standard RV LP Regulator has a 160,000btu flow rating
SO....
40K btu furnace
12K Water heater
9k and two 5k stove top burners
2k oven
2k fridge
2k outside grill
That's 77,000 btu/hr demand (IF you ran everything at same time)
5.5K Onan LP Gen
.8 gallon/hr at half load & 1.1 gallon/hr at full load
1 gallon propane has 91,600btu
77,000 plus 91,600 -------168,600 btu demand (runnign everything at same time)
SO Two standard 160k btu 2 stage LP Regs on a split system WILL handle the demand
One side primary for RV and one side primary for gen with cross tie so either can supply RV and/or Gen
High capacity auto changeover regs are also available in 350k and 400k flow rates
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Dodge 3500 w/Tractor Motor
US NAVY---USS Decatur DDG-31
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02-19-2019, 06:52 AM
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#4
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Senior Member
Join Date: Aug 2016
Location: Payson, AZ
Posts: 1,270
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what you are thinking would obviously work. but you may need to install another regulator so that each tank feeds a low pressure regulator. in your diagram i believe the regular on the 30 lb tank is a high pressure regulator. but before you go to the effort to do it i'd just get the generator installed and then install the dedication valves if you find that you are actually starved for lpg fuel. for what it's worth we have a lpg onan 5500 and have not yet run into a situation where we were starved for fuel. but we don't push it to the limits either. we did have a regulator failure but that had nothing to do with the generator.
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02-19-2019, 09:10 AM
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#5
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Senior Member
Join Date: Sep 2014
Location: Franklin, NY
Posts: 152
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FWIW .. my Sprinter Class C had an LPG Onan genny and had 2 separate regulators. I don't recall if the Onan was on it's own or not, but the coach also had a gas/electric fridge, gas/electric water heater, furnace & stove.
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2019 Winnebago Forza 34T
2022 Airstream Interstate 24GT
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02-19-2019, 03:27 PM
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#6
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Senior Member
Join Date: Nov 2015
Posts: 26,643
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Quote:
Originally Posted by khocke
FWIW .. my Sprinter Class C had an LPG Onan genny and had 2 separate regulators. I don't recall if the Onan was on it's own or not, but the coach also had a gas/electric fridge, gas/electric water heater, furnace & stove.
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Motorhomes have stacked LP Regs so one feeds coach and the other feeds the gen
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I took my Medication today. HAVE YOU?
Dodge 3500 w/Tractor Motor
US NAVY---USS Decatur DDG-31
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02-20-2019, 09:52 AM
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#7
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Senior Member
Join Date: Jul 2018
Location: Dallas, TX
Posts: 198
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Quote:
Originally Posted by Old-Biscuit
40K btu furnace
12K Water heater
9k and two 5k stove top burners
2k oven
2k fridge
2k outside grill
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No fridge on gas. Would likely be running nothing on that list while on generator other than the water heater, maybe one or two top burners. Generator will be a little-used use case for us, but there are one or two days a year we're in a location with no shore power and requirement to drive both A/C units. In that case likely none of the other loads. I woudn't be running it in a cold weather situation unless the batteries needed to be recharged to keep the furnace blower spinning.
Quote:
That's 77,000 btu/hr demand (IF you ran everything at same time)
5.5K Onan LP Gen
.8 gallon/hr at half load & 1.1 gallon/hr at full load
1 gallon propane has 91,600btu
77,000 plus 91,600 -------168,600 btu demand (running everything at same time)
SO Two standard 160k btu 2 stage LP Regs on a split system WILL handle the demand
One side primary for RV and one side primary for gen with cross tie so either can supply RV and/or Gen
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6.5K Onan QG
0.8 gal/h half load
1.2 gal/h full load
with 2x20 = 1x30 I have 70 lbs LPG, doing full load math that seems like a little more than 13 hours for generators only, and I can't see them running full power more than an hour or two, then half power to maintain. I think I'm good.
Seems like I'll be fine in any case with that math. I need to document the regulators I have. Need to find out size of gas line (looks like heavy rubber at that point) to determine fittings.
Quote:
High capacity auto changeover regs are also available in 350k and 400k flow rates
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I'd appreciate any pointers. I like to improve and have spares.
__________________
2020 Ford F-350 6.7l 4x4 SRW LB
2019 Palomino Columbus 289RL
2003 Thor Jazz 2780BH (sold)
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02-20-2019, 09:54 AM
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#8
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Senior Member
Join Date: Jul 2018
Location: Dallas, TX
Posts: 198
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Quote:
Originally Posted by bigchick
what you are thinking would obviously work. but you may need to install another regulator so that each tank feeds a low pressure regulator. in your diagram i believe the regular on the 30 lb tank is a high pressure regulator. but before you go to the effort to do it i'd just get the generator installed and then install the dedication valves if you find that you are actually starved for lpg fuel. for what it's worth we have a lpg onan 5500 and have not yet run into a situation where we were starved for fuel. but we don't push it to the limits either. we did have a regulator failure but that had nothing to do with the generator.
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Sounds about like I use case. I like the "install it and see how it goes" approach, I need to find out if there's a gas line for a valve that will be blocked once the genset is in the nose. I'm not dying to pull it back out.
__________________
2020 Ford F-350 6.7l 4x4 SRW LB
2019 Palomino Columbus 289RL
2003 Thor Jazz 2780BH (sold)
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02-20-2019, 09:49 PM
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#9
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Senior Member
Join Date: Nov 2015
Posts: 26,643
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Quote:
Originally Posted by manowell
No fridge on gas. Would likely be running nothing on that list while on generator other than the water heater, maybe one or two top burners. Generator will be a little-used use case for us, but there are one or two days a year we're in a location with no shore power and requirement to drive both A/C units. In that case likely none of the other loads. I woudn't be running it in a cold weather situation unless the batteries needed to be recharged to keep the furnace blower spinning.
6.5K Onan QG
0.8 gal/h half load
1.2 gal/h full load
with 2x20 = 1x30 I have 70 lbs LPG, doing full load math that seems like a little more than 13 hours for generators only, and I can't see them running full power more than an hour or two, then half power to maintain. I think I'm good.
Seems like I'll be fine in any case with that math. I need to document the regulators I have. Need to find out size of gas line (looks like heavy rubber at that point) to determine fittings.
I'd appreciate any pointers. I like to improve and have spares.
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Those High Capacity Regs should be used as the 'only' supply for the WHOLE system
Oversizing does NOT make it better....
Regs are used that CAN provide FULL Flow but actually are operating within the mid-range area so reg has ability to control pressure in system
Oversized reg would be operating at the bottom end vs mid-range UNLESS huge demand was placed on it.
__________________
I took my Medication today. HAVE YOU?
Dodge 3500 w/Tractor Motor
US NAVY---USS Decatur DDG-31
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02-21-2019, 08:41 AM
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#10
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Senior Member
Join Date: Jul 2018
Location: Dallas, TX
Posts: 198
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Quote:
Originally Posted by Old-Biscuit
Those High Capacity Regs should be used as the 'only' supply for the WHOLE system
Oversizing does NOT make it better....
Regs are used that CAN provide FULL Flow but actually are operating within the mid-range area so reg has ability to control pressure in system
Oversized reg would be operating at the bottom end vs mid-range UNLESS huge demand was placed on it.
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Not really interested in over-sizing, but auto-fail over. RIGHT-sizing. I've order a set of Mopeka Tank Check monitors, have read good things about them. If they're accurate enough that allows advance planning to not need auto-switch or just leaving all the valves feeding. I like a reserve somewhere.
__________________
2020 Ford F-350 6.7l 4x4 SRW LB
2019 Palomino Columbus 289RL
2003 Thor Jazz 2780BH (sold)
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02-21-2019, 09:03 AM
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#11
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Senior Member
Join Date: Nov 2014
Posts: 1,345
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i dont know that its enough gas. it the demand on the bottle created by the generator. using only one bottle (20lb) it may cause the bottle to freeze and loose pressure. the better alternative is to get a manifold so you can draw from both bottles same time. Larger regulator may cause this to happen sooner. Especially in cold temps.
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08 GMC C-4500 w/Custom bed. 8.1L
45ft 2007 Teton Reliance Experience XT-4
TSLB Trailer Saver w/ 3rd airbag
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