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Onan Propane Regulator Question


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  #1  
Old 04-07-2011, 09:09 PM
Cruiser Cruiser is offline
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Default Onan Propane Regulator Question

Should your tank regulator read 11" W.C. while the Gen unit is running?? Thks
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  #2  
Old 04-07-2011, 09:14 PM
Douglas123 Douglas123 is offline
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Default Re: Regulator ??

Can you post a pic of your fuel set up. Yes you should read 11"wc infront of your demand regulator on your unit. Some folks use different terminology. Are you using what I call a pancake regulator on your unit. What are you using at the tank?
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  #3  
Old 04-08-2011, 06:11 AM
Cruiser Cruiser is offline
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Default Re: Regulator ??

Using a 2 stage regulator. I borrowed a gauge where you can pull out the plug on the side of the regulator to set the W.C. at the tank.
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Old 04-08-2011, 08:06 AM
Max Thompson Max Thompson is offline
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Default Re: Onan Propane Regulator Queation

If you are having trouble maintaining 11" while the unit is running, you can raise the pressure at the tank regulator to15” & not cause any problem with the demand regulator.
I will assume you got a different demand regulator, & that you are still working on the JC. What did you find out about the old demand regulator? What did you replace it with?
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Old 04-08-2011, 08:14 AM
armandh armandh is offline
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Default Re: Onan Propane Regulator Queation

tank [or meter] regulator [where ever located] reduce the high pressure to that required by the following system.

for the typical BBQ grill a pressure that along with the orifice size
gives the right combustion mixture. or

for a stationary engine's demand regulator input.

the demand regulator senses demand from the suction caused by the venturi
as combustion air flows to [past] the throttle. [a regulator setting near zero.]

a vaporiser [typical in a fork lift] may include both functions and that of converting liquefied gas to the gaseous state. this "boiling" of the liquid
requires a lot of heat [even if done at very low temps] usually obtained from the engine cooling system.

and that is about the extent of my knowledge on the subject
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  #6  
Old 04-08-2011, 09:34 AM
Dave Edmonds Dave Edmonds is offline
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Smile Re: Onan Propane Regulator Queation

My 20ES is fueled by natural gas at 7" WC. Even though the book says to supply the generator with 10-20" WC, I found that, to supply the gas at this pressure, many dollars were involved on the part of the gas company
("2-pound" meter, regulator for the generator, another regulator for the house, etc.). The folks here advised, "Use big lines, hook it up, and see what happens!". I did, and it worked fine (1" line to the generator, 3/4" flex hose, 3/4" line inside generator). I do have a gauge on the gas line, and it holds 7" no matter what's running (heater, generator, etc.) So, I would say, Yes, the line from the first regulator to the demand regulator should hold about 11" all the time. If it drops significantly, there is a good possibility that insufficient fuel is being delivered. I seem to remember that the demand regulator needs a minimum of about 5" WC to function properly; my 7" is very close to that, but I saved a lot of money! The gas company told me that my meter is good for a maximum of 400,000 btu; if the heater (125,000 btu) and the generator (325,000 btu at full output) run together, I may have a pressure problem. I can see the generator getting close to full output in the summer (5-ton air conditioner), but not in the winter when the heater would run.
Dave Edmonds
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  #7  
Old 04-08-2011, 10:27 AM
Old Style Old Style is offline
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Default Re: Onan Propane Regulator Question

Thanks Dave,

Makes me think that even if everything is good, loading and all. Checking the WC just before/at the demand regulator would always be a good idea during load tests. Could be inadequate and someone might never know; especially during short load tests.

The bigger the size of the gen-set/load the more important? Natural/propane also.

I could be wrong... Not a expert here.
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Old 04-08-2011, 11:21 AM
DaGr51 DaGr51 is offline
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Default Re: Onan Propane Regulator Question

You may have covered this on another thread, but how far is your two stage regulator from the generator and what size line are you using? Many of us use a primary regulator at the tank and a secondary near the genny before the demand regulator so that the pressure is at the 11"+ number AT the demand regulator.
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  #9  
Old 04-08-2011, 12:53 PM
Cruiser Cruiser is offline
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Default Re: Onan Propane Regulator Question

Here a new wrinkle for you guys. I did it by accident. I was turning off the gas supply at the tank cause the unit was still stumbling.( Yes by the way Max ,still working on the 15KW JC, and sent back the old demand reg and got a new one. ) When the vavle was all but closed the unit sat there and ran perfect. So I just tried to plug in a shop vac and it all but killed it. Running 1/2" gas hose to the demand regulator off the tank,About 5' then a short 12" piece of 3/8" to the carb.
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Old 04-08-2011, 06:12 PM
Max Thompson Max Thompson is offline
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Default Re: Onan Propane Regulator Question

I went back to one of your previous threads on this subject. I copied & pasted since the same questions & suggestions still apply. No doubt you have a problem; I do not think it is with the generator since it will run well on gasoline. I am assuming the choke is wired open when running on gas, though once it warms & the choke opens this is a non-issue. Have you reset the timing to 35 BTC, though it should run on gas at 25 BTC just not as well.
I can not find the pictures you sent or I would post them though they were of the old set up. Some new pictures posted would likely eliminate some speculation.


03-29-2011, 04:49 PM

Re: Onan 15.0 JC to LP Help!

--------------------------------------------------------------------------------

Quote=About 6' between regulators with 1/2" gas line.

I was going to stay out of this one, but. If he has only 6’ of ˝” line, even if it is only 3/8” ID the unit should start & run at 1800 RPM with no problem. I have run a JC on 3/8” OD copper (1/4” ID) in a temporary set up & had no problem. It may not carry full load but he can’t even get it to run smoothly with no load.
I think I would be checking my regulators & pressures. Take the line off the demand regulator & open your manual valve (I assume you put a manual shut off ahead of all the generator piping), with GOOD VENTELATION, & no ignition sources, open the valve, you should hear gas whistle through the line even at 11”. Use your manometer to check the gas pressure ahead of the demand regulator with the engine running, I would not want to see it get much below 8” with the demand regulator open. Just seems like there is more to this than we know yet.
As has been mentioned some pictures would take much of the guess work out of this.

#11 03-29-2011, 09:56 PM
Re: Onan 15.0 JC to LP Help!

--------------------------------------------------------------------------------

The more I think about it, it sounds like the vent on your demand regulator may be plugged. I think these are regularly shipped with a plug in the vent opening. With the demand regulator removed, you should be able to suck air from the outlet side with little or no resistance, if not you have a problem with the regulator.

I just went back & reread your other thread on this subject, if you would keep all posts about the project in the same thread it would help.
That being said, you mentioned running a CCK with the demand regulator. Is this the same regulator you are using on the JC?
You also mentioned timing & the 25 BTC, the JC should be timed to 35 BTC for gaseous fuel.
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  #11  
Old 04-08-2011, 06:30 PM
Dave Edmonds Dave Edmonds is offline
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Smile Re: Onan Propane Regulator Question

Max has an interesting thought - if the demand regulator is not regulating properly and is "flooding" the engine, you would have a problem. When you turned off the valve and got the feed from the demand regulator to the engine down to the proper amount of gas, the engine ran fine. However, since the regulator couldn't adjust when you added the load, the genny died. (You might could have kept it alive by opening the valve a bit.) I don't know if you can check the outlet pressure of the demand regulator, but Max had a suggestion as to how to check it. Others have made comments on this forum about critters stopping up the vent opening in the regulator, thereby causing problems. Good hunting!
Dave Edmonds
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Old 04-08-2011, 09:28 PM
Max Thompson Max Thompson is offline
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Default Re: Onan Propane Regulator Question

Dave:
I think the demand regulator is the second new one. Should not be critters, but what you said about flooding & running when the valve is nearly closed makes one think.
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Old 04-08-2011, 10:26 PM
Kimbra Dean Kimbra Dean is offline
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Default Re: Onan Propane Regulator Question

If the primary regulator pressure is too high (maybee 1PSI or more for a KN demand regulator) it will probally overcome the diaphram spring pressure and push propane through the demand regulator and flood the engine, Could this be your problem? The spring can be ajusted to allow for some difference in pressure supply but not too much. The Garretson SD regulators can be had with a 11", 2PSI, or 5PSI spring but I don't think the SD has the capacity for a JC.
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Old 04-08-2011, 10:32 PM
Douglas123 Douglas123 is offline
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Smile Re: Onan Propane Regulator Question

this scenario seems to be getting a little comical and confusing. Sounds like my job everyday. Please post some pictures of what you are talking about. I think it would be an expensive service call if I had to drive all the was there for a simple fix. Post some pictures and you can resolve this issue for FREE!!!!!!
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Old 04-09-2011, 07:58 AM
Cruiser Cruiser is offline
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Default Re: Onan Propane Regulator Question

Quote:
Originally Posted by Max Thompson View Post
Dave:
I think the demand regulator is the second new one. Should not be critters, but what you said about flooding & running when the valve is nearly closed makes one think.
Yes this is the second new demand regulator and have tried 3 different regulators off the tank.
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Old 04-09-2011, 08:45 AM
Acableguy06 Acableguy06 is offline
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Default Re: Onan Propane Regulator Question

What kind of tank do you have? is your valve bad? does it have OPD? May have bad volume / flow from tank or valve not allowing enough vapor. I have got 20lb tanks in the past that would expel gas but not enough volume. (defective valve).
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Old 04-09-2011, 11:00 AM
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Default Re: Onan Propane Regulator Question

Quote:
Originally Posted by Acableguy06 View Post
What kind of tank do you have? is your valve bad? does it have OPD? May have bad volume / flow from tank or valve not allowing enough vapor. I have got 20lb tanks in the past that would expel gas but not enough volume. (defective valve).
I have it hookesd to a 100 Gallon tank. Someone else just said the valve could be bad on account of when I almost shut it off exept for a crack it has the most pressure but least volume. Thks
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Old 04-09-2011, 04:29 PM
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Default Re: Onan Propane Regulator Question

Just a update. I moved the timing from 35' to 40' and it smoothed out very nicely and will run about a 6 or 7 KW load. Anymore than that and it starts to starve. So i am going to get a first and second stage regulator and then hard pipe it with 1/2". I hope this will do the trick.
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Old 04-09-2011, 05:51 PM
K D Redd K D Redd is offline
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Default Re: Onan Propane Regulator Question

I have been reading this thread since it was started and NONE of it has made sense. I think your advancing the timing to 40 degrees is covering something else up. The shutting the tank service valve almost completely shut causing the engine to smooth out got me to thinking. My thought, I wish you would post picture set-up of you fuel system, is there any way you have the outlet of the KN demand regulator connected to INTAKE MANIFOLD VACUUM? This is the ONLY thing that to me make since of the poor running and NOT accepting a load. I can see IF the KN was connected to intake manifold vacuum you could adjust the load valve so it would run at no load. Then as soon as a load was applied, the intake vacuum would drop causing the engine to stall because the KN stop supplying fuel. I know this is a little OFF THE WALL but it is what I am thinking. Posting picture of your fuel system would help answer a lot of our questions.

Kent
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Old 04-09-2011, 08:24 PM
K D Redd K D Redd is offline
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Default Re: Onan Propane Regulator Question

I just got a PM from Cruiser. He said he tried up-loading some pictures but they would not load. I told him the file size was most likely to larger. He is sending them to me. He ALSO said his LP adapter is between the carb and the intake manifold. I told him in my PM back to him that this was the wrong place. The adapter should be between the carb and the air filter or one might modify the carb to use the venturi resident in the carb. I have done LP fuel systems on small generators both ways. Maybe WE ALL can now get his problem solved.

Kent
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