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Propane Fired Generator Issue......


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11-27-09, 06:27 AM   #1  
Propane Fired Generator Issue......

My wife and I operate a mobile espresso van which is powered by a Generac Guardian 13KW propane fired generator with a 100# tank. We live in NC and I have noticed the tank frosting up a bit on nippy mornings. Tank and generator are externally mounted. This morning it was in the mid 30s and the generator started cutting out a bit. It was still powering everything OK, but didn't seem to be running as efficiently as normal. I'd cut it off for a few minutes and then start it back up and it would be fine and did this a few times. As the tank warmed up it seemed fine. I have done alot of research this morning and see that some people insulate their tanks as well as use heating blankets. Didn't know if anything with electricity would be 100% safe around propane. Was thinking about possibly wrapping it (tank) with insulation and then waterproofing it..... or maybe it could be an issue in the regulator, in which case I could insulate the regulator and the plumbing going to it. Thanks for any info....

BTW have seen a tank blanket called the Power Blanket, but surely can't spend $500 for one......

 
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11-27-09, 07:43 AM   #2  
i have 'not' tried it, but i was talking to my propane supply dealer.
he stated that adding a second tank,& pulling drom both tanks at the same time would prevent the boiling off/frosting.
(as in you would only be pulling-1/2 as much 'volume' from each tank)

 
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11-27-09, 07:59 AM   #3  
Never knew anything like that could be done, but I highly doubt we'd have enough room to add a second tank. Space is somewhat limited as it is. Thanks.......

 
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11-27-09, 08:43 AM   #4  
Hi Shadow, yes a second tank would be a step in the right direction, if there was room to step. The obvious concerns are not creating something that blows up. But there is hope. First, you are not in Barrow Alaska. NC does have some cold temps, but your warming requirements should be minimal. Second, there should be a payback for controlling the tank temp, beyond it simply working when cold. Elevating the cylinder temperature should increase the usable amount of gas. Not my field, but seems logical and there is considerable reading on the subject.

Conclusion, I found some similar prices as to what you mentioned. Some lower as well, PowerBlanket - Concrete Curing and Heating Blankets. But these blankets seem to be designed for exactly what you need, hopefully increasing their safety. There was a lot more to look at, so search cylinder warmers or heaters.

I'm not sure how much gas you use, but if a properly heated tank can reduce your gas consumption and eliminate your frost problem, seems like a good investment.

Bud

 
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11-27-09, 08:47 AM   #5  
You might try a simple solution. Most tanks I see are white. Paint it black so it absorbs more sunlight and try to park so that the tank is getting some sun.

 
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11-27-09, 08:52 AM   #6  
Not sure the dimensions of your van but if you could build a water heater closet/shelter over/around the tank and insulate it (inexpesive safety blankets make great insulation), you could use a simple heat source such as a light on cold mornings...

 
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11-27-09, 09:48 AM   #7  
Posted By: BFHFixit Not sure the dimensions of your van but if you could build a water heater closet/shelter over/around the tank and insulate it (inexpesive safety blankets make great insulation), you could use a simple heat source such as a light on cold mornings...
Or a folding screen set up after parking. Just blocking the wind might help. Then add the light bulb if it didn't.


I can explain it to you, but I can't understand it for you.

 
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11-27-09, 05:06 PM   #8  
Check out this site for more information on the tank frosting.

Fuel Consumption

 
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11-27-09, 06:57 PM   #9  
Your tank frosting is excessive draw from the size of tank you have installed.
Placing any heat source near your tank that is not specifically approved for the purpose is not permitted and could be a hazard and placing insulation on the tank would make the problem worse.
Also, adding a tank heater would take power to energize and again would be counter productive.

Installing a larger or a second tank is what you need to do.


GregH.........HVAC/R Tech

 
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11-28-09, 08:19 AM   #10  
Posted By: GregH Placing any heat source near your tank that is not specifically approved for the purpose is not permitted and could be a hazard and placing insulation on the tank would make the problem worse.
Not permitted by "who" or "what" ?

Some customers set the cylinder near the exhaust of the engine to help keep the cylinder warm and have no problem using smaller tanks on bigger engines. This practice needs to be carefully monitored so that the cylinder does not overheat and cause the relief valve to check off. Fuel Consumption

 
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11-28-09, 09:35 AM   #11  
Prohibited by codes

This practice needs to be carefully monitored so that the cylinder does not overheat and cause the relief valve to check off.
Devices specifically for warming propane tanks are approved for the purpose and have built in safety limits.
US Carburetion does not offer the advice to warm a propane cylinder with an engine's exhaust they only state what others do.............
They are not that stupid to suggest this themselves!
They go on to say that this practice could cause the pressure relief to release.............a really smart move with a generator running next to it.

Even though they seem to cover their butts it is irresponsible of them to go anywhere near suggesting people do this.


GregH.........HVAC/R Tech

 
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11-28-09, 10:12 AM   #12  
I'm curious, have you looked at the actual power requirements for your concession trailer?

13kw is enough to power the average home, central HVAC and all, it seems excessive for your needs (to me). Downsizing the genset if possible would give you a ROI you might not have considered.

 
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11-28-09, 10:35 AM   #13  
Posted By: GregH Devices specifically for warming propane tanks are approved for the purpose and have built in safety limits.
US Carburetion does not offer the advice to warm a propane cylinder with an engine's exhaust they only state what others do.............
They are not that stupid to suggest this themselves!
They go on to say that this practice could cause the pressure relief to release.............a really smart move with a generator running next to it.

Even though they seem to cover their butts it is irresponsible of them to go anywhere near suggesting people do this.
I don't disagree with that at all. However you did not answer my question...just curious as to what agency heads the propane police....

A simple insulated wooden structure with a 20W CFL in a drop light inside is not exactly and IDE.
Just curious because if it is "Not Permitted" then I need to go hide my 20k BTU propane heater that screws on to the top of my tank.

 
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11-28-09, 01:29 PM   #14  
To answer your question, the propane police will be headed by whatever department oversees gas installations, either natural gas or propane.

If this simple wooden structure with a drop light in it is over the tank it would not be allowed because propane tanks are not meant to be used in enclosed places.

As far as your 20K BTU heater goes when screwed on top of your tank it would depend on where it is used and what size the tank is.
The rule surrounding these is that they are not to be used unattended and are not to be used indoors on a tank that is larger than one gallon of propane capacity.
So ya, if you are bringing your heater on top of a five gallon tank inside you had better hide it, especially if you have a fire.

If you want to confirm these regulations you would need to consult whatever "propane police department" has jurisdiction in your area.


GregH.........HVAC/R Tech

 
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11-29-09, 07:58 AM   #15  
LP Tank

Greg is giving you good advice. Around here the state fire marshall looks after this kind of thing. You cant have a tank inside an occupied space,and the enclosure for it must be vented. Check around and see what your local rules are then you know what you can do without getting shut down. Your LP supplier should be able to help. Not to be overly dramatic but that tank is a potential bomb.

 
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11-29-09, 08:29 AM   #16  
Just can't regulate "stupid" it requires common sense to be safe.
My LP distributor is a Convenience Store Cashier...

I am well aware of the hazards involved and while I do not disagree with much of the advice, I do not agree that there are regulations concerning the average homeowner using portable propane cylinders.
Should an accident occur do to improper use or application, then absolutely the person responsible will be at fault and responsible for the damage ensued.
If the fire marshal catches me using my propane heater in my living room, there is nothing they can do about it. While that is unsafe and not smart, there is no regulation prohibiting it unless you include the tags and warnings that come with the appliances as a regulatory agency.
Permanent installations, businesses and perhaps some towns or cities or even neighborhood associations, may well have codes that are enforceable, none have been provided or referenced.
I checked and there is no listing for Propane Police in my phone book

 
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11-29-09, 09:40 AM   #17  
I no nothing about propane. The answer to your problem may be at this link:
LP Gas and LP Gas Generators

 
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12-02-09, 07:45 AM   #18  
Thanks for all the replies... haven't checked here in awhile. Maybe adding a second tank or a larger one would be OK. Just have to make sure space and the platform will allow that.

The generator is rated at 13KW on propane. The equipment in the van does pull ALOT. The espresso machine (220v) alone pulls 4500W when the heating element kicks on. There is also 2 blenders that can pull 10+ amps at 110V each. We also have a 22 cu ft refrigerator/freezer, commercial icemaker, a large commercial drip coffee system, 3 grinders that sometimes are ran at the same time. Then the Carrier heating/AC unit overhead. As you guys can see there is quite a bit of energy being consumed.

We just found out there is the possibility that we might be able to have a 220v connection at our main parking site, which will be a huge help, especially in the cold mornings.

Our local generator repair guy said keeping the tank as full as possible is helpful in cold weather as well as insulating the tank. He said it wouldn't be a good idea to use anything that utilizes electricity or direct heat.

Thanks for anymore info.

 
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12-04-09, 11:36 AM   #19  
Well I finally got fed up with the issue and ordered a Power Blanket. It is specifically designed with the thermostat, safety limiter, etc. built-in and it's made exactly for this type of problem. I noticed as the tank got colder (when temps drop) and as the tank volume dropped it wasn't vaporizing nearly as well and was causing the generator to burn alot richer. In warmer months we had been getting 15-16 hrs. out of 21 gallons of propane between fillups, lately we've been getting 8-9 hrs. at most.

The Power Blanket should eliminate this problem. Like I stated before, adding a second or larger tank just wouldn't work due to space concerns. Getting a smaller generator would be the highest expense of all solutions and what we have gets the job done. I highly doubt anything much smaller would handle what we're doing.

In case anybody has the same issue down the road the Power Blanket regulates the tank temperature so the propane flows as efficiently as possible regardless of weather. Yes it does use some electricity, but it only requires 400 watts/3.3 amps at 110v and that is nothing for what it gives in return. Yes it was expensive at $500 and shipping, but right now I'm spending $2.20 per gallon for propane (very cheap in this area) and am filling the tank almost daily because of the freezing issue, so it will pay for itself in a matter of months. Thanks again for all the replies. Later!

 
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12-04-09, 11:55 AM   #20  
Good choice. Do stop back and let us know how it works out. A simple insulating blanket misses the point that the cold comes from within the tank and a blanket would make the problem worse, blocking access to any surround heat from the air, which is in short supply in cold weather. The heated blanket you have ordered should fix it and fix it right.

Bud

 
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12-05-09, 05:00 AM   #21  
One more question.... is there a simple/cheap way to test a propane regulator? There is some sort of regulator that actually feeds the fuel system onboard the generator itself and there is also the tank regulator. Once we receive the tank jacket and install it I have high hopes it eliminates all issues. I'd still like to check the tank regulator afterward or have somebody to do it to make sure everything is in check? Since it has turned colder it has been running really rich, but I'm assuming that is because of the tank freeze issue, just need to be sure. Thanks for any info as I'm new to propane on this level. Later!

 
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12-05-09, 05:32 AM   #22  
The pressure that most propane appliances are meant to operate is 11"" of water column.
You could temporarily install a manometer in the line while the appliances are operating and set the regulator.

You need to be careful that when trying to adjust the regulator you are not over adjusting because of low tank pressure.
You can make this tool out of plastic tubing or buy one for not too much money.

Click image:


Image courtesy of rverscorner.com

The picture shows connecting at the burner but it is common practice to connect before the burner either on a tee on the supply line or a testing tap on a gas valve.

A suggestion would be to adjust the regulator with only a partial load at the start of a warmer day then bring on other loads to see what it does.
You should soon be able to tell whether it is too much loading for the tank or low outdoor temps that are causing the problem.
Make sure you do not leave this device connected for too long as it is meant to be a temporary test.

I personally think that regardless of the outdoor temperature your tank is still too small.


Be safe!


GregH.........HVAC/R Tech

 
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12-05-09, 08:04 AM   #23  
GregH thanks for the detailed info and illustration. I think I will install the tank jacket to get things as consistent and efficient as possible and have a local generator tech guy check the regulator.

The tank might be a bit too small, but in warmer temps. it runs very efficiently and smoothly with NO issues. According to the generator owner's manual it should be using between 1.5-2.2 GPH (I think those are the #s) depending on 1/2 load or a full load and in warmer months we were getting 15-16 hrs. runtime before having to refill. It would be nice to have a larger tank or two 100#ers tied into each other, but space/weight load just won't allow it. That specific combo was sized according to the equipment in the van and it handles all of it nicely.

I will check back in once the tank temp. is stabilized and let all of you know how much difference a heated tank makes.

One more question.... say down the road this generator gives out on us, and I'm sure it will one day.... how good are diesel generators? Our van runs off diesel and it would be nice to have 1 fuel source. We could add the diesel generator and a second fuel tank/pump if need be then just fill as needed. Are they as quiet as propane? As efficient and clean burning? Thanks.... Later!

 
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12-05-09, 08:49 AM   #24  
A diesel engine is noisier and not as clean burning as a gas one.
The emissions can be on par with gas but the odor is best described as stinky.
However, diesel can be much more economical and more durable than a gas engine.

You would need to look at a diesel gen in the size you need to see if its size and noise would suit.
There are some out now that advertise as being quiet but again you would have to look at them.


GregH.........HVAC/R Tech

 
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12-15-09, 11:37 AM   #25  
Well the PowerBlanket came in and is installed and it helps keep the tank warm to enhance vaporization. Still lacking efficiency and now I'm wondering if something is faulty with the regulator causing the lack of fuel efficiency which could've been causing the tank to freeze over like that so badly. Any thoughts? Thanks in advance.

 
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12-15-09, 04:36 PM   #26  
What exactly is the pressure on the line with various appliances running.

Without checking this there really is no point guessing.
A regulator does a specific job and a manometer or pressure gauge is the tool to check it.

The power blanket is a fix for some circumstances but it has limitations.
Your tank only has the ability to vaporize so much liquid and the blanket will only enhance the evaporation according to the wattage of the blanket.
Is there any information with the blanket as to what it will do.

After checking the regulator pressures there is something else to look into and that is a vaporizer.
They are common here for larger installations but maybe your supplier can find something that will work for you.
How they work is you change your tank to a liquid feed type and the vaporizer is essentially a small heater that vaporizes the liquid propane for increased capacity.


GregH.........HVAC/R Tech

 
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12-21-09, 07:25 PM   #27  
Well we received our much anticipated PowerBlanket 1 week ago. I installed it right away. Will say even though it was/is expensive it is very well built and thoughout in design. It does a great job of keeping the entire cylinder warm. It is a bit thicker than I thought and I had to make some changes to accomodate it. BUT even with a much warmer cylinder we still have some efficiency issue. It is running smoother/longer than before with the tank freezing issue, but still not getting as much efficiency out of it. Have a generator tech guy looking at it tomorrow so that should shed some light on the issue. According to the manual it should be using approximately 2.18 GPH at full load. Right now it seems to be using about 3 GPH give or take. Better than before, but not solved. I will update when I get to the real root of the problem. Thanks for all replies. Later!

 
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12-27-09, 08:56 PM   #28  
Sounds as though either your generator is adjusted too rich, or you have leak in your system.

Let us know what you find

 
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12-28-09, 01:14 AM   #29  
Well I recently found the issue... a very clogged air filter. I knew it was dirty and had been somewhat saturated with some oil and after going to have it checked out by the generator tech guy have found it to be the problem. I knew it was an issue but had no idea it was laboring that much because of it. Until he did some simple voltage checks with the old and new filter. With the old filter it was pulling over 15 volts more under heavy load, meaning much more propane. Like I said.. I knew going there it could be a problem, but also wanted them to check the regulator pressure, proper hertz, RPM, etc.... everything else checked out fine.

In all fairness this is my first generator being used like this and at the moment we run it 6-7 hrs. daily. Apparently at this rate the air filter gets rather dusty quickly, leading to clogging, then backpressure building up leading to the oil saturation. I also noticed as the last few weeks went by it was starting much quicker, even on cold mornings. That air filter was acting as a choke somewhat and even in 20 degree weather it was firing right up.... With a new filter it takes a bit longer like it should.

Also came to the conclusion that the engine running rich was part of the problem with the tank frosting, pulling more fuel at any given time than it actually needed. I think it would frost over some anyway, but nothing like it was. However, the heating blanket does work well and should keep the efficiency high, especially on cold mornings. It was expensive, but I'm sure it will pay off soon. We are working on securing a 240V connection at our AM site so we can plug right in and no more propane. We will still use it of course when at other sites and weekend events, but this will give the generator a much needed rest. Thanks again for all the replies and useful info. Later!

 
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