Fuel oil furnace-vacuum leak or gelling?

moovyz

10 year old Coleman DFAA/DFAH oil furnace in a single wide mobile home.
Beckett Oil Burner B2007 AFG (I think that's the model)

Furnace ran fine for 4-5 weeks (35-50 degrees outside temps). This was after a 200 gallon delivery from Shipley (new supplier this year). They said they delivered "Winter Mix". I do have an above-ground outside tank.

The last 4 nights have been 15-20 degrees overnight. 3 of the 4 the nights the furnace goes into lockout sometime after 4 a.m.

I am fairly mechanical and over the last 4 years I have learned enough to trouble shoot, change nozzle, install new filter, etc. This year I changed the element in my filter (for fall tune-up) that I had put on feed line the year before (2-line system). It was pretty gunked up so I cleaned everything thoroughly and installed new element. As I said, the furnace ran great for about 4 weeks after this.

I suspected either water in fuel or gelling. Fuel supplier insists it can't be gelling. Now, here comes the strange part...

The first 2 times it happened, all I had to do was reset and the burner fired right up. This was after the outside temps had risen into the 40's (I sleep late). Today, I reset, it fired but I could hear the burner was sporadic, fluctuating. I installed a new nozzle (the other had been in for 3 days) and I decided to look at the fuel coming from the tank before connecting the input fitting. It took 4-5 second before fuel began entering clear tubing I was using and the first 10" or so was all foam. Then it started getting better but still not clear. I went outside and opened filter. It was empty. I buttoned everything back up and bled line again, this time using the bleed fitting. I let it pump about a quart. It looked better but still not absolutely clear.

I fired the furnace up, at first, it sounded a bit uneven, even noticed a slight vibration on the Becket Burner assembly. It cleared up after about 20 seconds. The furnace has been running fine for the past 4 hours.

Also note: I put foam insulation on lines that are outside from home to tank in case the strong wind chill was freezing the lines. After looking extensively online I added a quart of Lucas diesel anti-gel at the same time. Today's incident was after these last steps. Tomorrow I intend to install a new input line into tank from filter in cases I created a vacuum leak at a fitting when I changed the filter element. I will set the pickup height of tubing a bit higher, say 6" from bottom of tank in case I'm picking up water that's freezing or sludge.

So, is it likely a vacuum leak (if so, why does it run fine for up to 15 hours before issue)? Or is gelling still possible? Has anyone heard of gelling with these winter blends?

Sorry this is so long but I'm trying to give every detail. Any and all help is appreciated as I'm disabled and on a fixed income.

Jamie Hall

I'd bet on gelling or ice crystals forming in and clogging the filter.

HVACNUT

I come across this a lot with mobile homes.
This may not be your particular issue, and not conventional, but I leave the can only (no cartridge) outside as sort of a sludge/water collector and install a spin on filter inside the furnace cabinet with braided oil lines between the filter and fuel pump.
It's not always the cold, but the cold wind with outdoor lines. See if you can enclose it somehow.

moovyz

I can't figure out why this hasn't happened in past years.

STEVEusaPA

A vacuum gauge would help you troubleshoot.
Despite getting a winter blend, it didn’t disperse any water that may have already been in the tank. Winter blend just lowers the pour point. If it’s a bio mix, the bio part could still freeze below 32, as will any water.
If you have a drain at the bottom of the tank, and the tank is pitched toward the drain, drain out about a gallon, let it settle, see what it looks like.
You could have a restriction, a vacuum leak, a pin hole in the pickup in the tank, etc.

Robert O'Brien

A filter outside is asking for trouble.

EBEBRATT-Ed

I would say a suction leak

BDR529

Look at your last delivery ticket and see if it declairs amount of Bio-Fuel. At 20% burners get cranky. Some companies are delivering upwards of 80%!

moovyz

First, I want to thank all that have offered ideas.

Since my last post, the outside temp has not been below 25 and the furnace has run without issues. I have asked the fuel supplier to come out and add 2 bottles of Hot Shot and fill the tank (it's down about 40-50 gallons since fill) so that the additive gets circulated.

Due to a stupid rule (not state regulation) my mobile home park owner forced me to either buy a new double wall tank or put a containment vessel around my tank. Luckily, my wife worked at Keystone Petroleum at the time. So we put my tank, standing vertically on it's side, inside a 6' deep, 8' wide and 5' high 3/16" thick steel box that they had lying around. (this is why I can't get to my tank drain). In addition, I built a slanted roof on top of the box and my fill tube, guage and lines enter from the top.

Picture "Snoopy's Doghouse" with a fuel tank inside. The entire box has a sealed wood frame enclosing the entire tank so that no water can enter the containment vessel.

I have this idea.... directly next to my tank is my 12' X 12' wood frame custom storage shed. I have decided to build a steel box mounted to the inside of the shed with a bathroom light/exhaust fan installed (just like any bathroom). Then run a 4" dryer hose through the side of shed into one end of the containment roof and exiting the other end. Both of these hole would be made using 4" PVC. The exhaust end like a down-looking periscope.
Then I'll basically build a plywood addition to the back of my doghouse (where my filter and lines enter home). The exhaust vent would be inside this rectangular addition.

Using just a 100 watt light bulb I expect that I can cheaply exhaust the heat from the light bulb around the fuel tank. I'm estimating less than $140 for everything... plywood, light fixture, ducting and thermostat. I don't expect that it will be real warm but I only need to maintain 30 degrees or so. Bonus: the neighborhood stray cats will love living under my tank.

This will also prevent any possible ignition sources for any fuel vapors. The whole thing would be tied into a 20 amp GFI circuit (already existing in shed) and controlled by a thermostat set at 40 degrees.

Any thoughts or ideas I haven't covered?

Jamie Hall

Should work. Amazing what one can do in a mobile home park situation!

Jon_blaney

The big delivery of oil mixed up all the crap in the bottom of your tank. I bet the filter needs to be replaced/changed. I have had various fuel flow problems and have found that keeping the tank full and adding a Tigerloop has eliminated all my issues.

HVACNUT

Or, just wrap heat tape and insulate the oil lines. Still, get rid of the outdoor oil filter.

EdTheHeaterMan

OK, I have had this problem many times with new clients and have solved it with a fuel deaerator. I got flack from those that don't understand the concept but I'll explain it again.

BASICALLY your fuel pump in a 2 pipe system pulls 20+ gallons per hour (GPH) from the tank to the burner, burns .75GPH or less and returns the rest to the tank in the return line.

So you are circulating very cold oil in your 3/8" OD oil line or 1/4" (Inside Diameter) ID

The colder the oil, the harder the pump works to move that oil.

Install a fuel deaerator AFTER THE FILTER, and now you get the benefit of a 2 line system, but you only draw .75gph thru the 1/4" ID line Less work for the fuel pump.

Next benefit: The recirculating oil returns to the deaerator that is inside the building where it is warmer. so you have less than 1 pint of oil in the fuel lines from the deaerator to the pump and back to the deaerator. Add only .75GPH to the pint of oil that is recirculating in the loop and the temperature of the oil delivered to the burner is much warmer.

Just Sayin' fixed hundreds of outside above ground tank problems with this system. HUNDREDS OF THEM! HAPPY CUSTOMERS!

Criticize all you want you purest out there! The proof is in the results! AND, yes... ream & debur, before I flare! my flares don't leak!

Jamie Hall

Do you also have the filter in the warm envelope? I would, if only to minimize the possibility of ice crystals blocking it up. I don't think the purists should criticize -- it's an arrangement which works. Ouside, above ground, fuel oil tanks for mobile homes are common enough -- but they are a very different animal from the usual setup.

moovyz

The fact that my filter cup was empty, it makes me believe that the fuel in the tank was too thick to lift the 4' necessary to get to the filter, yes? So, I don't understand how the aerator will warm the oil in the bottom of my tank enough to allow it to flow.

(to the one who suggested filter change, it's a brand new element, everything clean)

It's now been running more than 12 hours, temp still above 25 tonight. I have to rule out vacuum leak. It would have started sucking air again by now.

I think my idea creating warmer air flow all around tank and also warming filter and line area is the answer. My only fear is that 100 watt bulb will not be enough heat but even circulating air around tank without an increase in temp should, in theory, also keep the oil a bit warmer. If I have to I'll either increase the bulb wattage (change to ceramic socket) or actually place a space heater in the shed and vent that air.

HVACNUT

All that sounds like a fun project, but heat tape and insulate the oil lines would be about 1/8th the cost and labor.

rick in Alaska

Virtually all of our fuel tanks here are outside, with quite a few of them having the fuel filter at the tank. The only fuel we get here is winter mix ( basically just number 1). I have never had a line or filter freeze up. Personally I would get rid of the two line setup, and either just run a single line to the tank, (most common around here), or run a single line with a tigerloop inside. There are very few jobs I have done where I actually needed the tigerloop, but they do improve the efficiency of the burner by at least warming the fuel a little.
It sounds to me like you might have had a bit of a vacuum leak originally, but after you put the filter back together, it sealed it up so that you could get a proper bleed of it. Also, if it is a General filter, and old trick I was taught years ago was to bleed the line until it was running mostly clear, then close the valve to the filter and keep bleeding until the fuel stopped flowing. Let it keep pulling to put more vacuum on the line, and then open the valve as fast as possible. Supposedly what this does is to rapidly force the fuel into all the fibers of the filter, which helps get rid of any air bubbles that want to "stick" to it. I have used this procedure quite a few times on stubborn bleeding situations and it really works well.
Rick

SuperTech

My preferred setup for Mobil homes is to run a single line to the burner, insulated and wrapped with heat tape outside. I like to avoid an outdoor oil filter, instead I like to install a tigerloop ultra inside the furnace, using the flex lines to the pump. Best possible oil filtration and air removal in case of any possible air infiltration under high vacuum conditions due to sludge buildup in the oil line or any other possible issues.
I always prefer to see kerosene being the fuel instead of regular #2 fuel oil or bio mixture in Mobil homes with outdoor tanks.

STEVEusaPA

Only have two mobile home furnaces in my customer base. Very claustrophobic trying to wedge yourself in to work on the burner, and reach your tools. Couldn't imagine in my case even a place for the tiger loop.
I don't think #1 kero will gel until it gets down to something like -40° (C or F at this temp). But you have to obviously keep the moisture out. Unfortunately, pretty impossible to get in the Philly metro area, so either winter blend, or additives are a must.

@rick in Alaska is referring to a 'power vacuum bleed' and it only takes less than an extra minute to make sure you get a proper bleed using my bleed pot, like the one in this article:
https://fueloilnews.com/2016/05/26/a-few-tricks/

SuperTech

> @STEVEusaPA said:
> Only have two mobile home furnaces in my customer base. Very claustrophobic trying to wedge yourself in to work on the burner, and reach your tools. Couldn't imagine in my case even a place for the tiger loop.

It's definitely not the easiest thing to do, without the flex lines it would be really tough. I install the Tigerloop Ultra above the burner and run the flex lines down to the pump. I've used the Sid Harvey Mitco version of the Tigerloop Ultra which is also nice, it has vacuum gauge included in the assembly which is always nice to have.

EdTheHeaterMan

moovyz said:

The fact that my filter cup was empty, it makes me believe that the fuel in the tank was too thick to lift the 4' necessary to get to the filter, yes? So, I don't understand how the aerator will warm the oil in the bottom of my tank enough to allow it to flow.

My suggestion is not to warm the oil in the bottom of the tank. My suggestion is to move less cold oil! OVER 3000% less oil.
You can move 0.65 gph of cold oil thru a 1/4" ID tube, much easier than 20 gph of cold oil.

EdTheHeaterMan

The fact that the oil inside the fuel Daerator will stay warm is a benefit to the combustion process once the deaerator resolves your problem.

Who here knows if cold oil makes a nozzle allow more of less oil to flow through it at any given pressure?
Clue:
The answer is the opposite of what you would think!

STEVEusaPA

On a lift job, your fuel filter and your fuel pump may not be completely full. Reasearch 'flooded' suction'.

moovyz

Thanks

STEVEusaPA

Yikes.

SuperTech

I can't understand why you didn't approach repairing the problem with a more conventional method.

STEVEusaPA

I think this guy may be an engineer.
The problem:
-sludge/water in the bottom of the tank.
The solution:
-treat the tank, and as others suggested wrapped the oil line in heat tape.
Get rid of 2 pipe and either go with 1 pipe or Tiger loop inside.

And the OP ignored all that, and went with...see photos...

HVACNUT

Would MacGyver be impressed? Not so much.

EBEBRATT-Ed

@EdTheHeaterMan
A nozzle will pass more cold oil than warm. The oil being more viscous goes straight through the nozzle less swirl

EdTheHeaterMan

The swirl chamber and the tangential slots (in the nozzle) create the beginning of the atomization process. The oil pressure is potential energy. as it is used to rotate the oil and push the oil out of the orifice the Pressure energy is dispursed In round numbers 20% is swirling the oil and 80% is pushing through the orifice. When the oil is more viscous, it does not swirl in the nozzle as easily. So less energy is used up swirling leaving more energy for pushing. So @EBEBRATT-Ed is correct. Cold oil makes the flame fuel-rich and that may cause soot formation. Also, the atomized droplets are larger so there is less surface area for the fuel to evaporate to become the vapor needed for the flame. Warm oil is better for combustion

1 more point for TEAM Tiger Loop. (unless it is installed outside)