Oil furnace problem, no oil mystery

[CordWrangler]

I have an oil burner (Beckett), forced air furnace (Lennox) that is not getting oil from the tank. The furnace is in attic and the tank is in the garage so there is 8 foot lift. This furnace has worked well for about 17 years. I have done the annual maintenance for the last 12 years.

I have replaced a few things but it still does not work. I am wondering if anybody has an idea of what could be the problem or what I may be missing.

Here is a list of things I have done so far:

- Replaced nozzle, and filter and checked electrodes and cleaned.
- Replaced oil pump with new pump.
- Checked coupler, looks good, not chewed up.
- Replaced gun line
- Ran new 3/8" OD copper pipe from furnace to tank, 60 feet.
- Checked suction tube inside of tank for leaks.

When I turn on the furnace and attempt to bleed it, no fuel.

Unfortunately, I do not have a pressure gauge or a vacuum gauge to test. I wonder if the new pump is bad. I can hear the pump working but no oil.

What am I missing? Any insights would be greatly appreciated.

Also, I hate to admit defeat but does anybody on Long Island know a good oil furnace tech or service?

Thanks, in advance.
CW

 

[heat seeker]

I had a similar problem. When trying to fix the whistle in the oil tank, I was removing the assembly from the tank, when a blob of something that looked like black seaweed fell into the tank. That's what was killing the whistle. The whistle worked fine after that, but the next day I had no oil to the burner, even with the line at the burner disconnected. I blew a few very short bursts of low pressure air back through the line into the tank, and all has been well for months now. I didn't want to overdo it with the air and blow holes in the filter. I'm hoping the "seaweed" stays wherever it is. I'm sure an oil delivery stirs it up. I just hope it doesn't block the line again, but if it does, I know what to do.

If you pull the line off the filter, will oil come out? If you dare, take the filter off and see if you have oil flow.

Good luck!

 

[CordWrangler]

The oil filter is at the furnace in the attic. There is no oil in the filter canister. It is, as if there is no suction. With a brand new line to the tank, I know it is not a blockage.

I did an experiment. I took 5 gallons of diesel fuel into the attic and put it next to the furnace. I made a copper line and connected it to the furnace and put the end into the container. When I bled the line, I got fuel oil out. So I am wondering why it would pull fuel oil out of the container sitting next to the furnace but not from tank in the garage. Is it possible the motor is not turning the pump at the required rpms?
CW

 

[heat seeker]

Maybe the pump lost its prime. Does it draw now?

 

[CordWrangler]

I'm way beyond losing prime. No it is does not draw now. That is the whole problem. There is no oil getting to the pump from the tank. If you look at the list of things I've replaced, I'm running out of things to consider as the cause. I've triple checked my flared ends, one at the tank and one at the furnace. So frustrating...

I changed the pump and ran new copper coil because I was not getting oil to the furnace. I thought maybe the pump was bad and then considered there might be a leak in the old copper coil. Neither fixed the problem.

@ Heat Seaker, thanks for the input.
CW

 

[heat seeker]

Sorry I'm not much help. Here's a looong shot - is the tank vent okay? If you pull the line off the tank, does oil come out?

You mention no oil in the filter. Is the filter cover on tight, and the gasket sealing? Could something inside the filter house be blocking flow? How about bypassing the filter for testing.

 

[brenndatomu]

I'm saying it is simply air locked...60' of suction line is a looooong line to bleed out...I'm betting that it will be darn near impossible for the pump to do this by itself without some assistance.
First things first...do you know for a fact that the outlet of the tank is open?
If it is good (and not plugged up with a blob as mentioned before) then I'd try to put a light pressure on the tank to help push the oil (and air) up to the pump so it can be bled out. You will have to plug off the breather to do this...and don't overdo it...these tanks are not rated for pressure!
Is this a return type system? (suction and return line both)

 

[Ashful]

You mention checking suction tube for leaks, but is it possible you have a clog in that suction tube?

 

[brenndatomu]

A $30 MityVac from the autoparts store might go a long way here too...use as a pressure/vacuum gauge, and also to pull a vacuum on the suction line to see if oil can be pulled up to the attic...may need to buy some fittings from the hardware to make it all happen...

 

[Hogwildz]

Do you have a fire safety valve or any on/off valve for that matter before the the filter or in line to the tank? Are you sure the line is not kinked anywhere. Did you use the thin wall light tubing?
There are only so many things to come into play, you eliminated everything from the pump after with the test running from a temp supply. All that leaves is the line, a valve, the filter, or the tank, pickup or vent.
I had mud wasps build a nest in my vent, and evicted the nest.

Take note on the fire stop valves, they are counter intuitive, closing the valve knob is really opening the flow & vise versa.

Just because you installed a new line, doesn't mean a chunk of crap didn't block the new end at the tank.

 

[velvetfoot]

t ake note on the fire stop valves, they are counter intuitive, closing the valve knob is really opening the flow & vise versa.

I don't think that's true. The wheel is left hand thread, so the stem goes up when you turn it on (counter clockwise). It messed me up too at first.

 

[CordWrangler]

Ok, let's if I can answer all the questions:

As far as the length. Prior to this problem, it bled just fine with the old copper line. This 60 foot line has been in place since 1978 without problems.

The suction tubes are large inside the tank. I have removed them 3 times and they have not been clogged. The suction tube and the return tube are the same length inside the tank. I don't think this is the way they do it currently but it has worked since 1978. I swapped the suction tube and return tube, putting the supply line on the the return tube and the return line on the suction tube but this did not make a difference.

Even if I had a pressure gauge or vacuum gauge, it would just tell me what I already know. Which I have no vacuum and there is no fuel after the pump to measure pressure. Right?

I removed the OSV to test and see if it was the valve and it did not make any difference.

The test I did was pulling fuel from a container 3 feet from the furnace which is very easy. Makes me wonder what would reduce the suction so the pump couldn't pull fuel from the tank. The suction line inside the tank is not blocked.

@ Hogwildz: When you say "vent" in the tank are referring the whistle pipe?

CW

 

[brenndatomu]

Asking a pump to prime from 3' away, and very little lift is easy...60' away and 8' of lift is very hard. I will probably work fine once primed, (assuming there are no air leaks that bleed off the prime while not running) but getting it primed initially will require some extra work.
One thing that comes to mind is to shut off the oil line at the tank. Rig up a 1 gallon container to be able to connect to the line up at the furnace. Fill the jug with oil and then let it backfill the line down to the oil tank...it will take some time to work all the air out. Hopefully you have the line running up hill the whole way to the furnace...or at least not up and down along the way creating air traps. Anyways, once you get some liquid to that pump it will purge the air, but they don't like 100% air.
Or, maybe a better idea is you could backfill the line with oil just letting the air push back into the tank, but to make this work you will need to have someone close the valve at the tank after the air is out, and before the oil in your jug runs dry. Then hook the line back up to the pump, open the tank valve and bleed out as per normal.

 

[CordWrangler]

There is no valve at the tank. It is pulling out the top. I have done maintenance on this furnace for 12 years. Each year that I change the filter, nozzle and screen I would lose prime . Every time when I was done, I would bleed the system and the pump would pull fuel from the tank very quickly. Never been a problem until now.

Here is a picture of the suction and return tubes from inside the tank.

 

[Hogwildz]

Yes whistle/vent, make sure it ain't clogged or no insect nests.
Did you pressure test the pu/suction tubes and make sure there is no corrosion or pin holes in either? Even the smallest hole will will kill suction from the tank.
Do you drain the entire intake line when servicing the unit? Most don't as that is what the shut off valve is for, and keep a majority of oil in the line or at least enough to prime the pump. If the pump is having to fill 60' of line that may be the issue.

Here is some things I would try:
Fire the furnace and see if it will run off the temp supply?
Try a manual suction pump at the pump end of the line to see if you can get any fuel at all to pull from the tank, see if you can gauge the pressure it takes to get it there, or not get there.
I assume the tank has plenty of fuel?
I doubt this is happening, but make sure the fuel is not gelling.
How old is the fuel? Conditioner added?

I'm with brenndatomu, 60' and an 8' rise is a lot to ask of an empty pump sucking air. I'd put a valve at the tank end of the line, and backfeed the fuel from the pump end to at least have a decent amount of fuel in the line for the pump to grab.

 

[peakbagger]

I saw a setup long ago that was top feed like yours. The piping went straight up from the pump to the ceiling, then across the ceiling and then back down to the tank. On the top of the vertical pipe from the pump, they installed a tee in the line with a valve pointing up. They had a funnel on top of the valve and would have to open the valve when they lost the prime and hand fill the vertical line with a squeeze bottle slowly. The vertical line would fill up and then they would shut the valve and start then prime the pump normally.

A long term issue is that heating oil and diesel has changed in recent years to reduce the sulfur content. Sulfur acted as a lubricant, and without that, wear on pumps have increased and that would be most apparent in a priming situation. Even if the pump is worn, as long as its wet with oil the oil will act as a seal. Many diesel owners are adding lubricity additives especially for use on older mechanical injection pumps that weren't designed for increased wear. You have changed the pump over so that shouldn't be an issue for you, unless the new pump is just plain has loose clearances.

My Unimog has a suction feed fuel system and losing prime was an ongoing issue for quite awhile. I tried lots of things without a lot of success until I set up an outboard motor fuel tank with a squeeze bulb and set the tank on the roof well above the injection pump. A couple of squeezes of the bulb, then a standard prime and the Mog ran great, switch to the standard fuel system and it would run for awhile and then get air bound. I swapped a bunch of fittings and hoses an eventually made it better but that boat tank was worth the time to isolate the issue.

The other rare chance is a bad flare fitting on the tubing. Over the years copper can work harden and the flared seat can crack.This crack may not be readily apparent from a distance and may not leak when full but pulling a vacuum can make it leak. This usually only happens at flares that are made and unmade. Another issue is using ferrule fittings instead of flare fittings. I on occasion do testing on large equipment that requires measuring very low pressure drops (inches of water), many of most experienced techs would only use flare fittings instead of ferrules as they had chased far too many air leaks over the years from ferrule fittings under vaccum. In some cases we would end up with hundreds of feet of tubing strung everywhere, so troubleshooting was a PITA.

 

[mustash29]

I had a buddy from my Navy days move from Florida up to CT and take a job at my work. The mega drafty place he was renting was built on a huge chunk of ledge rock so it only had a partial basement / crawlspace. The oil tank was outside, on the right front corner of the house, with the oil boiler in the left rear corner of the basement. The bottom of the boiler was about even with the top of the oil tank, about 4 foot uphill.

The tank had a bottom oil supply connection with no filter. The oil line ran uphill about 4 feet and diagonally across the crawlspace about 30 feet to the filter, which was mounted to the suction of the burner pump.

The first winter he ran his tank out of fuel on several occasions, sucked sludge into the supply line, clogged the filter and lost prime to the oil pump. It always seemed to happed at night during a cold snap, LOL.

The first time I drug my 30 gal compressor over there to blow the line back into the tank and clear it, but that was way overkill. Later on he just blew it back with lung pressure. We found that using the "blower" function of a shop vac was enough to slightly pressurize the tank via the fill line (had to duck tape the vent whistle to choke it off) while the other guy vented the burner pump. This re-established the prime to the pump and it worked well, until he ran the tank empty again.

 

[brenndatomu]

The first time I drug my 30 gal compressor over there to blow the line back into the tank and clear it, but that was way overkill. Later on he just blew it back with lung pressure. We found that using the "blower" function of a shop vac was enough to slightly pressurize the tank via the fill line (had to duck tape the vent whistle to choke it off) while the other guy vented the burner pump. This re-established the prime to the pump and it worked well, until he ran the tank empty again.

Excellent idea!

 

[CordWrangler]

First, I want to thank everybody for their input and ideas.

I want to refocus the attention to the fact that something has changed in the function of this setup. This house was built in 1978 and we've lived in it for 17 years. We've never had a problem getting the pump to prime. I realize the lift and length is not ideal but it has worked without a problem until now.
The OSV was originally installed after the filter so I didn't have a choice but to lose prime everytime I changed the filter.

So this problem surfaced when I couldn't prime/bleed the system. That is when I changed the pump and installed new copper coil (3/8" OD). The original copper supply line had dings and kinks from the original installation. They had used steel staples to fasten it down and crimped the copper line.

Anyway, something changed in the system to create this problem.

How would I pressure test the supply line from inside the tank. After removing the pipes from the tank, how do I plug one end of the pipe and test the other end with an air compressor?

Thanks,
CW

 

[brenndatomu]

Just me personally, I'd use that shopvac trick to pressurize the tank, get the thing primed up and running, and then if it loses prime after sitting unused, then you can check for air leaks...

 

[sportbikerider78]

A $30 MityVac from the autoparts store might go a long way here too...use as a pressure/vacuum gauge, and also to pull a vacuum on the suction line to see if oil can be pulled up to the attic...may need to buy some fittings from the hardware to make it all happen...

Yup...works great on bleeding car brakes too!

It has a nipple.. you can bleed anything with nipples.

 

[CordWrangler]

Question about MityVac. They have about 12 different models. Which model would be best for my situation and testing? Also, PepBoys and AutoZone don't seem to have it on their website. Where else have people bought a MityVac?
Thanks,
CW

 

[festerw]

I bought mine at Advance Auto, doesn't have to be a Mityvac brand pretty much any generic brake bleeder should work. O'Reilly should have them too.

 

[Hogwildz]

Yup...works great on bleeding car brakes too!

It has a nipple.. you can bleed anything with nipples.

View attachment 217858

Now that there is some funny shitsky Love those movies!

 

[Hogwildz]

Take your pick
https://www.harborfreight.com/automotive-motorcycle/brakes.html