Return line for oil burning furnace


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Old 03-02-16, 09:49 AM
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Return line for oil burning furnace

I bought this old house 11 years ago. I had problems with the burner tips clogging right from the start. I had three different service guys tell me something different. The first guy said the line was sucking crud off the bottom of the tank. He offered no solutions. The second guy said I needed a new furnace. And, the third guy said I needed a new tank. I watched them and saw how to change the tips myself. After a couple times doing that I went out to the tank and pulled the tubing out. There was maybe 4 feet of tubing coiled on the bottom of the tank. I cut it off and re-inserted the tubing about 8" from the bottom.

After cutting off the tubing I haven't had any clogging tip problems but I often have to "reset" if the furnace sets for a few hours without cycling on. Sometimes I have to bleed the line to keep it running.

I read in another thread where this may be an air-in-the-line problem if the furnace has only one feed. (It does.) On the tank the line comes out of the top through a dung which has two ports in it. The supply line comes through one to the furnace and the other has a piece of tubing sticking up about a foot that is crimped off.

The furnace is an Olsen and the pump is Suntech. I can see on the pump where the bypass plug is located. My question: would this issue of having to restart all the time be resolved by adding a return line? If so, what is the procedure for adding a return line? Any special fittings, how far into the tank should the return line be inserted? I already have 25' of tubing (more than enough) and a new filter I'm going to put on the supply line for added protection.

Any specifics, especially if this may be effective, will be greatly appreciated.

Thanks
Cdguy
 
  #2  
Old 03-02-16, 10:26 AM
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I never buy the "Crud" issue, there should be a filter on the oil line to capture any crud before it clogs up the nozzle. I would recommend a tiger loop for starters. Tigerloop
 
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Old 03-02-16, 10:42 AM
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Perhaps I didn't make myself clear. I don't have a clogged tip problem any more. Once I get fuel to the gun it works just fine. The problem seems to be an air gap of some sort. When I push the reset button the burner fires up. Sometimes it stays on, other times I have to bleed the line to get it to stay on. It reminds me of a problem with water pumps where a foot valve has failed allowing water to run back into the well instead of staying in the line.

After reading about two line systems that allows the pump itself to purge air back into the tank it sounded reasonable that this may be a solution.

thanks for your reply.
 
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Old 03-02-16, 11:48 AM
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Have you changed (or cleaned) the strainer inside that Suntec Pump lately ?
 
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Old 03-02-16, 12:04 PM
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I haven't done anything with the pump other than bleed it. I would be willing to try if you could describe the process. The problem is becoming more frequent for some reason.

Thanks Vermont
 
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Old 03-02-16, 12:27 PM
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Most Suntecs (or formerly Sunstrands) use a A70 Strainer which is accessed by the four (4) small horizontal screws/bolts on the outside pf the cap, opposite the burner motor (above the bleeder valve).

It's best to at least have a new gasket available when first pulling the cap off. A new strainer including the gasket will run you only $2.00 to $3.00; but you can clean them. I just think the potential damage to the gasket your first time cracking the pump open is hard to avoid.

An old tooth brush and kerosene is good to attempt to clean the paraffin off the fine mesh of the screen . . . . my Wife did it the first time we discovered this to be our problem.

If you're in that deep to cleaning the Burner, then it's not much more effort to clean the inside of the gun tube heading down towards the nozzle; but you can save that for a next step if this procedure provides evidence that the strainer is inhibiting the flow of fuel before it can even get to the gun tube.

I don't see that the new screens come with directions; but there's probably a video of this strainer replacement/cleaning online. I've got an SSC-109 Strainer Screen in my hand right now, and the box says that it's for Suntec A-70 Pumps . . . . you may want to find the Pump Number on yours before heading off to the Plumbing&Heating Supply Store, because you may need a slightly different screen. Many Service people around me will toss the Pump instead of replacing the Screen.

I'll look for a video and come back if I find one.

PS: Here's a decent video showing the innards of such a pump and the screen . . . . first one I ran across:

https://www.youtube.com/watch?v=OM-la2tVUo8

Hopefully yours is much cleaner . . . . it's obviously not locked up.
 

Last edited by Vermont; 03-02-16 at 12:37 PM. Reason: Added PostScript
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Old 03-02-16, 01:32 PM
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Thanks, Vermont.
I've been going to school on this thing and found the same video after your last reply. The one in the video is the same as I have. I can get a new filter and gasket from ebay shipped here for about $5 or I can check the local plumbing supply houses. Seems simple enough.

I think this unit has had plenty of hands on it over the years so I'm hoping no one has fiddled with any of the settings. When the furnace is working it works fine. The last guy who worked on it put in the "correct" tip and reset the spark rods to spec. He also replaced the transformer because it was working intermittently. He was going to install a line filter but he never came back. (Too busy for such a small job, I guess.) He said everything else seemed to be fine.

Can I ask you, were you having the same problem, i.e., furnace not kicking on automatically after not running for a period of time?
 
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Old 03-02-16, 02:05 PM
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This is a case where your local supplier may have a better price . . . . and you have it NOW and it will be the right one, and with no charge for shipping.

Originally Posted by cdguy
". . . were you having the same problem, i.e., furnace not kicking on automatically after not running for a period of time? . . ."
Similar; I have a very cold basement and anytime my Boiler paused in between heating cycles (the thermostat modulates between 66F and 70F), it seemed that the sludge and paraffin would coagulate and seal up the screen. So it varied a bit, depending on the heat loss (speed) of the building.

If it was mild outside and the wind wasn't blowing, there'd be a longer period of time between reaching 70F and the descent back down to 66F giving the contents of the Pump more time to harden, or congeal before a new cycle would start.

If it was really frigid, the Boiler would cycle on and off more frequently, and the coagulation didn't have time to occur between cycles. I didn't see the relationship, so it was driving me nuts (sort of, but not enough to be institutionalized).

And when the System failed, if I could coax the Boiler into starting, and there had been some seepage through the Screen down to the nozzle, I might be able to get the thing to run and keep on running . . . . making me think the problem had been solved.

Now, I routinely replace the Screen every two years or so. Just replacing the Fuel Filter at the Tank wasn't enough. The Screen isn't so critical because the original screen that came with my 1987 Beckett Burner survived in the same environment until around 2002 when I made this discovery; but eventually, it will need attention. I was amazed that my Burner could have possibly worked under those conditions; but it did . . . . a tough old bird !

Your problem may or may not be similar; but eliminating the "possible" strainer issue will be helpful for you. At least you'll know about it for the future.

Good luck !
 
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Old 03-03-16, 03:58 AM
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Seems we have about the same conditions. My house is 112 years old with an addition built around 1975. I suspect that is when the furnace was installed. That part of the basement has a dirt floor and even though the furnace is on that side it stays pretty cold down there.

Anyway, I took your advice and pulled out the filter. (Luckily, the gasket stayed intact.) The filter and housing were relatively clean compared to the one in that video but there was a little sediment and the screen did have noticeable buildup on it. At first sight I didn't think it was bad enough to be causing the problem and thought, well, at least, I'll have a clean filter and began resigning myself to calling in a pro.

I cleaned out the housing and then applied the toothbrush treatment to the filter using some of the oil I had previously bled off and the part of the pump that was exposed. When held up to the light I could no longer see any debris on the filter.

I put it all back together and hit the reset button. It fired instantly. Previously, there was about a 1-2 second delay between the pump kicking on and the burner firing. It cycled properly several times before I went to bed. I still had that feeling that I would be up around 3am romancing the reset button again.
As it were, I woke up around 2:30am for my routine visit to the bathroom and, to my great pleasure, I heard the furnace kick on. What a relief!

This morning the furnace is still operating as expected. It appears the little bit of debris and paraffin on the filter was the problem. Probably for the same reasons you mentioned above. We are expecting a cold spell for the next 3 or 4 days so the cycling will be more frequent. Next week, we will be back to warmer days and cold nights. Hopefully, I won't be back down there scratching my head again.

Thanks again for the great tip, Vermont.
Take care.
 
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Old 03-03-16, 04:20 AM
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Originally Posted by cdguy
". . . Thanks again for the great tip, Vermont . . ."
Thanks for listening . . . . and remember, it's just a theory; but a theory that has yet to be dis-proven in 12 or 14 years.

And I too have an old house (1832) which has caused me some sleepless nights when I have to deal with conditions not anticipated by the Engineers.

I'll be interested in hearing how your System performs when temps rise and you experience longer idle periods between heating cycles.
 
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Old 03-13-16, 06:20 AM
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Over the last 10 days we've had a range of temperatures near 80 during the day and 30's at night. The furnace has set idle long enough to put it to the test. It has worked perfectly since I cleaned the internal filter. What a relief it was to put an end to this ongoing problem without having to spend a ton of money on a $3 fix.

When the days warm up and the furnace goes into hibernation I'll be installing an in-line filter. I'll be sure to keep a spare cartridge on hand as well as a spare internal screen. Keeping up on these simple maintenance measures will be the best thing I can do to avoid going through another winter filled with frustration.

Much appreciated, Vermont.
 
 

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