Tiger Loop on furnace

[wjmst]

I have an oil furnace with a tiger loop installed since 2005. I installed a pellet stove about 10 feet away from the furnace in 2008 and had no trouble with either until January 2012.

Last January my furnace stopped working. The repairman came out, bled the line and it was fine. The problem continued periodically and I determined the tiger loop was the problem. There would be no oil in it, then if I tap on the side there was a hissing sound and the float inside moves and it seems to function correctly again for a little while.

As the weather warmed I shut the pellet stove off and just used the furnace to heat the house. The tiger loop seemed to be working correctly. I explained everything to the repairman this summer when he serviced the furnace and he even saw what I was talking about but had no idea what the problem is. It would be about $400 to replace the parts but that may not fix the problem.

Fast forward to this winter. The furnace and tiger loop seem to work okay when the pellet stove is off. When I turn the pellet stove on I seem to get air in the oil line and the tiger loop gets stuck. A little tap on the side and it works fine. You can see the oil and air bubbles flow through the tiger loop. Eventually, the tiger loop eliminates the air bubbles and there is just oil flowing through it.

Has anyone ever seen anything like this before? Do tiger loops wear out? Is there a gasket in them that could be dried up and causing it to malfunction?

I talked to several companies that install Tiger Loops and they have been using them for many years and never had any go bad. I am at a loss.

Any help or advice would be appreciated.

Since this is a rural living forum. I live in the woods and I like to do things myself!

Thanks
Wes

 

[Raspy]

It sounds like you may have restriction on the supply side going to the Tiger Loop. Do you have a pre-filter or strainer at the tank? Or is the fuel level in the tank getting down to a point below the level of the Tiger Loop? Is the fuel tank vent open and not clogged? There could even be a piece of debris clogging the fitting where the fuel come in to the Tiger Loop.

Is there any way the pellet stove is heating the fuel or the Tiger Loop?

Maybe the only time you are running the pellet stove and the oil heater is when the weather is extra cold and the fuel is more viscous, reducing it's flow and causing a vacuum.

You might just disconnect the supply line and make sure oil flows with plenty of volume.

 

[wjmst]

Thanks for the reply.

No pre-filter or strainer. The tanks are over 1/2 full and located about 20 feet away in the basement. I'll check the vent and lines or clogs. It just seems strange that is works fine when I don't have the pellet stove on.

I am sure the fuel and the Tiger Loop are heated somewhat by the pellet stove. The air temperature in the basement is normally about 60 with just the furnace running but rises to about 74 to 80 with the pellet stove on.

All I know is it is very strange, but I am sure their is a logical explanation.
Wes

 

[Raspy]

It simply sounds like your Tiger loop is de-aerating the fuel, as designed. But that the float valve is sticking or clogged, and not letting the air escape.

Temperature of fuel has an affect on the amount of air released by the fuel, as does the pressure or partial vacuum. Probably the only connection to the pellet stove is room temperature.

You can probably fix it by taking the Tiger loop apart and making sure it is clean and free to operate, or by replacing it. It's been in for seven years or so and needs maintenance. Clean it carefully, investigate what might make the float stick and then see if it works better.

I've also found that running bio-fuel can make a varnish that is a problem and water or algae can also gum things up. Is your filter black?

 

[wjmst]

What you say makes sense. I thought the tiger loop was a sealed unit, but will investigate it further tonight to see if it can be taken apart and cleaned.

The fuel and filter look good here, not bio-fuel.

Thanks
Wes