Oil boiler issue


Old 03-24-19, 06:00 AM
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Oil boiler issue

Good day all, Iím hoping someone can help me. In our home, we have in floor radiant heat. Supplied by Kerr model k-26 boiler with a riello motor and pump attached. Our oil tank is above ground approximately fifteen feet from the furnace, as we live in a ranch style home on a slab, the oil line runs from the bottom of the tank outside through a sleeve into the furnace room. Where it then comes straight up 32Ē to reach the pump. The system works great and has for years except for my issue. When the oil tanks falls to around half, about level with the pump, it loses its prime over a few hours of not running. Without head pressure it seems to not be able to prime itself. I recently changed the pump and hoped that was the issue, however once it feel to half a tank again, I had to prime it to work.
Old 03-24-19, 07:08 AM
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Probably a leak in the oil line somewhere allowing the introduction of air to break prime.
Old 03-24-19, 10:49 AM
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If you have a single pipe supplying oil to the pump with no return line or 2nd line, try installing a check valve in the supply line so the oil does not back out of the pump when the oil level falls below the oil pump. Another good upgrade if this check valve does not completely rectify the problem, would be, if you indeed do have a single oil pipe, to convert to a 2 pipe supply and return. This will allow the pump to quickly self vent the suction line fix the problem. To do this , you may need a service company to insert a by-pass plug and install the return line.
Old 03-24-19, 10:53 AM
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Welcome to the forums.

Thread moved to the boiler forums. A furnace heats hot air...... a boiler heats hot water.
Old 03-24-19, 11:26 AM
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If you are loosing your prime it's because your pump is higher than your oil level in the tank. It's the same as filling a hose with water and then raising one end to drain in out. That's what is happening to your oil.

If your delivery situation cannot be altered then as Steamboy mentioned a 2 pipe self bleeding installation can be done or what may be a better option without installing another line is to install a TIGERLOOP. It take the place of the 2 line system with what you have now. You can mount this right to your boiler casing near the pump.

Your current oil line will connect to this unit which will remove the air and then a separate line will go to the pump. The sight below will give you all the info.


Old 03-25-19, 03:47 PM
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I am cynic when it comes to check valves. Think flapper type are wishful thinking. Especially for low flow rate applications prefer the spring loaded type:
Old 03-25-19, 05:00 PM
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I never saw a "Tiger Loop" installed probably since most systems I worked on were commercial units that had oil firing rates up to about 200 gallons per hour. We did work on smaller stuff but very few home type units. So I never saw 1 so I couldn't recommend that fix. Glad some of you residential guys monitor this site
Old 03-26-19, 12:53 PM
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Do not install a check valve in a 1 pipe system. Doing so could cause over-pressurization of the pump in hot weather & rupture a pump seal. Riello specs a two pipe whenever the fuel level is below the burner.
I'm in total agreement with spott in regards to the Tigerloop, far superior to a conventional 2 pipe system.

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