Oil furnace pump bypass plug

This is an explanation of how the bypass plug is used to change an oil pump from one pipe to two pipe operation.
This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

15 Replies to “Oil furnace pump bypass plug”

  1. Think that pumps only around 150-200 psi max. Would blow out over that. Oh and I like the video too. A lot of people miss that bypass plug. Thanks for making this.

  2. You also need that if you going to put in the tiger Loop tigerloop is like a two pipe system

  3. Question on 2 pipe on 3400 rpm Beckett AFG in New furnace. Is squeal in return line due to cavitation? It varies but get loud sometimes. Barely hear it in the supply line. I just changed the filter and it wasn't real dirty but it did quiet it. I have about 20 ft of line each way to an outside tank. I am lifting about 5 feet then thru wall,, across ceiling in basement about 10 ft and down 5 feet to the furnace filter and into it. Beckett 10323 pump with bypass plug installed.
    BTW, I love your videos.

  4. Question, let's say I want to change a 1 line system to a 2 line system I. E. Tiger Loop. Is the bypass plug currently removed on the 1 pipe system? Do I need to add/purchase a bypass plug now for the tiger loop?

  5. Old and reliable. My american standard a-3 boiler usually runs without issue. However recently pump shaft seal started to leak. I had a J2CB-100-3 pump and suntech told me to use a J4PB-1000-G pump to replace it. Everything works as before, except now when the burner shuts off you hear a last 2 or 3 pulses of flame. Is this normal/ok. The old pump flame would just stop.

  6. Ive got an older beckett burner in a miller furnace in my shop. I recently mounted the heater about 7 ft up on the wall. Had it running yesterday. Took a while to bleed. Undersandable its prob 8 ft of line to the pump. Pump looks different then the one in your video. Do I need to put a plug in somewhere? Remove a plug?

  7. I tell my techs that oil pumps follow an ODD rule… 1 line = odd (or 1 thing), 2 line = even (or 2 things), 2 line + plug = odd (3 things). Always be ODD.

  8. I'm thinking of making a fuel oil transfer pump out of a old burner, motor and its pump. Strip off everything leaving only the motor and its pump. You thoughts and hints  will be respected. Thanks, Gregg

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