One pipe fuel line looks like 2 pipe

STEVEusaPA

Saw this today on a new customers ridiculously oversized boiler--Burnham V908 with a Beckett CR1400, on a 13000 sq ft. garage
Was wondering why the manufacturer recommends this? If it were the best way, why not do them all like this?

Bob Bona_4

It's called a cheater loop. Old school. I've seen them on rare occasions, the granddaddy of the Tiger Loop. I can't remember why they aren't used much. Firedragon would likely know.

STEVEusaPA

Thanks for the response Bob.
I actually did something crazy....download the manual. It apparently relieves pressure on the pump seal when switching from hi fire to lo fire.

Bob Bona_4

Interesting! I've not been exposed to much commercial burners. I can see that though

OuterCapeOilguy

I've not run into that setup yet. The commercial setups I've worked on are all two-pipe. I'd be inclined to replace that loop with a deaerator.