Guide to Heating Oil Piping for Duplex or Paired Oil Storage Tanks
DUAL OIL TANKS - PIPING - CONTENTS: How duplex oil storage tanks are piped for fill, vent, & oil lines.Heating oil tank fill and vent pipe requirements. Where should oil line fire safety valves and check valves be located?
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Oil tank piping: how to hook up fill & vent & oil line piping on duplex or dual oil storage tanks: this document describes the typical piping arrangements for heating oil storage tanks: how the oil tank fill, vent, and supply piping are arranged when two oil storage tanks (or more) are installed at a building.
TYPICAL OIL TANK PIPING for DUAL OIL TANKS INDOORS
Quick Guide to Fill and Vent Piping for Duplex Heating Oil Storage Tanks
At buildings where two heating oil storage tanks are installed, typically indoors, this Audel Oil Burner Guide sketch shows the proper arrangement of fill piping, vent piping, and oil line piping leaving the tanks.
We have seen an alternative arrangement that provides a fill line only to the first tank, with the second tank filled by a second pipe exiting the top of the first oil tank - not an arrangement we recommend as this forces the first oil tank to be fully pressurized at the oil delivery truck pressure during fill-up of the second tank.
The piping shown in this Audel sketch is better. [Click to enlarge any image]
Here are more details of dual oil storage tank piping
Our photograph of duplexed or a "pair" of oil storage tanks in a residential basement shows (left) [click to enlarge the photo) shows the most common oil fill, vent, and copper oil supply piping arrangement when two oil tanks are installed side by side at a building.
The oil tank filler pipe is connected to the first oil tank (the rear tank of the pair in our photo) at an oil tank top inlet fitting accepting a 2" diameter filler pipe.
A second tank top tapping is used to continue the same diameter 2" steel piping out of the top of tank 1 and into the top of tank 2.
The oil tank vent pipe is connected from the top of the second oil tank (the tank fully shown or "front most" in the oil tank pair in our photo) and routed outdoors to a location close to the filler pipe (so that the oil tank delivery driver can monitor the fill-up progress in the duplexed oil storage tanks.
The oil tank level gauge is on tank #2 in our photo but would work equally well on either tank.
Copper oil supply piping is connected at the bottom outlets of both oil tanks so that as oil is drawn from this heating oil storage system both tanks supply oil to the heating appliances, and thus the oil level will be the same in both tanks at all times.
A tee in the copper oil piping taps off of the common line between the two tanks to feed oil to the heating appliances in the building, where you will typically also see a shutoff valve (aiding in service such as changing the oil filter).
At installations that include a fire safety valve at the oil tank (useful for service in this case) we like to see an additional fire safety valve at each oil burner oil supply line since that's a spot where a fire is more likely to occur.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
(Aug 8, 2012) Help! said:
Have a dual oil tank system that was improperly installed (I have been told). There is a feed to oil burner only in 1 tank, but oil in both tanks. Can a feed be installed in the second tank, even though there is oil in it?
Well you could take an oil line feed off of the top of a tank filled with oul, but I think it would be a horrible mess to try to connect oil piping to the bottom of an oil tank that was full.
(Feb 27, 2014) John said:
This system is a poor configuration. The tank with least backpressure fills first them forces oil into the vent piping and is the forced out by air leaving the not full tank. This results in a full tank and a not full tank and sometimes a oil blowout from the vent pipe.
Thanks John, thats interesting. Since we're showing common oil fill and vent piping arrangements, what do you recommend and what sources can you suggest so that we can update or expand this information. I have not found an expert source that makes the same claim as your note.
Ask a Question or Search InspectApedia
Questions & answers or comments about how to pipe or hook up dual or duplex heating oil storage tanks.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: firstname.lastname@example.org
Arlene Puentes, an ASHI home inspector in Kingston, NY, contributed the example photograph of an outdoor aboveground oil tank. Ms. Puentes can be contacted at email@example.com
Audels Oil Burner Guide, Installation, Servicing, Repairing, Frank D. Graham, 1940's edition (obsolete). Updated versions of this guide are available in various editions, 1947, 1950, 1955, 1958, 1959, 1962, 1965, 1967, and at prices from around $3.00 to nearly $70.00 - useful for simple, clear, but not current, explanation of how heating equipment works. The original retail price was $1.00.
Dave Ferris - M&S Environmental Systems, Dutchess County, New York. Mr. Ferris was an
HVAC expert. Personal communication to DJF 1987. Remove the firematic or
fusible oil supply line valve on return oil-line side - in case of fire if this
one closes first the pump continues to run, blows its seal, and sprays oil all
over the fire. Proper installation is to have a fusible link valve only on the
supply side, and to install a check valve on the return line to prevent
back-siphonage from the tank.
"HUD Regulation for Manufactured Homes; Requirement that Heat-Tape not include a GFCI [ copy on file as /plumbing/GFCI_Heat_Tapes_HUD_CPSC_Letter1994.pdf ] - ", Meeting Log, US CPSC, HUD, Dennis McCoskrie, ESEE, 2/14/1994
Thanks to reader D.B. Harlow for discussing parallel or duplex oil tank piping arrangement, October 2010
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
More Reading and advice about oil storage tank leak testing
ABOVE GROUND OIL TANK (AST) GUIDE - "Visual Inspection of Above Ground Residential Heating Oil Storage Tanks - ASTs" provides photos of common and easily seen tank leaks and defects, and
a description of some easy visual checks of the condition of a visible oil tank, things that you can do yourself
"How do you choose the right tank testing method?", Cynthia Johnson, Fuel Oil & Oil Heat Magazine, November 1995
National Association of Oil Heat Service Managers, PO Box 380, Elmwood Park, NJ 07407
"Homeowners Guide to Fuel Storage," Agway Energy Products, Verbank, NY, November 1990
Web Link Exchange: Contact Us to list your website or contact information for oil tank testing, tank corrosion research, oil industry experts
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones