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Storage Tank
Hydronic Buffer Tanks
Model D4B  (10-119 Gallon Capacity)green line
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High Performance and High Efficiency

Vaughn's Hydronic Buffer tanks are designed to be used in closed loop heating systems with low-mass boilers, geothermal systems, wood boiler installations, and chilled water applications. A buffer tank helps to improve system efficiency in hydronic systems operating below the design load conditions by preventing the low-mass boiler from short cycling. System short cycling can cause the heat pump or boiler to operate less efficiently and may also lead to premature equipment failure. Vaughn buffer tanks are manufactured using a heavy gauge steel inner tank surrounded by a minimum of 2" foam insulation, resulting in very low standby heat loss. The vessel is protected by a high-impact composite jacket material which cannot rust or corrode.
The hydronic buffer tanks are available in sizes ranging from 10-119 gallons, and is manufactured with four 1.5" tappings for primary/secondary connections. An immersion temperature control well is located in the middle of the tank to ensure accurate temperature sensing for heating and geothermal applications, along with a conveniently located boiler drain for periodic sediment removal. Also included is a fitting for an air eliminator at the top of the vessel, reducing air accumulation (and the potential for corrosion) in the system.

Buffer Tanks

Quality Construction

  • Heavy gauge carbon steel storage vessel
  • Four 1.5" NPT primary/secondary connections
  • Air eliminator (not included) prevents air accumulation in the system
  • Immersion thermostat control well for accurate temperature control
  • 3/4" boiler drain provides easy access for sediment removal
  • 3 year, non pro-rated warranty
Buffer Tank Dimensions

Dimensional Data

10 20 16 21.5 13.5 11.125 8.0625 75
20 20 16 32.75 25.25 17.125 9 7.5
30 20 16 40.625 32.75 20.875 9 7.5
40 20 16 56.25 48.5 28.75 9 7.5
50 23 19 49.75 41 25 9.375 7.875
80 26 22 57.25 48.25 28.75 9.375 7.875
100 26 22 67.5 58.875 34.125 9.375 7.875
120 28 24 67.5 58.875 34.125 9.375 7.875

Recovery Capacity (Gal./Hour) For Various Wattages & Water Temperature Rises

Wattage 130° 120° 110° 100° 80° 60° 40° 20°
1500 4.6 5.0 5.5 6.1 7.6 10.1 15.4 30.7
2000 6.3 6.8 7.4 8.2 10.2 13.6 20.5 41.0
2500 7.8 8.5 9.2 10.2 12.8 17.1 25.6 51.2
3000 9.4 10.2 11.1 12.3 15.4 20.5 30.7 61.5
3500 11.0 11.9 13.0 14.3 17.9 23.9 35.9 71.7
4000 12.6 13.6 14.9 16.4 20.5 27.3 41.0 82.0
4500 14.1 15.3 16.7 18.4 23.1 30.7 46.1 92.2
5000 15.7 17.0 18.6 20.5 25.6 34.2 51.2 102.5
5500 17.3 18.8 20.5 22.5 28.2 37.6 56.3 112.7
6000 18.9 20.5 22.3 24.6 30.7 40.8 61.5 123.0
7200 22.6 24.5 26.8 29.5 36.9 49.1 73.8 147.6
9000 28.3 30.7 37.2 41.0 51.2 68.3 102.5 205.0
10000 31.5 34.1 37.2 41.0 51.2 68.3 102.5 205.0
12000 37.8 41.0 44.7 49.2 61.5 82.0 123.0 246.0


  • Custom primary/secondary connection size: specify 1.5", 2" or 3" (1.5" connections standard)
  • Optional electric backup elements (up to 12kW)
  • Available: 1 or 2 side-mount, all copper heat exchanger. Specify 3/4" (single or double wall) or 1" (single wall only)
  • Hydrastone Cement Lining

Buffer Tanks Specific Questions

Is the Vaughn heat exchanger removable?

Yes. The heat exchanger is fully removable in all Vaughn indirect water heaters. The benefit to having a removable heat exchanger is that the coil can be removed for cleaning and de-scaling for improved performance and efficiency when used in hard water applications. It should be noted that the heat exchanger is not removable and the coil cannot be cleaned in many other indirect water heater brands.

Do I need a drain pan under my heater?

Yes, Vaughn advises that a drip pan with a proper drainage connection be installed under your water heater. In some locations drip pans are required by code and in other situations they are highly recommended, but not required. In either case, if a water heater leak or a dripping relief valve could result in property damage then a drip pan must be installed under the water heater, even when not required by code.

Do I need earthquake straps or seismic restraints?

It depends. The Uniform Plumbing Code (UPC), section 510.5 states In seismic zones 3 and 4 water heaters shall be anchored or strapped to resist horizontal displacement due to earthquake motion. Strapping shall be at points within the upper one-third (1/3) and lower one-third (1/3) of its vertical dimensions. At the lower point a minimum of four (4) inches (102mm) shall be maintained above the controls with the strapping." If the installed location is in these seismic zones then a strap/restraint system is required. Otherwise please consult with a plumbing engineer to determine the proper installation method for your water heater.

General Questions

Are Vaughn heaters made in the USA?

Yes. Vaughn water heaters are all made in the USA and our factories located in Connecticut and Massachusetts and qualify for incentives under The Buy American Act and the American Recovery and Reinvestment Act (ARRA). For more information go to the following link Here.

Where can I purchase a Vaughn water heater?

There are numerous ways to purchase a Vaughn water heater depending upon the model you desire and your geographic location. The easiest way is either to visit our "Where to Buy" option in the red menu bar across the website, or contact Vaughn directly at 978-462-6683 and ask for the sales department where you will be directed to either our local representative or our order entry department for quick and easy ordering.

What code requirements are applicable for my installation?

The installation of water heaters are mostly governed by the Uniform Plumbing Code (or CPC in California), Uniform Mechanical Code, and National Electrical Code. These are standard codes that are used across the United States, and each state can amend them as they wish. To take it further, each city and county jurisdiction has assigned one or more building officials with what is called Administrative Authority. This Authority" allows each jurisdiction the right to interpret the codes as they see fit. Because of this many cities differ on their requirements. Vaughn strongly recommends that you contract with a plumbing engineer who knows and understands the intricacies of the building code requirements for your location.

Is it OK if my plumbing system has plastic pipes (PVC or PEX)?

Yes. All Vaughn water heaters will work with both types of plastic piping.

My question is not found in these FAQ’s, where do I look next?

Check out the Vaughn Product Center at Here for a complete listing of all technical Operation & Maintenance manuals documentation available by model. Get easy access to Installation Sales Brochures Service Bulletins Wiring Schematics Parts Breakdowns and various other technical documents related to the full line of Vaughn water heaters. Or if you prefer please call us at 978-462-6683 and ask to speak with Sales.


Technical Documents

Many of our products literature is available online for download. To open these files, a PDF viewer is required. If you do not have one, Adobe provides Acrobat Reader free of charge for viewing only. Use this link to download Acrobat Reader. You may also choose to download the file to your PC for future reference or printing. On most operating systems, simply right-click on the links below, choose "Save target as..." or "Save link as...", choose a location and it will save the document to your computer for future reference.

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26 Old Elm Street
P.O. Box 5431
Salisbury, MA 01952-5431
Tel: 978-462-6683
Fax: 978-462-6497

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