Small Chilled Water / Radiant Heat Buffer Tank
Stainless Buffer Tanks For Hydronic Heat Pumps

Low cost stainless steel multi-purpose hydronic system tanks for backup heat, hydraulic separation, buffer, or volume expander for use in hydronic, radiant, or chiller systems. Contact us for pricing or see the price list on our documents page.

Vertical & Horizontal Configuration Up to 8 x 1.5" Ports Use Up To 4 x 5500w Heating Elements

Robotic welded stainless steel tank construction is used for both inner and outer tank  These professional grade insulated water tanks are designed for use with chillers, radiant heat, hydronic heating, & floor heating applications. See buffer tank spec sheet. These hydronic buffer tanks are also perfect for use as a wood boiler buffer tank.

The Chiltrix heavily insulated small chilled water / hot water / boiler buffer tanks are tall and thin so they are perfect for thermal stratification as well as applications where a small floor footprint is required (18.5: diameter). Multi-port design allows a wide range of uses.   These stainless steel tanks are designed as a multi-purpose tank, they can be used an as accumulator tank, a buffer vessel, a volume expander tank, a backup heating tank, boiler buffer tank, etc. They are often used with chillers and hydronic heating heat pump systems as buffer (hydraulic separation) tank.

All-Stainless Steel
Buffer Tank or
Multi-Purpose Tanks

VCT 37 (37 gallons)

VCT19 (19 Gallons)

For vertical or horizontal installation.

VCT37 Tanks are 4 ft' 8"inches tall.

VCT19 Tanks are 3 ft. 3" tall.

Tanks are 18.5" diameter.


See VCT19 buffer tank specs

See VCT37 buffer tank specs

See VCT37B buffer tank specs

These small hydronic tanks can be used as a buffer tank, or to expand system volume, or as a backup heat tank.

Heat exchanger tanks with indirect coils
are also available here.

  image of stainless steel buffer or backup heat tanks for chiller or hydronic heat pump

What is a buffer tank?
Technically speaking a buffer tank is used for hydraulic separation whereby a pump circulates heated or chilled water into the tank from the source side, and a second pump circulates water out of, and back to the tank, on the load side. Buffer tanks are often used "smooth out" the operation of a boiler or chiller to prevent short cycling. With Chiltrix heat pumps, which are variable speed, short cycling is not an issue however due to Chiltrix unique controls, buffer tanks are needed whenever a Chiltrix heat pump interfaces with a radiant or floor loop. With Chiltrix there is a built-in pump, when used for floor or radiant heating, the Chiltrix controls are designed to maintain a specific temperature in the buffer tank but are not designed to circulate in the floor or radiant loop. Therefore, there must be a means of hydronic separation such as a buffer tank when using Chiltrix hydronic heat pumps for floor heat or radiant heating. In a Chiltrix heat pump system, an automatic seasonal valve can bypass the tank in cooling mode (when not being used for heating).

A buffer tank (or buffer vessel) will always have at least 4 water ports, two for the "source side", a supply and return, and two on the "load side", a supply and return. A vertical buffer tank is one that stands upright and this design allows strong thermal stratification. In some cases a horizontal buffer tank is needed for space requirements. In the horizontal design, less stratification will occur. In any case, the top of the tank will always be warmer than the bottom. Buffer tanks may be large or small, Chiltrix makes a small 37 gallon tank which is perfect for residential and small commercial applications including biomass, fermentation, thermal storage, chiller systems, hydronic heat pump use, hydronic separation, and use with wood boilers, gas boilers, or other type of hydronic or radiant heating systems that need a buffer tank.

picture of stainless steel chilled water buffer tanks
Shows wiring port

picture of staineless inner tank

This is an image of the VCT37 Chiltrix stainless steel buffer tank during production, it shows the "inner tank" before the insulation and outside stainless steel jacket has been added.

No corners have been cut, no shortcuts have been taken. This is a first-quality robot-welded buffer tank made from 100% stainless steel, inside and out.

What is a backup heating tank?
In a hydronic heat pump system, like any other heat pump, capacity falls when outdoor weather is extremely cold. for customers in cold climates, there will be a few days each year that cannot be handled solely by the heat pump, therefore a backup heat source must be available. The simplest and cheapest solution is an electric backup heat tank. Even though electricity may be more costly that natural gas, a gas water heater costs far more to buy and install and since it is rarely used, the electric tank is a better overall backup heat solution. Further, electricity can be replaced or offset by solar which is not the case with gas.
Picture of horizontal stainless steel buffer tank for hydronic heat pump system or chilled water (chiller)

Horizontal Mounted Buffer Tank

What is a volume expander tank?

This is just what it sounds like - a tank that increases the water volume of the overall system. With Chiltrix heat pump chillers, we recommend at least 10-15 gallons of water in the system. For small systems where everything is close to the outdoor unit, a small tank may be needed to make sure that there is enough volume (gallons) in the system. Other than very small systems, Chiltrix only needs a buffer tank during floor or radiant heating operation and the Chiltrix system can a automatically activate an optional "seasonal valve" to bypass or isolate the buffer tank when operating in cooling mode.

37 Gallon Buffer Tank Specifications Sheet

19 Gallon VCT19 Small Buffer Tank

VCT37B buffer tank specs

For Domestic Hot Water Tanks Click Here

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37 Gallons

All-Stainless Steel Inside and Outside

Vertical or Horizontal Installation

8x 1.5" NPT Ports

4 Element/Thermostat Cavities w/ Covers & Wire Entry Ports

2x 1/2" Sensor Wells

Anode Port

TPV Port

2x Drain Ports

All Ports Pre-Capped at Factory



Buffer Vessel

Boiler Buffer Tank

Chiller / Chilled Water Buffer Tank

Biomass/Fermentation Tank

Cold / Hot Water Storage Tank

Thermal Storage Tank

Hydronic Heating Tank

Hydronic Separator Tank

Backup heating Tank

High-Power Water Heater / Boiler Tank (up to 22KW (75,000 BTU)

Commercial Buffer /Storage

Wood Boiler Buffer / Storage Tank

Any Requirement Needing a All-Stainless Steel Insulated Tank

picture of caps for unused ports in water tank

All ports are capped with a NPT threaded cap.  Just uncap the ones you need to use.

factory picture of buffer tanks