MSS Carbon Steel Buffer Vessels
The Adveco MSS range of carbon steel primary system buffer vessels has been carefully designed to fit any hot water or heating application that requires an inertia tank or energy storage vessel.
The MSS range features numerous high-, mid-, and low-level connections to ensure compatibility with almost any heating application. Such tappings enable the tanks to be used with multiple return flow temperatures or multiple heat sources, such as renewables or low- and high-grade heaters.
MSS vessels are ideal for hot water applications using heat pumps operating at lower temperatures as greater flow is needed to raise the kilowatts of the system.
The range includes buffer vessels with capacities from 300L to 5,000L. All tanks are rated to 6 bar working pressure standard, options to 10 bar, and temperatures up to 95°C.
Features & Key Technologies
- 300 – 5,000 litre capacity
- Rated for 6 to 10 bar working pressure
- Rated for temperatures up to 95°C
- High, mid, and low-level connections
- Large connections for all commercial applications
- Ideal for use with heat pump based DHW applications
What is a commercial buffer vessel?
A buffer vessel is a storage tank that sits between a heat source and a building’s heating or hot water distribution system, absorbing the gap between how the heat source generates heat and how the building actually uses it. Instead of the heat source cycling on and off to chase every change in demand, it charges the buffer at a steady, efficient rate, and the building draws from that stored capacity as needed. MSS is Adveco’s carbon steel buffer vessel range, built specifically for heating and DHW systems that need higher working pressure, up to 10 bar, and multiple connection points for more than one heat source.
The problem MSS solves
Heat pump conversions often stall on a detail that only shows up once the system is running: the heat pump looks correctly specified on paper, output matches demand, but in practice it short-cycles, runs inefficiently, and wears out faster than it should. The usual cause isn’t the heat pump itself, it’s that gas boiler-era pipework and system design assumed a heat source that could deliver high output on demand, and a heat pump can’t work that way. It needs volume and flow, not just a bigger badge on the box.
MSS is the piece that’s often missing from a retrofit heat pump specification. Its high, mid, and low-level connections give the system the flow capacity a heat pump needs to hit its rated output efficiently, and let it plumb into multiple return temperatures or heat sources where the building is running a hybrid setup during transition. Get this right at the buffer stage and the heat pump performs the way it was specified to, rather than underdelivering on a technically correct spec.
Why heat pump systems need a buffer vessel
Heat pumps are increasingly specified as the primary or preheat source for commercial DHW as buildings decarbonise, but they behave differently to gas boilers, and that changes how the rest of the system needs to be designed. A gas boiler can deliver high output at short notice, whereas a heat pump operates at lower flow temperatures and needs a greater volume of water moving through the system to hit the same kilowatt output. Without enough buffer capacity, a heat pump system can struggle to meet peak demand even if its rated output looks sufficient on paper.
MSS is built to solve that specific problem. Its high, mid, and low-level connections let the vessel plumb into systems with multiple return flow temperatures, or accept input from more than one heat source at once, useful where a heat pump is paired with a secondary renewable or conventional heater. Rated to 6 bar as standard with a 10 bar option and temperatures up to 95°C, MSS covers the working conditions most commercial heating and hot water systems will encounter.
MSS is commonly specified across new build and retrofit projects moving to heat pump or hybrid heating, from offices and education buildings through to leisure and healthcare sites where consistent flow and Legionella-safe storage both need to be maintained.
MSS or MSB: which Adveco buffer vessel do you need?
MSB is the standard carbon steel buffer for closed heating and DHW systems, rated to 3 or 6 bar. MSS is the heavier-duty option in the same 300L to 5,000L size range, built for installations that need higher working pressure, up to 10 bar, such as larger commercial and industrial heating systems. If your system pressure sits within standard limits, MSB is the more cost-effective specification. If you need the extra pressure headroom, MSS is the one to choose.
Technical Specifications & Downloads
Literature
Specifications
Connection sizes given in inches. Dimensions given in millimetres.
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Frequently Asked Questions
A storage tank that sits between a heat source and a building’s heating or hot water system, absorbing the gap between how the heat source generates heat and how the building uses it, so the heat source can run steady, efficient cycles instead of constantly cycling on and off.
Sizing depends on the heat pump’s output and the flow rate needed to hit your kilowatt target at its operating temperature, not the litre capacity alone. MSS is available from 300L to 5,000L to match a wide range of heat pump and heating system sizes, get in touch and we can size it against your system’s actual flow requirements.
Yes. The high, mid, and low-level tappings let MSS connect to more than one heat source, such as a renewable source alongside a conventional heater, or multiple return flow temperatures within the same system.
MSS is rated to 6 bar working pressure as standard, with a 10 bar option available, and temperatures up to 95°C, covering the working conditions of most commercial heating and hot water systems.
Yes. MSS is commonly specified in retrofit projects where a building is moving from a gas system to a heat pump or hybrid setup, since the extra buffer capacity it provides is often the missing piece when replacing a boiler with a lower flow temperature heat source.
MSS is held in stock, with delivery within the month on all standard sizes, so it’s rarely the bottleneck on a project timeline.
A carbon steel buffer vessel needs relatively little ongoing attention: periodic inspection of connections and, where fitted, any control sensors. Most of the maintenance load in a heat pump system sits with the heat pump itself, not the buffer.
Yes, that’s the most common way it’s specified. MSS is designed to be added alongside existing plant to solve a flow or short-cycling problem, not to force a wider system replacement.
Why Choose Adveco
50 Years
Adveco Ltd. is the independent hot water specialist for the commercial built environment and has historically traded as A.O. Smith Water Heaters in the UK.
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