Improving domestic hot-water delivery for energy-efficient, modern buildings
Move your buildings forward with the Uponor AquaPort™
Improving buildings through smart, sustainable solutions
- Sustainability: Optimizes hot-water delivery times and minimizes water waste to make every drop of water count
- Energy efficiency: Reduces the amount of DHW and DHW recirculation lines, eliminating standby losses and maximizing boiler efficiency to reduce system energy costs by up to 35%
- Best-in-class hygiene: Eliminates more than 50% of the total DHW volume while enabling higher water turnover and decreased overall surface area of the domestic water piping system
- Maintenance ease: Features a QR code for quick access to technical support as well as an installation and maintenance log
- Installation efficiencies: Helps meet tight production schedules and budgets with a simple, repeatable design that reduces in-unit piping and eliminates gas and electric connections
Installing the Uponor AquaPort
Refer to the Uponor AquaPort Installation and Operation Manual for easy, step-by-step guidelines to get the system up and running quickly and accurately.
Frequently asked questions
An Uponor AquaPort is a self-contained, prefabricated heat transfer station (HTS), which is also known as a heat interface unit (HIU). It employs a building’s hydronic heating supply to generate on-demand domestic hot water (DHW) via a stainless-steel, double-wall heat exchanger. The HTS is located next to or very near one or more fixtures in any building with clusters of DHW loads of less than 5.25 U.S. gallons per minute (gpm).
|Capacity||100,000 BTU/hr (29.3 kW)||180,000 Btu/hr (52.7 kW)|
|Maximum pressure||125 psi (8.6 bar)|
|Maximum temperature||180°F (82°C)|
|DHW temperature range||95°F-158°F (35°C-70°C)|
|Width||14.5" (368 mm)|
|Height||25.6" (650 mm)|
|Depth||5.4" (137 mm)|
|Weight||47 lbs. (21.3 kg)||57 lbs. (25.9 kg)|
|Connections||4 x ¾" FNPT|
Mitigates Water Quality Issues
Supports Decarbonization Efforts
When deciding whether to use a centralized or decentralized solution for the hot-water supply of a building, various factors, such as capital investment costs, installation effort, pipe lengths, comfort, energy, hygiene, and water consumption all play a decisive role.
The system should also provide hot water for the individual applications in the right temperatures and in sufficient quantities, ideally even for an unlimited period of time and yet still be economical.
Combining the DHW supply to the central heating system is still very common in colder climates in many parts of the world. Water is heated in a central tank and then transported to the various points of use through an additional pipe system.
Due to hygienic requirements, the water must be preheated to 140°F (60°C) when it flows through long pipes. The temperature is then reduced by mixing in cold water at the tap. This may make sense in old buildings with a high heating demand, but for renovations and new buildings, which use the lower-temperature range, providing, storing, and transporting of hot water at 140°F (60°C) means high energy losses.
Energy economics divides energy losses in centralized hot-water preparation into circulation, distribution, startup, and storage losses. In a single-family home, these losses add up to at least 40% of the entire energy requirements. Add to that the higher investment costs compared to the decentralized solution.
Modern and economical: Decentralized DHW supply
Short water lines:
- Correct water amount delivered
- Correct water temperature with no need for mixing very-high-temperature water with cold to temper to utilize water temperatures per code
- Provide energy efficiency based on demand
- Delimit water supply with respect to demand
In North American decentralized systems, the hot-water supply is separated from the heating system. Electric instant water heaters meet the specific requirements for each application, if installed directly at the various points of use. The hot water is available without any lead times. Only the required amount of water is heated. Additional long piping systems are not necessary.
There is also no need for circulation pumps and hot water tanks, which saves installation and operation costs. The small units allow for a “hidden” installation in wall nooks or behind paneling. The central heating system can now be adjusted precisely to the requirements of the building and be turned off completely during the summer.
Circulation and storage losses are eliminated, since water is not preheated and stored in large quantities. The distribution, startup, and systems losses only amount to 3% of the energy requirements. Decentralized hot water supply with electric instant water heaters is a highly efficient energy-saving system.
But electrification has its limitations in retrofit application or in grid limited spaces such as unsupported regions. The middle ground, as discovered in Europe for the last three decades, is a centralized space heating system using water. Hot and cold supplies manage the comfort system for heating and cooling. The heating supply using an AquaPort harvests the energy from the space heating energy to heat DHW water on demand and at the point of use.
This way, you maintain a very controlled space heating system and use the additional heating load to create on demand, at temperature DHW. This reduces the long DHW piping challenges, realizes the energy efficiency of a hydronic heated/cooled building, and eliminates the need to create, store, and move 140°F (60°C) water needed for DHW systems.
This strategy removes the centralized DHW and recirculation piping resulting in water quality and energy efficiency benefits within the systems.
The AquaPort system needs a closed-loop hydronic heating source to generate DHW. This could be an on-site plant or connected to a district system. To get the most energy efficiencies out of the system, high-density hospital towers, assisted living, multi-family, and hospitality buildings, with low-flowing fixtures, are ideal.
Material Components and Properties
The heat exchanger is a double wall with stainless-steel plates and a brazed copper seam with atmospheric vents.
The hot water is generated through a double-wall, brazed-plate heat exchanger with atmospheric vents (to prevent cross-contamination) to transfer the heat from the hydronic system to the domestic system. It is designed specifically for applications requiring high thermal efficiency, minimal leakage, improved leak detection, and longevity.
The heat exchanger has a 10-degree Fahrenheit (5-degree Celsius) approach. So, if you need 120°F (49°C) DHW, you need 130°F (54°C) supply. This efficiency allows the system to work off low supply temperatures, which eliminates waste.
The 20-plate, 3.0 gpm unit has 0.16 gallons in the heat exchanger. The 40-plate, 5.25 gpm has 0.32 gallons (using conservative numbers). These minimal volumes ensure the heat exchanger can quickly act to generate DHW within a few seconds (approximately 2.5+ seconds) of the demand signal from the proportional control valve. Unlike tankless water heaters, the AquaPort system does not have a cold-water sandwich effect.
Note that the cold-water sandwich effect is another factor that must be taken into account when considering the installation of a tankless water heater. The cold-water sandwich effect is a condition where cold water is fed into a facility’s hot-water lines while the tankless water heater’s heat exchanger is heating up. This delay in providing hot water by the tankless water heater can result in 10 to 30 seconds of cold water being fed into the hot-water lines while the heat exchanger is heating up.
When this occurs, equipment and fixtures with low hot-water demand, such as low-water-demand dishwashers and faucets, may not receive the quantity of hot water they require for proper operation. Facilities with low-water-demand dishwashers or faucets may be required to install hot-water recirculation systems, booster heaters, and/or point-of-use water heaters to ensure that a consistent supply of hot water is available for all the fixtures and equipment.
The starting signal is the opening of the hot-water tap. The cold-water pressure pushes the PCV regulator to the left on the roller diaphragm to initiate hot-water delivery. The path to the heat exchanger for the heating system is opened in response to hot-water requirements. The only water heated is the amount needed at the tap, which eliminates storage tanks.
The Uponor AquaPort heat exchanger holds between 0.16 and 0.32 gallons of water, and there is a bypass valve on the heat exchanger that is always circulating a small amount of hot water to keep the unit charged. The unit works off a pressure differential, so once there is a call for water from a fixture and the heat exchanger and water within the piping flushes, you have instant heating hot water.
The AquaPort has atmospheric vents in the proportional control valve and vented double wall heat exchanger that can be visually observed for leaks.
The leak will appear out of the atmospheric vents on the heat exchanger and PCV valve.
The AquaPort has a DHW setpoint controller, which is a temperature-limiting device that allows you to set the DHW temperature to your desired setpoint. It will fail in the closed position to protect the end user from scalding. However, it is currently not listed to ASSE 1070 as an anti-scald device. If ASSE 1070 is required by your authority having jurisdiction (AHJ), you can consider an additional listed anti-scalding valve downstream of the AquaPort.
No, the mechanical system will be sized on the system diversity with buffer tanks to manage spikes in the DHW load profile. As such, DHW priority is typically not required.
No, there are no flow switches on or within the AquaPort.
The temperature setpoint determines the gpm through the bypass valve.
The minimum flow is 0.1 U.S. gpm.
Yes, you can install hydronic circuit setters before or after the AquaPort, which are typically used on the hydronic heating side.
If you have hard water, it is less likely to have an impact if you are using an AquaPort with a heat exchanger versus a gas-fired water heater. Because you have low temperatures feeding the heat exchangers, scale is not an issue because scale forms with high temperatures and stagnant water. In a typical gas-fired water heater, you typically see temperatures over 2,000°F (1093°C) and high temperatures on a heat exchanger is what drives scale and takes advantage of low-temperature profiles to help reduce maintenance. The water temperatures in an AquaPort system are 130°F (54°C) to 160°F (71°C). This temperature profile is not conducive to scale buildup, and the thermosyphon lowers the duration of time at these temperatures. Descaling your heat exchanger is not required.
For hydronic heating, the supply water may have to be conditioned to meet the heating system’s requirements. This should be sufficient to meet the needs of the AquaPort heat exchangers. Plus, the risk of scale buildup is mitigated by the point-of-use and on-demand nature of the device.
The soldered-plate heat exchanger features embossed stainless-steel plates, and the heat exchangers in the heat-interface units feature copper-brazed stainless-steel plates. Before using this product, the building services engineer or the installation contractor must address corrosion protection and scale formation according to local, state, and national regulations, in addition to considerations from the current drinking-water analysis.
For further information, refer to the Uponor AquaPort Installation and Operation Manual.
Refer to the following table for acceptable operational water quality values. Note that this table is also found in the Uponor AquaPort Installation and Operation Manual.
|Acceptable operational water quality values|
|Ingredient||Value||Unit||Exposure time limit|
|Alkalinity bicarbonate (HCO3)||70-300||mg/l or ppm||-|
|Sulfate (SO42-)||< 70||mg/l or ppm||-|
|Bicarbonate (HCO3-)/sulfate (SO42-)||> 1||mg/l or ppm||-|
|pH||7.5 - 9.0||mg/l or ppm||-|
|Ammonium (NH4+)||< 2||mg/l or ppm||< 24 h|
|Chlorides (Cl-)||< 100||mg/l or ppm||-|
|Free chlorine (Cl2)||< 1||mg/l or ppm||Within 5 hrs.|
|Hydrogen sulfide (H2S)||< 0.05||mg/l or ppm||-|
|Free (aggressive) carbon dioxide (CO2)||< 5||mg/l or ppm||-|
|Degree of general hardness (°dH)||4.0-8.5||°dH||-|
|1°dH = 21.8mg/l HCO3 (hydrogen carbonate)||87.2-185.3||mg/l||-|
|Nitrate (NO3-)||< 100||mg/l or ppm||-|
|Iron (Fe)||< 0.2||mg/l or ppm||-|
|Aluminum (Al)||< 0.2||mg/l or ppm||-|
|Manganese (Mn)||< 0.1||mg/l or ppm||-|
No, the current models do not have built-in submeters. However, a submeter can be purchased separately and placed outside of the unit. In many cases, you will just need one submeter versus two typically needed in a centralized DHW application. This also ensures the AquaPort can be located near the domestic load and not be dependent on the riser or terminal unit locations.
The cabinet is only assessable from the front via the cabinet cover.
Product Availability and Costs
Buy-sell through the rep network.
In comparison to a centralized DHW system and a 4-pipe FCU mechanical system, the AquaPort system is considered total-project-cost neutral. With further analysis, it could be less expensive considering all the savings in piping, insulation, hangers, gas, electric, venting, risk mitigation with lower water temperatures, avoiding legionella growth and single heat-source system, and compounding energy efficiencies. With an AquaPort system, the mechanical room does need to be considered to have in-parallel heat sources as well as a buffer tank to help alleviate temperature swings and delays.
The AquaPort ships from Silay City in Germany, which is part of the free trade with the U.S., but the product itself cannot be considered as an American product, which is the requirement for Federal agencies per the act. However, because there is no American-made equivalent, it may still be installed in Federal projects.
The Uponor AquaPort has a 10-year warranty on stationary parts and a 2-year warranty on moving parts. In comparison, most instant water heaters have a 5-year warranty. The heat exchanger, specifically, has a 10-year warranty and requires no mechanical maintenance. For details, refer to the following table, which is in the Uponor AquaPort Installation and Operation Manual.
|Product category||Affected products||Warranty term|
|Stationary parts||Heat exchanger, pipe, and compression fitting connections||10 years|
|Moving parts||Air vents, DHW controller, proportional control valve, hydronic flow regulator, temperature bypass valve, isolation valves, and purge drain||2 years|
Codes, Standards, and Listings
The AquaPort meets the intent of all code requirements. Because it utilizes new technology to North America with the use of the proportional control valve (PCV), we certified the PCV to ASSE LEC 2010. This Listing Evaluation Criteria (LEC) is in the process of becoming a standard before 2025. Once a standard, it can be adopted by plumbing codes. However, because ASSE LEC 2010 is not a standard listed in the current codes, it will be important to follow local requirements and approvals for implementing this new technology.
No, the AquaPort is not currently fire rated. Although, like many cabinets and boxes, fire-rated construction can be assembled on the job site.
Refer to the Uponor AquaPort submittal for complete codes, standards, and listings. Note that ORD 784 for Canada offers listing for the PM valves.
|IAPMO PS 92; NSF/ANSI 372; CAN/CSA F379.1; IAPMO/ANSI Z1157|
|IRC; IPC; IMC; UPC; UMC; CPC; CMC; NPC|
The ICC Evaluation Service (ICC-ES PMG) is an ANSI-accredited product certification program for North America, certifying plumbing, mechanical and fuel gas products to the requirements of International, Uniform, and Canadian codes and standards. ICC-ES has reviewed all AquaPort test data for individual components and as a whole unit and found it compliant to the codes and standards listed in PMG-1543.
LEC 2010 is Listing Evaluation Criteria for Proportional Flow Control Devices, with Protection from Cross-Contamination via Hydronic Water, for use in Drinking Water Installations. It is an Other Recognized Document (ORD) that establishes the initial rules for unique products in the marketplace. An LEC is an opportunity for new devices to gain a footing in the marketplace when combined with third-party certification. LEC 2010 is currently in the process of becoming an ASSE standard and will be submitted for the 2027 code cycle.
These systems have been installed in Europe since the early 1990s. It is estimated for Europe that more than 30k units are installed annually. When visiting Europe, there is a high probability you were using water connected through a heat interface unit (HIU).
The AquaPort mounts flush in a standard 6" plumbing wall. To improve the DHW time to hot water, place the AquaPort as close as possible to the fixtures. Common locations include wall cavities in storage rooms, closets, laundry spaces, pantries, or in the walls of the bathrooms behind doors.
There are two units:
100,000 btu/hr = 3 gpm
180, 000 btu/hr = 5.25 gpm
The 3 gpm unit achieves 3 gpm at a 70°F rise continuously, and the 5.25 gpm unit operates similarly at a 70°F rise. As flow increases above the value, the rise goes down. This is different from a tank system that can satisfy every fixture, but not continuously, and needs recovery.
No, 20 U.S. gpm is more than the allowed flow for the current two AquaPort offerings available.
With a design high limit fixed on the space-heating circuit, domestic flow demands exceeding the performance characteristics of the AquaPort will result in a degradation in the supply temperature to the fixtures. Flexibility on the space-heating circuit temperature provides flexibility on the load side of the AquaPort. In the case of a design error or unaccounted for increase in fixture load, an increase in the space-heating circuit temperature could be applied as a corrective measure, provided the heating system has this capability.
At a 70°F rise, suites requiring under 3 gpm or under 5.25 gpm are ideal candidates.
There are no consequences to the AquaPort in unoccupied spaces.
The AquaPort is your heat source. You will size this heat source the same as you would any other heat source. Ensure your tap demand does not exceed the AquaPort supply in your selection process. Contact Uponor Design Services at 888.994.7726 for assistance.
Heated domestic water is delivered to the fixtures within a few seconds (approximately 2.5+/- seconds). This is possible due to a constant microflow of heating fluid through the heat exchanger and low volume of domestic water within the heat exchanger. The 20-plate, 3 gpm unit has 0.16 gallons in the heat exchanger, and the 40-plate, 5.25 gpm unit has 0.32 gallons (using conservative numbers). There is a bypass valve on the heat exchanger that is always circulating a small amount of hot water to keep the unit charged. The unit works off a pressure differential, so once there is a call for water from a fixture and the heat exchanger and water within the pipe flushes, you have instant heating hot water. Uponor designs all systems to have <0.8 gallons downstream of the device to ensure proper performance for hot-water delivery and water efficiency.
The heat exchanger has a 10-degree Fahrenheit (5-degree Celsius) approach. So, if you need 120°F (49°C) DHW, you need 130°F (54°C) supply. This efficiency allows the system to work off low supply temperatures, which eliminates waste.
The heating supply needs to be 10 degrees Fahrenheit (5 degrees Celsius) greater than the desired DHW supply. So, a 120°F (49°C) DHW temperature needs 130°F (54°C) heating hot water supply to the unit. With electrification, it is worth noting that generally heat pumps max out at 130°F (54°C), though technologies are rapidly changing. At 130°F (54°C), COPs are lower than desired, so this is an opportunity to discuss 115°F (46°C) DHW temperature, which is adequate for most occupants. For reference, energy modeling simulations will use a 105°F (41°C) for showers.
130°F (54°C) hydronic supply will generate 120°F (49°C) DHW. If lower, then the DHW temperature will be impacted without some type of boosting, which is typically an electric boiler in the mechanical room boosting a buffer tank. There are other strategies for gas systems.
Depending on available domestic water pressures, it may be necessary to boost pressures in order to achieve the required design pressure drop across the proportional control valve. This valve is essential to offering a device that is 100% mechanical, which eliminates any need for electrical equipment.
3 gpm unit = 100,000 btu/hr
5.25 gpm unit = 180,000 btu/hr
From a system standpoint, it’s not a 1:1 ratio from AquaPort to boiler load. We account for simultaneity which assumes a portion of the devices are on and not at full capacity. This is common in plumbing design for DHW plant sizing in the U.S. today, and the curves we use are also standardized from Europe and modified for our fixture flow rates.
At this time, Uponor is recommending a buffer tank on each mechanical system until further testing is performed. Buffer tanks are standard practice, though Uponor is presently looking for field research opportunities to study the consequences of using the volume in the distribution network for thermal storage.
The engineering team of record will work with Uponor Construction Services to establish the domestic heating load required and combine it with the space heating load as well as establish the requirements of the buffer tank.
The system is heat-source agnostic, so long as the heat source system can produce the required water temperatures.
District heating is an ideal source for any connected building using AquaPorts. The resulting low-return temperatures improve the weighted average, which improves system efficiency. District heating requires low return water temperatures and low supply water temperatures. If the district system supplies 140°F (60°C), the return water temperature of the AquaPort at 4 gpm load is 70°F (21°C). That is a great return temperature for a district heating system. District systems are the highest-use case for these products is Europe.
A dedicated hydronic-based heat source is required for the AquaPorts. You could not use a VRF system unless you had dedicated boilers for domestic.
Regardless of system types, energy accountability occurs in all standalone domestic systems or integrated hybrid systems. Due to the summertime low-return temperatures, the AquaPort system performance actually improves heating plant efficiency. See page 10 of the Uponor AquaPort White Paper. This is a key criterion in district energy systems where cool return temperatures are often part of energy legislation, particularly in European countries. The same principle applies to buildings having their own heating plants. The graphs here are from buffer tanks connected to a district energy system in Germany.
DHW systems typically have built-in redundancy to allow the system to be serviced without a total interruption.
There are not any compatibility issues from a standard hydronic system. Below are all the materials for the AquaPort.
- Fittings tap water CW 724 R, C69300
- Fittings hydronic CW 617 N, C37700
- Seal type VDI 2200, DVGW, EG 1935/2004, FDA, GL, TA Air, VP 401, W270, WRAS
- Double-wall heat exchanger plates stainless steel ANSI 316, brazed-seam copper 99.9%
- Piping stainless steel 1.4101 / ANSI 316
- Shutoff valves CW 511 L, C27453
At this time, there is no fee for AquaPort requests. However, design fees may apply in the future.
Installation & Maintenance
The AquaPort has four FNPT threads at the bottom of the unit. Use ¾" NPT transition fittings (sold separately) to connect any piping material to the AquaPort.
Refer to the table and figure below. See Chapter 7 in the Uponor AquaPort Installation and Operation Manual for complete maintenance schedule details.
|Cycle shutoff valves (close/open)
Figure 3-1 9
Figure 3-1 3
|Inspect proportional control valve for leakage at inspection ports
Figure 3-1 2
As a general rule, it will not be necessary to descale the heat exchanger. Additionally, hard water characteristics do not affect the warranty on the AquaPort.
AquaPorts are different from instantaneous water heaters and racked systems, which require descaling procedures. Scale forms from exposing cold water to high temperatures in cycles over long periods. The heating water temperature profile for AquaPorts needs a minimum 10°F (5°C) heating supply over the target domestic temperature. It does not need to exceed the domestic water temperature by more than 30°F (15°C). Gas-fired water heaters have heat exchangers exposed to over 2,000°F (1,093°C). This industrial-grade temperature is a major contributor to scale buildup. Additionally, AquaPorts use a thermosiphon to quickly extract temperature from the heat exchanger after use, which reduces the time exposure, reduces scale formation, and preserves the thermal performance of the heat exchanger.
The AquaPort needs a 6" deep wall with 14.5" between the studs and at least 24" of available height.
There is a cover plate lock on the device. If additional security is needed, there are numerous suppliers of aftermarket tamperproof boxes and doors.