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Grundfos Scala Pressure Boosting System
Grundfos SCALA2 Variable Speed Constant Pressure Booster Pump - 115/230V, 13 GPM, 147 ft Head, 3/4 HP
Grundfos
Grundfos SCALA2 Variable Speed Constant Pressure Booster Pump - 115/230V, 13 GPM, 147 ft Head, 3/4 HP
- Price
- $1,488.88
Grundfos SCALA1 Self-Priming Pressure Booster Pump - 115/230V, 13-22 GPM, 150-180 ft Head
Grundfos
Grundfos SCALA1 Self-Priming Pressure Booster Pump - 115/230V, 13-22 GPM, 150-180 ft Head
- Price
- From $1,084.35
Grundfos Scala Pressure Boosting System
Grundfos SCALA
Pressure Boosting Systems
SCALA1 and SCALA2 — all-in-one self-priming boosters that put steady water pressure at every tap. Grundfos’ best-selling home and light-commercial booster line, stocked for the Gulf Coast with engineering-led sizing.
2 SystemsSCALA1 & SCALA2
26 ftSelf-priming lift
13–22 GPMPer unit
Up to 180 ftMax head
NSF 61 / 372UL & CSA listed
Grundfos is a Danish pump manufacturer and one of the largest in the world. SCALA is its integrated domestic and light-commercial booster platform: a multistage pump, motor, small pressure vessel, non-return valve and electronic control packaged in a single self-priming enclosure. There is no separate pressure switch or external tank to plumb — connect suction and discharge, set the pressure, and the system delivers water on demand.
The line splits into two systems. SCALA1 is a fixed-speed booster with Bluetooth, an external input and twin-pump capability. SCALA2 is a variable-speed unit that holds constant pressure at every tap regardless of inlet fluctuation, at one of the lowest noise levels in its class. Watermain Supply stocks the U.S. 60 Hz range with NPT connections and U.S. plugs, backed by engineering-led sizing to your fixture count, elevation and inlet pressure. Compare the two below, or call 1-888.510.4036 and we will size it for you. Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial distributor.
The SCALA Line
Two all-in-one platforms on the same self-priming, integrated concept — one fixed-speed and twin-capable, one variable-speed for constant pressure.
SCALA1
Fixed-speed, twin-capable booster
13–22 GPMnominal flow
150–180 ftmax head (60 Hz)
2 Models3-45 & 5-55
115 / 230 V1-phase
A self-priming multistage booster that packs pump, water-cooled motor, small vessel, check valve and controls into one composite enclosure. Fixed-speed operation with Bluetooth (Grundfos GO) and an external input for float-switch and irrigation control. Two units pair into a twin booster for standby duty or higher flow. Runs under 55 dB(A), self-primes from 26 ft of lift, 1 in NPT ports.
Available models
- SCALA1 3-45 — 13 GPM, 150 ft max head
- SCALA1 5-55 — 22 GPM, 180 ft max head
- Max system pressure 116 psi, self-priming to 26 ft
- Twin-capable, Bluetooth, external input
- NSF/ANSI 61, 372, CSA, CE
Best forHomes on city water with low street pressure, tank- and roof-fed systems, shallow wells, irrigation and water transfer, and installs that may need a standby or higher-flow twin.
View SCALA1
SCALA2
Variable-speed constant pressure
Up to 18 GPMmax flow
147 ftmax head
3/4 HPpermanent magnet
115 / 230 V1-phase
A fully integrated variable-speed booster. An integrated pressure sensor and inverter adjust motor speed continuously to hold a constant set point across the whole home, with soft starts and steady flow even as inlet pressure swings. Aluminum-and-composite build, integrated diaphragm tank, one of the quietest boosters in its class at 44 dB(A). Self-priming to 26 ft, 1 in NPT ports.
Key specifications
- SCALA2 3-45 — single model, 115 V or 230 V
- Default set point 43 psi, adjustable
- Max system pressure 145 psi, max inlet 87 psi
- pH 4-9, chloride to 300 ppm (harder feeds)
- NSF/ANSI 61, 372, UL, CSA, WRAS
Best forWhole-home constant pressure, city mains with varying pressure, multi-fixture homes, kitchen and bath comfort, and harder or chlorinated municipal feeds.
View SCALA2
SCALA1 vs SCALA2
Both are self-priming, all-in-one boosters with the same protection suite. The deciding factor is fixed-speed with twin capability (SCALA1) versus variable-speed constant pressure (SCALA2).
SCALA1 wins on range, irrigation control and redundancy — two units pair into a twin booster for standby or higher flow. SCALA2 wins on comfort and municipal duty — true constant pressure, quieter operation, a higher system-pressure rating and six times the chloride tolerance.
| Specification | SCALA1 | SCALA2 |
|---|---|---|
| Speed control | Fixed speed | Variable speed (VFD) |
| Pressure behavior | Boosts to a fixed curve | Constant set-point pressure |
| Models | 3-45 and 5-55 | 3-45 (single) |
| Nominal / max flow | 13-22 GPM | 13 GPM / up to 18 GPM |
| Max head | 150-180 ft (60 Hz) | 147 ft |
| Motor | 0.8-1.1 HP (P2) | 3/4 HP (P1 550 W), permanent magnet |
| Voltage | 115 V or 230 V, 1-phase | 115 V or 230 V, 1-phase |
| Max system pressure | 116 psi (8 bar) | 145 psi (10 bar) |
| Max inlet pressure | 43 psi (3-45) / 29 psi (5-55) | 87 psi (6 bar) |
| Noise level | < 55 dB(A) | 44 dB(A) |
| Self-priming lift | 26 ft | 26 ft |
| Twin / multi-pump | Electronic twin (comms cable, alternation, staging) | Parallel twin kit (pumps run independently) |
| Connectivity | Bluetooth (Grundfos GO), external input | On-unit display |
| pH / max chloride | 4-7 / 50 ppm | 4-9 / 300 ppm |
| Enclosure | Composite | Aluminum + composite |
| Ports | 1 in NPT | 1 in NPT |
| Certifications | NSF 61/372, CSA, CE | NSF 61/372, cULus, WRAS, CE |
Quick rule. Choose SCALA2 when the goal is steady pressure at the tap all day, quiet operation, or a demanding municipal feed. Choose SCALA1 when you need irrigation/float control, a wider flow range, or a coordinated two-pump system with alternation and standby staging (SCALA2 offers a parallel twin kit, but the pumps are not electronically paired).
Rated Performance
Documented duty points for the U.S. 60 Hz models. Use these to confirm your required flow at the required boost sits within the pump’s range with margin; request the manufacturer pump curve for the exact duty point before specifying.
| Specification | SCALA1 3-45 | SCALA1 5-55 | SCALA2 3-45 |
|---|---|---|---|
| Type | Fixed speed | Fixed speed | Variable speed |
| Max head | 150 ft | 180 ft | 147 ft |
| Nominal flow | 13 GPM | 22 GPM | 13 GPM |
| Nominal duty point | 15.8 GPM at 82 ft | 23.5 GPM at 82 ft | holds set point (see curve) |
| Start pressure | 32 psi | 41 psi | adjustable (default 43 psi) |
| Max inlet pressure | 43 psi | 29 psi | 87 psi |
| Max system pressure | 116 psi | 116 psi | 145 psi |
| Motor | 0.80 HP (P2) | 1.10 HP (P2) | 3/4 HP (P1 550 W) |
Boost in psi equals head in feet multiplied by 0.433. Fixed-speed SCALA1 delivers pressure along its pump curve; SCALA2 holds the pressure you set, up to its capability, and reduces speed at low demand. Confirm against the current Grundfos data booklet for your model.
Sizing & Best Practices
How we size a SCALA, and what to check before you install one. Send us your numbers and we will run this for you.
1. Calculate required boost
Required boost equals the pressure you want at the highest fixture, plus 0.433 psi for every foot of elevation from the pump to that fixture, plus friction loss in the piping, minus the pressure already available at the pump inlet. A two-story home wanting 50 psi upstairs, with the pump in the garage 20 ft below and 25 psi at the meter, needs roughly 50 + (20 × 0.433) + friction − 25 ≈ 34 psi of boost plus pipe losses.
2. Estimate peak flow honestly
Size flow to simultaneous demand, not the sum of every fixture. For homes, a water-supply-fixture-unit method (IPC Table 604.3 / Hunter’s curve) converts fixture counts into a realistic peak GPM; for light commercial, the IAPMO Water Demand Calculator is more accurate. A single bath rarely exceeds 8-10 GPM at once; a large home with several baths running is typically 14-22 GPM — squarely in the SCALA band.
3. Check inlet pressure limits
Confirm your static inlet pressure stays under the model limit — especially SCALA1 5-55 at 29 psi. On strong municipal mains, a pressure-reducing valve upstream protects the pump. On a suction lift, remember both SCALA systems self-prime from up to 26 ft, but longer or higher lifts reduce available flow.
Sizing rule of thumb. If your required flow at the required boost lands past 70 percent of a model’s maximum head, step up a model — SCALA1 3-45 to 5-55, or SCALA1 to SCALA2 for constant pressure. Leaving headroom keeps the pump off its steep end-of-curve and quiets operation.
Which SCALA Do You Need?
A selection guide by application. Flow figures assume typical fixture-unit demand; call us with your fixture count and elevation for an engineering-led selection.
| Application | Typical demand | Recommended | Notes |
|---|---|---|---|
| 1-2 bath home, one story | 8-14 GPM at 40-60 psi | SCALA2 3-45 or SCALA1 3-45 | SCALA2 for quiet constant pressure; SCALA1 3-45 for lower cost. |
| 3-4 bath home, two story | 14-22 GPM at 50-65 psi | SCALA1 5-55 or SCALA2 3-45 | 5-55 head covers upper-floor showers; SCALA2 for steadier pressure. |
| Whole-home constant pressure | Variable | SCALA2 3-45 | VFD holds set point across changing demand at 44 dB(A). |
| City mains with varying pressure | 10-20 GPM | SCALA2 3-45 | Adapts speed to inlet swings; 145 psi system rating. |
| Roof / storage / break tank | 10-22 GPM | SCALA1 or SCALA2 | Self-priming to 26 ft from an atmospheric tank. |
| Shallow well (to 26 ft) | 10-20 GPM | SCALA1 3-45 or 5-55 | Self-priming with dry-run protection; add inlet filter. |
| Irrigation / water transfer | 15-22 GPM | SCALA1 5-55 | External input and fixed speed move water A-to-B on demand. |
| Standby / higher peak flow | Up to ~40 GPM | SCALA1 Twin | Two SCALA1 on the twin kit alternate duty and stage in. |
| Harder / chlorinated feed | Any | SCALA2 3-45 | pH 4-9 and chloride to 300 ppm tolerance. |
What Makes SCALA Different
The engineering shared across the line, and why it matters on an installation.
All-in-one, self-priming
Pump, motor, small vessel and check valve in one enclosure that primes from dry to 26 ft of suction lift — draw from a tank, cistern or shallow well without a separate lift pump or external tank.
Constant pressure (SCALA2)
The inverter varies motor speed to hold your set point as demand changes, instead of cycling against a pressure switch. Steady pressure at the tap, soft start and stop, and no water hammer.
Twin capability (SCALA1)
Two SCALA1 units pair on a twin kit and communicate over a cable, alternating duty by runtime or starts and staging the second pump in when flow demand rises — standby redundancy without a custom panel. SCALA2 offers a parallel twin accessory set, without electronic pairing.
Water-cooled, quiet
Cooling by the pumped liquid eliminates the fan. SCALA2 runs at 44 dB(A) and both units install in a closet or recess with limited air movement — SCALA1 is rated to 131°F ambient, SCALA2 (60 Hz) to 113°F.
Full protection suite
Dry-running protection, anti-cycling / micro-leakage detection, adjustable maximum-runtime, and current- and temperature-dependent motor protection with automatic restart — no external motor protection needed.
Bluetooth & external input (SCALA1)
Configure and monitor over Grundfos GO, and wire an external input for a float switch or irrigation calendar — useful for tank filling and scheduled watering.
Robust, corrosion-resistant
Composite construction on SCALA1 and an aluminum-and-composite build on SCALA2 with corrosion-resistant internals; SCALA2 tolerates pH 4-9 and chloride to 300 ppm for harder feeds.
Drinking-water certified
Both systems are certified to NSF/ANSI 61 and NSF/ANSI 372 low-lead for potable contact, with CSA electrical listing (SCALA2 adds cULus and WRAS).
How SCALA Compares to Other Brands
We stock booster pumps from every major line, so we can be straight about where SCALA fits. Most residential VFD boosters below compare most directly with SCALA2; SCALA1 is the fixed-speed, twin-capable alternative. All hydraulic figures are single-unit.
Grundfos SCALA vs DAB Esybox
| Specification | SCALA2 | DAB Esybox Mini 3 | DAB Esybox |
|---|---|---|---|
| Control | Variable speed | Variable speed | Variable speed |
| Max flow | up to 18 GPM | 21.1 GPM | 31.7 GPM |
| Max head | 147 ft | 180 ft | 213 ft |
| Motor | 3/4 HP | 1.1 HP | 2.1 HP |
| Voltage | 115 / 230 V | 115 / 230 V (one unit) | 230 V |
| Max system pressure | 145 psi | 109 psi | 116 psi |
| Noise | 44 dB(A) | Quiet | ~43 dB(A) |
| Self-priming | 26 ft | 26 ft | 26 ft |
| Multi-pump | Parallel twin kit | Twin (Esytwin Mini) | Wireless to 4 |
| Certifications | NSF 61/372, cULus, WRAS | NSF 61/372, UL, CSA | NSF 61/372, UL, CSA |
Esybox offers more flow and head per unit and wireless multi-pump grouping; SCALA2 counters with a higher system-pressure rating and higher chloride tolerance. For higher flow or a commercial station, step to DAB Esybox or Esybox Max.
Grundfos SCALA vs A.Y. McDonald DuraMAC
| Specification | SCALA1 | SCALA2 | DuraMAC Residential | DuraMAC VS |
|---|---|---|---|---|
| Control | Fixed speed | Variable speed | Fixed speed | Variable speed |
| Flow | 13-22 GPM | up to 18 GPM | 20 GPM | 6-35 GPM |
| Boost / head | 150-180 ft | 147 ft | 35-70 psi | 25-65 psi |
| Motor | 0.8-1.1 HP (P2) | 3/4 HP (P1) | 1/2-1 HP | 1-2 HP |
| Max system pressure | 116 psi | 145 psi | — | 120 psi |
| Construction | Composite | Al + composite | Stainless components | SS 304/316 |
| Self-priming | 26 ft | 26 ft | Yes | Yes |
| Certifications | NSF 61/372 | NSF 61/372 | NSF 61 | NSF 61, UL |
| Origin | Denmark/Serbia | Denmark/Serbia | Made in USA | Made in USA |
DuraMAC VS offers more flow and full stainless-steel hydraulics with domestic manufacture; SCALA2 counters with quieter operation, a higher system-pressure rating and NSF 372. SCALA1 and DuraMAC Residential are the fixed-speed options in each line.
Grundfos SCALA vs Goulds Water Technology
| Specification | SCALA2 | Goulds ResiBoost | Goulds Aquavar |
|---|---|---|---|
| Control | Variable speed | Variable speed (VSD) | Variable speed (e-AB3 / e-AB2) |
| Max flow | up to 18 GPM | up to 35 GPM | up to 80 GPM (e-AB2) |
| Motor | 3/4 HP | 0.75-2 HP | 0.5-5 HP |
| Pump / motor | Al + composite | Stainless e-HM | IE5 Smart Motor / e-HM |
| Self-priming | 26 ft | Not self-priming | Not self-priming |
| Integrated tank | Yes | Yes (packed separate) | Yes (kit) |
| Install rating | IPX4D outdoor | Indoor | NEMA 1 / NEMA 3R |
| Certifications | NSF 61/372, cULus, WRAS | NSF 61/372 (Xylem) | NSF 61/372 (Xylem) |
Goulds ResiBoost and Aquavar scale to higher flow and horsepower with stainless e-HM hydraulics, and Aquavar reaches commercial duty. SCALA2 is the more compact, self-priming, plug-and-pump choice for single-residence constant pressure.
Grundfos SCALA vs Davey
| Specification | SCALA2 | Davey DD Series | Davey EvoDrive |
|---|---|---|---|
| Control | Variable speed | Variable speed | Variable speed (PM motor) |
| Max flow | up to 18 GPM | 15-34 GPM | 28 GPM |
| Max pressure | 147 ft (~64 psi) | up to 91 psi set | up to 95 psi |
| Max casing pressure | 145 psi | 116-145 psi | 145 psi |
| Self-priming lift | 26 ft | Flooded / limited | 13 ft |
| Construction | Al + composite | 304 stainless | 304 stainless |
| Multi-pump | No | Daisy-chain 2 pumps | Duty/standby (2 pumps) |
| Certifications | NSF 61/372 | NSF 61 (WQA) | NSF-oriented |
Davey DD and EvoDrive offer more flow and stainless hydraulics with dual-pump modes; SCALA2 counters with greater self-priming lift (26 ft vs 13 ft on EvoDrive) and NSF 372 low-lead certification.
Grundfos SCALA vs Franklin Electric
| Specification | SCALA2 | FE VersaBoost Pro | FE MH Series |
|---|---|---|---|
| Type | VFD constant pressure | VFD constant pressure | Multi-stage (bare pump) |
| Max flow | up to 18 GPM | 18-25 GPM | 15-90 GPM |
| Motor | 3/4 HP | 0.8-1.1 HP | 1/2-7.5 HP, 1 & 3-phase |
| Self-priming | 26 ft | No (submersible-based) | No |
| Integrated tank / CV | Yes | Yes | No (external drive/tank) |
| Noise | 44 dB(A) | 45 dB(A) | — |
| Install rating | IPX4D outdoor | NEMA 3R | Indoor/outdoor motor |
| Certifications | NSF 61/372, cULus, WRAS | NSF 61/372, UL, CSA | NSF 372, UL, CSA |
VersaBoost Pro is the closest Franklin match to SCALA2 — a comparable all-in-one VFD system built on an encapsulated submersible motor, though not self-priming. MH Series is a bare multistage pump for building a custom booster and scales to far higher flow. For duplex/triplex commercial stations, Franklin’s Inline SpecPAK sits above the SCALA class.
SCALA Accessories
Factory accessories that complete a SCALA installation. Order with the pump so the job ships together — product pages linked as they publish.
Inlet Filter
250-micron NPT filter that protects the pump from sand and debris on well and tank feeds.
Twin Accessory Set
Base plate, inlet/outlet manifolds with valves and comms cable to build a SCALA1 twin booster.
Flexible Hose Set
WRAS-approved braided connection hoses for vibration isolation and easy service.
Pump Stand
EPP stand that supports the pump, cuts vibration and noise, and lifts vents clear of drips.
Locking Pin (SCALA2)
Stops the clicking noise under positive inlet pressure; remove to restore self-priming.
Genuine Grundfos spare parts and service kits are available by model; contact us with the pump type and serial for the correct part.
Why Source Grundfos SCALA from Watermain Supply
Gulf Coast Stock
SCALA1 and SCALA2 in U.S. 60 Hz configurations ship fast across Texas and the Gulf Coast.
Engineering-Led Sizing
We size from fixture count, elevation, inlet pressure and pipe friction against the manufacturer curve — and tell you when a smaller model will do.
Multi-Brand Perspective
We also stock DAB, A.Y. McDonald DuraMAC, Goulds, Davey and Franklin Electric. If SCALA is not the right fit, we will say so and quote the one that is.
Twin & Standby Design
Guidance on SCALA1 twin boosters for standby redundancy or higher peak flow, with the right accessory kit and controls.
Account Terms Available
Net-30 terms for qualified contractor, property-management and municipal accounts, handled in-house.
Parts & Aftermarket
Genuine Grundfos accessories and service parts with model cross-reference, so you get the right kit the first time.
Frequently Asked Questions
Common questions from homeowners, plumbers and engineers selecting a Grundfos SCALA booster.
What is the difference between SCALA1 and SCALA2?
SCALA1 is a fixed-speed booster available in two models (3-45 and 5-55), with Bluetooth, an external input for float or irrigation control, and the ability to pair two units into a twin booster. SCALA2 is a single-model variable-speed unit that holds constant pressure at every tap, runs quieter at 44 dB(A), and carries a higher 145 psi system-pressure rating. Choose SCALA2 for steady whole-home pressure, SCALA1 for irrigation control, wider flow range, or twin redundancy.
Do I need a separate pressure tank with a SCALA?
No. Both systems include an integrated vessel and check valve. SCALA2 has a diaphragm tank sized for its VFD control logic, and SCALA1 has a small vessel with anti-cycling logic. An external tank is not required for normal installations.
Can a SCALA run on both 115 V and 230 V?
Each variant ships for a specific supply: 115 V uses a NEMA 5-15 plug, 230 V a NEMA 6-15 plug. Select the voltage that matches your service when ordering. Both are single-phase, 60 Hz.
How much boost does a SCALA provide?
Head in feet converts to pressure at 0.433 psi per foot. SCALA1 delivers up to 150 ft (about 65 psi) on the 3-45 and 180 ft (about 78 psi) on the 5-55; SCALA2 holds an adjustable set point up to 147 ft (about 64 psi). Available boost falls as flow rises — size with margin.
Can a SCALA draw water from a tank or shallow well?
Yes. Both SCALA1 and SCALA2 are self-priming to 26 ft of suction lift, so they can pull from an atmospheric storage tank, cistern or shallow well. We recommend the 250-micron inlet filter on well and tank feeds to protect the pump.
Can I run two SCALA pumps together?
SCALA1 is twin-capable: two units mount on the twin accessory kit, communicate over a cable, and alternate duty by runtime or number of starts, staging the second pump in as demand rises. SCALA2 offers a parallel twin accessory set (base plate, manifolds, valves) so two units can share one installation, but the pumps run independently — the communication cable, alternation and staging logic are SCALA1-only.
Is SCALA a good choice for hard or chlorinated water?
SCALA2 tolerates pH 4-9 and chloride up to 300 ppm, six times SCALA1’s limit, which suits harder or more chlorinated municipal feeds. For water with sand or grit, add the inlet filter regardless of model.
Is SCALA certified for drinking water?
Yes. Both systems are certified to NSF/ANSI 61 for drinking-water system components and NSF/ANSI 372 for low lead content. SCALA2 additionally carries UL, CSA and WRAS.
How does SCALA compare to DAB, Goulds, Davey or Franklin?
Most residential VFD boosters — DAB Esybox, Goulds ResiBoost, Davey DD/EvoDrive, Franklin VersaBoost — compare directly with SCALA2. Several offer more flow or stainless hydraulics; SCALA2 counters with a higher system-pressure rating, 26 ft self-priming, low noise and NSF 372. See the comparison tables above, or call us for a straight recommendation.
Can I install a SCALA outdoors?
Both carry an IPX4D rating suitable for outdoor installation; mount on a stand to keep the ventilation clear of standing water and provide freeze protection in cold climates. Keep 1.6 ft (0.5 m) of clearance on three sides.
Ready to Size Your Booster?
Send us your fixture count, number of floors, inlet pressure and required flow. We will respond with a sized SCALA selection, the accessories you need, and lead time.
Technical data on this page is taken from Grundfos SCALA U.S. 60 Hz product literature and is subject to change by the manufacturer. Confirm against the current installation manual and pump curve before specifying.
Grundfos, SCALA, SCALA1, SCALA2 and Grundfos GO are trademarks of Grundfos Holding A/S, used here for product identification only. DAB, Esybox, DuraMAC, Goulds, ResiBoost, Aquavar, Davey, EvoDrive, Franklin Electric and VersaBoost are trademarks of their respective owners.
Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
Grundfos, SCALA, SCALA1, SCALA2 and Grundfos GO are trademarks of Grundfos Holding A/S, used here for product identification only. DAB, Esybox, DuraMAC, Goulds, ResiBoost, Aquavar, Davey, EvoDrive, Franklin Electric and VersaBoost are trademarks of their respective owners.
Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
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