SCALA 2 Is the Future: Grundfos Phasing Out MQ3 Series

scala2 perfect water pressure ensures improved performanceSpring 2022 Update:

Grundfos has now released the SCALA1. if you want to check that out or learn all about the differences between SCALA1 and SCALA2, we have the resources for you.

Original blog post:

The latest and greatest in residential pressure boosting pumps is now officially the SCALA2 series. Our customers are very familiar with Grundfos. Though SCALA2 hit the market a few years back, many customers remained dedicated to the older MQ3 series for its reliability. So how does the SCALA2 vs MQ3 series measure up?

SCALA2 did have a few manufacturer flaws (more on that later), but they’ve now been fixed, and it is the superior pump. They have made it easier to meet the variable demands of your plumbing system while delivering the reliability and integrity you expect with Grundfos engineering.

When Will Grundfos Phase Out MQ3?

You could say that it’s already begun and probably will be complete in June. For customers who want to continue buying the MQ3 series, PlumbersStock will carry it as long as we can because we know plenty of people will still be looking for it. Here are the MQ3 models in question:

  • 115v MQ3-35 3/4 HP booster pump (all sold out)
  • 230v MQ3-35 3/4 HP booster pump (all sold out)
  • 115v MQ3-45 1 HP booster pump (all sold out)
  • 230v MQ3-45 1 HP booster pump (all sold out)

You no longer have to worry about horsepower when buying a residential booster pump. SCALA2 is built to meet your water flow demands. It ramps up and down when it needs to with its constant pressure system (more on that in a second). Here are the SCALA2 models in question:

Grundfos SCALA2 vs MQ3

Both models share many of the same standard features that you’d expect, like dry run protection and a max operating ambient temperature of 32 to 113-degrees Fahrenheit. Where they differ is what really matters. The SCALA2 is as quiet as a modern dishwasher, operating at 47 dba. Certainly, the show-stopper with SCALA2 is the intelligent pump technology that ensures perfect water pressure automatically. It works much like a variable frequency drive (VFD). The versatility ensures you have the machine you need. Remember that no matter what you want, PlumbersStock has the best prices on all kinds of Grundfos pumps.

scala2 vs mq3 pressure boost pump comparison

If you compare the specs on the 115v SCALA2 to the 115v MQ3, you will see a lot of similarities and a few important distinctions:

  • SCALA2 = rated head of 88.6 feet, max operating pressure of 145 psi, and max liquid temperature of 113-degrees Fahrenheit.
  • MQ3-45 = rated head of 75.5 feet, max operating pressure of 109 psi, and max liquid temperature of 95-degrees Fahrenheit.

Last, but not least, the engineers at Grundfos have been able to design more user-friendly controls and an easier installation process with the new SCALA2 series.

What Was the SCALA2 Recall About?

Back in 2019, Grundfos issued a recall of models within the PC codes of 1603 and 1901*. The issue was leak failure. It’s hard to say how widespread the issue was, but Grundfos advised/requested that if you had already installed the pump, then to keep it in place. Not all models were failing, but enough of them did that Grundfos reengineered the SCALA2.

*Signifying they were manufactured between the 3rd week of 2016 and the 1st week of 2019.

Save on Booster Pumps at PlumbersStock

Now that you know all the ins and outs of SCALA2 vs. MQ3, you’re ready to make a purchase. No matter which pump you choose, you can save at PlumbersStock. We have all kinds of booster pumps that will have you covered whether you have a house or a duplex. If you are buying in bulk, either because you are a contractor or are doing your own remodel, know that you can save even more with PlumbersStock if you contact us directly about special pricing.

27 thoughts on “SCALA 2 Is the Future: Grundfos Phasing Out MQ3 Series”

  1. Dear friends –
    Will the Scala2 lift water from a cistern?
    Approx 9’ from bottom of cistern to pump.

    Please advise

    • Sorry for the delayed response.

      Yes, it will. But not a lot of volume…it only has a 1-inch outlet. The good news is that means there will be plenty of pressure.

  2. I bought Grundfos Mq3-45 (115V) in May 2021 and had it installed in place of Grundfos Mq3-35 but the response when a tap is turned on takes a long time and the water pressure is terrible (worst than the Grundfos Mq3-35 , any suggestions. What should I do with the MQ3-45.I am in the Caribbean and bought it in Canada. Would it make sense to replace it with the SCALA2

  3. I decided to buy the MQ3-45 model to improve on the performance of theMQ3-35 model. The Mq3-35 model performed better than the MQ3 -45 model. I concluded that I got a faulty pump and but I was unable to find a Grundfos service provider in Grenada. Could you provide me with information regarding the warranty you offer. I was unable to get any service from the new pump I bought in Canada in May2021. I have gone from the ranks of satisfied repeat customer to that of dissatisfied customer.

    • We are sorry to hear that you are having problems. The manufacturer of the product offers the warranty to the original user only to be free of defects in material and workmanship for a period of 24 months from the date of installation, but not more than 30 months from the date of manufacture. Grundfos’ liability under this warranty shall be limited to repairing or replacing at Grundfos’ option, without charge, F.O.B. Grundfos’ factory or authorized service station, any product of Grundfos manufacture. Grundfos will not be liable for any costs of removal, installation, transportation, or any other charges that may arise in connection with a warranty claim.

      Fill out the required fields of Grunfos’ Customer Service form : Contact service | Grundfos. For more information, please refer to

  4. We have a SCALA2 3-45 AVCBDF, P/N 98562818. Installed about 6 years ago in a residential application to pressure all 3 levels of the home.

    Lately, the pump has been cycling on and then quickly cycling off again, very quickly (within about 1-2 seconds for the cycle up/down). Every time that happens, you can hear the pex system “thump”, maybe against a joist or other structural element of the home.

    There are no known leaks that would cause the switch to trigger cycle up.

    Is it possible to replace only the switch sensor?

    What other maintenance is suggested?

    Thank you.

  5. Purchased a scala 2 in 2018 to replace a 1.5 year old scala 2 that started leaking and making loud noises when running. The replacement started leaking after about 6 months I contacted Home Depot and they would not help so after lots of searching I found a distributor that sent me a replacement. Well I dealt with the leaking for a couple years until I had my basement refinished this year and finally installed the replacement. Wouldn’t you know that the replacement also leaks lol !
    All units should be replaced under a recall due to a defect in Engineering.

    • We are sorry to hear that you are having problems with your Grundfos SCALA2 Pump. Is the leak coming from the Shaft Seal? If so, it is normal that a slight leakage from the shaft seal of up to 10 ml per day or 8 to 10 drops per hour may occur. When the pump is started up for the first time, or when the shaft seal has been replaced, a certain run-in period is required before the leakage is reduced to an acceptable level.

      Under normal conditions, the leaking liquid will evaporate. As a result, no leakage will be detected. The leakage is visible where the screws are mounted on the base plate. If the unlikely event of an internal leakage occurs, the liquid
      will be drained through the bottom of the pump. Install the pump in such a way that no undesirable collateral damage can arise.

      Also, Always loosen and tighten the union nuts on the inlet and outlet ports by hand. Damage to the inlet and
      outlet parts increases the risk of leakage.

      For more information, please refer to page 13 of this Installation Manual.

    • Many of Scala’s leak issues are caused by a lack of thermal expansion protection. Homeowners with well systems, or municipal service without checks in the city meters don’t have a thermal expansion device on their water heater. The Scala has two internal check valves that create a closed-loop scenario. When you boost static pressure to 70psi and add thermal expansion during no demand the pressures can exceed the 145 maximum for Scala. Adding a properly sized expansion tank (70% of set-point maximum) to the heating system will protect the pump from excessive system pressures.

  6. My scala 2 pump manufactured in 2018 just started leaking as well. The pump seems not to be able to get up to pressure and leaks a constant stream of water. If I turn up the pressure up then down it stops. The plumber is coming later today. This better be under recall.

    • Hi there! We are sorry to hear that you are having problems. For optimal performance, please make sure that you are using the SCALA2 Pump as intended. It is designed for pressure boosting of city mains water, water from roof tank, break tank, and ground tank, as well as water supply from shallow wells. If the leakage is from the pipe system or the non-return valve is not properly closed due to impurities, you may need to check and repair the pipe system or clean, repair or replace the non-return valve. If the leakage is located in the inlet pipe, you may need to repair the inlet pipe. For more information, please refer to pages 14 and 15 of this Installation Manual for more information on how to troubleshoot you pump. Hope this helps!

      Installation Manual

  7. Hi,
    I have a leaking Scala2 at my home, Toronto ON. (M3K 0B7
    I know about recall. What are the steps to have it replaced? Thank you.

    • We are sorry that you are having a problem with your pump. All Grundfos products come with a 2-year warranty that complies with legal requirements. The warranty covers product and material defects that are not the results of normal wear and tear for a period of 24 months from the date of delivery. The warranty period may not, however, exceed 30 months from the date of production. For more information, please check this warranty sheet >

      Warranty claims may be submitted by contacting the local Grundfos sales company or the point of sale. Here is their Service Warranty Program > which includes the instructions and requirements for a product replacement. I hope this helps. Thank you for choosing PlumbersStock.

    • Hi there! We are sorry that you are having problems with your Grundfos SCALA2 Pump. Yes, Grundfos issued a recall of models within the PC codes 1603 and 1901 back in 2019. These are products that were manufactured between the 3rd week of 2016 and the 1st week of 2019. Please note that all Grundfos products come with a 2-year warranty that fully complies with legal requirements. The warranty covers product and material defects that are not a result of normal wear and tear for a period of 24 months from the date of delivery. The warranty period may not exceed 30 months from the date of production. For more information about Grundfos’ warranty, please refer to this Service Warranty Program Guide > We hope this helps. Have a great day!

  8. I am looking to replace my Grundfos MQ3-45. It is used in the basement to pump up rainwater from a underground well. Several taps and 2 toilets connected. Is the scala2 a good option or do I better look at the Scala1 5-55?

    • Thank you for choosing PlumbersStock! Both Grundfos SCALA1 and SCALA2 pumps are great replacement to the MQ3 series pumps. However, if you want a self-priming, multistage pump, which combines all the components of a pressure booster into a compact composite enclosure, then you ought to choose the SCALA1. It can communicate with the Grundfos GO Remote app through its built-in Bluetooth technology, which enables high customization options, making this pump a good fit for every application. On the other hand, if you want a fully integrated, self-priming, compact waterworks for pressure boosting in domestic applications, then the SCALA2 is the right one for you. It incorporates integrated speed control which allows maintaining a perfect pressure in the taps. This means that the pump performance will increase with the increasing demand.

      For more information, you can check page 3 of this SCALA Data Booklet >

      We hope this helps. Have a good day!

  9. my scala2 has run for 3 years. It has suddenly stopped running. you can see its powered up fine. no fault is showing. The eye logo shows 2 red lights blinking and no pump runs.
    I bought a replacement pump, plugged in my water lines and started right up.
    what you think it could be with the 2 red lights blinking ?

    • If the two opposite red indicator lights are flashing simultaneously, it means that the pump’s alarm has been triggered and that the pump has stopped working. All you need to do is eliminate the fault cause and manually press the “reset” button. The pump will then revert to normal duty.

      One of the possible fault cause it that the pump might be blocked by impurities. To deblock the pump, make sure to switch off the power supply before you start any work on the product. The end cover of the pump incorporates a plug which can be removed by means of a suitable tool. This makes it possible to deblock the pump shaft if it has seized up as a result of inactivity. Another reason might be is that the internal non-return valve is defective or blocked in completely or partly open position. If this happens, all you need to do is clean, repair, or replace the non-return valve.

      If two opposite red indicator lights are flashing three to five times and in between two opposite green indicator lights are flashing one time, you would need to contact Grundfos directly. For more information on how to troubleshoot your pump, please refer to this Instructions Manual >

      • Hi – i have an issue with a Grundfos Scala2 where, on the Grundfos eye, two red lights flash 4 times and then one pair of green lights. You above that I should contact Grundfos directly which i will do. Could you tell me what the lights signify in terms of fault? There is no fault code showing?

        • Grundfos 98562817 SCALA2 water pressure booster pump. If two red indicator lights on opposite sides are flashing three to five times, followed by two green indicator lights on opposite sides flashing once, this indicates that the pump has stopped and it is necessary to call Grundfos. Please see the fault finding chart on the 21st and 22nd page of the operating manual for additional information. We hope this helps. Thank you for asking for help from us! Have a nice day!

  10. I have a Grundfos Scala 2 in my recently renovated duplex apartment and it is incredible. The pressure boost itself was worth every penny. However, I have been having a strange issue. The pump will kick on every 2-4 minutes for a very brief 5 seconds and then back off, even when I am not running any water. I check on the pump every so often and it is silent and running smoothly whenever i turn on a tap but I see there is a leak error code after a couple days even after resetting it. I have checked toilets, sinks, showers, etc for leaks and found none. I also checked for moisture in the brick walls and ceilings and nothing. The meter, which is after the pump will move slightly every time this happens. I am considering having the walls checked for leaks with an ultrasonic scanner, but I wanted to ask here first. Any of you had a similar issue? How would you proceed?

    • Hi, Thank you posting a query about the Grundfos SCALA2 water pressure booster pump. Sorry for the delayed response, but this was a complicated issue. This could be due to several factors, including:

      – A water leak between the pump and water output: Any leaks can cause a pressure drop, triggering the pump to kick on more frequently.
      – Air in the water or a leaky suction line: This can cause the pump to rapidly turn on and off.
      – Low air pressure in the reservoir tank: If the inside air pressure drops, the tank won’t trigger the pressure switch correctly, leading to the pump turning on and off erroneously.
      – Damaged tank bladder or loss of air charge: This can cause rapid cycling of the switch as it tries to maintain proper pressure.

      You can try opening the bypass valve if your water filter has one to stop the pump from short cycling. If there is no bypass valve, turn off the pump and valves around the water filter, then remove the water filter cartridge and reassemble the unit. It’s worth noting that the SCALA2 has an “anti-cycling” feature designed to prevent the pump from continuously starting and stopping when there is a dripping tap or minor leak in the system. Please consult a professional or contact Grundfos’ customer support for a thorough diagnosis. We hope this information helps. We are happy to assist you in any way we can. Have a great day ahead!

  11. Hi.
    I have an off grid solar application and I would like to use the SCALA 2. I really like the Variable Speed soft start aspect and the efficient motor. In my application I would like to add my large irrigation system. I would likely require large volumes and pressure of water. I think I can make it work with double the capacity. Can I install TWO Scala 2 pumps and stage them for this application? The literature for the Scala 1 allows for staging for multiple pumps. Can the Scala2 be staged also? Or do I use a combination for the best of both?
    How would be the best to do this?

    • Good day! Thank you for showing your interest in the Grundfos SCALA2 98562818 water pressure booster pump. Yes, you can install two SCALA 2 pumps and stage them for your irrigation system. In staging, the pumps are connected in parallel, and a controller controls the flow and pressure output. You will need either the Grundfos MPC-C (compact, ideal for smaller applications) or MPC-E (expandable, ideal for larger applications) controller to set different parameters for each pump.

      To stage the pumps, determine your irrigation system’s total flow rate and pressure requirements to help you select the appropriate controller for your application. Then, install the first and second pumps and connect the inlet and outlet pipes, as well as the power supply and controller inputs. Next, set up the controller to manage both pumps at once. Lastly, monitor the performance of each pump and adjust the settings as needed to optimize their efficiency.

      However, yes, you may also consider combining a larger pump with a smaller one to provide better efficiency for different flow rate requirements and is cost-effective.

      We recommend contacting a qualified technician to ensure proper booster pump installation, configuration, and maintenance. We hope this helps. Thank you for trusting PlumbersStock. Happy shopping!


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