Grundfos CR vs CM: Which Multistage Pump Do You Need?

The short answer: choose a Grundfos CR when you need high pressure, and a CM when you need a compact pump for moderate pressure. CR is a vertical multistage pump rated to 362 to 435 psi with heads approaching 1,000 feet. CM is a horizontal multistage pump with a maximum operating pressure of 145 psi.

Both families are multistage, both come in cast iron and stainless steel, and both turn up in booster, water treatment and HVAC work, so the two get confused constantly. This guide compares them on the numbers that actually decide the job: flow, head, pressure rating, materials, footprint and cost. You can see the full range in the Grundfos pumps collection at ePumps.

What a Grundfos CR Pump Is

CR is the vertical multistage centrifugal range. Grundfos builds it as an in-line pump, which means the suction and discharge ports sit in the same horizontal plane, so the pump drops straight into a single run of pipe. The stages stack vertically, so adding pressure adds height rather than floor space.

That stacking is why CR covers such a wide pressure band. A CR3 with 19 stages produces far more head than a CR3 with 4 stages, on the same footprint and the same nominal flow.

• Range: CR1s through CR150, roughly 4.5 to 750 US gpm nominal flow
• Head: up to about 995 feet on the larger frames
• Max working pressure: 362 psi on CR1s through CR20, 435 psi on CR32 and up
• Materials: CR in cast iron and 304 stainless, CRI in all 304 stainless, CRN in 316 stainless, CRT in titanium
• Motors: two pole NEMA C-face, TEFC as standard and ODP on request

Typical work: boiler feed, condensate systems, reverse osmosis, industrial process water and high-rise pressure boosting. If staged pumps are new to you, our guide on single stage vs multi stage pumps covers the underlying idea, and you can browse the range in vertical multi-stage pumps.

What a Grundfos CM Pump Is

CM stands for Centrifugal Modular. It is a horizontal multistage pump, so the stages sit end to end along a horizontal shaft and the pump has a low, wide profile that fits under benches and inside packaged skids.

CM trades pressure for compactness. The whole range tops out at 145 psi, which is plenty for building water supply and washdown duty but nowhere near what a CR delivers.

• Range: CM1 through CM25, roughly 0 to 140 US gpm at 3480 rpm
• Head: up to about 400 feet on the smaller frames, closer to 180 feet on a CM25
• Max operating pressure: 145 psi, which is 10 bar, across the range
• Materials: CM-A cast iron, CM-I 304 stainless, CM-G 316 stainless impellers and chambers
• Self-priming versions: the O version lifts about 26 feet and the S version about 13 feet

Typical work: pressure boosting in commercial and domestic buildings, car wash and clean-in-place systems, cooling loops for chillers and server racks, tank filling and smaller RO skids. See the closed-coupled pressure pumps collection for the compact end of the lineup.

Side-by-Side Comparison

Not sure whether your duty point needs a CR or a CM?

Send us your flow, head and voltage and the ePumps team will confirm the model. Browse Grundfos pumps or vertical multi-stage pumps, or call (844) 378-6771.

The Deciding Factor: Pressure

Most CR versus CM decisions come down to one number. Work out the total head your system needs, convert it to psi by dividing feet of head by 2.31, and check it against 145 psi.

Under 145 psi with flow below about 140 gpm, CM is usually the cheaper and more compact answer. Above 145 psi, or anywhere near 200 gpm and up, CR is the only one of the two that will get there. There is no clever way around that ceiling: it is a pressure rating, not a curve.

Where the Two Ranges Overlap

CM10, CM15 and CM25 overlap CR10, CR15 and CR20 on flow, and this is exactly where buyers get stuck. The overlap is real on flow and not on head.

A CM15 and a CR15 can both move around 95 to 100 gpm. The CM15 gives you roughly 260 feet of head. A CR15 with enough stages gives you 800. If your duty point sits low on the curve, take the CM for the footprint and the price. If it sits high, only the CR reaches it.

Materials, Motors and Variable Speed

Both ranges follow the same material logic. Cast iron for clean cold water where cost matters, 304 stainless for potable and lightly treated water, 316 stainless where chlorides or chemistry are in play. Our comparison of cast iron vs stainless steel pumps covers where each one stops being the right call.

On motors, CR ships TEFC as standard with ODP on request, which our TEFC vs ODP motor guide explains. Both ranges also have a variable speed twin with the drive built onto the motor: CRE, CRIE and CRNE on the vertical side, CME on the horizontal side. If you are weighing that up, see our comparison of VFD pump systems vs fixed speed.

One practical note on power. At 60 Hz Grundfos offers CR in 1 x 115/208-230V, 3 x 208-230/460V and 3 x 575V, but many stocked CR and CM part numbers are three phase 230/460V only. Check the specific part number before you assume single phase is available.

Final Thoughts

CR and CM are not really competitors. They are two answers to different pressure problems. CR is the high-pressure workhorse: vertical, in-line, up to 435 psi and nearly 1,000 feet of head. CM is the compact one: horizontal, self-priming on some versions, capped at 145 psi.

Get your flow and head right first and the family picks itself. Once you know the family, our guide to Grundfos model numbers explains how to read the rest of the code so you order the exact pump. For application context, see what a booster pump is and what a boiler feed pump is.

Frequently Asked Questions

Is a Grundfos CM pump self-priming?

Some versions are. The CM type key includes an O code for a self-priming version with about 26 feet of maximum suction lift, and an S code for about 13 feet. The standard A version is not self-priming, and no CR pump is self-priming.

What is the maximum pressure of a Grundfos CM pump?

145 psi, which is 10 bar, across the CM range. If your system needs more than that you need a CR, which is rated to 362 psi on the smaller frames and 435 psi on CR32 and up.

Is a CR pump better than a CM pump?

Neither is better in general. CR handles far more pressure and flow. CM is more compact and less expensive for the same modest duty. Choose on your duty point, not on the range name.

Can I replace a CM with a CR?

Usually yes on performance, because CR covers everything CM does and more. The plumbing changes though. CR is a vertical in-line pump, so you will need headroom and a different pipe layout than a horizontal CM. Send us the model and we will confirm before you order.