Grundfos STR2 Twin Impeller Shower Pump Reviews Missed This: A Ski Lodge Field Story

The Call That Started It: Trevor's Ski Lodge

It was the first week of December 2023 when Trevor called. Trevor runs a ten-room lodge near a ski racing club. If you've never lived in a mountain town, you might hear the question: what is ski racing? The short answer is that skiers do timed runs down a course marked with gates. The longer answer, in Trevor's case, is that a lodge full of racers and parents all want hot showers at the same time, and his showers were only putting out a weak trickle.

The lodge already had a Grundfos CRT vertical multistage pump on the main incoming water line. That pump is built for pressure boosting, and it was doing its job. The weak link was on the hot-water side, where an old twin-impeller shower pump had been limping along since before Trevor bought the place.

I've been handling pump replacement orders for eleven years. I've personally made, and documented, thirteen significant mistakes, totaling roughly $18,000 in wasted budget. So when Trevor sent me a link and said why not this one, I did what I always do. I started reading.

Reading Grundfos STR2 Twin Impeller Shower Pump Reviews

The link was to a Grundfos STR2 twin impeller shower pump. The online quote for the pump alone was $319. Trevor had already pulled up a few Grundfos STR2 twin impeller shower pump reviews online. Most were glowing. A couple said the pump made noise at low flow. One review mentioned that a clogged inlet strainer caused the pump to cycle on and off. Nothing there suggested a disaster.

To be fair, the reviews weren't lying. The STR2 is a solid pump. But reviews tell you how a product worked in someone else's system, not whether it will work in yours. None of the reviews I saw mentioned the fine print.

I clicked through the online checkout to see the full cost. The pump was $319. Shipping was $58. The pressure switch, which the instructions require, was another $64. Two isolation valves were $78. Flexible connectors were $45. The online grand total was $564. The cart header still called it a $319 pump.

I asked the online vendor's chat what else was missing. The reply listed a pressure switch kit and installation isolation valves as optional. That phrase is what gets my checklist fired up: optional. For a twin-impeller shower pump, they weren't optional. They were required if you wanted the pump to last more than a season.

Then I called Chauvin, the senior rep at the local Grundfos distributor. Chauvin sent a one-page quote: $598 all-in, including the STR2, pressure switch, isolation valves, flexible connectors, and shipping. No line item named miscellaneous. No call for final price. Just a number that was close to the online total and a promise that it wouldn't change.

I get why Trevor wanted the lower number. Budgets are real. But the vendor who lists all fees upfront, even when the total looks higher, usually costs less in the end. The $319 pump became $564 before taxes. The $598 quote stayed $598. That's transparency, and transparency builds trust on a job site.

Installation, a Coffee-Grinder Noise, and the Real Problem

We installed the STR2 on a Thursday. Mounting, wiring, purging air, adjusting the pressure switch, all standard. The pump started up and ran quietly. I signed off, packed my tools, and drove home satisfied. The next morning Trevor called. It sounds like a coffee grinder.

Not ideal.

The noise only happened under low flow: a sink tap opened while a shower was running. My first instinct was to blame the pump. But the manual, which lives behind a QR code on the box, stated that the STR2 needs a minimum inlet pressure to feed both impellers. The Grundfos CRT on the main line was set to a lower pressure than the pump required. Someone had turned it down a long time ago, probably to protect the old hot-water tank and the aging copper pipes. I'm not 100% sure why, but the result was a pump that was starving itself.

(Note to self: check inlet pressure before you hear the word defective.)

We adjusted the CRT's setpoint within its rated range and added a small expansion tank to control pressure spikes. The noise disappeared. There's something satisfying about a shower pump that runs quietly after a morning of second-guessing yourself. It's like the system finally exhales.

The Invoice and The Checklist

The local distributor's invoice was $598. The online route would have been $564 plus the pressure valve tweak, an expansion tank, and my second trip. The extra trip alone was $220. Add the tank and fittings, and the cheaper path was over $890. It also cost Trevor a day of bad guest reviews during ski racing season.

In Q1 2024, after a third surprise line item in one month, I formalized the checklist we now use for every shower pump job. It's not complicated. It just goes:

• Ask the vendor for a quote with all line items, including valves, switches, connectors, and shipping.
• Ask what's NOT included before asking for a discount.
• Read the technical data sheet, not just product reviews.
• Check the existing booster pump's setpoint against the new pump's minimum inlet pressure.

This worked for us, but our situation was a ten-room lodge with a Grundfos CRT already in place and a plumber willing to call a rep named Chauvin. If you're in a single-family house with a different pressure-boosting setup, the calculus might be different.

According to the Grundfos technical documentation for both the STR2 and CRT lines (grundfos.com, accessed January 2025), minimum inlet pressure and pump setpoints are application-specific. The same model can run perfectly in one building and hum in another if those numbers are ignored. Prices as of January 2025; verify current rates.

Look, I'm not saying reviews are worthless. I still read Grundfos STR2 twin impeller shower pump reviews before I recommend a pump. But reviews are not the spec sheet. The spec sheet is the authority. And the vendor who is willing to give you a real, itemized quote is the one who's not hiding the stuff that makes the job go sideways.

We've caught 47 potential errors with this checklist in the past 18 months. That number isn't a flex. It's proof that the expensive mistakes happen in the details, not in the pump itself. Trevor still calls the STR2 the coffee grinder when he's in a good mood. But the hot water holds steady, and the checklist lives in the mechanical closet next to the paper manuals. A lesson learned the hard way: what you don't know about the pump is what costs you. In this case, the pump was the cheapest part of the repair.