Grundfos Comfort PM and Grundfos Timer Kit: FAQ From a Small-Office Buyer

I'm the office administrator for a 45-person company. That means I'm the one who orders everything from printer cartridges to—apparently—water heater parts. Back in March 2024, after three mornings of people standing at the breakroom sink waiting for hot water, I started researching recirculation pumps. This FAQ is what I wish I'd had before I bought the Grundfos Comfort PM and the Grundfos timer kit.

Is the Grundfos Comfort PM worth the cost?

For us, yes—but I can only speak to a small office with a predictable hot water demand. I manage roughly $40,000 of purchases a year across about 12 vendors, so I look at this from a cost-per-complaint perspective. We paid about $220 for the pump and $85 for the timer kit at a local distributor (prices as of Q1 2025; verify current rates). The old pump—or rather, the pump the previous tenant left behind—was a builder-grade unit that ran constantly. It kept the water warm but wasted a lot of energy.

The Comfort PM runs much quieter, and it doesn't cycle on and off every few minutes like the old one did. The most frustrating part of the old system was the water temperature varied throughout the day. With the Comfort PM, we get an even temperature, and the best part is I don't have to think about it.

Do I need a separate Grundfos timer kit?

This depends on the configuration you buy. If the Comfort PM you order doesn't include a timer module, the Grundfos timer kit is a separate accessory that lets you program circulation windows. We bought it because our office is occupied from 7:30 a.m. to 6:00 p.m. on weekdays. There is never a reason to circulate hot water through the pipes all night.

Per FTC guidelines (ftc.gov), energy-saving claims must be substantiated. That's why I looked for actual energy data instead of generic marketing. The timer kit obviously cuts runtime, and it probably paid for itself within six months. But I did not do a rigorous before/after study, and your usage may be different.

What's the best way to install the Grundfos Comfort PM?

I'm not a plumber, so Eddie handled it. He's a facilities guy who has worked in our building for a decade. He put the Comfort PM in the return line near the water heater, with the arrow on the pump pointing toward the heater. Actually, the arrow shows flow direction, and the pump should be placed in the return line so it pushes water back to the water heater. Follow the arrow and install it where a check valve would normally go.

One thing I learned the hard way: verify the return line actually exists before buying the pump. Eddie had to cut into a wall because the previous tenant capped off part of the loop. That added a day to the job.

Is it safe to buy from an online outlet like Eddie Outlet?

I almost did. There's a supply outlet online—let's call it Eddie Outlet—that listed the Comfort PM about $80 less than our local distributor. But the delivery window was 5 to 9 business days and they did not guarantee a delivery date. The local distributor quoted a firm two-day arrival. Given that our VP was already asking about the hot water, I chose the extra $80 for certainty. To me, an uncertain $80 savings is not worth a week of cold-water complaints.

If you have more lead time, an outlet might be fine. But I've been burned by vague delivery promises before. This purchase was tied to a deadline, and the extra cost bought certainty, not just speed.

Does Henry's age matter when choosing a pump?

Probably less than the age of the building. Henry, age 62, has been in this building for 20 years and has seen two water heater replacements. He reminded me that the old recirculation line was sized for 1/2-inch pipe. The Comfort PM handled our current pipe size, but if your building is older or the layout has changed, get someone to check pipe sizes before ordering.

And if you have a tankless water heater, verify compatibility first. The Comfort PM may work, but check the manual and local code. That's something I didn't know until after we ordered.

What maintenance does a Grundfos Comfort PM need?

Not much. Eddie flushes the line once a year and checks the pump for air locks. Actually, the Comfort PM has a built-in non-return valve, not a serviceable filter, so the main maintenance is making sure the pump is free of debris after a water heater replacement. If you hear a hum but no flow, there is probably an air lock. Open the vent screw for a few seconds and water should run out.

We didn't have a formal process for warranty registration, and that was a small mistake. I should have registered the pump online the day it arrived. Grundfos has an official warranty, but you need proof of purchase with the model and serial numbers. We found the invoice eventually, but it took a while.

What if the hot water still takes too long to arrive?

Check the timer settings first. We had the timer kit set to start at 7:00 a.m., but the water wasn't warm until about 7:20. Eddie pointed out that the pump needs to push the cooled water back to the water heater before the fixture gets hot—it is not instant. We moved the start time to 6:45 a.m., and that solved it. If you still get cold water at one fixture, check whether that fixture is actually on the recirculation loop or if it's a separate branch line.

This worked for us because we have one water heater and one breakroom. If you're dealing with a larger building, a longer pipe run, or a second bathroom, the calculus might be different. In that case, you probably need a different Grundfos circulation pump—not just the Comfort PM. As of early 2025, the Comfort PM is still one of the best options for a small commercial space like ours.