It wasn't a pump problem
At 2:30 on a Thursday, a maintenance manager emailed with the subject line "EMERGENCY: Watts recirculating pump needed." He attached a photo. The photo showed a Watts 174A relief valve. That's like asking for a circular saw—cordless or corded—and being handed a drill. Both are tools. Both do a job. But they don't do each other's jobs.
I coordinate emergency replacement parts for plumbing supply, and calls like that are more common than you'd believe. Based on our internal data from 200+ rush orders in the last 12 months, roughly four out of ten were wrong not because the customer was careless, but because the part category was wrong. They asked for "a Watts valve" and they got "a Watts valve." The problem was the valve did the wrong thing.
Part numbers create a false sense of clarity
Part numbers are supposed to remove ambiguity. They don't when you don't know what family the part belongs to. A Watts 174A has "174A" stamped on it. That sounds specific. But if you're not sure whether 174A is a temperature-and-pressure relief valve or a recirculating pump, the stamping is just noise.
Here's the thing: the 174A is a T&P relief valve. It stays closed in normal operation. If the water heater gets too hot or pressure exceeds the rated set point, it opens and discharges water. It's a passive safety device. It does not move water. It does not have a motor. And it won't help a shower run hot faster.
A check valve is also not a pump
The same confusion shows up with a 3/4 in. brass push check valve. Push-to-connect check valves are common because they install quickly. But a check valve is a gate, not a motor. It lets water flow one way and stops it from going backward. If you install one where a circulation pump should be, the water won't circulate. It will simply sit there.
Why do people mix these up?
Because they all live in the same part of a piping system, and they're all made of brass. The appearance doesn't tell you the function. A molded brass body could be a coupling, a check valve, a relief valve, or a pump housing. This is where the "is a pcv valve a check valve" type of question comes from—people know the words, but the categories are blurry.
Is a PCV valve a check valve? No, but it's not a dumb question.
Let's answer that directly: no.
PCV stands for positive crankcase ventilation. A PCV valve is an automotive part. It sends blow-by gases from the engine crankcase back into the intake manifold. It does allow flow in only one direction, so it's not crazy to think of it as a check valve. But it is not a plumbing check valve. It's not rated for water, it's not made for constant full-flow liquid service, and it has no place in a Watts product family. If you're replacing a plumbing check valve, a PCV valve won't fit, won't be code-legal, and won't work.
If you actually meant "PVC valve"—as in a valve in a PVC pipe—that's still a material, not a function. PVC just means the body is plastic. It still needs to be a ball valve, check valve, gate valve, or something else. The material alone doesn't make it a check valve.
The real cost of category confusion
The price of a wrong valve is not the valve. It's the downtime, the freight, and the service trip. I watched a facility manager cancel a plumbing contractor's inspection because the "emergency recirculating pump" he ordered was a 174A relief valve. The inspection was the following morning. There was no time to make the same mistake twice.
In March 2024, a facilities manager called at 4 p.m. about a 60-unit apartment building. The inspection was at 8 a.m. the next day. He needed a "Watts recirculating pump." We talked through the symptoms: hot water was running backward through the return line and making a cold water riser warm. That is a check valve failure, not a pump failure. The pump was already working. We sent a 3/4 in. brass push check valve by courier, and the job was done by 9 p.m.
That story isn't about a brilliant save. It's about the cost of guessing. The first call said "pump," but the system said "check valve." If we'd simply shipped the pump, the inspection would have failed.
The deeper problem: we remember products by shape, not by function
The old saying "a check valve is a check valve" was useful when installers carried a handful of products and knew every job site. That era is gone. Today, a valve can include an integral check valve, a pressure sensor, or a bypass. A recirculating pump might also contain a check valve inside the same brass housing. Product families overlap on purpose.
The deeper problem is that we remember products by brand and by shape, not by operating principle. When you search by shape, a relief valve, a check valve, and a pump all look like "brass things with threads." When you search by function, they're completely different categories.
This is also an efficiency problem. The supply chain can get you almost anything overnight. But efficiency doesn't mean "skip the identification step." It means "identify correctly once." A 30-second photo and a quick spec check are more efficient than a two-day wrong-part loop.
I have mixed feelings about the "emergency" part of my job. On one hand, the rush fee pays for the capability. On the other, roughly 40% of those fees are avoidable. The fix isn't more automation—it's better information at the front end. That's the efficiency that actually matters.
If you search for "circular saw cordless," you expect a saw
If you search for "circular saw cordless," you expect a saw that happens to be cordless. You do not expect a drill. The same logic applies to valves. A Watts 174A relief valve is not a Watts recirculating pump. A 3/4 in. brass push check valve is not a substitute for either one. The names are close. The functions are not.
Before you buy any safety-related valve, pull the product page on watts.com. The published 174A listing includes a set pressure, connection size, and capacity rating. That's the fastest way to confirm what you're looking at—and to realize when you're looking at the wrong family.
The 30-second fix: read the mark and say what it does
I'm not going to give you a 10-step process. You'll ignore it, and I don't blame you. Instead, do these four things:
- Find the markings. The model number is usually on the body, a tag, or the stem. For a Watts 174A, the rating is stamped right on the valve. If the marking says "174A" and your application needs a pump, stop.
- Describe the failure, not the part. "It's leaking" could be a relief valve opening, a check valve stuck open, or a pump seal failure. Describe when it leaks: "only when the pump is off" or "only when the heater runs." That points to the correct category.
- Take one photo of the installation. A photo of the valve in context, plus a close-up of the markings, saves more time than any phone call.
- Check the Watts spec sheet. The published data for the 174A tells you the set pressure, connection size, and BTU/hr rating. If your system needs a pump, the spec sheet for a relief valve is irrelevant—but reading it prevents you from buying the wrong part again.
Watts has a strong reputation in valves, and that's exactly why the brand gets used as a catch-all. But a brand is not a function. A recirculating pump, a 174A relief valve, and a 3/4-inch brass push check valve can all live in the same mechanical room. They still do different jobs. The next time you're in a hurry, take the photo first. Your deadline—and your inspector—will thank you.