Plumbing Picks is reader-supported. As an Amazon Associate, we earn from qualifying purchases at no extra cost to you.
Quick answer from a licensed plumber: American Standard pressure-balance showers pair a pressure balance unit with a cartridge. American Standard lists the 051337-0070A cartridge with the 077171-0070A unit, the 023529-0070A (volume and temperature) with the 051091-0070A unit, and either the 023529-0070A or the A954440-0070A (temperature only) with the M952100 unit. Flash rough-in valves take their own cartridge, the M970654.
051091 or M952100 unit with a volume-and-temperature handle? American Standard pairs it with the 023529-0070A. See the American Standard 023529-0070A on Amazon
American Standard Shower Cartridges at a Glance
American Standard lists two parts for these pressure-balance shower valves, a pressure balance unit and a pressure balance cartridge, and pairs them like this:
| Pressure balance unit | Cartridge that goes with it | Control |
|---|---|---|
| 077171-0070A | 051337-0070A | Not stated by American Standard |
| 051091-0070A | 023529-0070A | Volume and temperature |
| M952100-0070AP | 023529-0070A | Volume and temperature |
| M952100-0070AP | A954440-0070A | Temperature only |
That pairing is American Standard’s own answer to “which pressure balancing unit do I have?” Match the unit first, then the cartridge.
Step 1: Look at the Face of the Pressure Balance Unit
American Standard’s side-by-side photo of the three units shows faces that are easy to tell apart:
- 077171-0070A: a flat, round face with four round holes spaced around a small center screw.
- 051091-0070A: a raised, three-lobed face with two round ports near the top and a large round opening in the center.
- M952100-0070A: a smaller-diameter unit with oval, teardrop-shaped ports above a large round center opening.
Compare yours against American Standard’s photo (linked under Sources) rather than this description alone.
Step 2: Volume Control or Temperature Only?
On the M952100 unit, American Standard lists two cartridges. The 023529-0070A handles volume and temperature; the A954440-0070A is temperature control only. Work the handle before you take it apart: if the water comes on at full flow and the handle only sets temperature, that is the temperature-only design. If the handle also sets how much water comes out, it is the volume-and-temperature design.
Flash Valves Installed Back to Back
American Standard says Flash valves are designed for back-to-back installations; its steps below are for a valve installed that way, not a general fix for hot and cold piped backward (for that, call a licensed plumber). The steps: remove the cartridge, remove the C clip, take off the back end of the cartridge and rotate it 180°, reconnect it, put the C clip back, rotate the whole cartridge 180° so “Up” faces down, and reinstall it.
I send an occasional note when a new guide goes up — repairs worth doing yourself, and the parts that actually last. No spam, no course funnel; written by a licensed Georgia plumber.
What to Buy
Genuine American Standard parts, each sold by Amazon when we checked.
- 077171 unit: American Standard 051337-0070A cartridge, sold by Amazon. Its listing calls it an Ultramix cartridge for American Standard Hampton bath and shower faucets.
- 051091 or M952100 unit, volume and temperature: American Standard 023529-0070A cartridge, sold by Amazon; its listing describes a 47 mm plastic and ceramic cartridge with seals.
- M952100 unit, temperature only: American Standard A954440-0070A pressure balance cartridge, sold by Amazon; its listing calls it a temperature control pressure balance valve cartridge.
Parts You’ll Also Need
American Standard sells the pressure balance unit separately from the cartridge.
- If the pressure balance unit is the problem: American Standard M952100-0070A pressure balancing unit, sold by Amazon. We did not find the 077171 or 051091 units from American Standard in stock on Amazon, only other brands’ copies, so those are not linked.
This page covers American Standard pressure-balance shower valves. It does not cover thermostatic valves or two-handle faucets; American Standard notes that its 994053-0070A two-handle cartridge can be installed on either the hot or the cold side.
When to Call a Licensed Plumber
- You cannot identify the valve or the unit does not match any of the three in American Standard’s photo.
- The shower has no stops and the main valve will not shut the water off.
- The valve body is damaged, or the unit will not come out of the valve.
FAQ
Which cartridge goes with the American Standard M952100 pressure balance unit?
American Standard lists two: the 023529-0070A for volume and temperature control, and the A954440-0070A for temperature control only.
How do I tell which American Standard pressure balancing unit I have?
American Standard shows the three units side by side: 077171-0070A, 051091-0070A and M952100-0070A. Compare the face of yours with that photo; each has a different port pattern.
What cartridge goes with the 077171-0070A unit?
American Standard pairs the 077171-0070A pressure balance unit with the 051337-0070A pressure balance cartridge.
What is the cartridge for an American Standard Flash shower valve?
American Standard lists the M970654 pressure balance cartridge for its Flash shower rough-in valve. It comes out with a removal ring placed between the cartridge rib and the retaining ring.
How do I set up an American Standard Flash valve installed back to back?
For back-to-back installations, American Standard says to remove the cartridge and its C clip, rotate the back end 180 degrees, reconnect it and replace the clip, then rotate the whole cartridge 180 degrees so Up faces down and reinstall it.
Why Trust Plumbing Picks
Plumbing Picks is written by a licensed Georgia journeyman plumber. Every part number, marking and fit on this page comes from the manufacturer pages listed below, which we opened and read; product details come from the Amazon listings, not from hands-on testing. Each linked part was shipped or sold by Amazon and could be added to the cart with no low-stock warning when we checked on September 24, 2026. Nobody pays to be included here. Where a link goes to Amazon we may earn a commission at no extra cost to you. More on who writes this and how we pick.
Sources
- American Standard: Is there a way to determine which pressure balancing unit I have?
- American Standard: How do I remove the cartridge on the Flash Shower Rough-In Valve?
- American Standard: Does the Flash Shower Rough-In Valve have back-to-back compatibility?
- American Standard: 994053-0070A two-handle cartridge (hot or cold)
Bottom Line
Identify the pressure balance unit from American Standard’s photo, then buy the cartridge it lists: 051337 for the 077171 unit, 023529 for the 051091 unit, and 023529 or A954440 for the M952100 unit depending on whether the handle controls volume. Flash valves are separate and use the M970654.