When the temperature control is stuck and will not turn, or the knob turns but the temperature does not change, the cause is almost always a thermostatic control valve cartridge fouled by calcium, iron or other particles in the water. A TCV that only gives cold water, only hot water, or stays stuck on lukewarm no matter where the handle sits is the same problem from a different angle. The first thing to check is your water: scale on other fixtures or well water means the cartridge and its intake screens have very likely clogged, and cleaning or replacing the cartridge restores normal mixing.

Likely Causes

• Mineral scale or sediment on the cartridge and intake screens, which stops the valve from mixing. How the thermostatic control valve works shows what the cartridge does and which faucet sets include one.
• A governor and limiter that went back on out of their original orientation after an earlier service, which can send hot water through with the handle in the cold position.
• No inline filter or mesh on the supply lines, so hard water reaches the cartridge unprotected. See protecting the TCV in hard water.

What to Check, in Order

1. Confirm your faucet set actually has a TCV. The dual-lever 5-piece fast-fill faucet is not thermostatic, so on that set a temperature problem is a supply or valve issue rather than a cartridge.
2. Shut off both supply valves to the tub.
3. Have a licensed and insured plumber remove the cartridge: loosen the allen bolt and lift off the handle, remove the cover plate, slide off the governor, remove the washers and escutcheon, unscrew the collar using only its flat wrench area, then unscrew the cartridge.
4. Clean the intake screens and the bottom of the cartridge, including the check valve, with a soft brush and a lime scale remover such as CLR, or fit a new cartridge. The full walkthrough is in TCV cartridge cleaning and replacement.
5. Lightly grease the gaskets with lithium grease, reassemble without over tightening, and test the full range of the handle with the water on.
6. Fit an inline filter or mesh on the supply lines if there is not one already, and clean it on the same monthly rhythm as your vinegar flush.

The video shows the disassembly above, the cleaning of the screens and check valve, and the reassembly with lightly greased gaskets and no over tightening.

When to Open a Ticket

The TCV carries a 1 year limited warranty, and cartridge fouling from calcium, iron or contaminated water is not covered, so a photo of the removed cartridge and its screens is the fastest way for the team to tell you what you need. Include your serial number, a photo of the faucet set on the deck, and a note on whether an inline filter is fitted. Cartridges and complete valves come through your Ella dealer or the team at ellasbubbles.com/support or (800) 480-6850; the warranty exceptions guide explains what the 1 year term covers.

Common Questions