How the 3-way diverter works
A standard showerhead uses the full supply line pressure for one nozzle head. A 3-way diverter routes the single supply line to a valve that has three output positions: head A only, head B only, or both simultaneously. In simultaneous mode, the available flow is split between the two heads -- each receives roughly half the supply pressure and flow rate. At 60 PSI supply, each head operates at approximately 30-35 PSI in simultaneous mode, which is adequate for a useful shower experience but not full-pressure performance. The Aquadance HHC2's 3-way diverter is a rotary valve in the connection fitting -- it requires no extra supply lines or valve changes at the wall.
When to use simultaneous vs switched mode
Use simultaneous mode when: overhead heat coverage is needed while using the handheld for directed rinsing (e.g., washing a child, rinsing shampoo while keeping the body warm). Use switched mode (overhead or handheld, not both) when: full spray pressure is needed for a standard shower experience. Most daily showers use switched mode exclusively -- the overhead provides full-pressure performance, and the handheld is switched to for rinsing before the shower ends.
Aquadance vs Moen/Delta at the combo tier
Moen Magnetix combo units ($95-$130) and Delta In2ition ($90-$135) provide substantially better finish durability, smoother diverter operation, and longer mechanical lifespan than the Aquadance HHC2 ($30-$45). The Aquadance is appropriate for 3-5 year use in rental properties or secondary baths; the Moen/Delta units are built for 10+ year daily use in owner-occupied primary baths. If the total ownership cost over 10 years is the calculation, Moen or Delta is cheaper than replacing Aquadance units every 3-5 years.
Maintenance to extend Aquadance diverter life
The rotary diverter valve on the HHC2 develops stiffness or partial leakage in hard water areas as mineral scale accumulates on the valve ball. Extend diverter life by: (1) monthly spraying of the diverter area with a white vinegar solution, (2) operating all three diverter positions periodically to keep the valve ball moving freely, and (3) replacing the diverter if stiffness causes incomplete flow shutoff to one head (a replacement HHC2 at $30-$45 is the practical repair).