How to choose a proportioner

Start with output, not price. Rate a machine by pounds per minute at the pressure you actually spray, then match it to how many guns run at once. One gun on a large machine is fine; two guns on a small one starves both.

Check the electrical service before anything else. Primary heaters and hose heat draw hard, and an undersized supply shows up as ratio drift and soft foam rather than a tripped breaker. Then confirm your hose length is within the machine’s heated capacity — every added section costs you temperature at the gun.

Match the machine to your gun count, not just your crew size

A proportioner sized for a single gun will run out of heat and pressure fast the moment a second gun opens up, even if the crew is used to working in pairs. If you regularly run two guns — one on the interior, one outside — size the machine for that from the start rather than hoping it keeps up.

Heated hose length sets your real working radius

Every machine has a maximum heated hose length it can actually keep at temperature. Adding unheated extensions or running past that rated length doesn’t just lose you heat — it’s the single most common cause of a rig that sprays fine near the machine and drifts off-ratio at the far end of the hose. Plan your hose length around the largest job you expect to run, not the smallest.

Portability vs. output

Smaller, trailer- or skid-mounted units are easier to move and set up on tight residential jobs, but they trade off maximum output and heated hose length. Larger truck-mounted rigs carry more capacity and longer hose runs at the cost of needing more room to park and stage. Be honest about the jobs you actually run most of the time — a rig sized for the occasional large commercial job can be more machine than you need for a steady diet of attics and crawl spaces.

New, used, or reconditioned

A well-maintained used proportioner can be a good value, but hour meters and service records matter more than model year — ask for both. Heaters, hose, and transfer pumps are the components that see the hardest use and the ones worth inspecting most closely before you buy. If a machine has sat unused for a season or more, budget for a full service and flush before it goes back into daily rotation.

Whatever you land on, talk to whoever will be servicing the machine before you buy it. Parts availability and turnaround on repairs affect your uptime as much as the spec sheet does.