The combination “1.6 gallons and 100 hours” is not enough to identify a PureGuardian humidifier. Current manufacturer information distinguishes the H997W, a 1.6-gallon cool-mist model advertised for up to 90 hours on low, from the H1250, a 1.5-gallon model advertised for up to 100 hours. Read the complete model code before comparing listings.
Those details matter because capacity and runtime describe different things. Capacity is how much water a tank holds. Runtime depends on how quickly the unit uses it under the conditions specified by the manufacturer. A smaller tank can have a longer maximum runtime when output differs.
Use the model label to resolve conflicting listings
Copy the code from the bottom label if you own the unit, or request it from the seller before buying. Match the code to the official product page and manual. Do not resolve a conflict simply by choosing whichever listing has the larger number.
A rounded capacity in a retailer heading can also make two listings look identical when they are not. Photos help you recognize a unit, but a similar blue tank or white housing is weaker evidence than the model code. If a listing combines specifications from different models, ask for clarification.
What the low-setting runtime tells you
A maximum-runtime figure is useful when you read its conditions alongside it. It does not tell you how long the machine will operate at the output needed in your room. Higher output, room conditions, and control settings can change the refill interval.
Use the first few refill cycles to learn the practical interval at your chosen setting. That observation is more helpful for planning daily use than dividing the headline figure into an assumed number of nights. Water maintenance remains a separate routine even if the tank could technically last longer.
Consider handling as well as capacity
A large tank is attractive when refilling is inconvenient, but you still need to lift, clean, and dry it. Check whether the filling method fits your sink and whether the machine can sit where you can handle the tank comfortably. A top-fill design may suit one arrangement; another user may prefer carrying a removable tank.
Allow room for the complete unit, not just the tank footprint. Think about cap access, the nozzle direction, and where a removed tank can rest without being knocked over. The practical shape can matter as much as the nominal volume.
What to put on a comparison sheet
Record the exact model, stated capacity, maximum runtime and its setting, fill method, and humidity-control features. Keep the evidence next to each item so you can spot a specification copied from another model. If a detail cannot be confirmed, leave it unresolved instead of turning it into a benefit.
The H997W and H1250 illustrate why numbers must travel with model names. Choose the appliance that fits your handling and control needs, then treat the runtime as a conditional specification rather than a promise for your particular room.