WAYNE PC2 Portable Transfer Water Pump with Suction Hose & Attachments - Heavy Duty Utility Pump for Drainage, Irrigation, Flood Control & RV Use - Black

For the price, it is hard to beat this little pump. Like a couple of other purchasers, I used it to flush a Rinnai tankless water heater for 45 minutes per the manufacturer's directions. The pump ran flawlessly and was hardly warm at all. Here are some observations for those who will use it for similar purposes:1. The Wayne pump is suppose to be self-priming but the instructions say to prime it with a tablespoon of vegetable oil. I primed the input hose with the water heater company's specified flushing fluid (vinegar) and it started pumping right away.2. The illustration shows a transparent hose, but I received a 6-foot yellow garden type hose of high quality with brass connectors. It would have been nice to see the liquid flowing through the hose, but this was minor as I could verify the pumping action at the outlet end of the hoses.3. The pump comes with a replacement impeller, hose gasket, motor brushes/springs, etc. Nice touch.4. Mount the lightweight pump on a wood base to give it more stability. Otherwise, it will flop around every time your hoses are moved.5. Note that the pump inlet and outlet are male fittings. This means that to connect to the tankless water heater (or perhaps to another hose), you will need a female-to-female adapter. I made one out of a piece of 10' scrap garden hose with the original female fitting at one end and I installed a replacement female fitting (sold at Home Depot for repairing hoses) at the other. One end was installed at the pump, the other at the water heater. (Short lengths of hose with female connectors at both ends are available as hookup hoses for clothes washers. New ones sometimes appear in thrift stores for as low as $1.00.)6. Wear hearing protection when operating this pump indoors. While not ear piercing, it is noisy if operated inside a room.7. When you finish flushing the waterless tank with vinegar and then with water, don't forget to flush the pump itself with water as well as the hoses and fittings. The vinegar is dilute acetic acid and it will eventually eat away at the brass plumbing fittings if not well flushed with water.8. Finally, I noticed that there is a Hydropoint 1/10 hp utility pump similar to this Wayne pump sold by Amazon. It too is suppose to be self-priming, but I bought the Wayne pump because it had 10 times the number of feedback ratings and most of them were very favorable. While the Hydropoint may be just as good (it looks somewhat similar), I was not disappointed with the Wayne pump as it paid for itself the first time I used it.Update September 14, 2012: I again used this pump to flush the tankless water heater for 45 minutes. I did not prime it with vegetable oil or anything else to see if the pump is truly "primeless" as claimed and it sucked up the vinegar and pushed it through the water heater heat exchanger without a problem. I later flushed the pump with clear water from a 5 gallon bucket. It emptied the bucket in under 1 minute, living up to its claim of being able to pump about 340 gallons per hour. It's a neat little pump, already has paid for itself!Update October 5, 2016: This pump continues to operate flawlessly to flush the Rinnai tankless heater.