WIll electric pressure washer work with low water pressure?
You need at least the same flow rate out of the hose that the pressure washer uses. look at the GPM (Gallons per minute). With the hose on the roof, run the hose wide open for a minute or 2 so you will have the true flow rate. Then fill a bucket and time how long it takes divide by the size of the bucket if your unit uses 2.5 gallons per minute, a 1 gallon bucket would need to fill in 24 seconds, 12 seconds for a 5 GPM. You don't want to starve the pump or it will damage it. Many contractors use 5 GPM @ 5000 PSI and larger units. 1450 is probably 1.8-2.5 GPM from the units I have seen. If you have slightly higher than the flow the machine needs you should be good. There are also inline booster pumps with standard hose fittings that could be used at ground level to increase the pressure (Running on 120V) these can be expensive for a good one.