I have an Oster/Coleman Hot Water on Demand.  I can not get any pressure out of it.  I have tried both pulling from a container and hooking to a hose. Is this a general problem or just my unit?

I know nothing about the particular product you are asking about.

But in general ,  Tankless Hot Water Heaters have a complaint of low pressure.

I would love to install the energy efficient products in the new homes I build. But people are just not happy with the water pressure out of such devices.

The few times we have installed them, We've had to go back and add a traditional water heater.

I wouldn't expect a inexpensive  portable unit to have as much pressure as a $1000 built in unit.

I guess the real question is  "What is low pressure to you"   Does it just dribble out of the faucet? or does it come out of the shower with some pressure, but not enough to invigorate your skin?  What are you comparing it to when you say low pressure?

You state the one that doesn't have good flow, heats really well...that's because the flow of water is slow through the unit....which make me think there is an obstruction in a water line.

Maybe the hand held nozzle is clogged with calcium/mineral build-up?