Firstly, 900 calories per hour is a nearly unattainable rate. I don't know if you were just throwing it out there, but if your machines say you're burning that many calories, then it's wrong beyond belief. It depends on what your goals are. If you're crosstraining and looking to change it up, it might behoove you to go harder for a shorter period of time. If we're comparing directly to running, I'd say yes - keep your HR around the same. Perhaps more important is your rate of perceived exertion (RPE). This is just how hard you're pushing yourself on a given movement (typically in %s). You're not a rower - you're a runner, I imagine. Because you're not as efficient and haven't spent as much time rowing, your muscles aren't trained for it in the right spots. Because of this, you waste a lot of energy on firing muscles that don't really need to be contracting/tight. That wastes ATP and oxygen. I'd focus on form and lower the RPE until I got the hang of it.
Also, rowing is never as comfortable as running. Your body can start firing autorhythmic cells to keep you going. Sometimes on really long runs, you forget you're even running. However, you don't really get the same thing with rowing. On top of that, you're utilizing many more muscles against a heavier load. You've gotta keep all these things in mind. Rowing and running aren't the same thing so eventually I'd row at the same RPE and try to better my times on each.