What I'm guessing you're really doing is not a partial mash, but using grains as flavor adjuncts to an extract brew. That is, none of your grains are contributing fermentables to any large degree, but rather just flavor elements. I imagine you used something like crystal/caramel malt? That will contribute maltiness and an unfermentable sweetness. But it doesn't need to be mashed/sparged per se, so your approach is right on.
If your grain bill includes the likes of 2-row malt to contribute fermentables, then you really need to sparge it properly, which means making a mash tun. Then you might as well go all-grain entirely.
Why don't you post the recipe.
BTW, Downtown Brown is one of our local breweries. I love their IPA - Indica