I bought one of those "bulk propane to stove" adapters directly from Coleman a year or two ago. I think it cost about $20. It appears to be a straight hose (no bulky regulator-looking thing anywhere in sight). One end fits a standard 20lb propane tank. The other end looks like the top of a normal small Coleman propane cylinder like you'd buy in a sporting goods store. The original piece from the Coleman stove that normally screws onto the sporting goods store cylinder (for lack of a better word) instead screws onto this bulk adapter hose, which in turn screws into your big 20lb propane tank. That original piece has the round flow control valve built into it, so you control your stove's hi/low setting just the same as always.

Remember, a few years back they changed the fittings on those 20lb tanks. The Coleman bulk adapter hose I bought fits the new style 20lb fittings, not the old style.

I'd just call Coleman and tell them what you have and what you want to do with it. I'm sure they'll sell you the correct adapter (they did for me). If you're questioning whether you've got a good setup now, I'd say just spring the $20 and buy what you need from Coleman. $20 isn't terribly much to spend for the extra peace of mind to not have to worry about "Should I have a regulator on this thing or not?"

We also use a hose from Coleman that works with their propane stoves, and connects directly to a 20lb tank.

This is the current version: http://www.coleman.com/coleman/colemancom/detail.asp?product_id=5470A7931T&categoryid=27400

Ours is a little older, but, essentially the same. It works fine, a little tough to regulate output as you get to where the tank is almost out of gas, but, otherwise, it saves a lot of those little cylinders.

The hose I bought is for the new style tank/fittings. Still no word from Coleman...

I just had a look at the Coleman bulk adapter in a local sporting goods store.

It was in a clear plastic package, so I was able to have a good look at it. It's not just a tube; there's a mechanism inside it (probably a flashback preventer, I suppose?) and you can't see daylight through it. This inspires confidence.

The instructions on the back say, more or less, 1) attach bulk adapter to tank, 2) attach hose between adapter and appliance, 3) check for leaks ... not with a flame, ya loony. No mention of a regulator required.

Now here's the cool part: they sell a separate Coleman regulator that attaches *downstream* of the bulk adapter. According to the package, it maintains a constant flow at 15 psi.

(I assume that would be 15 psi over atmospheric pressure; every regulator I've seen has a diaphragm on one side that's open to the air on one side. If you put your finger over that opening, the flow increases and the appliance gets hotter, fast.)

I gather from this that the regulator is not necessary, but may be a convenience (if you're barbecueing a large haunch of beast and want a constant temperature, for example).