I can envision for you a small structure like you mentioned, with window boxes on the structure's sides. It could be very cottage-feeling, if that is your style. Like a gingerbread play house look. You may want to do an add-on (keep it separate) to house tools, so it will have some purpose. The main thing is to make sure the propane people have adequate access. You may want to ask them before you build anything about codes or access issues you need to address. The last thing you want to do is build something then have to tear it down. And, they won't care how much effort you put into something. They want EASY access. You will probably need some kind of 'chimney' or 'windows' (open, not glassed) in your structure, and several vents placed at the bottom. All propane tanks leak a little, eventually, and you don't want it to build up. It needs adequate ventilation. Talk to your propane company about that, also. (If they say their tanks don't leak, don't believe them!) Good luck with your project. I understand your need to disguise the tank as close to your patio as it is. But don't rush into it - I would hate for you to build something that doesn't have the adequate requirements that this may need.

Too late- we're committed! Hopefully, the house is sufficiently energy efficient that it won't be a big deal. Third gas company was a no show and the fourth was hilarious. He quoted $4,500 for the tank and when I told him he was at least $1,000 higher than his competitors he suddenly discovered a "typo" on his price list and reduced it to $3,100. I asked what brand of tank it was and I was told that it's "proprietary" to which I responded- Well if we're buying a tank, THEN do we get to find out? He very seriously told me at that point I'd be able to read the manufacturer off the side of the tank. These people crack me up. One more quote on Monday and I am putting this issue to bed. Someone today actually quoted $1.61/ gal which sounds pretty darn good to me! Thanks for all the feedback- keep it coming, please!

The info you provided isn't enough to size the propane tank. You also need to consider the scenario and what applainces will be running at the same time and for how long. The big drivers will be the heating system, freplace, generator and hot water. Find out the gallons per hour ratings for each of these and multiply by the number of days you need. Keep in mind that the propane tank is only filled to 80% of maximum capacity to allow for expansion, so a 500 gallong tank will only have 400 maximum gallons; 1000 gallon tank has 800 gallons. Also- you need to figure that when an outage occurs you probably won't have a full tank. I looked at the Kohler 15kW specs and it is rated for about 1.5 gallons per hour of propane usage at a 50% load (idle speed). A 2 week outage would use over 500 gallons assuming you ran the generator continuosly for that entire time. So that alone would put you in the 1000 gallon tank class. But I would really think hard about this 2 week requirement. If that is what you really want - then you probably would need a generator that is liquid cooled and not air cooled (air cooled are cheaper). The liquid cooled gensets may consume more fuel - check the specs. 2 weeks of continuous operation is a long time on a genset. I worked out the tank capacity with the propane service provider. They not only sized the tank, but they also provided a special valve to ensure that the pressure was regulated when the genset is running. The tank size won't change the gas pressure coming into the house since it the regulator keeps the right pressure. I would also look at the genset size. Since your hvac is gas, you don't need a lot of power to keep the house comfortable and rive all of you appliances and well pump. A smaller generator will use less fuel and will be cheaper to install. I have a 12kW Kohler unit and it is more than enough to run the house during an outage. We live in VA and have had some long outages - over 24 hours with no power with near zero degree temps is a long outage. The 12kW works like a champ. Also - make sure you get BOTH the carburetor AND batttery warmer heater accessories for your genset. These are a must in cold weather and will make sure the unit starts in very cold weather.

Presumably a T, a shut-off, and a quick-connect valve would do the trick. As maxdel says, I would have a contractor do this unless you know what you're doing with gasfitting, which if you're asking this question I suspect you do not. Check with your propane company--they may well do it for free since it means you'll be using more of their propane. It's certainly not a particularly involved job. I'm not a licensed plumber but I'd be more than comfortable doing this with water supply. Gas? Not so much.