Thanks to everyone for your responses!! We've included the info below for anyone who is interested. Kate and Jack Renewable Energy website run by a HP resident: http://www..renewnews.com/2007/10/30/im-in-hot-water/ <http://www.renewnews.com/2007/10/30/im-in-hot-water/> Fine Homebuilding: http://www.taunton.com/finehomebuilding/PDF/Free/021191068.pdf We have one, a Bosch Aqua Star although it's five years old now. It's great, our bills dropped, the water is always hot, and we gained basement floor space; we've never had one problem. Ours is gas, pilot light has only gone out once in five years. I owned a home several years ago for 20 years. It had a RUDD Instanteous Water Heater that was put in the house when it was built in 1904. I replaced the original copper coil once during my time in the house - the cost was less than $300 (labor and parts ~1990). What I liked about it was that the water stayed hot forever and forever. You could take a 4 hour shower and it would always be hot. What I didn't like about it (but not a big deal) was that it took 1-3 minutes for the cold water to pass through the heated copper coil. Once it got hot, it stayed hot. We sold some at my last job. They were commercial models that were for bathrooms that were far away from anything else. The customers seemed to be happy with the few that I sold. If you use water on a regular basis, or require large amounts of water at certain regular times, you may have to change your habits--maybe significantly--to use the tankless, or you may end up using more fuel, or be short on hot water. For example, if you use a lot of hot or warm water to wash dishes (even with a dishwasher you use preheated water) or bathe or cook, you may not get enough of it when you want it, or, if your heating component is sized large enough to handle your needs, you may end up using more fuel because it's being turned on numerous times throughout the day. Also, you may not be able to size it adequately or you may need more than one if you have more than one person using hot water simultaneously at different locations. That was the case with me--I have multiple people in the residence and in mornings and at nights, more than one bathroom is used simultaneously, and that occurs daily. I did some calcs, and for me, I wouldn't have saved much, if any fuel over the long haul w/o having forced people to space out their usage. I ended shopping for a high efficiency tank that was just large enough for my needs. I would go with a tankless in other situations though--fewer people in the house, or a house that gets used infrequently (i.e. a second home, or if someone's away a lot). Last thing to consider--generally, the total cost of installation (labor and materials combined) of a tankless system is notably more expensive than a reasonably sized tank that's in an area that's already been setup for tank usage. My brother has used one for about 10 years. They had to try several different models until they found one that consistently worked for them. Overall I would say they are pleased with it, but some of the cheaper models they tried first were pretty frustrating. Unfortunately, I don't recall anymore which models they didn't like. I live in Asia at the moment, but can give you a little information. These items are used all over Asia and in Europe. They work really well and save lots of money on wasted utilities. My old neighbor has one and loves it, her gas bills cut down by over 30%. Some of the big original houses in the neighborhood had them set up since forever. We have this and love it. We installed ours about 2 years ago after the 4th person into the shower in the morning got a cold one. The only adjustment we have had to make is that hot water takes about 30 seconds to start flowing so you have to run the water a bit. we got an estimate a couple of months ago for a tankless water heater. the thing that you need to know is that you need to have 3/4 inch pipes in order to have a tankless water heater. most homes only have 1/2 inch pipes, so you would have to replace all the pipes to have them be 3/4 inch. our estimate was $5k because of this expense (that was from mcnabb plumbing, who we've used for all our plumbing stuff). lowes wouldn't give us an estimate at all because of the pipe issue. so, the cost of replacing all your pipes if they're not 3/4 inch is definitely a consideration. given that, we're just going to get a regular one since that seemed like a WHOLE lot of money to spend on a water heater. I haven't owned one personally but know that on-demand systems have become more mainstream the last ~10 years, after being regarded as a somewhat older technology. Obviously it eliminates the need for a water heater and associated overhead, but they are typically more expensive to install. A friend in NY installed such a system ~20 years ago and they have the hottest, quickest water of anyone I know -- I assume this can be adjusted easily, but may be something to check out. My friend George installed one. He did have one issue with a sensor going bad and it took a week to come in. If you purchase, ask about spares that the plumber keeps and how long to get parts incase there is a problem. Otherwise he really likes it. He did have to install a liner for chimney because the exhaust isn't hot enough to cause correct ventilation. This is for gas. don't think electric heater needs one. Producers: Rinnai www.foreverhotwater.com <http://www.foreverhotwater.com/> Rinnai has customer service representatives available 24 hours a day, seven days a week. Customer service options are available by clicking here, or by calling (866) 746-6241 ((866) RINNAI1) * The Rinnai's minimum heating output is 15,000 BTU. Much better, it can handle up to about 90 degree input I figure. Once you get over 80 degrees the minimum flow per minute you need to run to keep it from turning off goes up, Bosch 800-503-5028 www.boschhotwater.com * It has a minimum heating energy output of 30,000 BTU. This means that the water going into the system needs to be no more than 70 degrees F or the system shuts itself off heating nothing. I'm in Florida, the ground water in the winter is 72 degrees. RUDD Instanteous Water Heater www.rheemtankless.com <http://www.rheemtankless.com/>