Tankless water heaters

Hey all , I have a 40 gallon water heater about to give up Im afraid its 12 years old, Ive cleaned it out replaced elements - needs gone - anyway any tankless hot water heaters users on here ? Hard to beleive they keep up on a shower but they do Im sure- how do they rate them ? Number of People in the house ? TIA  

Depends. I built mine and it works well, but it's modeled off of my Landa pressure washer and not to maximize profit for a manufacturer. Coiled copper tubing inside a stainless steel burner chamber fired by fuel oil when needed does a good job. Only electrics are a water flow switch and temperature limit. Both must be satisfied before the burner kicks on which is from an old oil furnace. You do waste about three gallons of water before/as it heats up, and I cut the burner off at a discharge temperature of 130 degrees which you modulate for comfort at the point of use, (shower). The three gallons of waste water is stored in the accumulator tank and is not kept heated. The cold water is purged with hot incoming water. This accumulator prevents hot and cold surges of the burner modulating to maintain water temperature in the burner chamber. 

If you are going to install a tankless water heater you need to install a large good quality unit . Bigger the better. Don't want to install and find out it won't keep up .200,000 btu or Bigger. Navien is the brand I have had the best experiences with. They have a 1 gallon bottle inside that stays hot .Don't have to wait as long for hot water to be created. Also has a built-in recirculating pump that can be connected to a return line. Also has AI where it learns your patterns and only recirculates when needed. Most units have a delay before it makes hot water and sends it on it's way. Also cheap units won't kick on until a certain flow is established. I have a customer who bought one online. When she showers in summer the flow is to slow to turn on .She has to have sink faucet hot water running in order to keep water flow up to where it works.
The only redeeming quality to most of these units it endless hot water. Do you really need endless hot water? If there was a young couple building a house and planning on having a bunch of children, this about the only scenario where I would suggest installing. As Jay stated mineral build-up needs dealt with yearly. Vinegar or citric acid needs pumped through to remove mineral build-up from all the sensors, switches , pumps and heat exchanger. Any savings from not keeping a tank heated is wasted. Also upfront costs are 2 to 3 times a conventional tank install. Modern tanks are insulated much better and after heating unit up you are basically only paying for what you use.

I don’t and won’t have one! In Omaha the one carpentry client I had that had the tankless water heater had trouble finding a plumber that would do the yearly maintenance. Once he found one it was very costly!

Doug, in 2009 we built a new shed for our honey business. I went to Menard's and bought a small one, but not the smallest one they had. It was electric. It worked till last fall. I had a professional electrician wire it. He told me a lot of these don't work right because they are wired wrong or wired too light. When that one quit, I bought one three times the size of the old one. It puts out enough hot water I can run a power washer full blast and never run out of hot water. When mine goes bad here in the house, I will replace it with the largest electric one I can get my hands on.

Edited by 200Tom1 - 18 Dec 2022 at 11:39pm

On softened water, just remember to remove the Cathode in the new heater otherwise will stink.