Tankless Hot Water Heaters?

[GasSavers_DaX]

Anyone using one? I hear they are wonderful!

[SVOboy]

My dad's got one, he loves it. I wish I had one too!

[Matt Timion]

I fully intend on getting one for the house when this one goes out. Right now I can't decide if I want the eletric kind or the gas kind.

During the summer it only costs $13 a month for natural gas. Since we have an electric oven/stove the only thing that uses natural gas is the water heater. now that the prices just went up 23% it is going to cost more like $16/month for hot water.

You can get a good tankless water heater online for around $350 I think. While the return on investment would take a few years it seems like a much more wise move IMHO.

Since our current one is working fine we can't justify just throwing it away. The next one, however, will be a tankless.

Besides, it takes up like zero space.

[bones33]

I hear they are great. I was considering one for the new house we are building, but decided to go solar. The tankless are cheaper in the short run, supposed to last a long time and very space efficient too. A really good replacement for a tank. I've been dying to do something solar, and hot water heating is a much faster payback that electric solar panels so that is what we're doing.

[Matt Timion]

Originally Posted by beatr911

I hear they are great. I was considering one for the new house we are building, but decided to go solar. The tankless are cheaper in the short run, supposed to last a long time and very space efficient too. A really good replacement for a tank. I've been dying to do something solar, and hot water heating is a much faster payback that electric solar panels so that is what we're doing.

How do the solar water heaters work? And the question everyone wants to know, how does it heat it during the night time?

[bones33]

Solar hot water is heated by a flat plate heat exchanger often mounted on the roof. The sun heats the exchanger which heats the water flowing through it by a small circulating pump. The heated water accumulates in a well insulated storage tank so you have hot water in the morning. There are lots of variations on how to set these systems up and with their sensors and pumps and controllers, are much more complicated than a tankless. In the end the sun does the hard work and the small circulator uses much less electricity than the 4500 watt heating element in electric units giving a net gain. These can also be used with tankless units where the tankless unit senses the incoming water temp from the storage tank and will fire up if needed to boost the delivery temperature if the storage tank gets cool. It's important to size the storage tank according to your needs so heating water at night isn't necessary.
Your question of heating at night is interesting, a guy I worked with had a house that had a solar heat pump. This works like a refrigerator working backwards where the house is the refrigerator, heating the house during cold temps. The solar part was on the roof as usual, so when at night there is no sun to heat the cold side, the thing barely worked! During the day when everyone was at work it was very efficient in heating mode though.

[SVOboy]

It just stays hot over the night, I had some soda in my car all night and its been in a heated building for 7 hours and is still cold.

[bones33]

A well insulated container will keep the water hot for several days, if it is not used of course.

[krmusher]

I've lived with some of this stuff: Re Tankless Htrs: the key is making sure it can supply the max flow rate you need. If yours can supply the flow rate for two showers, and you run two showers and the clothes washer- you're out of luck! The only downside I know of!
Solar: if there's any chance you live in a freezing climate DON"T use a drainback system (water as the heat transfer medium). The jury was in at least 10 years ago that sooner or later they freeze, crack, leak and do and are damaged. The preferred method uses propylene glycol as the heat transfer medium with heat exchanger(s) and a differential controller on the circulating pump. You need backup, tankless is good for that. No sun=no heat and you can't take out what you didn't put in, but can be great, there's alot of energy out there for the taking...

[GasSavers_Ryland]

my advice, don't go for the cheapest tankless water heater out there, spend a little extra money and get one that does both a better job, and will last many many years longer, I don't remember the brand off hand, but last summer I installed one, I think it was a Quite Side... in a house with solor hot water, they needed something to act as back up (3 people, to adults and a soon to be teenager, a washing machein, dish washer, and they didn't want to run out of hot water if they filled the hot tub...) they found with the solor hot water system, 120 gallon stainless steel storage tank, that they had to have 3 days of clouds, taking and normal water useage, befor the back up gas hot water heater kicked in, the really sweet thing about the instant water heater we installed was that it's flame could change size, insted of being just on, or off, so if you have "pre-heated" water that was say 80 degrees, a cheaper instant waterheater might be designed to boost the temp say 70 degrees, and might not do a good job monitering the outgoing hot water temp, giving you much hotter water then you need, or it gets confused, and cycles on and off, giving you burst of luke warm, and scalding hot water, that is also not good, but the variable flame water heaters turn the flame on just hot enought to heat the water as hot as you need it, saving you fuel, and your skin form burning.
useing a sealed system with propylene glycol in it, and a heat exchanger and storage tank is pretty much a standard now, some people still use a drain back system, and those people tend to make alot of money off repairing their old systems, keeping it a secret that there is another option.
personaly, I would over size my domestic hot water system by a bit, heat my domestic water first, then heat a room, or the whole house with any left over heat, that way you are more likely to alwas have enough hot water for showers and such, then in the summer, have it heat your domestic hot water, then waste heat gets dumped in your hot tub, pond, swimming pool, I still need to finish pluming it in, but my "hot tub" for dumping extrea summer heat in, is a 400 gallon stainless steal open top bulk milk tank, it should do a fine job of keeping the panals from over heating.