Pros? Cons?

I have a 75gal. conventional water heater in the garage and am considering going with a central tankless system.

George

From what I have heard the best ones are gas or propane. Electricity can't heat it quickly enough. I had one in NJ that was oil fired (off the central heat) and it worked very well.
Peter.

I don't have one in my house but i have used them in many houses that i have built. The good news is they will not run out of hot water. The bad news is that they only put out 7 gal per min. Add up the gal per min of a few items in your house and you will see the problem.
Most households will use more than 7 gal per min. If you add 2 of them together it will work much better, but the cost of two of them is way more than you will spend on heating water all the time.
I have even used 1 unit and a 30 gal HW heater as a storage tank. That worked good and much less money than 2 units.

FYI The gas one will work better than electric.

quote:

Originally posted by Chris Lozano:
I don't have one in my house but i have used them in many houses that i have built. The good news is they will not run out of hot water. The bad news is that they only put out 7 gal per min. Add up the gal per min of a few items in your house and you will see the problem.
Most households will use more than 7 gal per min. If you add 2 of them together it will work much better, but the cost of two of them is way more than you will spend on heating water all the time.
I have even used 1 unit and a 30 gal HW heater as a storage tank. That worked good and much less money than 2 units.

FYI The gas one will work better than electric.

I agree with what is posted, somewhat. I have a 50 gallon high-efficiency gas water heater and have never lacked for hot water-ever. My wife and I have 9 daughters and, guess what?, we taught them how precious water is. Our shower is not a spa, not a free lunch and not to be abused. Likewise, we do not have door stops on any of our doors. No holes in walls, either. A door is not made to be slammed. The knob should have a hand on it and in control of it in either direction. Just a matter of training and not too difficult.
Many houses could save money and conserve water by installing a recirculating hot water leg. This is a valve requiring no electricity and keeps the hot water at even the most remote fixture accessible within seconds. Made by the Nibco Company, the same company that makes all the copper fittings we all love.
Something to think about.

Stephen

If you are worried about enough, use a tankless for everything but the kitchen , and there put an on demand 5-7 gal hw heater, solves problem, but AM NOT convinced that a tankless will let you run out of hw unless you have the washing machine, dishwasher, 3 people showering and 2 cars being washed at the same time.

What do they use in Africa. Most of the farms and camps I was in and even homes in town had some type of flash heater. If they didn't use the old wood fire type flash heaters they seemed to be adequate. I know my PH friends home in town had one for each shower and I suppose one for the Kitchen. I have the small instant one in my kitchen sink that seems common. I asked the plumber about the large system he sells and he didn't reccomend them at all. Here in So Az solar is the name of the game for hot water and pool heaters. I would say from looking at the roofs in nearby new subdivisions about one in 5 have solar units on the roof. My son had a small unit for about 10 years till it developed too many leaks to repair. He was totally pleased with it and it was only about 6'x8'. And he liked to take a shower till he ran out of water. I like the idea of a flash heater but we only have electricity in my area. My home was built when they had a moratorium on natural gas hook ups.

Thank you all for your replies.

My current gas-fired water heater works fine, however, it puts out a lot of heat. The garage already gets hot due to the strong sun here is Las Vegas.

While I will enjoy the warmth the water heater puts out come January during reloading sessions, I was looking for an alternative.

Maybe I'll just wrap the water heater in a insulativ blanket.

George

My house was built with two of them, Rinnai's, from the get go. We like them a lot. We are on propane and they do suck gas when in use so I caution you to confirm your gas line size if you consider the retrofit. You will likely need a larger line to the WH. Just last winter when it dropped in temp to the high 20's (cold for SA, Texas) we had a problem getting hot water in our shower. The digital controller showed a "restricted gas supply" error code. Went outside and found the main gas valve just slightly closed. Opened it up and the problem went away.

The efficiency or cost of the system depends on the temperature of the incoming water !! In NY state with well water it's not a good idea but in FL or TX where the incoming water may be as high as 70 F it's a reasonable system !

George:
I'm a little late with this, but......
I'm in Alaska. Fuel is expensive here. I've had a tankless water heater in my house for 25-30 years. I did a lot of ciphering before I bought the first one. I figured I could pay for it in 3-4 years. They are more expensive to buy than regular water heaters.
Mine is natural gas. I didn't have to change any of the incoming gas lines. The old ones worked fine.
Here is the problem. They are not "install and forget" like regular heaters. You have to screw with the controls after installation to get the settings correct.Most folks are not willing to do this.
I use Bosch AQ 125 BNG. They vary the flame with the incoming flow of water. IE, flow decreases, flame decreases, vice-versa.
If you have a water flow and fuel source, you will not run out of hot water. They have saved me a lot of money over the years.
If you are willing to screw with the original setup, they are great.
Don't ask most plumbers about them. They hate them. They don't understand them.
Home Depot sometimes have the Bosch.
Good Luck.

A bit late too
BUT FWIW
I have a remote cabin with no services, everything is solarcharged batteries or LPG.
I installed an instant LPG hot water system in the shower a couple of years ago.
- approx 7gph nominal capacity
- fed by a 12v marine/caravan constant pressure pump from rainwater tank.
- more than adequate hotwater supply, my problem is rainwater storage capacity not hot water system capacity.
- the system has both water flow control & temp control, both are at low settings for more than adequate shower performance...........

If I correctly recall, National Fire Codes will not allow you to vent anything directly into the attic space!

What if flames went directly into your attic space?! I know firemen that have smoke detectors in their attics too!

Not sure about plumbing codes but I think you are supposed to have triple wall pipe. At least that's what I would use.

I've owned three tankless water heaters. The only reason to own a tankless, right now, is for space savings.

MHO, wait for technology to catch up on these water heaters before making the investment. I have had one (bosch) fail after one year, actually it failed twice. first time Menards took it back the second time it LEAKED and Bosch told me to get screwed. Never again.

Right now I own a richmond, it's better than the bosch as far as reliability and how well it produces hot water. I hold my breath a little every time I think about it though.

I have seen MANY commercial brands fail within one year. By fail I mean LEAK. Tokagi (I think) is one name brand, but I have seen others fail as well.

Are there operational savings? Probably. Weigh the energy savings against the initial investment, the probability that it will fail and the cost to hire a service tech to come out and fix it @ $100.00/hr. Like I said, if you have plenty of room to house a large tank style water heater and it delivers plenty of hot water, don't mess up a good thing.

I've never had an issue of a tankless running out of hot water when they work right. You would have to be running a LOT of hot water. I fill a jacuzzi and run the dishwasher at the same time and no problems. The idea of a tankless water heater is a sound one, it's just that the science hasn't caught up to the idea yet.

Just my .02 but I am in the Propane business. I love them. They will use, in comparison to a standard 50 gallon water heater, 4 times the amount of fuel to produce the hot water. Most tankless are in the neighborhood of 150,000 to 180,000 BTU's. A standard 40 gallon propane hot water is a 30,000 BTU unit, the 50 gallon is a 40,000 BTU unit. Albeit, the tankless doesn't come on until the unit calls for hot water but the technology with regular water heaters has improved and the amount of gas it takes to keep water warm is very minimal. If someone in your household likes very long showers or like mentioned before about the water temperature starts off colder like it does here in the CO mountains, they will impact the cost of use.

Thanks, all.

I will defer installing one of these until technology warrants it.

George