O/T on-demand tankless hot water heaters

Does anyone have one of the "on-demand" tankless hot water heaters or knows anything about them? If so, I would like to know what you think about them.

All we use. Perfect for two people that work. No reason to keep water hot 24/7 for a morning shower. Little different here though, dishwashers and clothes washers heat their own water, so the on demand is just for washing the hands, head, and butt. Several different ways to go. Point of use and central.

Dave

I've always thought about getting one for the back bathroom. How do they handle hard water? Awfully pricey if it is gonna plug with scale in 6 months or so.

In many if not most installations, there is little to no net savings. The tankless cost more to buy, costs more to install, and doesn't use much less energy than a tank heater - unless you hardly ever use hot water or - with one exception.

If you have areas in the house that are distant from your main tank heater - installing tankless units at the points where the water is needed can save some energy.

A well insulated electric tank heater doesn't use much energy to keep itself warm - about 1/2 % to 1% of its heat, per hour. So, a well
insulated 40 gallon tank heater wastes about 5 gallons of hot water per day.

Tankless heaters aren't any more efficient at actually heating the water than tank heaters, and sometimes less efficient. The hookup to put a tankless in can be expensive.

For example -
Small 4.4 GPM tankless gas with a 70 degree rise - needs 3/4" gas lines.
Very small 2.5 GPM tankless electric with a 40 degree rise uses a two 40 amp breakers with a 240 volt circuit.

Keep in mind that standard tankless heaters are rated by "temp rise", not "temp." So, a heater rated 2.5 GPM with a 40 degree rise - can raise the existing water temp by 40 degrees when flowing 2.5 gallons per minute. If you have cold well water - at 45F degrees - that means you're going to get 85F degreee water at the 2.5 GPM flow.

Nancy,
I built a new house five years ago and installed a new tankless hot water heater. The system required an additional 100 amp service be added during construction. The system will work fine for washing hands and other limited demands of water. However, if you like to take a hot bath you will be in trouble. I live in South Carolina. The ground temp changes the water temp output. I put up with the continued changing the temp settings on the heater for three years. I changed the system to a conventional hot water heater and have never looked back. The best guess at the additional cost during construction (elec service) and the cost of the unit is over $2,000. I have a three year old unit in like new condition I would like to sale. (864) 933-5073

Life is too short to live with hard water
Water Boss is the way to go.

On a different tact, I'm hoping to install a outdoor wood furnace that will heat the house, the garage, the hot water and a shop if I ever build one. While I will still have to run the water for a minute to get hot water out of the faucet furthest from the tank, I will pay next to nothing to heat the water with free wood.

Like others have said, more expensive to buy, more expensive to install and only a marginal savings. According to the Building code around here you have to increase the size on the gas supply line and the exhaust duct. Have you looked at a solar, it worked for us. That means we saved money and have enough hot water.

When I was in Germany back in my army days my friend Cyrus and his wife lived in a house (?) in Gelnhausen. One of the walls was the old city fort wall. Parts of it were hundreds of years old. They paid their rent with meat and rum they bought at the PX, and occasionaly traded cars and used their ration cupons to gas up the landlords Simca. They had one electric water heater that they moved back and forth between the kitchen sink and the bathtub. That was back when a dollar was worth just less than 4 DM. The good old days.

Nancy,
Tomorrow we are 1 month into a Stiebel Tankless water heater. (German Mfg. w/parts/service available out of two locations in US)I changed from Indirect tank on oil burner so I don't have data comparing to electric tank types but the following is what I have found so far.
Plenty of hot water for my wife and I. It is whole house system.Low GPM shower heads. incomming water temp.55F...water temp set @45C ~110F In short...plenty of hot water!
Now on the cost side...Water heater delivered $578.00 The size unit we purchased requires a 200A service (Two 60 Amp breakers)...Breakers and plumbing fittings to install cost approx $85.00
Now the power costs...April to October used .5 Gal. heating oil/day...boiler set to only turn on when call for hot water (low temp limit off)(HHO $2.50-3.40/gal)
Have Watt/Hr. meter on water heater circuit..Avg. 2.6 Kwh/ day so far. We pay $.16/ Kwh here in SE PA
I am sure costs would vary for others but based on current data I will keep the 60A breakers turned on!
Hope this data helps,
Andy

I have a big natural gas tankless. It will run two showers full bore. It is considerablly more efficient than a tank type gas heater. Electrical tankless are not practical because of the current requirements and are no more efficient than a tank type electric. If you have natural gas you do have to have a 1" line. LP gas only takes a 3/4 line. One of the problems I had, because my heater is located a long ways from my master bath. It took a long time to get the hot water to the shower. I solved the problem with a hot water circulating pump. It cost over $3oo but I am very pleased with the system. Gas bill is $10 or $11 dollars a month and I have all of the hot water I can use. Tried a couple of different pumps before I found one that would work on a tankless heater.

We looked long & hard at these and decided against getting one. As others have said, changing ground water temp means having to tweak the thermostat at least 2x per year if you"re in a winter zone (we are). Our gas line was big enough so that wasn"t a factor for us, but could be for you. Also, each unit has a different turn-on gal/min rate. A unit sized for shower + washer may not turn on if you just need a dribble of hot water from the kitchen sink. Also, our house is super-tight, and every unit we looked at required a continually-open fresh-air line (which would also let cold air in between uses - a consideration for a family of two who oft aren"t home much). Even those with a fan for combustion air still were open to the outside. Someone else here asked about hard water - these heaters hate it. We were told the heaters have to be/should be disassembled and soaked every year or so even if used with softened water. Lastly, although this wouldn"t have been a factor for us, some writers have also noted that "all the hot water you want" too often turns into wasteful super-long showers and tub-brimming baths, chewing up the $s you"re trying to save.

We ended up with a 40-gal conventional electric. Plan to super-insulate it and will likely add an on-demand circulator pump to more quickly bring hot water to each fixture. Since we installed this heater, we"ve also found ultra-high-efficiency gas heaters similar to the furnace we had installed, and may move to one of those whenever this unit gives up the ghost. Reason for considering the change is that we occasionally run out of hot water if we try to do 2 large loads of laundry immediately followed by a shower; a gas unit will recover a lot faster than electric.

Both the Journal of Light Construction and Fine Homebuilding have had articles about heater selection and articles specifically about tankless. Both are worth the money to get reprints of those articles (I think at least JLC lets you pay/print copies right online).

HTH

I kind of don't know who to believe but the company that I work for owns close to 200 restaurants and we are replacing all the old junk tank heaters as they go bad. I do not know what brand but I do know we have installed 3 of the tankless water heaters in the last month. We have to use a specific brand that BK Corp approved but according to our facilities guy it saves the restaurants about 15% of what they now spend on heating water.

I have a Aqua Star Tankless heater. I think Bosh bought out Aquastar now. I have had it for over ten years and still love it. Unlimited supply of hot water especially for my teenage children. It runs me $10-20/month for a active family of 5. I am on a well with very hard water and have not noticed any effect on the Water heater.

Our problem is we run out of hot water especially in the winter. The house is all electric, no gas.

I think the main problem is the hw heater is only a 30 gal unit.

Opinions on the tankless seem to vary. A friend of mine in the plumbing business didn"t recommend it. Some of ya"ll like it, some don"t.

I think when the current unit goes out, we"ll just replace it with a 50 gal. unit. That should solve the problems.

Not sure about your area, but our building code requires a second, separate water heater if to be heated by outdoor furnace. I think it has something to do with the anti-freeze/anti-corrosion fluids used in water jacket. Might be something to investigate?
Jay

Hi Nancy,
In the past few years I've had little to no experience with them. However, when I was living in England the house I was renting had one and it worked great. No problems or gripes from me. The house also had the radiantor type heaters in all the rooms. This said, I had a friend that was trying to decide which to use when he had to replace his water heater. Like I told him "it will cost you a lot more to change over/install the tankless water heater, but it will cost you a lot less to operate it once it's installed." I think if you give it a few years that there will be more of a choice for them here in the US and it will cost a lot less for a set up to have installed. Just my opinion for whatever it's worth.

Good luck with whatever choice you make. Now am not surprised you've run out of water since you have only a 30 gal heater. Forgot to mention in prev post that there's at least one "lifetime" elec tank heater now available, with a plastic tank and (as I remember it) also very well insulated. Pricey, yes.