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Tankless Water heaters

Scott_Randall's picture

Dose anyone have any info. on tankless hot water heater?

(post #172965, reply #3 of 10)

I lived in Europe and the Middle East for 4 years and used tankless water heaters in Eindhoven, Holland and Portugal. They worked excellent. Plenty of volume and pressure of hot water for shower and other uses. Believe me, I consider a hot shower with plenty of volume a luxury and a requirement. Wish I could help you with a brand name but didn't pay that much attention to it. Maybe you can make a connection in one of those countries to help you out. I also remember the unit in Portugal not working correctly at first. A repairman came and replaced a diaphragm and adjusted the unit to work efficiently. Good luck.

(post #172965, reply #4 of 10)

Scot, I too used a gas fired tankless water heater (sometimes called demand water heaters) for about 12 years and thought it worked fine. My husband would have liked a stronger shower though, but then he doesn't like the water-saver types. Jade Mt carries a bunch (Aquastar, Paloma) and there is a 'new' one out there, reveiwed by Environmental Building News [April 98] called 'Targa'. All cost considerably more than the off the the shelf plain Jane water heater and the Targa is really expensive. If you have the right application (eg not too many same-time uses for water, like taking a shower and doing dishes and the wash at the same time) ie if you are living simple then these are an excellent way to heat your water. They work best is they are located near the water you are using. I'm about to buy another for a cabin we're building. Like regular heaters, they can't freeze though. Sacie

(post #172965, reply #6 of 10)

Scott, Bosch makes a series of On-Demand Tankless Water Heaters for both residential and commercial applications. For specifications and more discussion, see

Model WR400-1K provides plenty of hot water (140o F) for all typical household demands – with one notable exception: large soakertubs. By their nature, soakertubs hold a large volume of water. Since the heater limits the hot water output (quantity varies from model to model), filling the tub can take a long time. Adding a second heater in parallel to the first unit will effectively double the volume of hot water and cut the tub’s fill-time accordingly.

When performing a cost-benefit analysis of an On-Demand heater versus a traditional tank, remember to check the homeowners home insurance policy. Often, rates will decrease when a Tankless system replaces a traditional tank.
--- Yann

(post #172965, reply #7 of 10)

Hi Folks,

I have been using the AquaStar 125 for about three years.
Our folk dance group installed two of these in the building where we dance, one to supply two women's showers, the other to supply the men's side.

I believe these are actually made by Bosch now.

The are activated by the pressure difference of the incoming and outgoing water.
Turn the hot water on some, get some hot water; turn it on a lot and get a lot of hot water.

A problem with the older ones is they require a higher volume of water going through them to start.
Mine takes 3/4 gallon per minute, the new model takes 1/2 gallon.
When our 24 year old pump started to die we had problems with the heater cutting off.
This was solved with a new pump.

The 125 is the BTU rating of the burner.
Other AquaStar models have 38, 80 and 170 BTU and take differing amounts of water through them to start.

Our 125 will do two of these at the same time with hot water: run a shower, wash dishes or fill the washing machine.

Since there is no tank, the heater cannot be allowed to freeze. They are compact and light and can be mounted in a closet.

They are fuel efficient.

E-mail if you want to know more.

Good health, Weogo

(post #172965, reply #8 of 10)

Dose anyone have any info. on tankless hot water heater?

(post #172965, reply #1 of 10)

(post #172965, reply #2 of 10)

If I am not mistaken, it is also referred to as "on demand" I had one installed in my business about ten years ago. I do not recall the brand. It was a waste. It only worked if you ran the water v.......e.......r......y slowly. And even then, it never got very hot. I wouldn't want to shower in it! Of course, it stopped working in less than two years (but past the warranty). I think it cost almost a grand installed!

Be sure you know how much it can raise the water temp at what flow rate! Maybe they have improved.


(post #172965, reply #5 of 10)

I've been debating if there's a way to get the advantages of tankless (continuous hot water supply and energy efficiency) and tanked (steady temperature, insensitivity to flow changes, allows mulitple users). I've been thinking of this: space heating by radiant slab run off of a 100,000 BTU/hour tankless and an unplugged electric water heater (used as an insulated, pressure-rated tank) wired as the highest prioity zone in the heating system.

The direct-vent tankless keeps the house tight (from a air leakage perspective) and doesn't lose heat up the stack like a standard tanked heater does. The upper thermostat in the electric water heater can call for heat and cut off the other zones when hot water is needed. (When I'm in the shower, that's highest priority. The radiant slab can wait 15 minutes to get heat.) The electric water heater has no stack losses and can be more throughly insulated than it comes from the factory with those after-market blankets. There would be limitless hot water - 3 showers, 2 loads of laundry, and doing the dishes could all happen without waiting for recovery. The temperature flucuations with flow rate are eliminated because of the averaging effect of the 50-gallon tank. And if there's been a power failure and the tankless doesn't go (do the direct-vent ones need some power?), I've still 50 gallons of hot water.

I realize there would be some mixing of water between the radiant slab and hot water, but the radiant slab tubing is rated for potable water. I don't worry about scale in the radiant tubing because there's not much mixing. When there's hot water use, the new water flows into the hot water heater, not the slab. So the slab water mostly stays within that loop. Some mixing will occur but less scale will buildup in the radiant tubing than normal plumbing, where all the water used flows through the pipes.

It would be a lot of piping and a non-standard system, but I think a good reason to live in the last half of the 20th century is good plumbing. I think that will be even more true in the next millenium. -David

tankless water heaters (post #172965, reply #9 of 10)

I recently installed a Marley 10L unit. I have had good success with tankless in foreign countries but all these were 1. located close to the shower or sink, and 2. electric. 3. Single outlet use.

I am having difficuties I'm sure others have had as well.

1. Due to "sensing" the water must flow for a bit before getting hot.

2. Forget about a trickle of hot water. They aren't designed to do this.

3. The Marley, which uses pressure to regulate the burner, is temperamental when more load is placed on the system. There is NO WAY this unit can live up to it's claims unless there is someone there to manipulate the controls. It really need a VOLUME or MASS sensor to regulate the burner, and a decent feedback loop. I suspect the higher end units - that publish minimum flow rate do this.

4. For a single shower or faucet, or washer, the unit works well. This seems to be a common thread on the tanklless debate.

5. I tried this to save space in my man cave. This is more important to me that the savings which I think might be negligible.

Still determined to get rid of 50 gallons of hot water. Might try a "hybrid" of a tankless feeding a small 5 or 8 gallon reservoir water heater.

CU said no some years ago. (post #172965, reply #10 of 10)

In an article a couple of years ago, Consumer Reports concluded that the payback to convert to tankless was likely 10 years, if not longer. Hopefully, that article is still available online. As it was some years ago, perhaps the tankless technology has improved? I dunno.

There are also numerous reports of issues when the heater needs to supply a small quantity of hot water instead of full blast.

IIRC, the water flow has to exceed a certain volume for the heater to activate.

Good luck.