tankless water heater

[coldshower]

i am looking into replacing my hot water heater, and am considering purchasing a tankless one.  i would like to know anyones experience with tankless water heaters.

any experiences good or bad, i know very little about it.

specifically i would like to know if you really never run out of hot water, if you have had trouble with mineral buildup, and if you really save money on power consumption.

thank you.

[cvo]

I have a propane tankless heater and I love it.

You'll never run out of hot water unless you run out of gas or water supply!

Why cook water all day the old fashion way? Its wastefull.

The technology has been around since '40s, due a patent search.

[jimjjnn]

I have had a Takagi TK-1 tankless for almost 5 years now. We can run 2 showers at a lower flow since only one has a low flow head. We always have enough hot water. 216 gals hot all day long 24/7. Best buy we eever made. Summer time our gas bill is at the minimum. Just the minimum charge , which is bad enough. I like the way it vents through a sidewall too.

Ours was priced pretty high but has almost paid for itself.

The new Takagis are less now and put out even more hot water than ours.

Even tho it cost 2000 installed, it is worth it. 1/2 the price was due to the guys that installed it. Cutting hole through bricks nad the fact that they sent 4 union guys to do it. 2 sat around watching the other 2.

Would I do it again? You betcha!!!!!

[drdongle]

I recently installed a BOSCH whole house on demand Propane heater and so far I love it. I installed it myself. Cost me $600.00 US Yikes!! But in the long run I think it's worth it

[chibear]

I have a Rinnai 2532C (commercial) unit which was installed in August 2004. It provides both domestic hot water and also heats the water for the radiant floors in my 1500+ sq ft house and basement. It supplies around 6 gal/minute of hot water until you run out of gas. I have a water softener, so mineral buildup is minimal so far. The energy savings are BIG! How big, I will let you know in the spring. Check my diary. If you go tankless there are a few things to consider:

1. You will have to wait a little while to get the hot water. The unit must heat the water and then the hot water has to make it through the plumbing to the fixture. Thus rinsing your hands in warm water will be a thing of the past unless you don't mind waiting.
   
2. Your tankless is flow activated, which means it won't come on unless there is sufficient flow for the computer to detect (.8GPM in my unit), so I had to get rid of my water-saver shower head so as not to take a cold shower or have the unit cut out on me when my pressure tank approached the bottom of its cycle. So no more trickles of warm water either.
   
   

Both the above are minor adjustments that have to made. If you live in a cold climate, though, read the following:

3. There are operation problems with these units in extremely cold climates. Takagi only certifies their units to -5F, Rinnai to -30C, and Bosch I haven't been able to find. Be warned that none of the companies publish this fact on their spec sheets and the info may be buried deep in the manual (Takagi) or not mentioned at all (Rinnai).

Now the specific problem with the Rinnai is that when the wind chill drops below -30C, the exhaust gasses a sucked back into the intake and condense and freeze, eventually blocking the intake and causing the computer to shut down the unit. At -40(C or F) the exhaust actually freezes from the velocity of the cold intake air causing extreme wind chill. Rinnai was not at all helpful with either problem. My supplier and I did come up with a fix (see my diary). Another fix also exists, but neither are approved of by Rinnai.

In spite of the above, I am saving mega bucks in home heating alone. The real test of the fix will have to wait until next January and some really cold weather again. I intend to keep the unit.  

[ghurd]

Good and bad.

My parents have an old HeatMaker.  It is great.  Heats the house, and Never runs out of domestic hot water.  Really saved them a TON on gas bills. Just needed service, and the only guy around who understands them said the new ones are junk.  Another company bought HeatMaker and quality went to crap.

A big shop bought 10 new units for floor/ radiant heat, maybe 3 years ago.  The service bill has been over $5,000 PER YEAR !!!  Figure they only run for 5 months a year, and that is $1000 a month maintainance!  Seems a little 'high' for brand new units.  The guy now refuses to sell them.

I try not to brand bash, but bad is bad.

You should run softened water through them or deposits lower the efficiency.  My parents had to have acid run through theirs (not cheap) after the softener broke for an extended time (like a year), but it was 10 years old too.

G-

[jimovonz]

We currently use a Rinnai system as a 'booster' for our solar hot water system. Prior to installing the solar, the same unit provided all out hot water needs without any trouble whatsoever. I would highly recomend the use of such systems. These units have a rated throughput above which they will either restrict the flow or allow the water to cool. My unit is rated at 18l/min (~5gal/min) raising the water temp 45degC. If the cold water supply were cooler then the unit could not supply the same volume of water at is its set temp of 55degC. On the other side, if the incomming water is warmer (such as it most always is in our solar heated system) the capacity of the unit is increased. If the water in our 400gal solar heated tank was 30degC then the unit would be capable of supplying roughly double its rated capacity as it doesn't have to work as hard. These heaters will provide their rated flow as long as their gas supply lasts.

[Nando]

What type of tankless water heater?. Gas or Electricity ?.

Electricity will draw heavy KWs, I have data around for the electric units, Let me know.

Regards

Nando

[coldshower]

Natural gas

Thanks

[mungewell]

Hi,

You mention that you also use your tankless water heater to heat for your infloor system.

Can you please describe how you have hooked this up? Where does the 'used' water end up?

Simon

[chibear]

The system works like this: zone thermostat calls for heat; zone valve opens; when zone valve opens an end switch is tripped; this activates a relay that turns on 2 pumps: #1 circulates the glycol mixture through the infloor #2 circulates potable water in a loop through the Rinnai ; the Rinnai detects the flow and turns itself on; the heat transfer occurs in a fluid-fluid heat exchanger. There is a flow switch so that when you call for domestic hot water, the heating pumps are turned off so that domestic hot water gets priority at that time.

[mungewell]

Hi again,

I assume that the 'used' water (from tankless heater via exchanger) is returned to the storage tank, otherwise you'd just be burning gas when there might be plenty of heat in the tank. Please confirm.

In all systems I had thought about there is a mixer valve to prevent scalding water coming out of taps (and in this application thermal shocking the concrete). I had imagined this before the tankless heater - this could cause a problem in your system as it would introduce more water into an effectively closed loop system.

So do you have any scald protection? If so where, and if after tankless is there any worry that a very hot tank could damage the tankless heater?

How do you prevent your storage tank boiling when too much solar exposure?

Simon.

[chibear]

Hi,

To answer your questions in order:

Since it is a tankless heater, there is no storage tank. The water is returned to the heater again in a very short loop. When the water re-enters the heater from the heat exchanger it is still over 100F. The Rinnai senses this and only applies enough heat to heat the water again to 140F. If you have read my diary, the storage tank I am talking about there is actually to be used as a preheat before it gets to the domestic hot water or radiant floor.

The Rinnai is set to deliver 140F water. If the output temperature exceeds 140F, the unit shuts the gas off until the temperture drops below 140F. The actual output of the unit is from 15000BTU (If I remember right) to 185000BTU per hour. The burner flame is modulated between this minimum and maximum to produce the set output temperture (or shut off if too high). The heat exchanger delivers 100F water to the radiant floor with the Rinnai set at 140F.

I did install a mixing valve in case I had to run the Rinnai above 140F to heat the house, but that was not the case even when outside temperatures dipped below -40, so the mixing valve was not really needed.

I do not have the solar option up and running at this point. That is my summer project after the snow is off the roof. My storage tank is 1500 gal, so response will be slow. Once the tank tops 160F(the limit for the resin I used in the tank), I will just cover the collectors until they are needed again.

[scottsAI]

Tankless gas Bosch, $500 + $100 installed myself, 5 yr ago.

One shower at a time.

Can take no limit showers! couldn't do before.

My only regret is I did not get the unit with an active damper.

The unit has a 5" stack, open all the time, You can feel the heat loss.

In Michigan, you can't put it outside.

Does not have electronic ign.

Does very the heat controling the temp.

Manual said not to use unit with preheated water.

Has 10 year warranty (15 if pro installs). Most tanked do not.

In my mind, I had trouble justifying the $600, then I found a good high

eff. Tanked was $470 it become easy to justify. Only $30 more.

I would have liked to get the damper/ele ign/solar, but it was $700 + $100.

Could not justify doing so.

Would have liked the two shower unit, did not like the .8gpm min flow. Did not like the cost $1200. Figured I could buy two Bosch for less, that could do more.

Only couple times would it have been nice.

During the summer the minimum flow can be a problem, end up with a hot shower.

You Can run the hot in the sink...

Wife likes it, so do I.

Have fun.

[jimjjnn]

I bought a damper at a plumbing and heating place. They come in many diameters. @ inches to 10 inches is what they had. Paid $54 US for it

[jimjjnn]

That should read 3 to 10 inches in diameter. Guess I should use preview before posting

[scottsAI]

Interesting Idea. Does the damper open with heat? What happends for the firest few seconds? when the burner starts up.

The water heater does not have any electronics.

Thanks.

[Joseph1]

About 2 years ago I replaced my leaky tank water heater for a tankless water heater. It has been working without a flinch. We love it! I would recommend it to anyone considering replacing their old tank heater.

The fact that tankless (instantaneous) water heaters work on demand, meaning that they only consume electricity when you open the hot water tap, is what accounts for the efficiency and of course, energy savings.

[Joseph1]

About 2 years ago I replaced my leaky tank water heater for a tankless water heater. It has been working without a flinch. We love it! I would recommend it to anyone considering replacing their old tank heater.

The fact that tankless (instantaneous) water heaters work on demand, meaning that they only consume electricity when you open the hot water tap, is what accounts for the efficiency and of course, energy savings.

[mmc]

I realize this is several years later after your original posting but I have the same problem with an in-floor radiant heat system using a Rinnai Infiniti 2532.

We have shut downs of the system that have no pattern to them and get an error code 10, (ventilation) when it goes down.  The local service group for Rinnai completely changed the location of the system and charged my contractor $2,ooo, he said it would resolve the issue by improving the ventilation.  

Since that time we have had two more shutdowns, we do not have a pattern of temperatures for the shut downs but being in the Colorado Rocky mountains, our winters can be harsh and we are at 9,000 ft.

Can you tell me more about the solution you used and has this resolution lasted? Did Rinnai help you with this solution?  They have not been much help to us.

Thank you,

MMC

[mmc]

One additional question is your Rinnai unit an interior or exterior unit?

[TomW]

This user has not posted since 2005 [all his posts are in this thread] I doubt he will respond any time soon.

Tom