PDA

View Full Version : Another new guy...with a question



Bob Mooney
07-12-2005, 5:30 PM
Hi, I'm new here, and I'm gonna start off with a question! :D I'm finishing my basement, and one of the things thats got to be replaced is my water heater. I'm considering a "Tankless Water Heater" made by Rinnai. I know the initial cost will be higher than a traditional water heater, but given the ever increasing costs of energy, I believe that it'll pay for itself down the road with savings from reduced energy use heating water that may not even be needed. So, here's the question: has anyone used a system like this before, and if so, what are your impressions?

BTW, I've enjoyed looking at quite a few of your old posts here, and I'm sure that I'll be asking for advice down the road, and hoping that I can give some good advice as well.

Bob

John Hemenway
07-12-2005, 6:11 PM
Bob, I've been considering tankless. If you don't mind me asking, how much was the unit and which one did you get?

The only tankless I've seen locally is by Bosch. Amazingly it's not blue! :) Cost at BORG was about $1K.

OK I read your post again for understanding :o and see you haven't purchased it yet. So, what have you been quoted?

Don Baer
07-12-2005, 6:16 PM
http://www.sawmillcreek.org/showthread.php?t=18620&highlight=Tankless+water+heater


welcome tothe creek where the water is always just right.

Bob Mooney
07-12-2005, 6:38 PM
Thanks John and Don. The unit that I'm considering is about 1K. Its supposed to generate 8.5 gal of hot water per minute, and is stated that it can handle 3 uses of hot water simultaneously. Check them out at foreverhotwater.com

Bob

John Hemenway
07-12-2005, 6:43 PM
Thanks, Don...

Ken Salisbury
07-12-2005, 7:08 PM
In order to be a bona fide member of Saw Mill Creek the Terms of Service (http://www.sawmillcreek.org/terms.php) requires you to use a real first and last name. Please send Jackie Outten a Private Message (http://www.sawmillcreek.org/private.php?do=newpm&u=6) with that information and she will update your registration to reflect your real name.


http://www.oldrebelworkshop.com/misc/moderator.gif

Frank Hagan
07-12-2005, 8:14 PM
Someday, "Consumer's Report" or someone will do an expose' of the efficiency claims made by water heater companies. I work for one that is honest, but there are some really spurious claims out there regarding energy consumption.

First, to get more than 84% efficiency, the boiler or heater has to go into condensing mode to extract heat from the water vapor in the flue gas. When you do that the flue gas temp drops, so you need a blower on the appliance to force the flue gasses out. The remaining water vapor will condense in the flue. Stainless steel or plastic vent pipe is needed; for some of the smaller appliances the vent pipe cost is not too much of a factor, but as you go up in size, you will have a much higher cost for venting.

The efficiency of the heater is also dependent on the temperature of the water coming into it. For a tankless water heater, you do get a good low temp inlet water source, so you can go up the efficiency scale. For a heating boiler, where you maintain 140F or more in your heating system, you will never see efficiency above about 85%. If there isn't condensation pouring out of the boiler, you aren't above that 85% number. Even in condensing mode, the tests my technicians have done show that you usually are about 10% higher than a less expensive heater ... right around 94 - 95%. Remember to factor in the extra cost of running the combustion air blower also.

The problem with some of the tankless designs is the cost of replacement components. Some use hot surface ignition, which typically fails after about 2 years, with an average cost to replace of about $200. Some use direct spark ignition which is more reliable. Most also limit water hardness to around 10 grains per gallon; the passage ways inside the water heater are small in order to heat quickly, and they will lime up. (In the other thread, someone asked what happens to the lime in a tank type water heater ... it accumulates on the bottom and eventually causes the tank to fail as it insulates the burner from the water ... which is why older tank type water heaters will make popping sounds as they heat the water).

I have never seen a ROI on these that makes them a good deal ... yet. I'm sure the cost will come down, but until that time, I would hold off and get either a tank type water heater that will need replacement in 8 - 10 years, or a boiler/tank combo unit with larger heat exchanger tubes (and 84% efficiency) that will last longer.

Bob Mooney
07-15-2005, 4:47 PM
I'm still looking into this question, and have considered the input here as well as elsewhere. I'm hoping to finalize my decision soon.

Don Baer
07-15-2005, 4:57 PM
I will say that I have never had the tankless. That said I replaced my 17 year old tank type last year since I knew it was due to go with a new GE 50 Gal unit from HD. It is supposed to be self cleaning and came with a 12 year warantee. I will say that it has been a great unit we never run out of water any more no matter how many showers we take.

I think after buying the unit, buying new tubing to connect it up with and installing earthquake straps (Code in California). I spent abut $400 and my son and I did the labor.

Jim Becker
07-15-2005, 5:34 PM
I had planned on going tankless when I replaced the waterheater a couple years ago, but could not accomodate the strict flue requirements due to our basement being entirely below grade with 2' thick stone walls. The existing flue could not be used without breaking code. But I would consider one for the future planned addition...I happen to like their designs and capablities, even if the marketing is a little, umm...creative.

There are a number of good brands out there. A site that shows several of them is http://www.tanklesswaterheaters.com/tanwatheat.html . I'm not endorsing them since I don't know them from Adam, but merely providing the linke for illustration purposes. I was looking at the Tagaki. (Who also makes the large 240gpm Bosch labeled product, I believe)

Dan Stuewe
07-15-2005, 5:53 PM
Just a quick anecdotal example...a friend bought one from HD but returned it when he found out that to keep the warranty it had to be professionally installed and that was going to be quite a bit of extra money. The idea still intrigues me too, but with a wife and two daughters, I'm not sure I could afford a tank less that will be able to keep up once the girls are teenagers! :eek:

Bob Mooney
07-15-2005, 6:12 PM
Jim,

Thanks for the link. Just checked it out. I was hoping they'd list the Rinnai. Based on Rinnai's site, they state they're able to produce 510 gallons of hot water per hour (they say 8.5 gal/minute), which is considerably above the figures noted at the noted link. A friend of mine has a tankless unit, and has had it for quite a few years. Her complaint is that it doesn't produce sufficient hot water. I think 510 gal/hour should be more than enough for the wife & I.

Also, I don't have the problem that you mentioned of being completely below grade. I can vent the unit, or I think that it can be installed outside, and then venting isn't even needed.

Bob Mooney

Ken Garlock
07-15-2005, 6:15 PM
When we built back in 2002, I ordered and had installed an electric on demand tankless unit. It is a 36 KW heater with 3 12 KW elements. It sequences the elements on and off based upon the temperature of the water leaving the unit. When all 3 elements kick on, you can see an ever so slight dimming of the lights. This heater handles only the bathrooms in the bedroom area, so it is never overloaded.

For the kitchen and utility area, I had the Rudd Marathon electric heater installed. It is a 100% fiberglass tank, and should last for ever. It also has about an R-20 insulating blanket around it.

When the electric company installer put our pole pig in, I asked him why he only put in a 24 KVA transformer. He said that I would never pull enough to overload it. I told him that my hotwater heater pulled 150 Amp when it fired up, and that was 50% in excess of the rating on the transformer. He just shook his head and walked away. :rolleyes:

The tankless can be seen here. (http://www.hotwaterheater.com/whole-house.htm)

No it is not gas, but in our case electric was the only choice. ;)