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theo827 · Feb 12, 2007, 12:38 PM

I am going to be replacing my hot water heater soon and was wondering if going with the hot water on demand system was worth it? Is it better than a traditional hot water heater?

Many Thanks

malex27 · Feb 12, 2007, 06:23 PM

Is it better than a traditional hot water heater?

Absolutely! We've installed several and they work great. Obviously, the units are more expensive. On most units there is a $300 tax credit which helps to offset your initial cost. The stainless steel vent pipe for natural gas units is pricey at approximately $10 per foot, so it's best if you can put the unit on an outside wall and vent directly to the exterior as opposed to going vertical through the roof. Some units actually mount on the exterior of the home in climates that allow. There really is a great range to fit your individual needs.

You do need 3/4" lines to feed most of the tankless units on the market today, so be sure to check on that.

Your energy bill will thank you and the endless stream of hot water is great. Let me know if I can answer any other specific questions.

iamgrowler · Feb 12, 2007, 07:25 PM

Originally Posted by theo827

I am going to be replacing my hot water heater soon and was wondering if going with the hot water on demand system was worth it? Is it better than a traditional hot water heater?

"better" is a relative term -- In the long run, it will most definitely be a better investment, OTOH, the initial cost outlay can be a bit daunting.

The units themselves aren't cheap, not by any stretch of the imagination, nor is the installation, but the long term value is appreciable in about 3 to 4 years.

One of the most important distinctions to make, though, is that an 'on demand' H/W generator is *NOT* an 'instant hot' -- Depending on the distance from the heater to the outlet, there will be a lag between the time the tap is turned on and the arrival of the hot water, of course a way to shorten this lag is to insulate the hot water piping -- And if the distance is greater than 100 feet, to install a 110 volt 'low boy' H/W tank and re-circulating pump.

It's a great system -- But like any other efficiency system, it must be engineered for the particular application it is servicing.

doug238 · Feb 12, 2007, 10:20 PM

Originally Posted by theo827

I am going to be replacing my hot water heater soon and was wondering if going with the hot water on demand system was worth it? Is it better than a traditional hot water heater?

Many Thanks

I read the other answers and I am OK with them. I will address another issue on this. What is your hot water demand? Are you using multiple showers or a large tub? If you typically have not run out of hot water you will find the expense of going tankless to be very high. A typical tankless job costs about $2,500.00 complete, and up. A tax break is nice and some areas give a $500.00 REBATE EVERY NOW AND THEN. I have a rinnai and am a certified rinnai installer. I love mine, but I have the demand for tankless, plus I got the rebate and the labor free.

labman · Feb 13, 2007, 07:08 AM

I have done the math, and tankless doesn't add up, as I said in https://www.askmehelpdesk.com/plumbi...ter-61400.html

iamgrowler · Feb 13, 2007, 07:44 AM

Originally Posted by labman

I have done the math, and tankless doesn't add up, as I said in https://www.askmehelpdesk.com/plumbi...ter-61400.html

It should be noted that a number of your issues, particularly the ones about clearance requirements and electrical supply/gas supply requirements were handily debunked months ago, Labman.

labman · Feb 13, 2007, 07:54 AM

Originally Posted by iamgrowler

It should be noted that a number of your issues, particularly the ones about clearance requirements and electrical supply/gas supply requirements were handily debunked months ago, Labman.

I somehow don't remembert that. You are saying the specifications on Bosch's website don't apply?

iamgrowler · Feb 13, 2007, 08:17 AM

I'm saying that there are far too many variables involved for you to have made a thorough enough analysis to dismiss their usage.

Did your analysis include:

The number of different manufacturers -- Bosch, Takagi and Rinnai being the big three?

The differing applications?

B-vent versus Direct Vent?

The number of different models offered by the differing manufacturers?

110v versus 220v?

The location of the proposed installation?

The flexibility offered by the innovation of ductile gas piping materials?

The efficient, programmable remote thermostatic system offered by most manufacturers?

The competency of the person engineering and installing the system?

Look, the list can go on and on.

doug238 · Feb 13, 2007, 10:39 AM

Doing the 'math' on a tankless water heater is simple. Do you have the demand for hot water that exceeds a tank type unit and can you afford the luxury of constant hot water that will decrease your utility bill is used the same as a tank type?

labman · Feb 13, 2007, 10:40 AM

To make an intelligent decision, a competent person can read the specifications and check their gas bill in the summer time. Better than the dollars is the cubic feet or therms. Even with a gas dryer too, no way does my gas usage approach what the tankless hype suggests for hot water alone. Anybody can check the specs on line. You may or my not be able to make a good estimate of your current usage.

No I can't claim I have checked every model out there. But the several I did check were all about the soma. When I was looking for a hot water heater to fit in my crawl space a couple of years ago, Tom did some checking too, and didn't find anything, or more recently for another question.

There may be cases where a tankless heater makes sense especially in new construction. For the average homeowner thinking about replacing a water heater themselves? They need to do a careful analysis. Get an estimate of having a tankless heater installed and look at what a conventional one would cost. Don't forget to look at the interest the difference would earn over the next 20 years.