I've heard that the On Demand WH will save me money in the long run. What kind of matinence issues would come w/ an On Demand set up? Is there a disivantage to the On Demand, out side of it being more expensive?
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When our water heater went last month, I faced the same question. Not only would the tankless on demand unit cost more both to purchase and to install, we discovered it would take us 12 years to recoup those costs in the savings based on our useage. The venting is different and would have to be replaced, too which in our case was more expensive than the unit itself because of how it is routed. There is a website where you can do your own estimation based on your situation and it may save you
http://www.plbg.com/education-tankless-water-heaters.html
http://www.tanklesswater.com/ed_costsavings.asp
We talked to some people that have it, and they all recommend it highly.
It saves on your bill because you’re not heating water until you use it.
It doesn’t take up a lot of space.
You can supply 2 appliances at one time with hot water.
Just a few points they made to us. They had absolutely nothing but good things to say about it. We are planning on having it installed when it’s time to replace our water heater.
The on demand units cost more to buy and to install. Install in an existing facility can be fairly difficult and therefore costly. You have to cut into the water supply to insert the on demand unit and you also have to deliver either electric feed or gas feed to fuel them.
Some claim to have energy saving advantage as they claim that conventional water heaters lose heat via radiation from the heater and the hot water lines. While this is true, the on demand style has to have a substantial and inefficient means to heat the water to meet the on demand nature. Many engineering calculations suggest the energy savings of these units are over stated and usually not seen.
On demand will not run out of hot water which some like. Usually the on demand type is made of stainless and other very long life metals so you should see a much longer life with these.
If your utility has interruptable rate for electric water heaters you cannot get them for the on demand style.
In my opinion, they do not deliver the savings often claimed and they are not worth installing in existing facilities. I strongly question their value in a new facility where install is a lot easier.
On demand water heaters require their own electric circuit breaker running 110amps. You must first have an electrician come and make this change. If you don’t already have 200amp service then you will need to have the entire service upgraded first in order to even get 110amps separated. The next time you would need to do is change the venting. The on demand water heater itself is very expensive and you must pay someone to install it. All in all it is very expensive for one of these systems, and I’m not even completely sure of the reliability. I plan on replacing my water heater within the next year and have looked into the on demand systems, however it totally not worth the extra upfront money so I will be getting a new standard tank water heater.
We had the on-demand system and just hated it. It was in this house when we bought it and was just 3 years old but we had it replaced with a traditional system. Our problem was that the on-demand unit was in the basement and the water had a long way to go to get to the showers. The unit doesn’t come on the second you turn on the hot water. It wants to know you are serious so a gallon or so has to pass first. We just got tired of waiting forever for the hot water to show up. And then if you turn down the hot water like while washing dishes you have to start over from square one.
on demand units have been in use for many years in europe, The price is of course the issue. also modifications will be needed on your house . the unit will have to be installed outside the house because of heat issues. I would like to see someone develope a solar/on demand unit combo.
I bought a house a few years ago and it had an on-demand water heater. But, it was old and small (3.2 gallons per minute or GPM). So, while I loved the fact that I had endless hot water (our teenage daughter used to take 30-minute showers in the morning, draining our hot water tank), I didn’t like the fact that you could only use hot water one place at a time without severely lowering the water pressure.
The way they rate the GPM is based on a 55-degree temperature differential. If you have the temperature setting at 115 degrees and the incoming water is 60 degrees, that’s a difference of 55 degrees and you get the rated flow. If the temperature of the incoming water is 50 degrees, you’ll still get an output of 115 degrees. But, the flow is less than the rated GPM. This is because the water has to stay in the heating coils longer to reach the desired temperature. An automatic flow valve with a thermostat is what regulates the flow through the coils. And, particularly in winter when the incoming water is especially cold, you can see a significant decrease in available flowrate for a given temperature.
Last year, I remodeled my house and got a 7 GPM unit (Noritz gas unit with electric start). The unit itself was $1000 delivered from a site on eBay. But, it required an additional $250 in ducting parts and installation. Since I was replacing all of the gas, water, and electrical in my house, it didn’t cost much more to have it plumbed to code or to have a 110-volt outlet installed in the heater location. But, building codes require that any on-demand unit be supplied with a 3/4-inch gas line, and water supply and return lines. So, figure on hundreds of dollars more to plumb the heater.
Overall, I am very pleased with the 7 GPM unit. I can run 3 hot water sources (for example, shower, washing machine, and dishwasher) simultaneously with very little to no reduction in pressure. Except maybe in winter time, when the incoming water is about 45 degrees.
I don’t know how much energy savings I get with it versus a water tank heater. But, I absolutely love the convenience of having an endless supply of hot water. Not to mention the extra storage room I get in the water heater closet and the fact that I don’t have to worry about an earthquake knocking over a big water heater tank.
ok, here is a real world answer. i just went through this all myself and im one of those anal guys that doesnt make a move untill i have all the facts. after extensive research the way to go is an indirect hot water heater, not on demand. i direct works just like a regular hot water heater but it has no flue for the heat to escape. i went with a buderus st-250 which only loses 1/4 of a degree an hour which means it does not run unless you use hot water basically…so you get the best of both worlds… i cut my hot water bill in half…couldnt be happier…
I have been plumbing for over 14 yrs now…..i’ve seen alot of different setups and installations….I am also Rinnai certified…..so i put alot of these in…..as far as everyone sayign it is hard…i would rather put in a rinnai(on demand) heater than a traditional heater anyday of the week…..also it does require a little power but only 120volts like a reg electric and thats only for the sparker(igniter)…it doesnt run all the time it just lights the gas like a grill does….it DOES NOT require a 110 amp breaker or anything like what was said above and does not take forever to heat…its instantaneous….it will only take a min for the water to get to u depending on how far it has to run and what size lines u have installed……it does not need venting as its installed outside and has a built in vent on front of the unit….i just replaced my electric water heater last yr as i didnt have gas here yet….not that i do have gas i cant wait for my heater to go out again so i CAN get a rinnai…..just my two cents hope it helps….
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