*
I currently have a gas hotwater heater- maybe ten years old – bought the house in 1995. The output of hot water is down plus I had what looked like rust coming out of the faucet. I’m wondering if it is better to replace it now or wait or ? If I were to replace it, what is the most energy and cost effecient replacement: 1. standard energy-efficient gas, 2. standard energy efficient electric, or 3. one of those on demand hot water heaters (you know, those little boxes) that can be gas or electric. The only time I’ve ever used one of those was in Brazil for showers(a sizzly little thing that gave hot water when the electricity was working)years ago. Barb
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
To prevent moisture buildup and improve performance, install a continuous air barrier—such as drywall or specialized membranes—under tongue-and-groove boards or other interior wall paneling.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Fine Homebuilding Magazine
Fine Home Building
Follow
-
Fine Homebuilding
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial Now -
GBA Prime
Get instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
*
This will open a large can of worms!! First your water heater should be replaced. Second, two types to pick from, instant and standing. instant pros: non-stop hot water, maximum efficient as in $ per hot gallon. cons: A little slow for filling the bath higher startup cost as install is more involved. standing pros:takes up more room, about 10% more $ per gallon than instant, bigger units better for filling bathtubs, often reheats when idle. I have the bosch aquastar and the whole house is very happy with it. A lot cheaper to run but we changed from electric and I wanted the space. What ever you pick install a water filter to cutdown on the "junk" in the water.
*My contractor friends always yell at me when I say "hot water heater." "Hey Jim, why would you heat water if it's already hot? It's a water heater, ya dummy." Not that I'm calling you that, Barb. Just maybe saving you from someone else doing it. :)
*Well, hot water heater is what most of us non-pros call it. However, I agree with you and stand corrected. Now, about that advice I was asking for ---
*when you say the output of the water heater is down - do you mean the water is not as hot as it once was??If that is the case you most likely have sediment built up on the bottom of the tank. The sediment in a gas water heater is stuck to the bottom and will act as an insulator, reducing the heat transfer to the water. Sediment, if allowed to accumulate, also reduces the volume of the tank.It is possible for the sediment to be forced up off the bottom. If your water heater rumbles, you have sediment and an airbubble has pushed off the bottom, causing the sediment to disperse through the tank. This may be where the rusty look in the water came from. Or not.Have you ever drained the tank? Most often recommended time frame is a few gallons every 6 months or so. There are ways to clean the tank and if you have a lot of sediment you should because the tank can fail a lot sooner when gunked up than when clean. I have a gas heater, in another house, that is still going strong after 31 years.
*I'm with Nigel. I, too, have the Aquastar. I wouldn't have anything else in my situation. I love the extra space gained from not having a huge tank to deal with. And those long showers, or several showers in a row, or washing the dog, or doing your laundry and never running out of hot water is a luxury.However this is not a quick and dirty decision. You MUST understand your house and the requirements for an instant heater. Most importantly, the venting. It requires a 5" flue. Many homes have a 4" for their present heater. You CANNOT cheat! It must have the 5" or better. Also, the installation is not for the usual DIY'er. And therefore more expensive - IF you can find a plumber willing to take the time to do it. My take from reading many of the posts as well as talking with others is that most plumbers won't.Also, if the search feature is working, there have been many, many posts on the subject here.
*yeah, barb. more than likely, you've been ignoring the maintenance on your water heater. there should be a hose bib valve that you can connect a hose to. shut off the gas, turn off the water supply to the heater, connect the hose, then open the hose bib valve and let it drain. open (for a minute) and close the water supply several times to flush out the system. shut the hose bib valve, disconnect the hose, refill the tank, and follow directions on the water heater for turning your heat back on.if you choose to replace your heater (10 years - it's about time anyway), practice this procedure at least once a year, preferably every six months and you'll keep the efficiency and lifetime of your next heater optimized.brian
*B J I have an Aquastar demand water heater also. Could not think of suggesting anything else. May take a bit getting used to using it due to different water capacity and flow rates, but once you do, you will be good for life. It is especially useful in hard water areas as sediment build-up is minmized. Also the new Aquastars have a pilotless ignition . Space savings, energy use savings, as well as unlimited hot water.Installation is not all that difficult if you have some skills. However contracting out the work should not be that expensive depending on your situation. You could have the stove shoppe install your flue, standard 5" metal-vent pipe. Plumbers/gas installers can run your gas line. If it is in the same area as your existing heater than water hook-up can be easy using flex connectors. Just remember to plumb in a new pressure relief valve.walk gooddavid
*When hot water quantity decreases and the heater is 7 to 10 years old I think dip tube. There was a class action suit against the manufacture of dip tubes and a settlement to repair or replace the heater. This affected virtually every manufacture.I believe the time is up on the free repairs. If you have to pay for the repair it is about the cost of a new heater.
*Also, go to http://www.heatinghelp.com and get their handbook on domestic water heaters which explains very well how to maintain one, and how to improve any heater so that the maintainence will be most fruitful. (like replacing the crappy hose bib on the bottom of your new one with a ball valve, and other things like that).
*Well, to answer your other question, gas vs. electric, the gas will be far cheaper to operate and is well worth the additional first cost.Even if your old water heater is shot, the suggestions above should still be considered because you have to know the cause of the problem so you don't repeat it with the new unit. For example, draining the sediment periodically, and possibly filtering, etc.As for the instant on, there has been much heated (pardon the pun) discussion in the recent past. You can have unlimited hot water when it works, but my personal experience with Aqua Star was terrible. There was a 12 day period without any hot water at all because the dealer could not get parts. Then there was the day that steam came out my shower head and I had to rip out walls to replace the melted sections of PVC pipe. The third time it broke I gave up on it.
*Barb,How much does electricity cost where you live? How much is natural gas (if available) or propane? Although Wayne is probably right, it depends on how much you pay. Where LP is $1/gal, electricty would have to $0.04/kwh to compete.Wayne-pvc hot water supply? There is a reason that's not a common practice ;>.
*I put a Rinnai 2424 in my house and couldn't be happier. These are high end and they are expensive. I paid about $1,000. But they can handle the volume. Great for filling the hot tub, washing the car in the garage during the cold months, two showers running in the morning. It's also really good for a hangover. Set to 104 on the controller, turn on the hot water and enter the shower for a long as it takes. Good luck Ron
*BJ - Click here for my suggestion - but what do I know?Jeff
*Ron... Your water temp should be kept higher so nothing is growing in your tank. The way to reduce water temp is by using a tempering valve.near the stream,aj
*Tim, good catch. I was not careful in what I said. PVC is rated for 140°F, CPVC for 180°. It was CPVC that I had. The areas of pipe that "melted" were not truly melted into a blob, but a distortion of the threaded connections. Every place where I had threaded a CPVC adapter to a brass valve leaked after the steam came out, including the connection to the shower valve itself.I've since learned that it's bad practice to thread plastic fittings into metal components on hot water systems. The pipe manufacturer makes a special union style adapter fitting for this which is what I should have used. Had I done that, I probably would have gotten by without leaks from that one incident. Live and learn.
*Wayne,I did an old house that way, replumbed it all using pvc for cold and cpvc for hot. Worked really well, but because I like it better and because I'm always tinkering, adding on and modifying things, I like copper.
*Wayne: When you exceed the temp limits on plastic pipe, it gets, well, plastic. Long sections of unsupported pipe will sag. And threaded fittings can ooze out of a joint. Sometimes all the way out. Sometimes just a thread or two and that results in a leak. I've had this happen in PVC at 150-160F even at quite low pressure (1-5 psi). The surprising thing is that the fitting, when cooled, looks just fine (and proably is) - same shape, dimensions, etc. But it is sitting outside of the threaded joint in an otherwise intact pipe run. -David
*not much mention of pricing for the instantaneous heaters or especially their replacement parts.or the availability of parts.
*Old construction with existing gas water heater, the cheapest method is replace with the same. Instant gas fired with cost extra to install because they need a 5"flue for the 117,000 btu flame. Aquastar is priced around $475+ the installation materials. Normal gas water heater $165 (5 year unit) and up for longer warranty. Not many parts in the aquastar, thermo couple, flow switch, gas control etc. My main reason for getting the aquastar was the change over to gas fired and the very small footprint of the unit with no standing water being re-heated and then when we need it running low on hot water. Seems everyone want to shower at the same time!!
*Another factor to be aware of is the desirability of sealed combustion.With a standard gas water heater, every time you turn on an exhaust fan (bathroom, range hood) it will pull replacement air into the house from the most accessible source, quite likely down the flue of your furnace or water heater. If the furnace or water heater is running at the time, in come the combustion products you thought you were sending up the vent. Depending on the air pressure patterns in your house, this can occur at other times as well and lead to major indoor air problems. Worse in tight homes. Sealed combustion avoids this.Does anyone know if any of the current on-demand units are sealed combustion?
*If you are asking if there are models that take their combustion air from outside, then yes. I know them as "direct vent", even though that only partly describes the function. They are mounted on an outside wall, and vented "directly" throught the wall. Combustion air is taken in through the same opening (pipe within a pipe).
*Just a general comment to those who are wondering: Whole house instantaneous water heaters are not available in electric versions. Why? Because it would take more electricity than most houses are wired to supply. 120,000 BTUs is something like 35,000 watts.Its good to see positive, and informed, comments on instant water heaters. It wasn't always like that :-)
*Thomas - do you know which of the instantaneous water heaters are available as sealed combustion units?
*Now let's go back to standing gas water heaters: does anyone have advice on choosing a model? For example: is there a difference between linings? Are there features to prevent layering? Are some brands more reliable than others? Is there a decent review of models/manufacturers (online or elsewhere) anyone can point us to?We're on a low budget and suddenly have to replace a 25+ year old gas model that has begun to leak out of the bottom. While moving to an on-demand system or going solar probably isn't affordable for us, we'd like to go with something relatively energy efficient, and long-lasting.
*Sorry to change the subject in the thread.But just thought I would point something out after seeing comments on PVC. I don't know if this is a common practise anywhere else but here a lot of plumbers know you can't use PVC for hot water but they use it for the blow off on the T&P releif valve. Well guess what temp. the water is in that blow off? We had a service call once where the T&P had blown and it blew the PVC male adapt right out of its outlet, so the water went everywhere except where it was supposed to.
*Annette: Yes, are there are different linings. Some are "glass-lined" and claim to have much longer useful lives. One has to be careful in their installation because they are heavy and shouldn't be dropped. Not a problem with a little practice (I've installed 80 of them). In a regular (steel) tank, I'd strongly recommend you get one that has a replacable anode (a zinc rod) and buy one or two replacements. If the store doesn't stock the replacements, go elsewhere. Then, if the tank has a 8-year warrranty, replace the anode at 5 years (or at least inspect them). Compare it to new and assess when to replace it again. As long as zinc remains, the steel will be in great shape. -David
*For longer life one of the best things you can add is a basic water filter. I added a Sears unit with the clear filter container and its stunning to see the "junk" collect from the water. Go against the trend and flush the tank often. Before you install loosen the anode rod and re-install so it can be replaced at some time with ease.
*Just curious how well the on demand heaters work installed in a system with a re circulating pump and hot water loop (to eliminate waiting for hot water at remote corners of the house). It seems the heater would be cycling on and off quite frequently when the recirc pump is running. If so would this reduce its longevity or efficiency?Thanks, Karl
*Royboy, sorry, but I don't have current information. I remember a company called Myson made the first sealed combustion instant water heater I had seen, but that was about 1996. I have since read a few posts on this site, and others, describing units of more current manufacture, but I can't remember what they are. Not Bosch/Aquastar. Maybe Takagi?
*Someone please figure this one out!I have a standard sized (45 gal?) , gas fired,hot water tank that is just 6 years old. It is a Servistar brand. It's about shot! I will have to change it very soon.Nomatter what brand I use...Moreflow, Servistar, Rheem, they all seem to only last me 6 years.My Mother's hot water tank, same size, (its a Rheem), connected to the same city water line just a few blocks away from my house, never goes bad. Has this tank ever been drained? absolutely not! Do I drain my tanks? the last 2 , yes, this one, no. Did draining make a difference in my case? no. My mother has lived in the same house since 1949. If memory serves me right, that house has gone through a total of 1 waterheater! She's on her 2nd one now. Never been drained.Beats the heck out of me!Can anyone tell me this? I thought that nowadays, Moreflows, Rheems, Rudds, and a few other brands were actually being manufactured all out of the same plant in Johnson City TN. Can anyone confirm this?I'm beginning to know why these tanks only have 5 year warranties...because they go kaflooey in their 6th season.Just my 2 cents worth.Davo
*DavoJust be proud your contributing to the american economy. Tanks are not engineered to last they are engineered to fail. If they built them to last the production crews would be cut in half.p.s. Just installed a Rheem the other day it was manufactured in mexico.
*All suppliers sell lifetime tanks. Get a lifetime tank. Sears... Lowes... Home Depot all carry them here. That's all I would use in your case.near the stream,aj
*Hi Kevin,I'm proud to do my part to keep the American Economy rolling, but....Rheem, in Mexico. Time to boycott Rheem.Friggin NAFTA!Davo
*My thanks to all of you for taking the time to answer my questions. Turns out that one of you lives in the same town as I do and has installed an Aquastar. He has offered to let me come over and see it in action. He also will help me find a good source of installers. I am intrigued with the fewer number of working parts, the longer longevity, and the reduced maintenance requirements. I appreciate all of your help. I'll let you all know what I do.However, I have one more set of questions. Several years ago, I replaced the furnace and added an air conditioner to the house. They tied the vent for the water heater directly into the vent for the gas furnace located adjacent to the water heater. And, they installed two pipes in the basement, one of which is vented through the exterior wall. I notice that moisture comes out of one of them, so I am assuming (that's bad) that they have something to do with venting the new forced air Trane furnace and air conditioner. It would seem that this venting would also work for the tankless water heater. And, that a larger connection could be made to the existing vent of the furnace. Does any of this make sense? Also, I just looked and the only flexible gas piping is that used to tie into the gas inlet at the bottom of the water tank.Barb
*Bjsb. Sounds like you have a condenser type of furnace installed. check the rating on the front plate to see if its 90% plus efficent. Two pipes, one is the breather and the other the exhaust.
*
I currently have a gas hotwater heater- maybe ten years old - bought the house in 1995. The output of hot water is down plus I had what looked like rust coming out of the faucet. I'm wondering if it is better to replace it now or wait or ? If I were to replace it, what is the most energy and cost effecient replacement: 1. standard energy-efficient gas, 2. standard energy efficient electric, or 3. one of those on demand hot water heaters (you know, those little boxes) that can be gas or electric. The only time I've ever used one of those was in Brazil for showers(a sizzly little thing that gave hot water when the electricity was working)years ago. Barb