Water Heater Selection

[laen64]

I'm Preparing to build a home. What are your opinions on Tankless - VS - conventional water heaters?

 

[AndyMA]

I'm Preparing to build a home. What are your opinions on Tankless - VS - conventional water heaters?

Personally absolutely go tankless. I recently changed from a 50 gallon tanked propane heater that was out of hot water after 2 showers to a Rheem 74 series tankless that provides endless hot water and saves you over 30% a year on energy costs. Tanked hot water heaters are obsolete technology that just waste energy keeping a tank of hot water hot. The water from the Rheem tankless is also absolutely constant temperature and is only heated to 118 degrees or what ever I set on the digital remote control, The tanked water varied in temp during a shower and I had to keep adjusting. As you can see I am a big fan of tankless.

PS I bought my Rheem on eBay for about 1/2 the local price.

Andy

 

[Treemonkey1000]

I agree with tankless philosophy and it's savings. What I have seen on older units is they restrict your water flow to heat that water.That made it hard to get a lot of volume of water.
So get a larger unit to heat the water. One advantage of a big water tank is that you have a large tank of water for use in an emergency like tornados or earthquake if your water supply is cut off.

 

[Erik_in_Hoyt]

since I use a 98% efficient pilotless 50 gal tank for domestic hot water and the heat coil in my furnace, I chose not to go with tankless.
OTOH, if you go with tankless, get the one that uses a waterwheel to spark the ignition rather than one that uses wall current - that way if your power goes out, you still have hot water. (unless you're on a well)

 

[Pirwin21]

I recently built a home and used a Bosch Powerstar AE-125 unit. I got mine off of ebay and it was just about as cheap as a tank. So far, I have been very pleased with this unit. The endless hot water is very nice. Be careful though, if you have people living at your house that take "endless" showers, you might actually see a rise in your electric bill.

 

[ampsucker]

i'll lay a couple of thoughts on ya....

i personally believe the tankless popularlity is based on a lot of hype.

first, they require a significantly higher btu input. it is not uncommon for a tankless to run 180,000 btu input where a regular tankstyle may run 40,000. in a retrofit situation, going to a tankless will not only require a larger gas supply line but also a larger gas meter outside the home. this is because most residential meters are rated for 250,000 btus or so. if you have a gas fired furnace, theres 80-120K btus. if you are going with gas to save money, you probably have a gas cooktop/oven and a gas dryer. so, you can see that your originally correctly sized meter will not handle the tankless demand. add up the cost to change out the meter, replumb the line and install the tankless unit and payback period is not realistic. if you are building new, this is a lot easier and less work up front, but still needs to be factored into the payback equation.

second, to get the current 30% tax rebate, you have to install a qualifying system. most of these are either geothermal heat pump or solar systems costing 2,000 or more. MOST tankless systems, IF they save you money, do so by running on demand and not heating the tank of water. that doesn't mean they have a high efficiency rating when operating. ie, a significant percentage of btu's still goes up the extra large flue vent during the time they are on. this means you need to buy a high end tankless unit to get a high enough efficiency to get the 30% tax rebate. there goes the payback period again.

lastly, the tankless unit are being marketed as a one size fits all solution. they are not. they are best for empty nesters or single folks who are gone all day and only need hot water in the morning for showers and then not again until the next morning or something like that. a situation like this is where you MIGHT make a good savings by not having to heat a tank of water all day. if you for example have kids, do a lot of hot laundry or dish washing or have people home using hot water during the day, a tank model is the way to go. they will heat the water and have it ready for you and do so with less overall btu usage.

the newer, better insulated tankless units loose very little heat. i was recently away for 4 days weekend. turned the heater down all the way before leaving. when i returned four days later, i still had 110 degree water (down from 120). that's pretty good in my book.

one last tidbit. i know for a family of three with one being a toddler and doing lots of laundry that our bill to heat our hot water runs about 30 dollars a month on average. we use 4500 gallons a month of water. that was with our older 80% effecient tank style hot water heater that probably cost $350 when new. IF i was able to get a 95% efficient unit, i would be improving my water heating bill by 15% or saving $4.50 a month. over a typical life of say 20 years, the most i could spend on a new hot water system to BREAK EVEN is $1080. try to find a 95% efficient hot water heater of ANY type installed for less than 1100 bucks.

think about it. is it really worth it or is it all hype?

amp

 

[ampsucker]

i forgot to mention that one of the most important things you can do to save on water heating when building a new house to to properly design and insulate the water delivery system. this means centrally locating the heater, insulating all hot water pipes in the walls or slab and using pipes of the correct size to eliminate dead time or the amount of time the water has to run before getting hot at the faucet farthest from the heater. most folks err on the side of larger pipes is better for more flow, but this is usually overkill and just makes it take more water and time to get hot water from the tap. it is also better to use a slightly larger central line with multiple smaller tees to serve each room (kitchen, baths, bar, etc.) than trying to daisy chain all the rooms together in sequence.

you wouldn't design a natural gas or central heating system this way, but you would be surprised what builders and plumbers try to get away with thinking their work will be hidden and before the home owner ever notices it they will have their money and be long gone.

amp

 

[Pirwin21]

I agree that tank heaters are certainly more efficient than they used to be, but the novelty of the tankless heater is it only runs when needed. I grew up in a house that had a tank heater and for the last year, have had a tankless heater. I have noticed basically no difference in water temperature fluctuating and the amount of time it takes to get hot water between the two. The biggest benefit is that my wife and I can both shower in the morning without worrying about running out of hot water. I actually think that if you have several kids, it would provide the same benefit in that everyone can shower without worrying about the hot water. So long as this novelty of having eternal hot waters isn't abused, it is absolutely more efficient than tank heaters. They also make tankless heaters that are powered by electric. They do use a lot of current while in use, but the heater is only on for 45 minutes a day tops, whereas the tank heater is slowing using electric for 24 hours a day. I agree with previous posts that this application is probably more beneficial to new homes, but I believe that tankless is the way of the future and not a fad. They've been using tankless heaters in Europe for years now and we are really the exception in the world using tank heaters.

 

[fish6942]

Like has been said earlier, the efficiency rating (tanked or tankless) will make the biggest difference in operational costs. I'm looking at replacing my 80% efficient tanked unit with a 90+% efficient unit called Vertex from A.O. Smith. This unit has the capability of producing endless hot water even though it has a tank.

 

[ultrarunner]

I have both and there definitely is the convenience factor... especially around the Holidays when family comes to visit... other than that, I'm very please with my old fashion, tank-type heaters...

I just don't see savings because some will stay in the shower as long as the water is hot and with forced water rationing... this is a bad thing.

Also the cost to retrofit and shorter longevity can be quite expensive.... My first tank-less only lasted 7 years and would have cost more to fix than buy a new one... I have tank heaters 15 to 20 years... or more in my rentals and some of them cost a little more than a $100.

I just don't see the savings for a typical family with teenagers... It's also harder on the bathroom with all that steamed water on everything.