Anyone have a tankless hot water heater??

Lots of great info here. I now know for sure that a tankless would not do for us. Once we had three showers and an tub going at the same time (family plus guests and we were all getting ready to go out). I was actually glad we had an 80 gallon water heater. Yes, that's 80 gallons. My parents have one too. It's big, but we have never run out of hot water, even if the dishwasher and washing machine are running too. I have mine wrapped in two layers of insulation, so energy losses have been minimized.

Maybe I could run 4 or 5 tankless water heaters in a parallel setup. That would increase capacity (as well as the price!).

 

I've heard that adding a tankless heater in the line before your traditional heater and using the traditonal heater as a storage tank can also work. Anyone have this setup?

This is purely curiosity since I live in a rented 600 sq ft apartment that shares a water heater with the rest of the building.

 

I was looking at the tankless.. I hot water baseboard heat. It runs off a propane powered furnace and uses a stainless stotage tank.

They make claims that they could replace the furnace, but would it be worth it since my furnace runs for heat also say mid-late Oct through mid March?

 

<div class='quotetop'>QUOTE(Catskillguy @ Jun 24 2006, 08:30 AM) [snapback]276312[/snapback]</div>

You would only run the boiler for the amount of time it takes to heat the hot water in the summertime, so the energy use in that regard is exactly the same (depending on the efficiency of the combo unit, of course).

My company makes a couple of "combo" units. The boiler water is used to heat the "domestic hot water" (the stuff you shower in) by a couple of methods. In one of our units, the boiler water is circulated through copper coil in a 40 gallon tank. In another method, the boiler water is circulated through a "flat plate" heat exchanger that has numerous small passages in it ... on one side of the passage is the hot boiler water and on the other side the cold water flows through it "on demand" and becomes the "domestic hot water". Flat plate heat exchangers are what is in most of the tankless designs ... the hot water being circulated by the heater is exchanging the heat with the cold water flowing through it when you turn on a faucet.

You have the benefit of NOT having a burner on the bottom of the tank. In your typical hot water heater, the burner is on the bottom of the tank, and over time, sediment builds up on the bottom of the tank (just like it does when you boil a pot dry on the sink). Purdue did a study a number of years ago that showed that the build up of even 1/8" of sediment lessened the efficiency of the tank type water heater by several percent. As the years go by, your efficiency drops to about 60% ... the sediment actually insulates the bottom of the tank preventing heat transfer. It also gets hot enough to "snap, crackle and pop" as the water heats up. In either the "coil in a tank" or the "flat plate" heat exchanger, your efficiency on day one is your efficiency after 5 years. (There are some exceptions; flat plate heat exchangers may need to be "de-scaled" also, but that is done by removing it and running vinegar through it, rather than replacing the entire heater).

Tankless water heaters have this same benefit, by the way. No sediment build up in the bottom of the tank.

Usually, combo units only make sense if you have a space problem, or have both your boiler and water heater go out at the same time. OR, you have to replace one, you get a good deal on a combo unit that is much more efficient than the boiler you have now, and you qualify for the tax credits. Then it could make a lot of sense. Some of the older boilers are 78% efficient; newer ones can be "up to 98%" ... but that efficiency rating is never acheivable with baseboard, radiator or radiant in floor heating. You can achieve 85% efficient with those systems (the reason takes a little bit of explaining, but I can go into it if you want).

 

<div class='quotetop'>QUOTE(fshagan @ Jun 24 2006, 12:54 PM) [snapback]276366[/snapback]</div>

Can this be done by the homeowner or does it have to be done by a plumber or repairman? I have hard water and thought I had to install a water softener with the tankless to prevent scaling and buildup. That's been the big thing delaying me.

 

<div class='quotetop'>QUOTE(Godiva @ Jun 24 2006, 11:43 AM) [snapback]276375[/snapback]</div>

Do you know what the hardness is? It is usually expressed in terms of "grains per gallon", but can also be expressed in "parts per million". For example, the Rinnai and Bradford White tankless design state you can use them in water hardness up to 11.7 grains per gallon, or 200 parts per million of hardness. The "total dissolved solids" cannot be higher than 500 parts per million. I would imagine the others are similar. Your water utility will have the water quality information; the library may have it in a quarterly report.

Can you clean the heat exchanger yourself? The manufacturers all recommend that it be done by a service person, as you have to disconnect plumbing unions from the exchanger, unplug molex connectors, and properly purge the heat exchanger of air upon reinstallation. But I would say a person with good technical skills, who can replace a faucet or garbage disposer, would be OK with it.

 

<div class='quotetop'>QUOTE(JackDodge @ Jun 22 2006, 12:16 PM) [snapback]275277[/snapback]</div>

Ban this person! A post like this should not go unpunished!

Tom

 

My water is treated by Alvarado. My hardness range is 10.9 to 17.1

So, does that mean I'd have to install a water softener "upstream" of the tankless system?

 

<div class='quotetop'>QUOTE(Catskillguy @ Jun 24 2006, 10:30 AM) [snapback]276312[/snapback]</div>

If you already have a hot water system for heat, a simple plate heat exchanger is used to heat domestic hot water. This company makes them and I've used their products in the past with good results

http://www.weil-mclain.com/netdocs/ultraplus.htm

Seasonal efficiency is much higher if you use one of the newer "low temp" water heaters. Cast iron heaters must use a mixing valve in the manifold to prevent return water from "shocking" the boiler and cracking it. Newer aluminum heaters can directly run in low-temp mode and achieve amazing efficiency

http://www.weil-mclain.com/ultra/modelultra.htm

If you already have a geothermal heat pump system, a desuperheater can be used to provide most or all of your domestic hot water needs. All of the geothermal heat pump systems here are configured with desuperheaters to heat domestic hot water.

As far as the issue of water hardness, you had better use a water softener upstream of the water heater. Regular hot water heaters have a short life with hard water, especially if there is rust in the water as well. The scale buildup really buggers things up.

 

<div class='quotetop'>QUOTE(Godiva @ Jun 25 2006, 11:34 AM) [snapback]276549[/snapback]</div>

Yep, you need to get the hardness down below that 11 grains range.

There are a couple of options. One is a monthly service which, when I last checked, ran about $22 a month. They install it and maintain it. The other is to buy a softener and have it installed. When I did mine, the payback was about three years over renting by the time I paid for the softener and materials to do the installation (I had 100' of copper pipe in there as well ... expensive!)

The softeners use "ion exchange" to trade the hardness ions with sodium ions. If you use your tap water for drinking water, and are limiting salt intake because of a specific medical problem, consult with your doctor. If you use bottled water for drinking, you are OK in that respect. The water is safe for most houseplants and pets, as we're talking about very little in the way of sodium in the water.

I like our softened water ... our hardness was 22 grains here, and after the softener went in we really did find we could use less detergent in washing clothes and dishes, which we found a beneficial aspect from an enviornmental aspect. I was concerned about the salinity of the water discharged during the regeneration process, but our waste water here flows to the ocean after treatment, so the salinity issue is not as important as when the waste water is used to replenish aquafiers (I'm sure the same is true in San Diego).

The softener will have benefits even with the standard, tank-type water heater, making them last much longer. If you are not planning to stay longer than five years in your present house, then I'm not sure the expense of a softener and tankless is worth it. A tank-type replacement water heater should run around $350 to $400, and will work fine.

In San Diego, I suspect you use a hot air furnace, so the combo units don't make sense for you (no sense spending $5,000 on something you won't really use). A tankless water heater might make sense, but it does sound like you need to find out if any can be used with hard water.

 

Well, I don't know how big water softeners are but I was planning to put it in the same space as the tankless water heater and only soften the water going into the water heater. I have a huge crawlspace underneath the house so if it won't go in the closet it will go right below. That's where the water pipes come from up into the closet.

I plan on staying in my house until I die, which hopefully will be longer than five years from now. I'm only 51.

I don't drink much tap water as it doesn't taste so hot. I am supposed to limit my sodium intake but I don't think softening just the hot water is going to impact that much. It will be nice to use less detergents.

Thanks for all of your info. I think I have much better grasp of the situation when the time comes.

 

<div class='quotetop'>QUOTE(Godiva @ Jun 25 2006, 05:19 PM) [snapback]276621[/snapback]</div>

Winnipeg has soft water as it is piped all the way from Shoal Lake, Ontario (Near Kenora on the Manitoba border).

At my hobby farm, the water not only is VERY hard - 28 hardness - but the well water has rust as well. I have a Sears rust treatment tank and a Sears UltraSoft 800 water softener to treat BOTH the cold and hot water.

The only water not treated is the hose bib on the outside of the house. I have a second hose bib for washing the car that IS treated, otherwise I'd end up with hard water spots on the car.

I'm sure you're close enough to a large Sears store to have a peek at their line of water softeners.

There is maintenance associated with water softeners, not just adding salt. You sometimes have to run a chemical treatment - sodium hydrosulfite and sodium metabisulfite - to clean the scale and rust buildup from the resin bed. With regular water softener salt, that was as often as every month. I currently use Windsor Rust Remover salt, and only have to clean the resin bed every 4-6 months

http://www.windsorsalt.com/soft/rustremover.htm

 

I went for a tankless in our NW Oregon home. Our 40 gallon water heater broke last year and I knew the tankless was perfect for us. We have a small home, rarely need two hot water appliances running concurrently, and we use hot water only in the morning and the evening.

They make units large enough for a large family but we only needed a moderate sized Bosch. I went for one with an impeller driven pilot light so there is no gast wasted on maintaining a pilot light. Our cost savings have been significant. It is now unbearable to me the thought of paying so much to maintain a large reservoir of hot water when you may not even be home.

There are drawbacks, the faucet flow is less than when we had a tank because part of the incoming water needs to be split both to the hot water and the rest to the cold. We try not to do laundry during showers, things like that but you get used to those really minor inconveniences when compared to the space savings and the energy savings.

If you are constantly using hot water during the day, this is not likely for you. For the 95% of the rest of us, I personally think it is a waste not to get one.

We project a payoff in 3 years for the installation expenses ($1100) and the unit itself was only about $600. Installation is not rocket science but venting perfection is not something you want any error in. These units have very specific airflow requirements and venting needs for safety.

 

We use the Rinnai tankless heater. It is rated at 180k btu or 190k btu on propane. It will produce 6 gpm at a 50 degree rise or 4.6 gpm at a 70 degree rise. A typical shower temperature for a shower might be 98 degrees F. and about 2.2 gpm. Our incoming water is 70 degrees F. That means that you can operate around 4.5 showers at the same time before the unit is maxed out and they will never run out of hot water.

We install them in all our homes and usually install them on the exterior of the building. They are freeze protected to -30 F as long as you have electric power. Installing them outside eliminates the need for exhaust venting, combustion air venting, PTR plumbing, emergency pan and plumbing, and saves at least 9 square feet of interior space. It also keeps the gas connections outside.

It is the size of a small carry on luggage. They are quiet and reliable. Installation should include hosebib attachments on the incoming and outgoing sides of the heater along with cut off and isolation valves. This makes draining the unit or decalcifying the unit quite simple for a home owner with the ability to say hook up a washing machine. A small pump, a five gallon bucket, a couple of gallons of vinegar and 30 minutes are all that is required. I have needed to do it once after 3 years on the well before we switched to rain water.

By the way, the Rinnai provides thermal efficiency up to 88% and energy factor up to .87 so it is close to the best tank type heaters but with zero standby losses.

The unit comes with a remote control device that is installed in the house with slave controllers available for multiple locations. The control allows control of the temperature of the water and will give the temperature and gpm of the water leaving the unit as well as trouble codes in case of problems. For instance a code of LC means that limescale buildup in the heater needs to be addressed.

Not sure what brand others are talking about on this thread but the Rinnai is apparently superior to them in about every way. When installed outside in climates that allow it, and in new construction the cost is no more than a standard tank type that must use venting and real estate. I highly recommend their use.

The downside is in getting them serviced in the rare instance of failure but that is improving as they break into the american market.


<div class='quotetop'>QUOTE(DocVijay @ Jun 24 2006, 07:35 AM) [snapback]276277[/snapback]</div>

Three showers and a tub at the same time are not a problem for the Rinnai. We have been there and done that.

 

<div class='quotetop'>QUOTE(Ray Moore @ Jun 25 2006, 07:07 PM) [snapback]276719[/snapback]</div>

I've also heard good things about the Rinnai unit (in fact, my parent company private labels their unit under the Bradford White Everhot brand name). They are larger than some of the tankless units out there, at 199,000 BTU/hr, so that's why they can really put out the hot water.

Their literature lists an energy factor of .82 for natural gas (the .87 is for Propane models), so for most customers, that's what they will get. They aren't listed in the GAMA directory, but they may not be a member of GAMA. They do have a web site that says they are eligible for the tax credit of $300 ... see http://www.tanklesstaxcredit.com/

I don't work in that division of my parent company, so I don't really have hand's on experience with them. I didn't specifically recommend them, or any product, because I work for a manufacturer. Now that you've mentioned the brand name, I felt it was important in the interest of full disclosure to let people know I work for a company that sells them under a private label. I try to remain objective and independent, but people should know that I might have a bias that I don't correct for when making their decision.

 

<div class='quotetop'>QUOTE(mcbrunnhilde @ Jun 22 2006, 12:18 AM) [snapback]275083[/snapback]</div>

I had the Aqua Star for about 5 years.
I unstalled it myself, not a big job, if your replacing a gas heater in the same place their is only miner plumbing changes.
Aquar Star tech. help is excelant. I had one problem about 4 years age which was miner but it took a long time to figure out, it was a sticking sencer switch, just a few strokes with a file and it was been fine ever since.
I does take a longer time to get hot water to the tapes but once its runing I have never run out of hot water.
Two people showering at the same time is no problem, filling the hot tub, its hot water all the way to the top.