Tankless Hot Water Heaters (specifically gas)

Hi,

We put two Rinnai R85i units running on propane in our new lake home in SW Virginia. Each serves one half of the house (left/right) keeping the runs of pipe shorter. We also made provision for adding an additional heater in each location if we found that the amount of hot water was not adequate.

We are pleased as we can be. We love always having hot water regardless of how many people are staying with us. We don't have to worry about being the last one to shower and having no hot water.

For now we only stay in this home during the summer and not paying (when we are away) for heating water that nobody is using is a plus. Yes you can turn off a tank but then when you arrive you have to turn it back on and wait. With the tankless units anyone can drop in at anytime and have hot water.

Based on our experiences to date we will be putting tankless units in any future home we may build.

As an aside the home is built using SIPs and the heating and cooling costs are amazing, much less then our previous six year old stick built home. A neighbor with an older stick built home of about half the size pays around twice as much for heating/cooling. Highly recommended.

Regards, Frederick C. Wilt
 
I have not seen much dialog here on brands. If any one has a brand they love or hate, I would like to know that name. I am building a new house so I don't have to deal with retrofit cost. Although gas is a better deal here in Oklahoma than electricity (I think), I decided on electric because the locations I wante to put my main unit and some other booster units would have created major headaches for vents and connections needed for gas.
I did some web reasearch and eventually decided to spec the Stiebel Eltron Tempra model for my builder to use. If anyone have any good/bad to say about that unit, I would like to hear about it.

Like the other guys in the souther climate, I decided that the temperature rise I can get from a tankless unit will meet my needs.
 
Solar HW works well in many northern climates. Heck, I live in NORTHERN virginia, and I have no problems! :rolleyes: The cost equation for tankless is different if you are retrofitting vs. installing new.

If you are installing a NEW unit with the same type of heater, than you're almost always better off with tankless. For example:
1) You were planning to install an 80g propane water heater. A propane tankless is going to save you money.
2) You were planning to install an 120g electric water heater. Installing 2 electric tankless systems is going to save you money.

This makes the assumption that the tankless systems are within a couple hundred dollars of the storage tank systems of equal quality. Compare apples and apples (eg: if you are shopping for a bosch tankless system -- cadillac -- compare it with the high end, high efficiency water heater system).

If one unit can't heat your water enough because the incoming water is too cold, or because you need to draw more GPH than the unit is rated, the solution is to install two tankless systems (either in parallel or in series, depending on the problem. )

In my case, my builder included an 80g electric water heater with the house (for free). Replacing it was a no-brainer (electric water heaters have the highest operational rates, have slow recovery times, therefore they need to be sized larger, and therefore they have higher standby losses). Once I compared the cost of the tankless vs. solar, it was an easy decision. A good tankless system would cost a few thousand dollars installed (no chimney in my house, so it would need to be power vented if I put it where I wanted it to go), and after the tax credit, I could get solar for only a bit more.

Operating costs on solar on paper are pretty good. For fun, I'm measuring my actual performance now (instead of using electric heating element, I have to run 3 pumps) to determine how much the solar saves over normal electric. I can use a Kill A Watt to determine the cost for the solar pumps, but I have to find some way to meter the electric backup heating elements.
 
Steve said:
Ranger Digital said:
tank water heaters should just be outlawed. I cant imagine even wanting to install one. Tankless is the only way to go, IMO>

You dont have to install gas to save energy. the electric tankless saves money as well.

Tankless is just NOT expensive. I dont get the complaints on the cost.
Click to expand...
That sounds like a very emotional reply from a happy customer who either has a financial stake in tankless sales, or doesn't really know all the facts :rolleyes:. I should be a better candidate being in Fla as my temp rise is not as great as the great white North. But... we don't have gas, so either I would need to bury a really big tank or use electric. Going the gas route is not practical to depend on for something like hot water because what if the tank runs out early - you have to call the gas company and hope they can send out a truck between normal trips to refill - not too practical. So that really only leaves electric. Depending on flow rate, temp rise, etc I would need a rather large unit to cover the house. The large electric heaters are an absolute beast, taking up to 150A. Considering the whole house is only a 200A service, that means putting in a whole secondary main panel. That would run in excess of $3000 (probably closer to $5000). The unit itself is probably around $800 and then installation. So, I am looking at least at $5k just to install it. Now look at how much electricity is gonna cost me to run it. I think it would be like a 20-30 year payback last time I did calculations. Bottom line is they do have their place and work well in many circumstances, but nowhere near all. Looks like I'll be replacing my 60Gal tank with a new efficient 80 and call it good.

Now Ranger, if you want to pay for the up front costs, then maybe the tankless would be worth a try :rolleyes:
Click to expand...

In my world, I stand behind my claim, OUTLAW TANKED WATER HEATERS, lol. Besides, I think your numbers are WAY off. Look at other brands? Redo the math? Something is not right. Also, a tank in-ground is SO common I am surprised you quickly rule it out. Maybe Florida is different than the country of Texas. :rolleyes:

No I have nothing to do with a "stake".
 
Well, worrying about running out of gas isn't an issue for me....I'm going to end up with a 500 gal tank in the ground, and currently the only item we have that consumes gas is a kitchen stove, which uses about 25 gal a year.....so I think I can up the consumption a bit before I need worry about suddenly running out...
 
Well, I've solved one of my concerns...I've found a tankless water heater (Rheem) with a 90 deg rise at the lowest rate. That means I can manage a 5+ gpm rate with a 65 deg rise. I just measured my ground water temp today, and it was 52. So I'm not concerned anymore that a tankless just wouldn't have the umph to do it.
 
Hi,

Running out of gas is not likely to be a problem.

For example (in very round numbers) the R85i uses up to 180,000 BTU/Hr. Propane has about 90,000 BTUs per gallon. So we are going to use around 2.5 gallons an hour running the heater at max. So if my wife and I each take a 15 minute shower (and we use so much hot water that we max the heater) that's about 1.25 gallons a day.

I've got a 1000 gallon tank in the ground and yes there are other uses of hot water and propane but 1000 gallons of propane is going to go a long way.

So you can see we have plenty of time to get a refill.

Regards, Frederick C. Wilt
 
During my recent and multiple mass power outages. I have learned whatever you do, do it with gas. :rolleyes:

I was being the nice guy and told the people next door if they provided the outdoor extension cords I would help them out with power assuming they kicked in on the gas. Both had tankless electric heaters... So they at least got hot air. Unfotuantely then I had to deal with them wanting to take showers at my place which was counter productive. I can understand it being a PITA to retrofit gas but at this point I would go way way out of my way to do it if I had to, luckily I don't plan on moving for a while so I can swap the tank out if need be.

So if it comes down to $250 more to go gas (which I doubt for most), I won't bat an eye. 30 more days taking sponge baths from a 25 gallon pot I heated on the BBQ, %$^#$^ that!!!
 
Here's a well written explanation on evaluating the standby heat loss of the tank:
http://www.leaningpinesoftware.com/hot_wat...ank_insul.shtml

The conclusion is that a typical 80g tank @ 120 degrees in an roomthat averages 60 degrees, and the tank with R16 insulation, will cost $36 in standby loss. In general, I'd probably double this calculation because of thermal losses through the piping, through the pressure relief valve, the drainout valve, etc.
 
CollinR said:
During my recent and multiple mass power outages. I have learned whatever you do, do it with gas. ;)
Click to expand...

Hehe...well, I'll admit Collin...I referenced your plight often when we were making design decisions in the house. Because of the possibility of the big snow, we spent the extra to get a generator subpanel for the house (just enough to keep going, essentials only, off a portable generator) and it was a consideration when we chose to get a gas kitchen stove and wood burning fireplace. Even if such a catastrophic event happens once every 10 years....that one time can be the difference between an inconvenience and a survivial situation if you're prepared.

So I'll admit, it is also a factor in deciding which water heater system to get. If we went electric, I'm fairly sure we would NOT put that on the generator subpanel...too much possible draw. But a tankless gas water heater is a trivial draw electrically, by comparison. Besides, our strategy would be to just use the generator for a couple hours a couple times a day, which with a tank would present its own problems keeping the water hot.

Thanks for that website, pol123. That might just contain enough info for me to finally try and compare heating costs for electric and gas water heaters, since I know how much BTU are in a gallon of propane, and how much that gallon costs....so maybe I can finally compare actual costs to heat 50 gallons. For what it's worth....
 
beelzerob said:
CollinR said:
During my recent and multiple mass power outages. I have learned whatever you do, do it with gas. ;)
Click to expand...

Hehe...well, I'll admit Collin...I referenced your plight often when we were making design decisions in the house. Because of the possibility of the big snow, we spent the extra to get a generator subpanel for the house (just enough to keep going, essentials only, off a portable generator) and it was a consideration when we chose to get a gas kitchen stove and wood burning fireplace. Even if such a catastrophic event happens once every 10 years....that one time can be the difference between an inconvenience and a survivial situation if you're prepared.

So I'll admit, it is also a factor in deciding which water heater system to get. If we went electric, I'm fairly sure we would NOT put that on the generator subpanel...too much possible draw. But a tankless gas water heater is a trivial draw electrically, by comparison. Besides, our strategy would be to just use the generator for a couple hours a couple times a day, which with a tank would present its own problems keeping the water hot.

Thanks for that website, pol123. That might just contain enough info for me to finally try and compare heating costs for electric and gas water heaters, since I know how much BTU are in a gallon of propane, and how much that gallon costs....so maybe I can finally compare actual costs to heat 50 gallons. For what it's worth....
Click to expand...

My tankless water heater draws less than 1 watt in standby, then 60 watts for a few second for the ignition, and then 15 watts for the fan to vent the unit outside. I keep meaning to throw a UPS on it and not have to worry if you are in the shower and the power goes out :D

I also put a small generator switchpanel in that can select up to 10 circuits and has a 30 A rating. I can hook up my 5K generator and run a few things at a time (forced hot air heat, or one or two AC's, or microwave, refrig a few hours a day etc). I have it 6 years and never used it other than testing it every few months.
 
Digger said:
I also put a small generator switchpanel in that can select up to 10 circuits and has a 30 A rating. I can hook up my 5K generator and run a few things at a time (forced hot air heat, or one or two AC's, or microwave, refrig a few hours a day etc). I have it 6 years and never used it other than testing it every few months.
Click to expand...

Ya, that's pretty much exactly what we'll have. It's the classic case of spending $$$ and making effort for something you hope you'll never have to use. ;)

However, we're quite rural, and even worse, low property tax rural....so if there is an outage, we'll undoubtedly be last on the list to get repaired.
 
[/quote]
I am a builder in West Texas and have installed gas tankless water heaters in almost all of our homes. No customer call backs or complaints. I just think everyone should have one. I've been in our new 2500 sqft home (4 bdrm, 3.5 bath on slab) for over 2 years and absolutely love our unit. There is no circulating loop and it takes only about 3 minutes to get hot water to the master shower (heater about 35' away) - about the same as a tanked unit. When we have a family gathering with all the kids and grandkids, we always have hot water! The unit for this house is the Noritx 0751 series. (http://www.noritz.com/homeowners/products/view/0751_series/) For larger homes that I build (3000 sqft or more), I install the same unit with an insulated circulating loop with UPB smart switches in each bathroom to turn on a UPB smart receptacle at the water heater to turn on the circulating pump. An Aqustat turns the pump off when returning water in the loop reaches a set point of 100 degrees. [/quote]

Where does the circulating pump put the cold water? And what products do you use?
 
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