To go tankess or not

[Eden]

If we were to go tankless it would be gas, not electric, but with all the problems they seem to have that is really sounding like a less likely option...

 

[Jadnashua]

In the right set of circumstances, a tankless can work, but they do come with generally lots more costs both up front and in maintenance along the way of its lifetime. Most people never touch their tank water heater until it starts to leak. A tankless can last longer, as parts are designed (often, anyways) to be replaced as needed, but that's if you can find them along with someone that knows how to do it. Some companies are better at keeping parts on older models, but there's no guarantee they'll be available. With the sometimes large up front costs which may include upgrades to power or gas lines, the regular maintenance, and the service issues, there often isn't any cost savings in the real world. If you size a tank properly, most people won't run out of hot water, either. Only you can decide if the benefits outweigh the detractions.

 

[Sponsor]

 

[Eden]

Hah - the cost of the tank heaters that have been recommended isn't really much less... although if we were to get a new electric one we'd probably put it in ourselves, and a gas one we'd have installed, which would of course add to the cost. Whether our gas line would up to the task will have to be looked into. I do know that because we are an earthquake prone area, all the old gas lines were replaced (or at least relined with a flexible material) sometime not too long after we moved in and all the meters were replaced with new ones that have a motion activated cutoff switch around the same time. What this means for our gas pressure, I haven't a clue. I do intend to go and chat with someone in the area, but I like to get a better idea of what to expect before I do that.

 

[WoodenTent]

Mine uses 3 x 40A for the electrical, if I open everything I got to max it out, it will go to 104A, which is the de-rate you mention. Typically a shower for me it will pull about 60A. So with a 1 shower house, plenty of margin. I have a 200A service, no issues. Here it's a matter of where you live. I grew up in country, so all houses are 200 Amps. Moving to an urban area I was shocked to find 100A to be the norm, but looks like that was largely due to Natural Gas service being around, and code hasn't yet banned anything less than 200A. So yes, people will be limited. But of course trying to run a big gas tankless unit will be a struggle for a lot of folks too. Upgrade to a 200A service is just a good all around idea, was one of the first things I did to my house, and certainly cheaper/easier than getting a gas service upgraded (if a person can get gas)

Far as getting water heated up, I experience no issues. Yes, it takes a few moments. But so does pushing cold water out of the pipes with a tanked unit. I do not see any difference in getting hot out of the facet verses when I had the NG tanked unit.

The biggest issue I see facing tankless units is flawed building code/water conservation code. As some things are power based (GPM) and other things are energy based (gallons). Sizing a tankless becomes difficult because code hasn't forced ever water using item to be "power based" with GPM limits so you can size to a worst case flow needs. Washers being the main issue. Modern ones pulse water flow, and don't have a limit on the flow. I put a flow meter inline to see what my front loader would do, it was in the 4GPM range for a couple seconds at a time. They need to get them limited to the same low flow rules as showers. Get devices that our based on Gallons to have flow limits too, and in the case of washers, store some of the water so it becomes a continuous flow, and you will be able to size tankless for houses much easier. In time if houses develop any form of power management, it will be even easier. When devices can talk and do things like command the AC to turn off while the Water heater runs, give priority to Ovens, have EV cars charge only when other items aren't using the power. When that happens then tankless will meet needs without concern of kicking a breaker.

 

[Jadnashua]

Many washing machines pulse the water on/off, and that can mean no hot water available since first, there's a delay in sensing flow, then a delay in reaching full temperature, then a delay in shutting off (often too short to overcome the pulse timing - continuing to run the heater with no water flow can quickly turn things to steam and create problems, so it needs to shut off pretty quickly with a stop of flow).

Most of the deciding factors on whether a tankless will work are related to two things:
- incoming water temp and the maximum rise required
- maximum desired volume
followed by the maximum energy available.

If your conditions fit, a tankless can provide satisfactory results, but the infrastructure, installation costs, maintenance costs all may overwhelm the costs of a tank which is much simpler that nearly anyone can maintain and service when the time comes.

 

[SteveW]

I am in process of deciding about what to replace some old natural gas tank water heaters with. I toyed with the thought of tankless but after reading about the various problems as described in this thread, and elsewhere, have decided to stick with tried and true tank technology.

Another resource is http://www.waterheaterrescue.com/Longevity/tankless-water-heaters.html

 

[Dana]

Lol - my bath is a much more zen like experience, but I will look into that water heater. I get the feeling it's time to go and have a face to face chat with a supplier.

A right-rectangular prism makes it even easier to measure the true volume, rather than just estimating the 95 gallons.

 

[Eden]

Well... even if I take some measurements and do the the calculations, which actually I did, it is still an estimate of how much water I use on any given day, because I am not so OCD that I have put a mark on the side to be sure I fill it to exactly the same level each and every time I use it...

Also it is not a right-rectangular prism either - it is first order trapizoidal tank, not that the volume of that shape is much harder to calculate (It may have been a some years ago, but I took up through calculus...and even got good grades), but again, no matter what shape it is, it doesn't matter if I don't always measure the water that I put in.

ahem.. I shall show my work - to the point at which I think I normally fill the tub... (46.25 +50.5)/2 *19*24 =22059 cubic inches =95.49 gallons...

total volume if it were filled to the brim (46.25 + 53)/2*24.5*24 = 28881.75 cubic inches = 125 gallons

 

[Randyacton]

I know this thread has been dead awhile, but I will throw in my 2 cents.

When we bought our house 6 years ago the water heater was dead so I replaced it with a Bosch tankless and don't regret the decision at all.

We are on propane and a well so the heater had to be ordered as such. Think it is around 155,00-175,000 BTU. Only paid around $1000.00 so it was actually cheaper than most tank models I was looking at.

The only issue/gripe we have had with it is that when the pressure tank recharges it takes 3-4 seconds for the heater to readjust to the colder water.

You can literally take a hot shower til the well runs dry and I figure that it has paid for itself already in the amount of propane it has saved vs. a tank model.

 

[Jermaine]

Just stumbled across this post and would like to give my thoughts. I actually prefer gas tankless water heaters over electric because it has a greater heating capability. That being said, it is also very important to choose the right gas heater. Buying a wrong one could be a disaster. I hope it will help you guys choose the right one.

 

[GTOwagon]

With two of us living in our home plus many guests coming and going, and seven loads of laundry a week plus washing dishes în DW four nights a week,our 75 gal Rheem power direct vent propane who is using about ten to 12 gallons of propane per month. At a price of $1.50 per gallon, on a heavy month that is 18 bucks. Whoopty doo. How much would I save going to tankless? Five bucks a month maybe? So how many years of saving $60-70 per year would it be to cover the nonsense. If I had I thought to do over I would of bought two cheaper fifty gallon tanks in series. If one stopped heating, I would be able to Still have HW while the parts were on order or I could replace the broken WH. Yeah,maybe the price for propane would be $25 a month, then... I wouldn't fool with tankless.

 

[Jadnashua]

There are situations where a tankless might make sense, but most of the time, a simple tank may end up a better choice. Modern tanks are more efficient in standby losses than the old ones and don't have some of the operational issues of a tankless.