Electric Hot Water Heater, Tank Or Tankless OR Multi Tankless? - Appliances - DIY Chatroom Home Improvement Forum

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Old 10-16-2015, 02:32 PM   #1
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Electric Hot water heater, tank or tankless OR multi tankless?

Hi everyone,

I am hoping to hear from some people that have had experience with 2 or all 3 of the listed hot water heaters in my posted subject. I will be moving to a rural area next year, building a house and am trying to decide what electric water heating option would be most efficient. I had assumed that tankless would be best but I spoke to a planning engineer at the local power company and he said that the tankless units use more power than the tanked ones since they need a huge boost right at the start BUT, the tanked ones turn on and off all day and night so I am lost! Then I stumbled across some posts online from people using multiple small units and wondered if that would be even better such as, 1 in the master shower, 1 in the guest shower, 1 in the laundry room and 1 in the kitchen etc. It will only be my wife and I in a 2000 sq foot home with a little rug rat on the way. Any info is appreciated!


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Old 10-16-2015, 06:53 PM   #2
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Old 10-17-2015, 01:32 AM   #3
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Opinions vary......here are mine:

1. Tankless systems require large energy inputs for a short period of time. Thus you have to oversize the feeder systems.....wire, breaker, panel, gas pipe, valves, etc. POCO's are moving to demand charge billing systems, you should check that out. Tankless systems require more maintenance especially in hard water areas or will require you to install water softener system. Then there is the "cold water sandwich" syndrome in most tankless systems. Look it up it may affect your decision.

2. I have my water heater on a timer. It saves me energy, but there are many people out there that disagree. Depends on how you set the timer up and how well it matches you hot water usage patterns. I use a lp gas "power shot" heater which works well on a timer. Power shots are noisy and the timer also quiets the house in the middle of the night.

3. I attached a heat pump supplemental system (a Nyle Geyser) which I run only in warmer weather and it also is on a timer. Very good experience with the Nyle and I highly recommend.

4. Finally, I installed Metlund hot water recirculating systems throughout the house. I save a lot of cold water from going down the drain and a certain amount of hot water.
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Old 10-17-2015, 01:40 AM   #4
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Good points made by Dan ^^^

Is gas or propane an option? If so, you could save there.

What is the climate where you are going? If a warmer climate on average, then a hybrid water heater might be you best bet. It's basically a heat pump....depending on your air temp, it can be 2x-5x more efficient than a resistive water heater.

Usage......if you are home all day and using hot water throughout the day, a tankless is not really saving you anything. The heat losses on a tank water heater are only of any significant value when water is only used for a very short period of time during the day and stays idle for long periods.

I did a lot of research into tankless units when I was planning my 2-story addition. When you factor in the higher cost of the unit, they are not that much of a good deal. If you have gas.....it's not even a fair argument.
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Old 10-18-2015, 11:38 PM   #5
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I am pretty much against tankless units for the reasons above plus when you need parts, they are all specialized, expensive and on back order. Tank type go to the hardware store and you are back in business.

I don't know about reliability concerns, but a heat pump unit ought to be the most energy efficient solution. No way you could use a heat pump on any kind of tankless but they cause the energy efficiency to be well above 100% and heat loss through modern insulation is not that bad.

Last edited by Hoek; 10-18-2015 at 11:51 PM.
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Old 10-22-2015, 05:28 AM   #6
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I have a natural gas tankless and find it to be a mixed bag. Besides the energy savings it can provide (exactly how much will of course depend on household usage patterns) the biggest plus is not having to worry about the eventual tank leak and damage that causes. Which should hold true for an electric setup.

One big negative is that being sized for whole house usage means supporting multiple usage applications (one person taking shower, while also washing clothes, etc) means that the heating element does not cut on until the flow rate is >= 0.6 gallon/minute (IIRC), which is a high flow rate if just washing hands at the kitchen sink or even when taking a relaxed shower. And on top of this flow rate issue, there is extra lag in getting hot water at the tap, since it takes some time (seconds not minutes) for the element to reach operating temperature as compared to having a tankful of hot water waiting at the ready. So I find that we now sometimes use a higher than otherwise needed water flow rate + need more water to flow through before getting any hot means that the cost savings and environmental impact is not so clear cut (e.g. now using more water than before).

I am just a consumer, but it was my understanding that 5 years ago, an electric whole house unit was not cost effective due to the big energy spike needed to provide instant hot water. That said I have been intrigued by the smaller electric units at each service point, which should minimize wasted cold water traveling through your hot water pipes. I am not sure if they are economical yet, and there may also be physical mounting space and electric wiring costs to consider, but I like the idea.
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Old 10-23-2015, 12:34 PM   #7
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There are quite a few variables involved in a successful tankless system.... inlet temperature, flow rates, delays, ampacity... etc. Where I live for example the inlet temp can vary from 33 degrees in the Winter to 60 or 70 in the Summer. Unless you're quite a bit oversized, that would have a drastic affect on output quality. At any rate, all of this has to be thought of and if all the variables are considered and met then a tankless system works.

From my POV however a tank system is much simpler since almost none of those variables affect it. Just pop a proper sized tank in, and it works regardless of any change in the variables.

If you want to take a risk to try and save a buck or two in operations.... go tankless. If you want simplicity and reliability than a tank is your only answer.
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