Tank vs. Tankless Water Heater Questions

[trikkonceptz]

I have been researching the tankless water heater systems lately. Now if you go by all the propaanda written by the manufacturers they usually lean towards the tankless heaters being more efficient.

However, here is my question, I have run a tank system on a timer for a long time. Basically the timer has a bunch of off switches all at 15 min intervals. I have found out that my tank takes less than that to bring the water back up to temperature and allows for me and the mrs to shower with hot water, do laundry, etc.

I am getting ready to construct a home and will have the window to decide on individual tankless heaters at point of use or a large tank heater for a growing family. My concern is which is worse, 15 minutes to reheat a tank or 15 minutes of water being heated by the tankless ...

Anyone have data to help me figure this out?

And my immediate concern is not the rush of cold water coming from the tank but the energy needed to sustain a 15 minute shower or a more wasteful bath.


Thanks

[Laurentiu]

You live in FL, right ?

Here in Cyprus, 99% of homes are equipped with one of these and I find that between Feb-Nov (sometimes Dec), you don't need any electricity.

Also , having looked at these climate charts and compared Homestead FL & Limassol, Cyprus my advice would be : pull the plug and go green, you will thank yourself later on .

[ShadeTreeMech]

Google tank vs tankless water heaters and it should be a very informative read. I would steer clear of the propaganda sites and stick with the various reviews from average Joes.

But I would consider Laurentiu 's advise and consider a solar heater with a tank heater backup. I do know the electric tankless require a ton of instantaneous electric (to the tune of 14kW) for a larger house, and the gas tankless is nearly even in efficiency to a gas tanked heater, giving you a ROI of nearly 22 years according to one article i read. There are also water heaters that make use of otherwise wasted heat from your heat pump, which I'm certain you'll be using in Florida.

OMG I just found out about a great combo, a tank water heater that uses a heat pump! I'd heard about the ones that use the heat from the home heat pump, but here's one that is a stand alone system. A heat pump is inherently more efficient than a resistance coil in that it simply moves heat from one point to the other. This site from the Energy Star site mentions that it is most efficient if put in a hot area of the house (can we say attic?) because it puts out cooler air as a byproduct. (can we say stick it in the garage for a cooler garage??!!)

[trikkonceptz]

Thank you for the advice,

There is no doubt that I will look more closely at the solar tank heaters. I mean, here in S. Florida we don't even have a measureable winter.

In addition I am considering putting whatever tank type collection device necessary in the attic for additional insulation. I was in the attic of my current residence the other day and at 7pm it was still 105 degrees in there. Luckily the attics in these homes are large and tall thanks to the roof lines and all I would have to do is construct a door to remove said tank if it were to ever need replacing.

After that attic experience I need to look into attic cooling and the most efficient way set that up.

[Laurentiu]

of course, solar powered attic fans would be the most energy efficient, I was looking around at some sites, depending on the size of your home (and attic subsequently) it would cost ~500-600$.