Tankless Water Heater & Traditional Combined?

[ItsZep]

I have a small log cabin that I just built. Space was very limited so I was advised to have a "low-boy water heater" installed in the rather large crawlspace under the cabin. The problem is I like to take long showers and if guests are there the hot water runs out pretty quickly. There is only one shower in the cabin. So my question is...would it it be dumb and/or possible to now after the fact add an electric tankless system combined with my low boy so that if the low boy ran out it would automatically kick over to the tankless system? Also is it possible to go with an additional low-boy that would kick in as first ran low?

 

[Terry]

So much of that depends on what you have on the electrical panel. To heat water for a shower takes so much more at a time then a 4500 watt element that simmers the water over time. A standard 50 gallon tank takes an hour to heat 25 gallons. That's 1/2 gallon a minute.

 

[Sponsor]

 

[ItsZep]

Thanks Terry for the response. I am not much on anything mechanical/electrical. Are you thinking I should just convert completely over to electric tankless? By the way this cabin is primarily a weekend get-away.

 

[Leon82]

Rather than switch between the 2 it may be better to preheat the water for a tankless unit. Maybe mix the tank water to 90 deg or so.

So you will get a decent flow from an electric unit.

 

[Reach4]

I think he was mainly saying that your electrical service might not have enough capacity to power a tankless WH.

 

[ItsZep]

Thanks guys.....I think I would have enough electrical...but I will check.

 

[Terry]

The easiest fix would be to add a tempering valve on the water heater you have, and then crank up the thermostats.
You can run the water heater hot, and blend it down to a usable temperature.

For tankless, to run one shower you need something like 2 gallons per minute. If you can run that from the panel it would work.
Something like this could be nice.
https://www.rheem.com/product/point-of-use-tankless-electric-rte-27

RTE 27 (27kW/240V) requires two dedicated 60 AMP breakers

 

[Jadnashua]

Read the tutorial on tankless in the tutorial section - it will give you some insight on the energy requirements...electrical tankless systems generally are not a great idea, and require very significant power capacity. WOrk very well for say a sink, but a typical showerhead, especially if you may be dealing with cold well water, or winter cold water temperatures, you'll likely be disappointed. It would be rare to have 120A free capacity in your electrical panel, and much more may be needed.

 

[ItsZep]

Ok guys thanks a bunch. I will do some homework and get back with you.

 

[ItsZep]

re: "The easiest fix would be to add a tempering valve on the water heater"

Terry is this what you are referring to?

http://www.sharkbite.com/product/tankbooster/

 

[Jadnashua]

That would work, but may not be the most economical choice. It's probably the easier choice, though.

 

[Dogwell]

That would work, but may not be the most economical choice. It's probably the easier choice, though.

Jadnashua, can you please help with a cheaper option? I can't find anything cheaper than what ItsZep posted above. Many thanks!

 

[Jadnashua]

There are numerous ways to add a tempering valve. If you can't solder, or don't want to, then a pre-configured one is easier, but that ease of use costs more. IF you can solder, something like the one in the sticky at the top of this forum topic would probably be cheaper. If not, there are a couple of choices...the Sharkbite approach or a kit like the Honeywell-Sparco one

 

[John Furbee]

You would be better off using an on demand water heater that way you only use energy when it is needed. The gas units can produce more hot water but for showers an electric will do just fine without ever running out of hot water. When you are away you don' have to worry about shutting it off. It only comes on when you need it. Some of the smaller electric units will work on 110v but most require 220v 50-60 amp. Check the specs on the unit you pick. Generally the more amps the more hot water. I'm using a single gas unit for whole house 3 br, 2 bath. There is a delay getting water hot in the bathroom further away which wastes water. We're remodeling a larger house, 5 br, 3 bath. We plan to use a gas heater for kitchen & 2 baths that are close togeather. The third bath & wet bar will run off an electric heater.