Is a preheat tank the right choice for me?

[strider3700]

I'm working on a solar setup to assist in heating my water during the summer.   My space is very limited within the house but in the crawl space I can add a second hot water tank.  I'm pretty sure that a preheat tank is the way to go but I'm looking for verification.

The house is empty during weekdays and the majority of our hot water is used in the evening for dishes after dinner and showers before bed.   The main tank currently is a top of the line very well insulated 40 gallon electric hotwater tank.  The tank I want to use for the preheater is an old bottom of the barrel 20 gallon tank.  I will heavily insulate the old tank since I need to build a box for it anyway.

My thought is if I was heating the main water tank then at night we'd use up the hot water and the regular electric heating would take place at night with the fresh cold water.  Basically we'd just be offsetting any standby costs of the heater.  So I was thinking I'd put in a preheat tank and heat it during the day.  Then at night the hotwater would come from the main tank and the tank would be refilled with hotwater from the preheater.  My cold water coming in is very cold.  Somewhere around 5 degrees celsius.    

Long term I'd like to plumb the woodstove into helping with the hotwater as well and due to the layout of the house a preheat tank makes this possible I think.

Does this make sense or am I thinking about it wrong?  At this point my largest energy user is the electric hotwater tank so I figure this project would be worthwhile.  

Thanks for any help.

[huntedheads]

How much does the sun light cost there? Here it's still free and any amount the sun warms the water going into your electric heater is money your saving!

Feed the electric heater 50 degree water or feed it 80 degree water I prefer the 80!

My thought on it.

[strider3700]

Oh sorry if I wasn't clear.  I will be doing solar heating no matter what.

My question is am I better off heating a preheat tank or am I better off heating the main tank directly?  

[elvin1949]

strider3700

 I would use a preheat tank if it was me.

later

Elvin

[spinningmagnets]

A Domestic Hot Water (DHW) pre-heater is often cited as the best bang-for-your-buck project. Build a box covered by an old glass door with the tank inside. No pump is needed as the municipal water pressure creates the flow.

With some scrounging and a few bucks, you'll be in business. Check out "builditsolar.com" for 300+ ideas.

[jonas302]

Sounds like a great project  Have you checked with your power company for off peak programs? I was interested in a solar set up but It would never payback for me I have 2 80 gal electric tanks and a 60 gal tempering tank costs about 6.50 a month I dont know if all companys have these programs though

[huntedheads]

Heat the preheat tank, even if the sun's not a shinin the basement is most likely warmer than the water supply.