German -

By definition - since you only have ONE Well - any two WH installed - are either in Series or Parallel.

Sounds like you are planning on installing in Parallel.

Your Electric Bill for WH's will essentially double.

However - WH's built today - are EXTREMELY efficient. Moving a WH out of a Heated space - and into an UNHEATED space - does increase base energy loss. Since the minimal heat loss - in a heated space - contributes positively to your home environment.

Crawlspace - less access. All WH's eventually leak - and one far away (40') much more difficult to work on; and see what condition it is in...

However - very doable. TWO - do of course also require TWO totally separate circuits. They draw a LOT of current - when ON. So you would have to run from your box - totally NEW wire for the second unit. Adding a junction box from the existing wire; for the second unit - WILL result in your circuit breaker constantly tripping from overload. (And if you 'cheated' and just increased the capacity of the breaker - WOULD result in a very overloaded supply wire; and a very unsafe situation...) TWO heaters - DO require TWO totally separate supply circuits.

You are discussing putting into a crawl space - for more room. A crawl space is unheated. You desire TWO WH's because the smaller unit is decreasing your available supply.

Have you considered building a small Insulated Box - mounted on the Outside of your house? Easy to insulate. Normal Height level. Emergency drain outside. Not hard to pour a small concrete pad. Insulate, and add appropriate siding. Put in a 80 gal into this INSULATED box. Heater will keep it warm. One heater; less electricity; full capacity.

The idea of water conservation is a good one. If you add two; or change location - CPVC pipe is very self insulating; and rated for both hot and cold. Then you can insulate as well... But it has less inherent thermal transfer - since it is not metal.

http://www.lubrizol.com/BuildingSolutions/FlowGuardGold.html

For instant Hot Water at virtually any outlet - while your doing this minimal work - add the following:

https://www.wattspremier.com/products.php?product=Instant-Hot-Water-Recirculating-System

Or Laing makes some similar products:
http://lainginc.itt.com/LG-pump-Autocirc.asp

With either one of these - if you run any new plumbing - also run a second dedicated RETURN line. (back to your WH). This will eliminate the 'tepid' warm water - which initially comes out of the Cold faucet - when your return line utilizes the Cold supply...

Either way - these systems do save a lot of wasted water; and truly provide almost instant hot water at virtually any tap.

D.

Also - for the previous reasons already given - building a small Box (for an 80gal) outside on your house - (with of course an access door) which you insulate and pour a small concrete pad - is probably going to be your best bet.

You mentioned that your current WH is 23 years old. Virtually No new WH built today - is going to last anywhere near that long. The tank walls are much thinner - for energy transfer; and consequently - they rust through and leak a lot sooner.

Have you considered the servicing and inevitable remove/replace situation in a crawl space??

For longevity - you are supposed to completely flush a WH every year. (I know - no one ever does.) It does help keep up the energy efficiency. Hard to see all that water leaving though...

But in a crawl space - no way are you going to be doing that... and when it starts leaking and needs to be replaced (9 or so years from now) a 35 gal water heater will weigh OVER 280lbs. (filled with water.) Hard to drain in a crawl space...

The more expensive 'LifeTime' WH's sold at the box stores are very well insulated. Available for around $240.

A very energy efficient WH which will NEVER rust through - or Leak would be the MARATHON. You could still of course build a separate outside sided and insulated box for it; (I don't think they make a short stubby version) but it is inherently VERY well insulated. No steel tank to rust. Available for a much better price (then found virtually anywhere) on special order from Home Depot. Probably Lowe's as well... Neither this one, OR most of the other WH's manufactured today - require a separate insulation blanket. In fact - an Insulation Blanket can shorten the life of a present day manufactured WH - by trapping heat around the electronic circuit board. (Just a side noteworthy comment.) For more info on the totally rust proof Marathon - please see below...

http://www.marathonheaters.com/

D.

Here is a link that might be useful: Marathon Water Heaters

My apologies. They do make a Marathon as small as 15gal - with a height of slightly less than 36"

They also make some other sizes including a 'stubby' 50gal with a height of about 67" (I think that is too high for your crawl space...) But a 20gal 3000Watt with a height of 34.5" exists...

What I like about these - is NO steel is involved. They will NOT rust through or leak. Not cheap though. Look around at their web pages and talk to Home Depot. Have them look into their special order book. They CAN get them; and at an EXCELLENT price.

http://www.marathonheaters.com/cons_specs.html

D.

Here is a link that might be useful: Marathon Sizes

Apologies again.

The 2nd 'reply' made reference to a "LifeTime" WH being available for around $240 from the large box stores.

That is aprox what the regular price was for a "LifeTime" 80gal (one time replacement) about 3 years ago at Lowes.

Just walking thru Home Depot; and noticed that their current 80 gal/12 year warranty (not "lifetime") WH is priced at: $645.00

OUCH!!

What with Oil, and Fuel - Prices have definitely taken a STEEP upward climb.

D.

"Any problems with putting an electric WH in a crawl space? "

No, apart from cussing during installation, maintenance and removal. The T&PR piping must daylight in an obvious place. Replacement anodes need be the segmented "flex" type with your low headroom.

"Would two independent 30-38 gal. WH present any real gains for us?"

Given your description of the second heater being used 40' away, the least gain is not waiting so long for hot water, which absolutely cuts down on well pump cycling. How the numbers work out for you regarding double standby losses, I dunno. New electrics don't lose much heat, but give careful thought to piping design/layout (thermal trapping) and attendent insulation to minimize heat loss.

"...I don't believe we'd be doing a parallel or series configuration in this example, just two cold lines out to two WH with independent hot water lines."

Yeah, why should this be complicated? Your electric bill won't "double" either, though of course, it will increase...offset by aforementioned pump running and probable radiant loss in the current 40' run.