ECN Forum Forums General Topics of the Trade General Discussion Area Load calc for added bath with 26850w on demand w/h

The main heat losses in DHW are always, [no matter what system you select], in that little piece of pipe between the heater and the faucet. Every time you draw hot water, that length cannot be used and the heat is lost...
A conventional modern foam lagged storage cylinder, properly sized for family needs, has very low heat losses because the surface area is low compared to the volume stored. Surely the additional costs of new panels and wiring able to carry over 120 Amps will never get recouped?

Has anyone seen geothermal H/C equipment yet?

The main advantage of tankless water heaters is the fact that you cannot run out of hot water, no matter how many people shower.
In Europe this is even worse, since our typical tanks have reheating times of up to 4 hours. Typical tanks around here (for a single family home) are 150l (roughly 40gal.) and either 1500W 230V or 6kW 400V (3 elements). In Germany electric tankless heaters are fairly common, usually being 35A 3ph 230/400V. In Austria they aren't, because all our power companies will flat out refuse to connect such large residential loads (if the #@*$ thing alone draws more current than your service supplies you can't just connect it without asking).

These days with the low flow shower heads, it is pretty hard to run out of hot water. I am starting with 80F "cold water" anyway most of the year. I put a small water heater in the attic to get hot water into the far bathroom and kitchen a little faster. In the summer the element seldom comes on.

Ok so i got a sub-panel for disconnecting means, debating wiring with 1/0 aluminum romex rated at 120amps re 75 degree 310.16 (customer also bought that 5 years ago for different part of house he's no longer improving, I have experience terminating alum. but no real expans./contraction evidence heating at top end most subs are only loaded about 1/2 load, in my experience. otherwise #4 copper,

Alright chris, stop and slow down, sometimes I look at my posts and think how can anyone decipher what I'm trying to say......my concern is will aluminum feeders at near top of its load capacity expand and contract too much to be safe? I've only heard that some people don't use it as a rule.....or is there enough cushion in the tables to allow for that of course proper torque and no=alox being used. or is the load too high for aluminum?

I assume you must take this considering the source but the Alcan guy says aluminum wire performs better in the typical aluminum lug than copper.
If you properly torque the lug and use the goo I wouldn't worry about it.