Will Service Support.....

daArch

Before I take another step in the direction of having a tankless hot water system installed, I was fearful my electrical service was not enough.

The main breaker is 200 AMP

The tankless (Steibel Tempra 29) requires 3 x 50 AMP breakers and has max amps of 120

All well and good, BUT being on well water my well pump (Grundfos 10S05-9) is on 2 x 20 amp breakers. I can not find what it's max amp usage is.

Since the hot water would be used for dishes and/or laundry, throw in those machines.

In the summer, most likely the following would be drawing electricity at the same time:
Swimming pool filter - 2 x 15 amp breakers.
Refrig - rated 7.9 amps
Window A.C.'s - rated 12 and 9 amps
Basement Dehumidifier - rated 5 amps


Plus other normal lights, computers, etc.
One good factor is that the kitch range is gas.

And then I may want to run my table saw or radial arm.

Our winter electrical draw goes way down and should not be an issue. The oil burner is only on a 15 amp circuit. No pool filter or AC's

Have I calculated correctly that I am pushing the limit?

Can any one suggest whether I can safely have the tankless heater installed or not with my existing service?

thanks

-Bill

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Wallcovering Installations by Bill Archibald|paperhanger|Eastern Mass|Greater Boston Area|Dover|Wellesley|Franklin|Sharon|MA

JohnJ0906

Without more info, we really can't do a real service calculation, but I am almost certain that 200 amp service won't cut it.

Also, those things have a reputation of causing all your lights to dim when they operate. As well as your neighbors that are on the same transformer.

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John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

daArch

Thanks John,

Even if it's ify, I ain't gonna do it.

But is there any more info I can supply for you to have a better idea?

Number of breakers and amps?

Average kwh per summer months (875 in July 08)?

Other uses that may be used at the same time?

Family of three?

I just gave an outline cause I thought even the basics were reaching the limit.

But hey, if it'll dim my neighbors' lights, it may be worth it

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Wallcovering Installations by Bill Archibald|paperhanger|Eastern Mass|Greater Boston Area|Dover|Wellesley|Franklin|Sharon|MA

Speedy Petey

Those tankless pieces of junk are sold as the greatest thing, but then reality sets in and they are realized to be no better (cheaper). ESPECIALLY if you figure in the cost of installation/upgrades.

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woodchuck2

X2, i have to agree with you on that.

Ponsse

Have to disagree with you on that one Petey, at least on the gas ones. I put a natural gas one in my house and I love it. If you don't use the supposed savings as an excuse to buy one, everything else about them is a plus.

1) I never run out of hot water, my wife has a huge soaking tub which we could never fill completely before with enough hot water.

2) As most women do, she never used to come out of the shower until the hot water was completely gone, and then I had to wiat 1/2 hour before i could shower. Not anymore

3) The water is always the same temperature, it doesn't keep dropping as the tank empties.

4) It's small, before I was always trying to reach around the storage type water heater to access my furnace, not anymore.

Mind you I also think the electrics are junk, but if you have natural gas or propane, and also a wife or kids, it's the only way to go.

Speedy Petey

I should have clarified that one. Gas units are different, just as in regular units.
I will say though, I do know that you need a HUGE gas supply to feed them.

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Grumpyplumber

Bill, these guys are reiterating what I said about electric tankless's before.

For the added cost of wiring, upgrades & the unit itself, you'll save about $5 a month in standby heat loss over a 50 gal tank.

There is utterly no efficiency difference on electrics, the only savings is standby heat loss and that comes to about $5 a month.

Start talking about a gas unit and it's a whole new ballgame, they work very well, you save about 30% off the gas for hot water atop that $5 a month.

Consider also the fact that maintanance is going to be more expensive, the parts for these units aren't exactly stacked in the isles at Ace hardware.

Parts for tank types are relatively universal.

daArch

Thanks guys,

As I said a while ago, gas is not possible for my application. There is literally no place to vent. With decks, porches, windows, etc etc, venting would be either REAL ugly, or real expensive.

Also, as stated, a lot of gas is needed, refitting the line from the tank would be costly.

Electric is the only practical way.

I've considered all your input, and will replace the water heater with another one, not a tankless.

thanks

-Bill

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Wallcovering Installations by Bill Archibald|paperhanger|Eastern Mass|Greater Boston Area|Dover|Wellesley|Franklin|Sharon|MA