Know anything about these? Can you recommend a brand or type? I’m going to look at a bath remodel where the owner wants to switch to a tankless but does not have propone. He has done some research and come up with a unit that apparently will produce 3.5 GPM at 105 degrees, and requires a 100A circuit. I’m quite familiar with the gas units but not with the electric. 3.5 sounds a little low if the washing machine is filling up and you’re in the shower.
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Looking to dim the lights in the neighborhood? The numbers are a little optimistic for winter ground temps even in PNW.
Thought about building one of those once, but figured would need the whole 200 A for a decent hot water flow when the kids were still at home.
3.5 GPM = 1680 pounds per hour, at 50F rise from ground temp of say 55F on the island = 84,000 BTU/hr or 24.62 kW ; divide by 240 = 103A. NEC Code would want a 20% derating.
The other thing to consider is the distribution transformer. Often 5 houses with 200 A services are served by a single 50 KVA distribution transformer. Take a look what size yours is and how many houses it serves, you could be setting yourself up for some severe voltage drops.
"NEC Code would want a 20% derating."Not unless you take 3 hour showers.
>>>Not unless you take 3 hour showers.
...but just think...with a tankless you could take a 3 hour shower!! And watch the meter spin like DVD.
Not being an EE, but having a pretty good understanding of this stuff, I've often wondered why there has not been an exploration of other forms of electrical heating other than standard "resistive".
I am guessing that if you had a way to pull heat from the center of a live arc that you'd be on to something. Granted, we don't want to electrocute the poor schlep in the shower, but do you et what I am talking about here?
I'm picturing something that could sink heat from a live arc, but not be conductive. Let me get out my tin foil hat and think about this for a bit. . . .
Then again, if electric heating elements are already converting 100% of the electricity into heat, then maybe there isn't any more heat to be got from a given voltage and current. . . .
At my last job I worked on the design of large plasma arc torches (they were used to convert hazardous waste into nontoxic byproducts.) I remember when we got the very first one running; after a minute or so of operation I noticed that the video camera we had set up ten feet away to record the event was melting. :-)
So, they do kick out a fair amount of radiant heat but I don't think they would be a very efficient way to heat the house; if I recall correctly that first one had a 300kW power supply. They are now building them up to 3MW.
The arc itself is REALLY warm, around 6000 degrees C. We amused ourselves by using the arc torch to melt gravel.
Resistive heat does convert 100% of the electrical energy into heat, so there is no more heat to be gotten. And resistive elements are cheap and reliable.
If you want more energy from the electricity you use you have to get the heat from somewhere else. That's what a heat pump does, it uses electricity to "pump" heat from somewhere else, like the outdoors, in contrast to resistive heat.
We mainly use cronomite & emaax ones pretty spendy.
I don't want to start an arguement about efficiancy of electric tankless/point of use heaters.
They work & depending your rates determines if it is a good investment.
Oh by the way I have to be to work at 4:30am in Bellevue & pipe in an electric tankless. The box is 32" wide 24" tall about 6" deep.
Here is the kicker the dang thing is 36KW that's right it's 36,000 watts I'll take a picture of it & post it.
OK I know I took forever to get this pic but I kept forgetting my camera so here it is an electic tankless & yes it will spin a meter like a DVD
Wow. 36kw. That's 150 amps. So what size conductor is that, #1?
Do you know the cost and whether the owner is happy with it?
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Owner----- Westin Hotel
Cost--------Heater was about $3500 I heard------electicians said it was about $4000 to hook up about a 180' run they had to make.
I think they pulled #6 I'll check tommorow electricians told me it was a 50 amp service to the heater.
Owner happy?----- they just want hot water--- this was a lame brain idea to fix a circulating problem---- project manager was trying to play engineer.
Here is the problem this system is below the domestic boilers & fed through a PRV (pressure reducing valve)--- so the circ going back up is a lower pressure than the circs that are at the boiler level so they don't mix the hw goes stagnet & cools takes about 45min of flushing to get 120 degree water.
I could have fixed this by putting in a small circ pump just on this part of the system----cost---- about $100------ go figure
One last thing all this heater is -----6 --277volt point of use insta hots hooked in series.
>>>I could have fixed this by putting in a small circ pump just on this part of the system----cost---- about $100------ go figure
What a waste. I hate it when idiots convince management about stupid stuff, like a $7500 water heater.
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
David: We have the largest SEISCO made. Uses 4-60 Amp breakers. No, we don't dim the lights in the neighborhood, but when it first kicks on the lights in the bathroom dim a bit, but come back in about a minute or less. We get all the 100 degree water we want. It produces enough hot water at the DW that it will scald you if you stick your hand under it. We have been using it for over two yrs, & are happier than a pig in slop with it. We are going to buy one of their small versions for our shop, where we don't need as much hot water.
Our water comes from a well, so it is universally cold all year long. About 50 degrees F, or thereabouts. Guts are some sort of polymer, so don't collect mineral deposits.
Expensive, yes, but we feel they are really worth it. I think we paid about $600 for it. We'll never haver to replace a water heater, or get forced into paying someone to do so as in some jurisdictions.
Don
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