NG on demand water heater

[J_J]

You can get an electric one instead, but they take 2 or 3 x 220v circuits, around 90 Amps.

If you have a family sized 4+, you really won't save any money on fuel, it just means that you'll always have hot water.
These are very good though to use in a holiday house that you hardly goto.

I have one of these units, but not hooked up yet. It has a 9600 watt rating, at 220v, and it will draw 44 amps. You hook it up with #10 wire.

Another thing is that it is not always working at 9600 watts. Inside the box, it looks like three tubes, with the electrical elements inside , and some thermistors and relays. So I am assuming that it uses what ever power is required to heat up the water at the time and duration of use.

And then, there are the under counter hot water devices for coffee, soups, etc. These are actually little hot water heaters with cold in , and hot out, and I am talking coffee hot.

 

[Redneck in training]

I have one of these units, but not hooked up yet. It has a 9600 watt rating, at 220v, and it will draw 44 amps. You hook it up with #10 wire.

Another thing is that it is not always working at 9600 watts. Inside the box, it looks like three tubes, with the electrical elements inside , and some thermistors and relays. So I am assuming that it uses what ever power is required to heat up the water at the time and duration of use.

And then, there are the under counter hot water devices for coffee, soups, etc. These are actually little hot water heaters with cold in , and hot out, and I am talking coffee hot.

We used one of those 10kW units when living in our garage while finishing our house. It was a pain to take a shower because the unit was able just barely supply hot water at low shower flow. The shower had to be adjusted just about right otherwise it was either too cold or too hot. It seems to me that it takes more power for constant substantial flow than 10kW. I would think 30 or 40kW could do it. There is also difference in temperature control. Our small unit had none. There was only a flow switch. I am guessing that some of the big units have electronic control that will be able to maintain set temperature regardless of flow rate.

We also have installed hot water recirculation in our house. There is a small pump pushing hot water from HW heater to the house. There are thermostatic valves located strategically under most distant vanity in bathrooms. When the temperature of the water in the thermostat drops below 90 F the valve opens and connects hot to cold water line and allows water recirculation. When the temperature raises to 100F it closes. That way the hot water line is always held at at least 90F. The trade off is that cold water line contains water at about 80F.

 

[heehaw]

i bought an installed the hot water recirculating pumps a couple months ago: it works great, even though it does put warm water into the cold water line: costco has dropped the price of the unit from $170 when i bought it, to $140. i do have the pump turned off right now, but will turn it back on when we have company.
heehaw

 

[J_J]

If the recirculating system were installed during the building phase, then I think you could add a third line from each of the valves and route back to tank. Also, I would insulate all the lines. With a house already built, and adding a recirculating system, then a third line could also be added through the attic/basement and back to tank.

 

[heehaw]

this pump system was a lot easier to install than a third line, i like the way it works, an like i mentioned, i just shut it off when not needed...
heehaw

 

[J_J]

These are some picture of one of the electric hot water heaters.

There is a 5000w heating element inside each tube, which are in series. There are some SCR to control the voltage to the elements. There are temperature sensors inside the unit and also a knob to regulate the heat.

 

[heehaw]

great pictures: thanks: i tought a NG on demand water heater was a waste of money, until i priced a new NG 40gallon water heater: kinda put things into a new light. spend a couple hundred more and get a unit with a longer warranty and cheaper to operate.
heehaw

 

[BobRip]

I have one of these units, but not hooked up yet. It has a 9600 watt rating, at 220v, and it will draw 44 amps. You hook it up with #10 wire.

.

I am pretty sure that #10 wire is only rated at 30 amps. This may be some special use, but it seems strange. #8 is rated a 40 amps.

 

[J_J]

I am pretty sure that #10 wire is only rated at 30 amps. This may be some special use, but it seems strange. #8 is rated a 40 amps.

You are probably right. I was trying to recall from memory but my data banks are full , and I lose some zero's and one's in my recollections. Anyway, each element is 5000w X 2. At 220v that figures out to 45.45 amps. So #6 is the better choice.

Now, you got me thinking about the wiring for my plasma cutter. I may have to rewire of keep the amps down when cutting.

 

[BobRip]

Now, you got me thinking about the wiring for my plasma cutter. I may have to rewire of keep the amps down when cutting.

Welders (I don't know about plasma cutters) can have smaller wire for some reason. It's probably the low duty cycle. I believe (don't quote me and double check) you can use #10 on a 50 amp circuit. Sounds a little crazy to me.