I have a tankless water heater that I need a transformer for and I'm not having any luck for. Plus, I don't really understand the purpose of the transformer anyway. The voltage, freq. and resistance is the same both in and out

1) Copy following link for wiring tankless electric water heater:
http://waterheatertimer.org/How-to-wire-Tankless-electric-water-heater.html

2) Look at label on side of unit for total KW

3) Product manual shows 24 Kw or 24,000 watts
24,000 watts divided by 240 volts = 100 amps
So your service panel must be about 250Amp rating to support this tankless electric water heater.
http://waterheatertimer.org/pdf/Tempra_tempra-plus-Tankless-electric-water-heater-manual.pdf

4) Look inside the unit to see how many L1L2 terminals show.
You should have two sets L1L2 terminals
http://waterheatertimer.org/images/Terminals-2-tankless-200.jpg

5) You need TWO 60 amp double pole breakers to supply power to this unit.
This means you need TWO #6 wires from one breaker going to L1L2.
And you need TWO MORE #6 wires from 2nd breaker to other set of L1L2 terminals.

6) Add comment for more help Jan 2013

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

11-2-12
Copy following links for Rheem tankless error code 11, and other useful resources.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Tankless-error-code-11.pdf

Repair tankless water heater, any brand, same day, yourself for around $350 by replacing 1 part > the whole thing.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Before calling service technician, copy following link for troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If tankless comes on when HOT tap is turned on, then that is normal.
If tankless comes on when cold is turned on, then you might have crossover:
http://waterheatertimer.org/Crossover.html
If tankless comes on when single handled faucet is lifted in center, then that draws water from hot pipe and will activate tankless > so don't install single handled faucets to save water heater energy, regardless what type water heater you have.

Tankless require monthy-to-yearly maintenance to avoid common error codes. The product manual recommends yearly service. Since Rheem does not post service manuals, you generally have to pay somebody to take apart and test the unit. The cost of this far outstrips expected savings from owning expensive water heater that requires lots of maintenance, yet is heavily promoted as the solution to water heater problems.

Never install tankless water heater is best way to avoid complications of expensive water heater that is maintenance heavy, hard to diagnose, expensive to fix, etc.
Never expose tankless to more than 11 grains hard water.
http://waterheatertimer.org/pdf/Rheem-CondensingTankless-maintenance-2012.pdf

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Which type Richmond water heater?
Is this a tankless water heater or tank-type?

Tankless are notorious for 'cold water sandwich' under exact conditions you describe. You might need tankless with larger BTU burner.
Don't install a tankless.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If you have tank-type water heater, then I suspect a clog in the hot water line, or single-handle faucet cartridge in show is going bad.
Same problems can contribute to tankless problems.
http://waterheatertimer.org/Low-hot-water-pressure.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Before calling service technician, open following link for troubleshoot resources including Rheem chat and contact, possible manual, error codes, etc.:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

C8 76 is generally bad PC board. Call 800-432-8373
Just like a motherboard on your computer, the tankless PC board is operational center of tankless water heater.
Various sensors gather information from water pipes, gas line, vent pipe, and air supply to determine when to activate burner.
Most people understand that when their computer motherboard needs replacement, that computer will probably not work reliably again.

Tankless is basically connecting a complex computer to your plumbing and electrical lines and to a gas burner with a vent pipe to outdoors, despite knowing that plumbing lines, vent pipes, gas burners, and household electrical systems have plenty of problems on their own.

Age factor: When tankless is new and everything operates perfectly, the tankless works correctly.
And each tankless manual recommends yearly and monthly maintenance, just to maintain operation, the cost of which can exceed the expected 1-8$ monthly savings. And who wants to clean the water filter each month and delime the exchanger every year?
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Don't buy a tankless water heater because the only folks promising unlimited hot water and effortless water heating experience while saving money with a tankless are the tankless promotors.

Solve most tankless problems yourself, same day, any brand for about $350.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Here's Bosch's A2 error code pdf:
http://waterheatertimer.org/pdf/Bosch_A2_error_code_troubleshooting.pdf

Want the truth?
I answer Bosch, and other brand water heater questions at fixya.
Never, ever install a tankless water heater unless your wallet is 2" thick and you enjoy nuisance problems that you can occasionally fix yourself plus doing recommended continual maintenance.
Tankless with never pay back, otherwise the news would be filled with stories of people saving money. The only reports of savings comes from sellers of the product. Averages savings on gas bill is $1-8 per month, but all costs are energy.

I cannot recommend a solution to fix the Bosch problem if trained service reps cannot solve problem.
If other product-owners report same problem with that model, then problem is likely related to software and/or PB-board problems, which is same as saying your computer motherboard is no good. And most people know that when a computer motherboard has failures, then the computer is unreliable and should be replaced.
Always research a product before buying.
You can solve most tankless problem yourself, same day, no waiting for parts, Sept 2011, for about $350.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Sell the defect tankless for parts, or get up to $12 per 100 pounds for scrap metal at the recycler.
Other resources that you can read:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

New remote control costs $99/ June 2011
Error 76 is communication problem between remote and water heater.
Open following link for step-by-step troubleshoot, and Rheem tankless resources.
http://waterheatertimer.org/pdf/Rheem-error-code-C7-76.pdf
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

1) All tankless water heaters require voltage to operate electronic sensors and circuit board.
This is true for gas and electric tankless.

2) Check that circuit breaker is not tripped. Push circuit breaker all the way one direction and then all the way back other direction.

3) There are fuses located inside the tankless unit, so check your manual for location of each fuse.
Manual is filled with useful maintenance and troubleshooting steps.

4) Before calling service technician, open following link for troubleshoot resources including manuals, Rheem on-line chat, and useful links for maintaining tankless water heater.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

5) If you had nearby lightning strike, I don't know if your tankless is protected from surge.
I recommend whole-house surge protector for tank and tankless water heater electronics, and household circuits. Surge protection is installed in main breaker box, and is replaced after each surge event. Separate protection needed for co-ax TV satellite, co-ax surge protection can be found on some ordinary power strips.
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#surge

Rheem makes a number of tankless models
http://www.rheem.com/products/tankless_water_heaters/

They make a tankless 95 outdoor series
http://www.rheem.com/product.aspx?id=EBA80FAA-3C0F-411D-AF83-82061C28ED1B

The 95 outdoor series spec sheet says .4 GPM minimum activation and .26 GPM flow to keep burner activated. The colder the incoming water, fewer users can take a shower at once.
http://globalimageserver.com/fetchDocument.aspx?id=ea5f0816-dfd4-4bcf-a605-79945619f5bb
The .4 GPM and .26GPM numbers are fairly typical for tankless units.
These numbers are good when the unit is new.
After a few years the number may be different because the tankless is a high-tech machine with sensors that are susceptible to particulate in the water, and susceptible to perfect-functioning of other parts in the machine.
The outdoor series spec sheet says the tankless is good to minus 30 F.
But remember that's when the unit is new.
Outdoor tankless water heaters have an electric heater that keeps water pipes inside the unit from freezing, as long as electricity is ON.
If electricity goes off, the house stays warm inside for several hours.
But a steel box located outside would get cold immediately without electric heat.
The electric heater adds standby cost to operational expense.
The tankless has a heater, but you still have to protect the incoming and outgoing pipes.
If your incoming water is very cold, the tankless heater may not be able raise the temperature fast enough to give two showers -or- even 1 shower depending on age and efficiency and capacity.
You can add a tempering tank located in naturally warm area that passively pre-heats incoming water before it enters the tankless burner.
It might be best to locate tankless inside the house >> and use direct vent through the wall for both incoming air supply and outgoing vent gas.
If incoming air is taken directly from the living space, then tankless will draw air into the house through cracks and around doors.
A lack of sufficient air, or poor air quality can cause the burner to shut down.

When buying a tankless, read the spec sheets and really ask questions about everything you don't understand.

it depends how much water you use. you may want a 5 gallon model. the tanklwss heat the water as needed and the tank kind heat justr the 2 1/2 gallon so if you use alot of water go with tankless most of the tankless are gas so you would need a supply and exhaust