Haw do i hook up the wires corectly for a hot water heater

have you got hot water coming through the cold tap?
not possible unless the pipes are not connected corectly

Anon, It would only work if that was meant to be hooked up that way. Check the specifications in the manual or the plate on the heater itself. Check the attached links,instruction and guides, 1st link shows typical wire hook up on both 120 and 240 v. Good luck .
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Copy following link to help identify timer:
http://waterheatertimer.org/Boxtype.html
http://waterheatertimer.org/How-to-wire-EH40-hot-water-heater-timer.html

March 2013: Add a comment and describe timer in detail

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Most Larger water heaters are 220 volt ac single phase. This means you need 3 wires, two hot wires one neutral or ground. You will need to come from the breaker box off of a dual breaker of 30 amps or better. See the manual with the new heater. In your breaker box you have two sides or in coming service. The right side and the left each side is hot 110volts ac. you need to pull one leg (hot) from each side into the dual breaker out to the heater connections. The ground or neutral wire is un-insulated copper. Run these wires out to the heater. One black hot at 110 vac, one white hot at 110 vac and one plain copper ground.

Links below show specific wiring diagrams and explain 240V with two hot wires vrs 120V with hot and neutral wires.

Then if you have more questions, add a comment and I will fill in blanks:
http://waterheatertimer.org/How-to-wire-water-heater-thermostats.html
First diagram will be for your water heater.

http://waterheatertimer.org/B220C.html

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No. You have to find out if you have 3 phase or single phase power. If this is a new unit you will find a wiring diagram inside the front cover. 3 phase power has 3 "hot" wires. Single phase has 2 "hot" wires. There is a big difference when you hook it up wrong. I don't know if this is a new installation or if you are replacing an old one. The terminals are numbered for 3 phase. If you look in your breaker box, 3 phase 208 will haven a breaker with 3 spaces hooked together by one bar. Single phase will have two spaces hooked together by a bar. So if the breaker kicks out it will flip all 3 space on 3 phase or 2 spaces on single phase. If you already have wires to the location of the booster heater, you may have to use single phase if that is all that is at that location. If you have single phase power you will have to look at the wiring diagram and you will see the terminal block represented for both single and 3 phase. Normally running from the terminal block will be six wires marked 1 through 6. The wireing diagram will say something like "for single phase put 1,3,5 on terminal 1 and 2,4,6 on terminal 3. Leave terminal 2 out all together. Of course at this point your 2 hot wires will go to terminal 1 and 3. There are other considerations as well. With 3 phase the circuit wires will be smaller gauge and may not carry the current you need for single phase. This is a booster heater. You need to hook up your hot water line to go into the heater and the boosted hot water to your appliance. It will not work to heat your water for other purposes. It is meant to take 140 degree water and boost it to 190 degrees. Good luck, hope this helps

Call an electrician. you have hooked up wiring wrong

you will need to have a 115 curent for electric, run a line off the panel box, turn off water to the house drain it down, disconnect the lp gas line and cap it off, remove the water heater, install the new heater run the cold side water to the cold side {blue on the heater} the hot side to the red, take the cover plate off on the water heater run the wires, hook up the groung wire then the red and white wires to the wires comming off the panel box,, fill the water heater with water have a open faucet on the hot side, and bleed the air out, DO NOT TURN ON ELECTRIC TILL THE AIR IS OUT OF TANK AND WATER IS FLOWING THRU COMPLETELY, after you get water commming out of the faucet turn it off and turn the electric on to the water heater ,, wait about 30 min, you will have warm after an hour it will be hot and you are done,, good luck write me if you have questions, [email protected]

did you turn the unit off before hooking it up ? Any function on a tankless rennai the pwer has to be turned off and the priority button has to be pushed in,, if you have the manuel it tells you haw to do this,,