Dimming Lights when Water Heater Cycles

[Johnxa]

Hi-

History:
I've recently remodled my kitchen so I decided to upgrade the electric water heater that was located in one of the cabinets. I decided to install a tankless model to save space and energy. The new heater required two 40 amp breakers, double pole, 240 volts and has two heating elemets. I saw no problem in upgrading to this heater because the existing water heater outlet had a 40 amp, 6GA service already there. The other 40 AMP circuit came from the double wall oven circuit. During the remodel I opted to get a single range to replace the cook top and double ovens. The cooktop 40AMP independent circuit now runs the entire range.

Problem:
When I turn the water on I hear the first element in the water heater kick in and all appears normal. When I turn on more water the second element cycles on and off to compensate for the additional demand. This is where the problem occurs. The lights brighten and dim when the additonal demand is required and the second element kicks in (syncroniously). It's very annoying...

More history:
My condo is all electric and has radiant ceiling heat (7 zones, very expensive to run) a personal sauna and has A/C. I've tried turning everything on to see if there is any change or if anything blows but all appears normal. Every appliance in the kitchen has its own circuit (fridge, range, water heater (2), dishwasher, micro, disposal). 200 AMP main.

Any advice is appreciated.

John :D

[Ohm1]

Check your name plate, and make sure the rating in volts and amps meet your load demand.

also, most H2O's do not require a grounded (AKA Neutral=wht) conductor. Example--using a 30 amp circuit: All they normally need is a 10-2/w grd. The neutral on this 10-2 can be reidentified. Yet, if you have 10-3, then cap off the wht conductor.

Get back to us. You may have destroyed your second element, do to over heating--from no water being in the tank when you first hooked it up. I've seen guys leave the breaker on--when a H2O had no water inside. This destroyed the element.

Get back to us, and check to see what others have to say.

[Johnxa]

Hi Ohm1-

I'm talking about a tankless water heater that requires the neutral. These tankless water heaters are the next generation water heaters that come in either gas, propain or electric.

If you have time, please see the following url:

http://www.tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/manuals/ae115125_manual.pdf

See page 3 or model 115



John

[Speedy Petey]

I have done several of these. One I did took 4 (four)-30 amp 240v. circuits!

This may be inherent in this unit and you wiring system. I am not convinced of this since you are all electric and why is this not happening with other things.
Have you checked the amperage? If the elements are the same there should be the same amperage on both elements. You may have a bad connection on that circuit and it's upping the amperage.
Or... it just may be the 60 or so amps being drawn while the heater is running. These things draw huge amperage for short periods of time as opposed to moderate amperage for longer periods like a conventional heater. Probably nothing you have will draw this much amperage all at once.

Those ceiling heaters you have really suck, don't they. I've had to rip many of those out for customers and all hated them. I have hot air heat with the vents in the ceiling and I detest it. I want to run all new duct work for the heat and keep the ceiling vents for A/C.

[Wgoodrich]

Ohm is partially correct. You do not use a neutral wire in this heater. What you read saying "ground" is an equipment grounding conductor not a neutral wire. Your heater uses two hot wires reading 240 volts between the two hot wires and an equipment grounding conductor. No neutral is used.

However this model is rated for 40 amps not thirty.

You are using a pile of power on demand. You may be experiencing a service wire too small to carry the load at the distance from your transformer that is set. What you may be experiencing is a lag in power due to the large drain on the power.

First make sure your heater is wired 240 volts with an equipment groudning conductor but no neutral wire.

Next tell us if this water heater is coming directly from the main service panel or a sub panel.

If from a main service rated panel no sub panel then take off the cover of your panel. At the main breaker where the service conductors feed that main service panel read the voltage without the heater running then turn on your water full so the heater pulls full load. Then test that voltage again same place on the line side of the main service panel. Tell us if voltage drops on water heater load.

Curious

Wg

[alwayslearning]

No neutral is used.
Wg


More off topic, electrical theory questions, if it is not too irritating...

Is the reason for no neutral on this 220 setup because they do not expect any "unbalanced loads"? Seems like UL's are the explanation for the neutral on other 220 hookups, such as a dryer, hot water heater etc.
Thanks as always!

[Ohm1]

I spoke on 30 amps as an example. Yet, WG is correct. Get back to us with the question I asked.

[Speedy Petey]

WG,

A quote from the original post.
the existing water heater outlet had a 40 amp, 6GA service already there.
Along with the other 40amp ckt. from the wall oven.

I don't think an undersized wire is the problem.

[Ohm1]

I want open the file, but if someone could paste it, then this would be nice. I haven't seen or heard of the new generation tankless Hot Water tanks. This sounds great! I spoke on no neutral (reidentifying NEC 200.7) in my first response, but if the new one accepts a neutral, then I would like more information on this unique creature!!

[Wgoodrich]

Alwayslearning;

Only appliances that have 120 volt components required a neutral wire that carries the unbalanced load of 120 volt components in that 220 volt appliance. This tankless water heater has no 120 volt components but only 240 volt components with no need for a neutral wire serving this appliance only an equipment grounding conductor and two hot wires reading 240 volts between the two hot conductors.

Speedy Pete;

Sorry I did not word my last reply very well. This units uses two double pole 40 amp breakers with two branch circuts requiring 8 awg copper or larger for each of the TWO branch circuits serving this unit. We are speaking only of the 125 modle. If it was the larger unit it would require THREE 40 amp 240 volt breakers on three different double pole breakers. Total combined load of the model 125 he is asking about is 80 amps for that one appliance only.

Now consider the 80 amp load for this water heater on demand then add the cooking appliances alone and you are pushing 200 amps without the rest of the house load being involved. This is why I questioned service size and distance between utility transformer and main service rated panel. Also this is why I wanted to confirm this 80 amp combined appliance load is coming directly from a main service rated panel not a smaller sub panel which would compound the problem of dimming of lights.

Ohm;

Look at your first reply on this subject. Look at the original posters reply just before that. You will find a PDF file you can open to read the manufacturer's specs on this on demand applaince model 125. Quite enlightening !

Hope this helps

Wg

[Speedy Petey]

WG,

My mistake. I didn't read close enough to see you mentioned the service wire being too small. Sorry.

[Johnxa]

Hi-

Just a short message to let you know what’s going on... Thanks for all of your responses and advise...

I decided to hire a licensed electrician to evaluate the problem and to validate that wiring was done correctly (this is always money well spent). The wiring was done correctly but we overlooked one factor.

The heater is wired into the sub-panel/breaker box and not into the main. In most circumstances this would be adequate, however, the main box is located about 150 yards + away from the box. This causes a lag creating the lights to flicker as the second heating element kicks in. The water heater was designed to pulse the second element if the demand was there. And most of the time it does. I reduced the temp on the water and the problem went away...but I like hot showers.

The 200AMP main was adequate since we did not add an additional load and used the wall oven circuit. The electrian did state that the flickering is minimal and that he has seen plenty worse...

Since I can't wire into the main I've decided to get a traditional tank water heater. The flickering bothers me even though the electrician claims that everything is safe and to code.

Is anyone interested in buying this heater? It retails at Home Depot for $430.00 but I'm willing to deal. If not, it will be up for auction at EBay.

Thanks again for all of your help!

John

Speedy Petey…

This radiant heat is such a joke…it will be the next upgrade on my list. This condo has high loft style ceilings and it takes forever to heat this place. If I turn it off it will take two days to heat again.

The builders overlooked the fact that this area is a high-humidity foggy area and mold runs rapid…. Oh well, it could be worse. The view here is awesome and I can see all of downtown San Francisco. It’s incredible!!!

John

[Wgoodrich]

To wire that heater correctly you would be requried to install TWO 8 awg copper branch circuits on TWO different double pole 240 volt breakers. That is a total amp load of 80 amps. Your oven or range only pulls 1/2 that. You then added other cooking equipment in load also. You may still be able to do it if you can run directly to the main service rated panel.

Good Luck

Wg