Using 220v single phase water heater on 240v 2-hot wires

[Waterant]

Hi guys,

I need advice from someone with experience with 220/240v systems.


My water heater was leaking more and more and the only replacement I found which will fit and is in stock right now was Quick B3 60L Round Water Heater.
with stainless steel tank, right dimensions and price.
I ordered 220v version because the old one was 240v so it sounded like the proper replacement.

The installation was easy but when I started doing the electrical connections I noticed they want one hot, one neutral and one ground. And I know for sure my boat's 240v system has 2 hot wires with 120v on each and one ground ( there is no neutral on 240v wiring).

The only thought I found on the Internet is to proceed with connecting the second hot to the heater's neutral wire because the system voltage between hot and neutral will be 240v which is what the heater wants.

I asked the manufacturer and they said this heater is a single phase 220V and use a professional electrician to install it. Which does not help much.

Question is: can I connect one 120v line to hot wire of the heater and the the second 120v line to the neutral of the water heater to get 240v total ( this is how the old water heater was connected and how my ac pump and ac units and the stove are connected )?

Anyone has any experience in this area?
Thanks in advance

 

[twistedtree]

It's probably fie to wire it to L1 & L2 of your existing power system, but I'd check one thing first. Use a meter to confirm that neither of the heating element connections are also connected to the metal screw-in part of the heating element. The should be isolated.

 

[O C Diver]

I would look at the thermostat and over temperature switch on the water heater. My recollection is that 220 and 240 volt thermostats and over temperature switches are supposed to switch both lines as both carry voltage. 120 volt thermostats only need to switch the positive.

What does the label on the water heater say regarding voltage?

Ted

 

[Waterant]

> What does the label on the water heater say regarding voltage?

It says 220v and the manual says +-10% so 240v will be fine.
A good point about the thermostat breaking both lines, but if one hot line is open and one is closed, there will be no circuit?

> Use a meter to confirm that neither of the heating element connections are also connected to the metal screw-in part of the heating element.

Thanks, I'll check

 

[porman]

The water heater in our 430 says 220 volts on the label, but is wired for only 120 volts. I assume it's wired that way so there is hot water when the only available shore power is 30 amp 120 volts. Does your boat have a washer/dryer? Ours does and it would have to be removed to replace the water heater. Not looking forward to that.

 

[Lepke]

Sounds like a Euro heater. They use a single line 230v line and neutral. And run at 50hrz.


US power won't work w/o a transformer.

 

[twistedtree]

I would look at the thermostat and over temperature switch on the water heater. My recollection is that 220 and 240 volt thermostats and over temperature switches are supposed to switch both lines as both carry voltage. 120 volt thermostats only need to switch the positive.

What does the label on the water heater say regarding voltage?

Ted

Very good point.

 

[O C Diver]

> What does the label on the water heater say regarding voltage?

It says 220v and the manual says +-10% so 240v will be fine.
A good point about the thermostat breaking both lines, but if one hot line is open and one is closed, there will be no circuit?

> Use a meter to confirm that neither of the heating element connections are also connected to the metal screw-in part of the heating element.

Thanks, I'll check

The issue regarding one line switched versus two isn't about whether the heater element will shut off, but following electrical wiring codes of switching all positive lines.

Something I thought of last night:
Most of these heaters sold are probably 120 VAC. There is probably only one installation / owner's manual to cover all the units. The only difference between all the models is probably the heating element, thermostat, safety switch, and the label.

If the label says 220 / 240 VAC, I would wire it as you intended. Worst case scenario (assuming your boat is wired correctly) is the circuit breaker tripping or the element burning out.

Ted

 

[ranger58sb]

And I know for sure my boat's 240v system has 2 hot wires with 120v on each and one ground ( there is no neutral on 240v wiring).

??

A 50A/250V shorepower cord is often 4 wire: L1, L2, N, and G.

But I dunno much about 220V appliances...

Are you saying that Neutral never gets hooked up to any actual appliances?

Or...?

-Chris

 

[Waterant]

??

A 50A/250V shorepower cord is often 4 wire: L1, L2, N, and G.

But I dunno much about 220V appliances...

Are you saying that Neutral never gets hooked up to any actual appliances?

Or...?

50A cable is coming into the boat.

I already replaced ac pump which is on a 240v breaker similar to water heater and it had only 3 wires: 2 hots and ground. Same for 240v old water heater which I'm replacing - 3 wires coming in. Green, black and yellow. As far as I can see, this boat was not modified in anyway by the previous owner and this is how it was wired from the factory.

Manufacturer confirmed the only difference between 220v and 110v models is the heating element. Everything else is the same. I can order 110v element to put in instead of 220v but this means I will have to get the new 110v wiring from the panel and the old 240v heater breaker will be not be used. Something I want to avoid but seems like the safest option.

The heater is from Italy so 220v single phase option is probably for Europe boats. I just wish the seller in Florida would mention this in the product description.

 

[johnrupp]

??



A 50A/250V shorepower cord is often 4 wire: L1, L2, N, and G.



But I dunno much about 220V appliances...



Are you saying that Neutral never gets hooked up to any actual appliances?



Or...?



-Chris

In US 240 volt service using the neutral halves the voltage. So L1 to neutral and L2 to neutral will be 120volts. L1toL2 is 240 volts. Appliances such as a range or dryer use both. The controls are wired for 120 and the heating elements are wired for 240.

A 240 volt US water heater only uses 240 volts and therefore the neutral isn’t used.

John

 

[Waterant]

> Sounds like a Euro heater. They use a single line
> 230v line and neutral. And run at 50hrz.

Correct

> US power won't work w/o a transformer.

That would be the case with anything using motors or electronics. In the heater, there is only a simple thermostat and heating element which would not care about 50/60hrz
The 120v of this heater has only different heating element, everything else is the same.

> The issue regarding one line switched versus two isn't about whether the heater element will shut off, but following electrical wiring codes of switching all positive lines.

The breaker on the panel shuts off both hot lines when heater is not in use.

 

[Waterant]

In US 240 volt service using the neutral halves the voltage. So L1 to neutral and L2 to neutral will be 120volts. L1toL2 is 240 volts. Appliances such as a range or dryer use both. The controls are wired for 120 and the heating elements are wired for 240.

A 240 volt US water heater only uses 240 volts and therefore the neutral isn’t used.

Does it mean I can wire L1 to hot and L2 to neutral on this heater or it can fry the thermostat?

 

[Waterant]

Here is the old heater wiring.
Thermostat is cutting off only one black hot line ,
I think the safety breaker is shutting off both hot lines.

On the new unit I do not see the details of wiring but there is a pictogram on the unit which looks super simple with a thermostat cutting hot black line

 

[johnrupp]

Does it mean I can wire L1 to hot and L2 to neutral on this heater or it can fry the thermostat?

If it’s a 120 volt US water heater it would likely burn up the thermostat and possibly the element. Looking at picture 3 it appears it may be a European 230 volt unit.

Could you post a photo of spec page from the manual?

John

 

[ranger58sb]

In US 240 volt service using the neutral halves the voltage. So L1 to neutral and L2 to neutral will be 120volts. L1toL2 is 240 volts. Appliances such as a range or dryer use both. The controls are wired for 120 and the heating elements are wired for 240.

A 240 volt US water heater only uses 240 volts and therefore the neutral isn’t used.

Thanks, John; I had no clue... and never had 220V appliances onboard 'til now...

Does that mean there would be three connection terminals on the typical 220V (U.S) appliance, one each for L1, L2, and G? If so, is it always clear which L goes on which terminal?

-Chris

 

[johnrupp]

Thanks, John; I had no clue... and never had 220V appliances onboard 'til now...



Does that mean there would be three connection terminals on the typical 220V (U.S) appliance, one each for L1, L2, and G? If so, is it always clear which L goes on which terminal?



-Chris

Under the old code there were three. L1, L2 and neutral. The ground and neutral were tied together in the appliance. Under the current NEC there are four wires. L1, L2 neutral and ground.
A water heater still only has three as its only 240. L1, L2 and ground.
On appliances that mater it’s clear where L1 and L2 attach.

John

 

[gsholz]

The US L1/L2 leads will provide 240V. However, I'd expect the European 220V device to be grounded. That is, you'll end up with either L1 or L2 on the metal parts of the device. This is not safe.

At a minimum, you'd have to remove the ground connection in the device. Not ideal but better than having one of the split phases on the exterior of the device.

 

[Comodave]

I asked the manufacturer and they said this heater is a single phase 220V and use a professional electrician to install it. Which does not help much.

Sounds like good advice. With the new electrical codes and the docks having ELCIs on them you want to get it right, and BTW safe too.

 

[ranger58sb]

Under the old code there were three. L1, L2 and neutral. The ground and neutral were tied together in the appliance. Under the current NEC there are four wires. L1, L2 neutral and ground.
A water heater still only has three as its only 240. L1, L2 and ground.
On appliances that mater it’s clear where L1 and L2 attach.

Thanks, again.

This is also going a long way toward 'splainin' how our 3-wire (L1, L2, G) shorepower cord works, too. I'm assuming wiring after the isolation transformer provides the Neutral after 250V is brought onboard.

-Chris

 

[Waterant]

If it’s a 120 volt US water heater it would likely burn up the thermostat and possibly the element. Looking at picture 3 it appears it may be a European 230 volt unit.

Could you post a photo of spec page from the manual?

Specs is attached.
This is 220v water heater but manufacturer said it's 220v "single phase"

Water connections are 1/2" so i thought its built for US market but I did not hear about any US boats having single phase 220v on board (without after market installation).

I'll check if neutral is grounded to the case there.

 

[Waterant]

just an update. I decided to play it safe and plugged the heater into 110v line which was used by the central vacuum (which was removed) to get some warm water going. as i understand, i get only 25% efficiency from 220v heating element running on 110v. it took an hour to get the water warm enough for a shower without adding cold water.

I also ordered 110v heating element replacement to get the efficiency back. The manufacturer said this is the only difference between 220v and 110v models.

If anyone is looking to replace a heater, check out Quick heaters:
https://www.mauriprosailing.com/us/category/Quick-Marine-Water-Heaters.html
stainless steel tanks and very easy to install in tight places.
Just make sure you get 110v model for US boats.
220v models will only work for European boats running on 220v single phase and not converted to 110v for US.

 

[johnrupp]

Thanks, again.



This is also going a long way toward 'splainin' how our 3-wire (L1, L2, G) shorepower cord works, too. I'm assuming wiring after the isolation transformer provides the Neutral after 250V is brought onboard.



-Chris

That’s correct Chris. The isolation transformer is is basically like the transformer that your home is connected too except it’s a one to one ratio. In other words there is no step down in voltage between the primary and secondary windings.
On the secondary winding L1 comes off one end and L2 off the other end. The neutral is “center tapped”, in other words attached to the middle on the winding. This is what gives you 240 L1 to L2 or 120 L1 to neutral or L2 to neutral.

 

[johnrupp]

Glad you got if figured out and you’re able to use it by changing the element.

John

 

[gsholz]

Replacing the 220V element with the 110V element will double the current. Make sure your wiring is sized appropriately.

 

[Waterant]

Replacing the 220V element with the 110V element will double the current. Make sure your wiring is sized appropriately.

thanks.
it's 1200W 120v element and 14GA wiring coming in.
looks like an appropriate size for max of 10A the heater will be using.

 

[EngNate]

It will not matter that your 'N' is actually hot. It's a European unit and labeled for that power. There is no physical difference, except the heater voltage and this does matter because it is going to run at 20% higher wattage which will shorten the service life. If possible replace the heating element with a 240V one.