Running 220v water heater on 110v supply

[Andina Marie]

Huh, the washing machine uses 6 gallons on the first cycle, that would never work.

[Terra Nova]

It may use 6-gallons, but that is hot and cold mixed.

[Andina Marie]

Replacing our 60 gallons of hot water with 6 is unthinkable.

I plumbed them in series, the hot water, unmixed with cold, comes from the second heater while the fresh mix is re-heated in the first.

[Nicholson58]

Originally Posted by transmitterdan

No, you will have a 300 watt heater. It will take 4 times longer to heat the water. The wiring will be fine unless you change out the heater element for a 110V version.

This is the correct Answer. You win the star

The 1200 Watt rating is only realized at the rated voltage. The heater will not draw more amps at lower voltage (like an induction motor). Resistance for the device is fixed.

Volts * amps = watts. Solve for amps. 1200/220 = 5.45 amps

Volts = Amps * R (R-Ohms resistance) You need R because the resistance is fixed for the heater. Solve for R = 40.33

Using the same equations @ 110 volts. Solve for Amps = 110/40.33 = 2.73 Amps.

Solve for watts. Watts = 110 * 2.73 = 300 watts.

Your wires are OK given this exercise. You can run the heater on either voltage assuming you can get it.

We have a 220 isolation transformer for shore power that knocks shore power to two 110 volt secondary legs. I can also bypass the iso transformer with 110 shore power or combine correctly phased 110 shore power to 220 for the transformer.

[senormechanico]

Re the tank plumbing, I'd hook them in parallel.
During a large demand, both would be heating the cold input whereas in a series config, the second would be seeing already heated water.

I have probably started a hornet's nest as usual...

[Stu Jackson]

Originally Posted by senormechanico

Re the tank plumbing, I'd hook them in parallel.
During a large demand, both would be heating the cold input whereas in a series config, the second would be seeing already heated water.

I have probably started a hornet's nest as usual...

Steve, no hornet's nest. Parallel is the way we do it in buildings with multiple heaters for just that reason.

[rwidman]

Originally Posted by Andina Marie

OK next question.

My boat has two 30 gallon water heaters (due to size constraints where they are installed). Each has its own thermostat, both set to the same temperature.

Should they be plumbed in series or parallel?

I would think they are already plumbed but they should be connected in parallel. There's little to be gained by heating water in the first tank and then sending it into the second tank where it will just sit waiting to be used and reheated if necessary.

[monte]

Just an update on our water heater. It still seems to be overheating, but only when it's heated from the engine, not 220v. The pressure relieve valve is opening and releasing water into the bilge and when using the hot water the first few litres is brown like rust...
I'll check if there's some sort of mixing valve that regulates the temperature

[svlamorocha]

Originally Posted by monte

Just an update on our water heater. It still seems to be overheating, but only when it's heated from the engine, not 220v. The pressure relieve valve is opening and releasing water into the bilge and when using the hot water the first few litres is brown like rust...
I'll check if there's some sort of mixing valve that regulates the temperature

You said before that the heater is a Quick B3. I am familiar with those because I took two of them apart last week.

The mixing valve, if any, is irrelevant to your problem because it is downstream of the heater.

The thermostat that cuts the electric heating is also irrelevant because you say the problem is when the engine runs.

IMHO most likely immediate root causes are

a) engine coolant is too hot because engine thermostat is not working well, air lock, low coolant, etc.

b) pressure relief valve is defective.

c) combination of a) and air trapped in the top of the tank that expands a lot when the temperature increases from the electric cutoff to the enginve coolant temperature). I have not looked in side this model but other models will let some air get trapped on top.

You can do the differential on the first two by measuring temperature of the hoses that take engine coolant into and out of the water heater. That is easy to do with an infrarred thermometer or a multimeter with temperature probe. If you will be in the BVI next week I can help you out.

Regarding the last one, check if the hose that takes hot water out of the heater goes uphill all the way to a tap somewhere (as it should). If yes, open that tap and let any air out. If not, you wil have to purge the air out.

I do not like the "rust" finding. AFAIK those Quick heaters have stainless tanks (at least the ones I have worked on). Are you sure you are not losing engine coolant into the hot water through a puncture in the water heater´s exchanger. Make sure you save a sample of that "rusty water" and compare the color to your coolant´s color..

By the way, if you want to take out teh heating element to see inside you will need a 55mm socket.... Only $5 from Amazon...

While you are at this check out if your heating element comes with a magnesium anode and if not check if it has the female M6 thread to insert an anode... The old ones don´t, and if you use shore water that is not RO product you may get corrosion over time.

Cheers

Charlie

[monte]

Thanks Charlie. I'll look into the coolant tomorrow, but last check the level was fine. The boat/boiler is less than a year old so I doubt rust as well. The engine hasn't shown signs of overheating. There was a link above that allowed the boiler (different type ) to have the heat exchange water mixed with the inlet water to give the desired temperature via a gate valve. I'll poke around and see if I can see a gate valve in line. Thanks for the offer but we left BVIs a couple of days ago and I'm hesitant to sail upwind to antigua twice in a week ! Will keep posted what develops. Thanks again

[senormechanico]

+1 for Charlie's post.

[matureee]

Originally Posted by ericoh88

Wow this subject is very interesting.

So I did a bit of experiment. Each morning I heat up the 240v small electric kettle. Usually I let it boil until the auto switch cut off the power.

Exp 1: Supply 240V, Water temperature 26.2 C Vol = 0.8 liter Time = 2 min 21 sec

Exp 2: Supply 120V, Water temperature 28.7 C Vol = 0.8 liter Time = 10 min 01 sec

In my case, half the voltage the time took more than 4 times longer. Mains is 240v 50 hz and step down transformer is giving 120v 50 hz.

note: I am sure there is a lot variables in my simple set up in the galley.

Good info from CF members. thanks.

Let me give you a small clue as to why the time was more than four times. Surround your kettle with 3" of insulating foam and repeat the experiment.

[monte]

Well I just checked the engine and the coolant is green and at the correct level and hoses look fine. No valve there. I'll check the boiler later and see if I can make any sense of the connections that end. One thing I noticed on the quick website is an optional thermostatic mixing valve. I assume this would go on the return coolant side and close when it become a set temperature to avoid overheating?

[transmitterdan]

No the mixing valve is designed to add some cold water to the hot outlet to reduce the hot water temp to a safe level. These are a really good idea.

Hot water does not expand much. Hot air on the other hand expands a lot. Before looking for exotic problems try to see if there is air in the hot water heater. If you get the air out the pressure relief leak should stop.

But the crud in the hot water is a concern. The source of that needs to be found. Does the hot water have any odor? For example, does it smell like antifreeze, onions, rotten eggs, etc.? Sometimes that will help identify the source/cause.

[svlamorocha]

Originally Posted by monte

Well I just checked the engine and the coolant is green and at the correct level and hoses look fine. No valve there. I'll check the boiler later and see if I can make any sense of the connections that end. One thing I noticed on the quick website is an optional thermostatic mixing valve. I assume this would go on the return coolant side and close when it become a set temperature to avoid overheating?

You are making things more complicated than required. Of course it is your boat, your money and your time.

Once again, even if you had a mixing valve it would not be relevant because it is DOWNSTREAM of the heater. In addition it would be in the pressurized water circuit (typically blue and red plastic tubes) not in the coolant circuit (black rubber hoses).

You have to a) check the temperature of the coolant hoses in and out of the heater with a warm engine and b) purge any air through the hot water outlet hose.

You can do b) before heating the water, that may be safer. If you can find a route that goes uphill all the way between the heater and a tap you can just turn on the water pressure pump, open that tap and let it run for a while until all the air burps out. If you are not that lucky because the installation is sloppy you will need to rig a temporary hose that goes uphill, or loosen a connection at a high point that is all tbr way uphill from the heater.




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