Instant Water Heater Wattage On 15 Amp Supply

[davehowden]

What wattage can I connect to a 15 amp supply, what happens if I exceed the 15 amps, does the heater just not function, does the fuse blow or what.I am thinking about a 4500 watts unit on my 15 amp supply, will that be OK?Thanks

[ThaiWx]

The way I see it, your water heater wattage is allowed up to just over 3000 watts before 15 amp fuses/breakers start tripping. This is on a 220 volt line. At 3300 watts you are drawing around 15 amps using ohm's law P = I * E. (Watts=Amps X Volts).

[Dante99]

What is it that limits the supply to 15 amps? Breaker? Fuse? ????

[moe666]

Depends on what your service box has most are breakers but some have fuses.

[harrry]

If you are talking about a 15 asmp metre supply they actually cover the range 15 to 45 amp. I believe the pole fuse is 64amp.

If this is the case there is not really a problem providing your wiring can handle it.

[Dante99]

Depends on what your service box has most are breakers but some have fuses.

Yes, probably.

If that is the case, all he has to do is take out the 15 amp breaker or fuse and put in a breaker or fuse which is the size he needs, isn't it?

Edited October 4, 2011 by Dante99

[Tywais]

Depends on what your service box has most are breakers but some have fuses.

Yes, probably.

If that is the case, all he has to do is take out the 15 amp breaker or fuse and put in a breaker or fuse which is the size he needs, isn't it?

Only if the wiring size supports it.

When I had them install my 2nd floor water heater they tapped directly into the power line entering the house. They fed that to a 30A switch/breaker and a RCD.

[Dante99]

Depends on what your service box has most are breakers but some have fuses.

Yes, probably.

If that is the case, all he has to do is take out the 15 amp breaker or fuse and put in a breaker or fuse which is the size he needs, isn't it?

Only if the wiring size supports it.

When I had them install my 2nd floor water heater they tapped directly into the power line entering the house. They fed that to a 30A switch/breaker and a RCD.

Yes, you need big enough wires. Thanks.

[davehowden]

Depends on what your service box has most are breakers but some have fuses.

Yes, probably.

If that is the case, all he has to do is take out the 15 amp breaker or fuse and put in a breaker or fuse which is the size he needs, isn't it?

FROM OP

My distribution box has 16, 20 and 32 amp breakers so i guess I just need to check the required wiriig size and connect into the C32 breaker?

Any ideas what wire size (mm) I would need for a 4500 watt heater?

[Dellboy218]

For a 4.5kW heater load, the recommended cable size is 4.0mm and a fuse/breaker rating of 20.0A

[ThaiWx]

For a 4.5kW heater load, the recommended cable size is 4.0mm and a fuse/breaker rating of 20.0A

I think I would use the next higher rated breaker/fuse size available. At 4500 watts on a 220vac line you will be drawing just over 20 amps already.

[Mekong Bob]

I cannot answer your question, but I have a related question to add to your post:

I have a Solahart solar-heated water system on my new house in Chiang Mai. Embedded within this unit is an electric water heater which serves as a back-up on days when sunlight is not adequate to heat my water. I am very interested in having capability to measure and monitor the energy consumption of this electric water heater each month. Is there a meter which I can purchase and install on this water heater? Bottom line - I want to know what part of my monthly electricity bill is the water heater.

[davehowden]

For a 4.5kW heater load, the recommended cable size is 4.0mm and a fuse/breaker rating of 20.0A

Many thanks Dellboy218

[Tywais]

For a 4.5kW heater load, the recommended cable size is 4.0mm and a fuse/breaker rating of 20.0A

I think I would use the next higher rated breaker/fuse size available. At 4500 watts on a 220vac line you will be drawing just over 20 amps already.

I agree. It should be loaded at 80% and not at the edge so 25 - 30 Amp breaker.

[Dellboy218]

For a 4.5kW heater load, the recommended cable size is 4.0mm and a fuse/breaker rating of 20.0A

I think I would use the next higher rated breaker/fuse size available. At 4500 watts on a 220vac line you will be drawing just over 20 amps already.

I agree. It should be loaded at 80% and not at the edge so 25 - 30 Amp breaker.

The info I gave was from a UK water manufacturer...........I didnt stop to work it out, maybe I should have done as it looks like they have had a typo in there. 20A would be right on the limit wouldnt it. 30A would be a bit over the top unless there are other items on the circuit. but a 23 or 25A breaker should do nicely.

Edited October 6, 2011 by Dellboy218

[DavidOxon]

I cannot answer your question, but I have a related question to add to your post:

I have a Solahart solar-heated water system on my new house in Chiang Mai. Embedded within this unit is an electric water heater which serves as a back-up on days when sunlight is not adequate to heat my water. I am very interested in having capability to measure and monitor the energy consumption of this electric water heater each month. Is there a meter which I can purchase and install on this water heater? Bottom line - I want to know what part of my monthly electricity bill is the water heater.

We have solar water heating.

We have no hot water about 10 days a year.

I would suggest you turn the heating element off so that it's not drawing any power

and just turn it on when you need it...

you will work out what works for you

David

[Tywais]

I would suggest you turn the heating element off so that it's not drawing any power

and just turn it on when you need it...

He is referring to on-demand water heaters so the heating elements are off until water flows.

[Tywais]

The info I gave was from a UK water manufacturer...........I didnt stop to work it out, maybe I should have done as it looks like they have had a typo in there. 20A would be right on the limit wouldnt it. 30A would be a bit over the top unless there are other items on the circuit. but a 23 or 25A breaker should do nicely.

^Yep. One problem is the unstable voltage in Thailand and need some margin to cover it. For example, the voltage at my house is 236 volts meaning more current drawn for the same heating element resistance. My numbers come from the US NEC standards regarding the 80% operational capacity.

[ThaiWx]

The info I gave was from a UK water manufacturer...........I didnt stop to work it out, maybe I should have done as it looks like they have had a typo in there. 20A would be right on the limit wouldnt it. 30A would be a bit over the top unless there are other items on the circuit. but a 23 or 25A breaker should do nicely.

^Yep. One problem is the unstable voltage in Thailand and need some margin to cover it. For example, the voltage at my house is 236 volts meaning more current drawn for the same heating element resistance. My numbers come from the US NEC standards regarding the 80% operational capacity.

Talk about unstable voltage, we're near the end of a service feeder so when the consumer load changes on the line our power jumps all around. It's the dips in the power where you draw more amperage, that is, his 4500 watt heater will require 20.45 amps if the line voltage is at optimum 220v. A dip to say 200 volts (which is not uncommon) will require 22.5. I leave a meter on our power to monitor it and have seen it down to 185 volts here before. It's good that you mentioned the 80% margin needed to allow for the power swings.

Edited October 6, 2011 by ThaiWx

[Paagai]

Not wishing to be the party pooper, but if the OP needs to ask these type of questions, with all due respect, he doesn't have much in the way of electrician knowledge or presumably skills.

Electricity is deadly enough, mix it with water and the combination is more lethal. OP might be better off getting a decent electrician to install it, rather than risking one's life to save a few Bhat?

Of course, finding a "decent" electrician here is also a challenge.......

[Tywais]

Of course, finding a "decent" electrician here is also a challenge.......

The key is to use the information supplied here and tell the electrician this is what I want rather than rely upon the electrician to make the correct decision.

[Tywais]

Talk about unstable voltage, we're near the end of a service feeder so when the consumer load changes on the line our power jumps all around. It's the dips in the power where you draw more amperage, that is, his 4500 watt heater will require 20.45 amps if the line voltage is at optimum 220v.

Actually not quite right. You don't draw more current as the voltage drops but less as the heating element is a, for the most part, a constant resistance. You know I=V/R.

[ThaiWx]

Talk about unstable voltage, we're near the end of a service feeder so when the consumer load changes on the line our power jumps all around. It's the dips in the power where you draw more amperage, that is, his 4500 watt heater will require 20.45 amps if the line voltage is at optimum 220v.

Actually not quite right. You don't draw more current as the voltage drops but less as the heating element is a, for the most part, a constant resistance. You know I=V/R.

good catch, sorry 'bout tthat. I flipped the equation. Coffee hasn't woke my remaining brain cell up yet.

[Litlos]

:

I have a Solahart solar-heated water system on my new house in Chiang Mai. Embedded within this unit is an electric water heater which serves as a back-up on days when sunlight is not adequate to heat my water. I am very interested in having capability to measure and monitor the energy consumption of this electric water heater each month. Is there a meter which I can purchase and install on this water heater? Bottom line - I want to know what part of my monthly electricity bill is the water heater.

Have a look at Ebay Australia and search on "lcd energy power meter" there are a couple of different type of units to give you some ideas, probably better to look at the hardwired single Din type as opposed to the plug-in types. My experience with the solar hot water systems is they use a lot of electricity, so best to leave the power off unless hot water is required. Is very common in Aust to have a timer installed on these solar units as well. This gives the warm water for the morning shower etc, but stops the unit keeping water hot all night.

Cheers

Edited October 6, 2011 by Tywais
Fixed quote

[Dante99]

:

I have a Solahart solar-heated water system on my new house in Chiang Mai. Embedded within this unit is an electric water heater which serves as a back-up on days when sunlight is not adequate to heat my water. I am very interested in having capability to measure and monitor the energy consumption of this electric water heater each month. Is there a meter which I can purchase and install on this water heater? Bottom line - I want to know what part of my monthly electricity bill is the water heater.

Have a look at Ebay Australia and search on "lcd energy power meter" there are a couple of different type of units to give you some ideas, probably better to look at the hardwired single Din type as opposed to the plug-in types. My experience with the solar hot water systems is they use a lot of electricity, so best to leave the power off unless hot water is required. Is very common in Aust to have a timer installed on these solar units as well. This gives the warm water for the morning shower etc, but stops the unit keeping water hot all night.

Cheers

A Timer on the solar water heater here is not difficult. On mine, I run the electricity with the timer, an hour in the morning and an hour in the evening and it is more than enough. In the sunny season I just turn the electricity off for many months. But if you are running a recirculating pump that will cool the water down.

[dickyknee]

Talk about unstable voltage, we're near the end of a service feeder so when the consumer load changes on the line our power jumps all around. It's the dips in the power where you draw more amperage, that is, his 4500 watt heater will require 20.45 amps if the line voltage is at optimum 220v.

Actually not quite right. You don't draw more current as the voltage drops but less as the heating element is a, for the most part, a constant resistance. You know I=V/R.

actually, it's I=V/Z since we are talking AC.

[Tywais]

actually, it's I=V/Z since we are talking AC.

No, this is a resistive element with a PF of 1 and not a reactive element. In which case Z=R.

[dickyknee]

actually, it's I=V/Z since we are talking AC.

No, this is a resistive element with a PF of 1 and not a reactive element. In which case Z=R.

um yes actually, but whatever. pointless arguing over the detail.

so long as no-one calls it RMS power i'll be content.