Power Miser

[green3*3]

Live in a 3000sq ft home and have finally decided to get rid of my old oil and(money) burning hot water heater and replace it with a 60 gal 240v hot water tank.
Have a 100A power panel and no room for an additional 30A breaker. A local electrical contractor has quoted me $2500 to replace the panel with 200A.
A friend suggested to install a "power miser" connected to the 30A dryer breaker
that will disconnect the water heater whenever the dryer is in use which is in our household is max. 3-4 hours/wk.

Q: Do these devices exist, and who makes them?
Are they within NEC code?

 

[charlie b]

I am not sure I understand the situation. Are you asking about saving the $2,500 by not replacing the panel, and instead installing this ?power miser? device, so that the existing breaker serving one load can be used to serve two loads (somehow interlocked so that they don?t both run at the same time)? I have not heard of such a device. I suspect that if it exists, and if it is properly connected using proper size wires, it might be acceptable under the NEC. But we are not allowed (under forum rules) to help a person who is not electrician, if that person is planning on performing his or her own electrical installation work. So I would start by asking if you have asked the electrician (i.e., the one who gave you the quote) for an opinion, or for an estimate, on the device?

 

[bikeindy]

You might call around and find out if there is an electrician who can replace your existing panel with a 100A panel with more space. with the size of your home they will need to do a load calc to find out if you can do this. It might be wise to upgrade anyway. I am also unfamiliar with the device you are talking about.

 

[360Youth]

I would not be surprised to see the technology out there, but I would be surprised that it is comparable to changing out the existing panel and the additional benefits that would come with it (I have no doubt a similar problem will arise in the future.) Even if you find the device, it seems there would be a necessary control circuit that tells it when the water heater is on in order to shut the dryer supply off, and that control circuit would have to tie into the WH somehow.

 

[brantmacga]

I did a load calc @ 3k ft and included the following:

2 SABC @ 3kva
1 Laundry @ 1.5kva
1 Dryer @ 5.5kva
1 Refrigerator @ 1.4kva
1 Dishwasher @ 1.2kva
1 Microwave @ 1.7kva
1 Water Heater @ 4.5kva

I assumed you have what I listed above. That's an 87A demand load, and that's pushing it on a 100A service.

At least you're finding out now though. I did a service change about two months ago where the customer had the electric WH installed and then called me to do the wiring; 2k ft. home w/ all electric appliances & hvac on a 100A service.

One other thought: It could be possible to take a couple of DP 30A contactors, one NO and the other NC, and set them on a timer to switch between the WH and dryer. If you wanted to dry clothes when the WH is running, just use the manual switch inside the timer to change the appliance that is running.

 

[weressl]

I did a load calc @ 3k ft and included the following:

2 SABC @ 3kva
1 Laundry @ 1.5kva
1 Dryer @ 5.5kva
1 Refrigerator @ 1.4kva
1 Dishwasher @ 1.2kva
1 Microwave @ 1.7kva
1 Water Heater @ 4.5kva

I assumed you have what I listed above. That's an 87A demand load, and that's pushing it on a 100A service.

At least you're finding out now though. I did a service change about two months ago where the customer had the electric WH installed and then called me to do the wiring; 2k ft. home w/ all electric appliances & hvac on a 100A service.

One other thought: It could be possible to take a couple of DP 30A contactors, one NO and the other NC, and set them on a timer to switch between the WH and dryer. If you wanted to dry clothes when the WH is running, just use the manual switch inside the timer to change the appliance that is running.

One can use a single contactor that is turned off by a current sensing relay. Whenever the dryer is turned on - draws current - the contactor to the water heater would be de-energized.

I am not aware that there is a single approved device to perform the above function, but certainly an electrician or a panel-shop can assemble it and install it for the OP and make sure that the installation complies with the NEC.

 

[green3*3]

Power miser

Power miser

Live in a 3000sq ft home and have finally decided to get rid of my old oil and(money) burning hot water heater and replace it with a 60 gal 240v hot water tank.
Have a 100A power panel and no room for an additional 30A breaker. A local electrical contractor has quoted me $2500 to replace the panel with 200A.
A friend suggested to install a "power miser" connected to the 30A dryer breaker
that will disconnect the water heater whenever the dryer is in use which is in our household is max. 3-4 hours/wk.

Q: Do these devices exist, and who makes them?
Are they within NEC code?

Thanks for the interest and advice received,

Agree, upgrading to 200A is the best solution. Besides the boiler change I have no home improvement projects planned in the future that require additional ac breaker capacity. With all other priorities in our lives that require part of the household budget I prefer the best economical solution within the NEC rule book to get this job done.
Some of the posts suggested to install a switching device such as a relay connected to a 30A breaker to switch power between boiler and dryer on demand or automatically.
Most likely I will find a local electrician to install a working solution.

The question is: does NEC allow this type of switching configuration to feed 2 separate loads?