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-   -   Automatic Power Switch to Appliances (http://www.diychatroom.com/f18/automatic-power-switch-appliances-145364/)

travisintrouble 05-30-2012 01:57 PM

Automatic Power Switch to Appliances
 
I've recently placed an under-sink water heater in my kitchen but the only place to power it is already being used by the dishwasher. This outlet is on a 15 amp breaker and when both appliances are on it goes over 15 amps and shuts everything off.

The water heater turns on automatically whenever it needs to heat up the water in the tank. I don't need to have power to the water heater all the time. It can run only when the dishwasher is off. What I'm looking for is an automatic switch that will deliver power to the water heater only when the dishwasher is drawing no power and keep the total power to under 15 amps.

Is there such a device available for purchase? Is there another option that I should consider?

Thanks for your time.

rjniles 05-30-2012 02:09 PM

Install a new circuit for the WH.

k_buz 05-30-2012 03:06 PM

Some of those point of use water heater require more than a 15A circuit on their own. You will need to look at the specs and see what is actually required and then install a new circuit and receptacle for the water heater (as rj stated above).

curiousB 05-30-2012 03:28 PM

1 Attachment(s)
Quote:

Originally Posted by travisintrouble (Post 932231)
Is there such a device available for purchase? Is there another option that I should consider?


You can do what you are asking but it requires an expensive current sense relay and some knowledge of control systems to install. You would sense current to dishwasher and when you see current draw you would disable (open relay) to heater. I think it would be easier to run a new line from the panel.... But what you are asking is technically feasible.


http://www.patriot-supply.com/produc...item.cfm/31969

travisintrouble 05-30-2012 03:33 PM

Quote:

Originally Posted by k_buz (Post 932274)
Some of those point of use water heater require more than a 15A circuit on their own. You will need to look at the specs and see what is actually required and then install a new circuit and receptacle for the water heater (as rj stated above).

It's not a big one. This model states that it takes 12 amps. It works fine when it's alone on this 15 amp breaker.

travisintrouble 05-30-2012 03:49 PM

Quote:

Originally Posted by curiousB (Post 932286)
You can do what you are asking but it requires an expensive current sense relay and some knowledge of control systems to install. You would sense current to dishwasher and when you see current draw you would disable (open relay) to heater. I think it would be easier to run a new line from the panel.... But what you are asking is technically feasible.


http://www.patriot-supply.com/produc...item.cfm/31969

This is exactly what I'm looking for. Something simple and affordable.

THANK YOU curiousB! I don't think I would have found this on my own.

ddawg16 05-30-2012 03:54 PM

Doesn't your DW use the hot water from the tankless heater? Where does it get it's hot water from?

In the long run, you would be better off with adding a new ckt. Putting in the relay is a bandaid at best.

travisintrouble 05-30-2012 04:00 PM

Quote:

Originally Posted by ddawg16 (Post 932304)
Doesn't your DW use the hot water from the tankless heater? Where does it get it's hot water from?

In the long run, you would be better off with adding a new ckt. Putting in the relay is a bandaid at best.

The DW uses hot water from the main(gas) hot water heater on the other side of the house. It's a long way over there and so it took a very long time to get hot water to the kitchen sink. To fix this we installed this smaller heater directly under the sink for near instant hot water. Also, the under-sink heater has a small 1.5 gal tank on it so it can take hot water from there when it has no power.

I understand this is a bandaid. However, it's one I'm comfortable with.

ddawg16 05-30-2012 04:43 PM

Quote:

Originally Posted by travisintrouble (Post 932310)
The DW uses hot water from the main(gas) hot water heater on the other side of the house. It's a long way over there and so it took a very long time to get hot water to the kitchen sink. To fix this we installed this smaller heater directly under the sink for near instant hot water. Also, the under-sink heater has a small 1.5 gal tank on it so it can take hot water from there when it has no power.

I understand this is a bandaid. However, it's one I'm comfortable with.

Sounds like my house. I'm trying to decide if I use a tankless or go with a water circulating system.

Just out of curiosity....what size is your hot water pipe going to your kitchen?

travisintrouble 05-30-2012 04:57 PM

Quote:

Originally Posted by ddawg16 (Post 932344)
Sounds like my house. I'm trying to decide if I use a tankless or go with a water circulating system.

Just out of curiosity....what size is your hot water pipe going to your kitchen?

It's 3/4" and it's got to go something like 50-60' before it gets to the kitchen sink.

ddawg16 05-30-2012 05:07 PM

Quote:

Originally Posted by travisintrouble (Post 932347)
It's 3/4" and it's got to go something like 50-60' before it gets to the kitchen sink.

I'm in the middle of a 2-story addition to my house right now...I'm getting ready to move the gas hot water heater which is next to my kitchen to the rear of the house where it will be about 30' (by pipe) closer to most of the demand....

Hence, my kitchen will end up being about 50' (of pipe) from the water heater...
The point where I will T off the hot water supply to go to the kitchen is going to be about 30' or so of pipe. Existing pipe is 3/4".

So I did some calculations...that 3/4" pipe holds about 1.45 gallons of water....so that means I have to turn on my tap and run out about one and a half gallons of water before I get hot water....

If I change that pipe to 1/2"...the volume drops to 0.645 gallons....or, more than half the volume with the 3/4"....

This translates to droping the time to less than half....

Since the only items using water are the sink and dishwasher...going to a 1/2" line is not going to have any real impact on flow....

I will most likely be replacing that section of pipe this weekend....

Yoyizit 05-30-2012 05:23 PM

You can do it for a few bucks with a relay.
http://www.hosfelt.com/contents/en-us/d117.html

The relay coil needs to be 120 vac and powered off the DW just downstream of the DW controller
and the NC relay contacts control the WH and they are rated for the WH load, 1A or so.

travisintrouble 05-30-2012 06:17 PM

Quote:

Originally Posted by Yoyizit (Post 932375)
You can do it for a few bucks with a relay.
http://www.hosfelt.com/contents/en-us/d117.html

The relay coil needs to be 120 vac and powered off the DW just downstream of the DW controller
and the NC relay contacts control the WH and they are rated for the WH load, 1A or so.

I considered this route before posting and I'll likely roll my own solution using something like this if the RIBX doesn't work out. The big problem is it's been about 15 years since my last EE class in college and so it would take a lot longer than it should. Thanks for the link and the advice.


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