Electrical question

Page 1 of 2  
The heat has motivated me to have central air installed at my home. I am trying to avoid getting ripped off on the electrical part of the job.
My understanding is that central air conditioning units generally pull about 30 amps, depending on the size. At any rate, when I look at my electrical service box, there are two 20 amp breakers that are unused. Is it easy to somehow combine these two to support the needs of the central air? Should the contractor that installs the AC be able to handle this as a standard part of the job, or am I looking at additional expenses?
Thanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
probably OK.
what is the main breaker marked 200 amp your fine
100 amp probably OK
60 amp time for upgrade
the big issue is what is the overall capacity and how much are you using?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They'll quote you a full price which includes the $500 the electrician will charge them to run a ckt out to the unit. I had them back that out of their bid and installed my own ckt. Before you try to figure out what you're going to do in the panel, you need to get a hold of the spec sheet for the A/C unit. Some need 30A. Some 40A, Some 50A, etc... The literature should give you a minimum amperage for a breaker as well as a maximum. It'll also tell you your full load amperage, RLA, etc... From that, you can do some quick calcs on your panel to see if it'll support your A/C or not. Before just automatically telling the HVAC guys to skip the electrical, you really should find out what's going to be needed and price it out. Copper wire has gone through the roof so it may not save you as much as you think. That being said, I saved about $350 by doing it myself. Good luck. cc
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It's a little more complicated than that. You have two unused breakers in the panel, but unless you have a forced hot air heat system, you'll need four spaces in the panel. A double pole for the condenser, and a double pole for an air handler. You also must have enough service for the additional load. Personally, I'd wait until September when AC guys aren't so busy, then get a couple of prices

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Naaah. The air handler will be a 120V load.
--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In the Northeast, the only ones I've ever seen that were 120 volt were part of a furnace
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

And what are the 240V blowers part of? Commercial installations?
Using a 240V blower in a residential application is just a bit of overkill, dontcha think?

--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Just stand alone residential central AC air handlers. Virtually all of the blowers attached to furnaces are 120 volt, but I don't believe I've ever seen a 120 volt stand alone airhandler
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I have one in my basement... house has central air, and hot-water heat. 3700 sq ft, and the 120V air handler is more than enough to keep the house cool.

--
Regards,
Doug Miller (alphageek at milmac dot com)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 23 Jul 2006 16:31:43 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I know this is a foreign concept in places where a furnace is installed but South Florida air handlers will have 10 or 15 KVA of heat. We only use it about 10 days a year so the funace would be overkill. BTW it is not unusual to have that on the same circuit as the condenser since it is a non-coincident load. You use the breaker in the outside disconnect to limit the "maximum O/C device" requirement for the condenser. Having that 6 ga or 4 ga wire (satisfying the heater requirement) in the attic satisfies derating issues you have in the summer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@aol.com wrote:

I probably wouldn't call that a mere "air handler," but a combination unit or something similar. But you may be right about people on this thread using terms to refer to different sorts of things entirely.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form snipped-for-privacy@prodigy.net.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Most "mere" air handlers will still have a bay for toaster wire heaters. It is really a pretty small unit. You really need to read all the labelling and inspect them when you wire one..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RBM wrote:

Since this is alt.home.repair, isn't as "part of a furnace" where you'd typically find an air handler? Typically a furnace fan will only draw about 5 amps at 120 volts anyway, so there's not much motivation to move to 240V.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form snipped-for-privacy@prodigy.net.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Most of the furnace mounted blowers I've wired,(residential) draw 12 amps @ 120 volt

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RBM wrote:

That surprises me. Mine draws about 5.2 amps, for a >2000 sq. ft. house. I guess you must be dealing with some pretty big houses, but I would have thought those would be zoned systems.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form snipped-for-privacy@prodigy.net.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Most tend to be around four to five thousand square feet, but generally have two units in them. I'm wasn't doubting 120 volt units exist, in fact I've often wondered why they used 240 volts with a relatively small draw. I'll have to ask an AC guy what the deal is

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew Taylor wrote:

If the breakers are truly unused, they'll pull them out and install the double 30 or 40 that your new compressor will need. What are you gonna do for the air handler? Unless you have central heat already with an air handler, tou'll need at least one more breaker. If your electrical service is large enough but you are just out of spaces, use the 2 remaining slots for a 60A or 70A breaker to go to a subpanel. If you have a 100A panel you may can ad a feed-thru lug kit to it and wire a small 100A "main lug" subpanel right next to it without using those last two spaces. (if you use feedthru lugs, the subpanel and the feeder wires must be rated for as much amperage as the main panel)
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lots of interesting answers. Assuming they are full size breakers, your contractor will pull them out and replace them with what he needs. No problem. Even if they are half size, he can still probably finagle something without too much trouble.
But the person who said it depended on the size of your service was right. If you have a 60a service you won't have the capacity. Maybe not even with 100a unless you make sure you don't use any heavy electrical devices at the same time.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for your comments. I have a 100 amp service, with gas heat, gas stove, gas clothes dryer, so hopefully there will be adequate capacity.
Andrew Taylor wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 23 Jul 2006 02:24:26 GMT, Andrew Taylor

I see people replying to this about yoru orginal question, but I have one of my own. Why do you have two unused 20 amp breakers in the panel?
later,
tom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.