Rheem air handler wiring


I am going to wire my new Rheem Air Handler myself. It is 220V. It has two CB's on the front; one 60A and one 30A. There are a few different size knockouts in the top of the unit. I would figure that a disconnect adjacent to the air handler is required. Back at the meter, I'm going to come off the new 200A meter into a 200A load center which has 4 spaces (it says room for 8 circuits on the carton) It comes with the 200A main CB, and I'll get two 100A/220A CB's. I want to punch holes in the back of the load center then directly into the structure. This is OK? How do I attach it to the house. We have cheezy PVC siding over what I suspect is wood clapboard. Comments and suggestions? Thanks
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timO' wrote:

Did you mean to say 100A/220 VOLT CB's?
One breaker should be enough to handle that air handler's needs, use 1 gauge wire to connect to a disconnect switch adjacent to the air handler, and from there to the unit.

I'm no code mavin, but the ones on our home were done that way and passed inspection. Just make sure you use a suitable cable clamp in the holes, and it would be a good idea to put a blob of silicone caulk around the clamp before you push the load center against the house, just to avoid water/insect entry.
How do I attach it to the house. We

I'd go for No. 12 wood screws about 2" long.

Use a non-fused disconnect switch inside. The kind where you pull out a "shorting plug" works well.
I personally had my fill of fused disconnect switches when one of the ones on an air handler in our home would fry a fuse every couple of years because the switch blade contact resistance rose over time and the heat generated during high current auxillary heater operation would get conducted to the adjacent fuse end cap. Eventually it would get hot enough to melt the solder connecting the fuse link to the end cap and open the circuit. Not a classic "blown" fuse, the link was still whole and the fibre fuse body was charred to a crisp. <G>
Cleaning the switch contacts and fuse clips and replacing the open fuse would "fix" things for a year or so, but the problem always came back the same way. BTW, the disconnect was located in a dry cool area.
I replaced the fused disconnect with a brand new one and after a few years it started doing the same thing, so I gave up and last summer replaced it with a non-fused disconnect. So far no problems.
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Is the panel rated to have 2-100 amp branch circuits? Check the label on the inside of the panel if nothing is mentioned on the box. It should say something like "Maximum branch circuit size....."

Use a hole saw big enough to accommadate the connectors that you will use to come out the back of the panel. Pull the stripped wire out of the holes. Put the connectors on the cable without the locknuts. Bring the wire and connectors into the back of the panel and install the locknuts. Bushings would be good also. Put duct seal in the holes in the house and around the connectors and push the panel against the house and screw it to the siding with long enough screws to catch wood. Use #10 or #12 cadmium plated sheet metal screws. Be careful not to pull the plastic siding in too much. Put caulk or duct seal at the top edge of the panel where it meets the siding to prevent water from getting behind.
This is not as easy as it sounds.

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I will add that if screws do not seem to hold the box to the wall securely, use toggle bolts. Larry
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On Mar 10, 4:40 pm, snipped-for-privacy@webtv.net (lp13-30) wrote:

Yes I meant 100A/220V breakers. My old meter panel was in place when they installed the cheezy PVC, the 'framed' around it. Boltig the new meter panel and outdoor load center up against the PVC will no doubt distort it, so I was thinking standing the units off the siding.
With a 100A up at the load center, and CB's in the air handler, I was thinking a fused disconnect would be redundant, and problematic, although I already have two of these (one for the water pump and one for the water heater, and never had the problems described.
How do I branch off the disconnect to supply the two seperate breakers in the Air handler? There is no buss, just 4 cpnnection points; two for each breaker. Thanks for the ideas. This work is by no means easy, but I am experienced in handling thee materials, I just wanted to get some ideas back from y'all. From speaking to numerous electricians, there apparently are typically several ways to do a job and still be doing it right thanks again for the feedback
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(lp13-30) wrote:

How do you plan to do that? You could mount a piece of plywood over the siding, but that will compress the PVC. The alternative would be to cut out an opening in the siding, mount a piece of plywood in that and trim out the siding with the appropriate drip edges and such. Any chance that the new meter will fit where the old one is now?

I don't think that you need a fused disconnect since the 100 amp line would be protected by the main breaker. An unfused disconnect should suffice, but see my response below.

That's a concern. It sounds as though the manufacturer wants two separate feeds. Check the nameplate and the installation manual. If you don't get answers there contact the manufacturer for technical support and ask them if you can feed the unit with one 100 amp line. If it is required to have two feeds than you should install a small circuit breaker panel near the unit. You could run both feeds in the same conduit. It is possible that those internal circuit breakers are just on/off switches and there must be protection for each circuit outside of the unit.

Can you post some pictures of this puppy so we can get an idea of what you're dealing with?
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I wanted to mount the new meter next to the existing one with a new mast and the load center in place, then maybe the utility company could do the switch over on one trip.

Yes I'll contact them. the paperwork for the unit does not seem to address details on wiring

Yes. But I'm on the run until Friday, so please stay tuned. How do I do it, attach them? Never mind I'll figure it out.
It was in the 70's around here today so there isn't any huge pressure to get this project done. besides, it's going to be a few hundred for the materials, so that puts the brakes on it too. The load center with the breakers is about $200. The mast and hood and service wire probably $75. (2" PVC pipe and a hood and the service wire and clamps). 30' feet of branch wire and the disconnect maybe $100. misc hardware $20. #4 or #6 solid and clamps to connect the electrode; $10- $15. A case of beer for the electrical inspector....no no I'm just kidding. but it adds up. thanks again
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(lp13-30) wrote:

out
the
new
That would be nice if it works out that way.

would
but
separate
get
them if

two
unit.
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Hi All: I called Rheem for a little tech support, and they told me to go screw myself, call an electrician. BUT The installation instructions for the air handler listed a jumper bar kit to convert single phase multiple two circuit units to a single supply circuit. That's what I need The manual also said the two CB's on the unit are for short circuit protection of the unit, and not over-current protection and therefore may be sized larger than the branch circuit protection; the supply circuit wiring must be 75C minimum copper conductors only; that the supply circuit protective devices be either fuses or HACR type CB's. and that an adequate size disconnect should be installed within sight of and readily accessible to the unit. So my interpretation is I'll use an HACR in the load center; copper for the branch; A 100A disconnect near the air handler, and get the jumper bar kit to keep it Kosher. There is a copper wire size chart in the Rheem book. Thusfar I'm understanding it to say that for a 50' wire run, for a 100A circuit, use #3. For 110A use #2. But it also says "wire based on copper conductors 75C minimum rating. For more than three conductors in a raceway or cable see NEC for derating the ampacity of each conductor" Don't I need to run 4 conductors out to the air handler? 2 hots, a neutral and a ground? I'm unclear on this detail.
This whole episode started when the heating contractor initially told me to run a #12 off my existing electrical panel to the air handler location, and we'd be good to go. I should have realised then, but I already have an existing branch cicuit that was for the coutside compressor, and I didn't fully understand the components in a split heat pump system. (I still don't fully understand, but better) then he changed his mind when he took a second look. He must've not figured in the heat strips. The fan will run on the 220V/30A on a #12, but the heat strips are the hogs. No pix yet it's raining and cold. <>
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(lp13-30) wrote:

wall
when
PVC
the
the
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out
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one
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suffice,
breakers
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don't
have
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Very unprofessional of them. I guess whoever you talked to didn't want to bother explaining things or didn't want the responsibility if you screwed up and burned your house down.

The ground doesn't count since it is not normally a current carrying conductor. Does this unit require a neutral? Most wire sold these days is rated for 90 degrees Celsius, however you must be concerned with the temperature rating of the terminals on your disconnects, circuit breakers, and air handler. The most common rating is 60 degrees for terminals although some can be 75. I don't think anyone makes 90 degree terminals. To play it safe, just go with the 60 degree column when sizing your wire.
What does the nameplate on the unit say for maximum circuit ampacity or maximum fuse size?

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