HVAC guys, any idea how to make this AHU run?

Blaze

Blaze

The Jeeper Reaper
Joined
Aug 9, 2005
Location
Wake Forest, NC
So the system in my house needed replacing. The coil went out and burned up the compressor so I went ahead and replaced all of it since it was 17 years old anyway.

The old AHU was dirty but the heater pack and fan still worked great. I did not see the need to trash it, especially since my garage has air conditioning and no heat. See where I am going with this?

I removed the coil section and just have a box with the fan and heater now. I want to wire it up to a switch so that I can turn it on and just have it as a constant on heat/fan setup in the garage. When it gets too hot, just cut it off.

Or maybe wire it to a cheap thermostat so it can regulate as well as blow air?

What do you guys think? It is a 2.5 ton Carrier unit.

Here's the panel inside.
2013-05-04 16.33.39.jpg
 
Try connecting red to green to run fan, add red to white #2 for heat
 
The black and yellow wire will need 240volts. Should be tied to where power comes into ahu. You need to make sure u use the correct size wire and breaker to be safe electric heat pulls a lot of amps. Also be sure u have large enough power service ran to shop to handle the extra load. What kw is your strips should be on that tag u can see part of in pic. You will need to use the control wiring to turn the system on and off. You can get a mechanical thermostat cheap. Red is 24volts, w is signal wire for heat strips and g is the signal wire for the fan. So if u jump from r to w and r to g it will run but all this will be done in the thermostat but if u insist on switch tie red to one side an w and g to other side of switch. you can remove the current jumper wire from r to y it is not needed for heat it is to call for a/c compressor. One last thing be aware of any fumes from a lot of painting or anything flammable. Heat strips is basically an open flame with a fan pulling all the surrounding fumes and blowing them threw it. Knew a guy that had his in his shop and was painting a car not thinking and when it turned on blew a fire ball out the end. This takes a lot of fumes but can happen.
 
Gotcha, thanks. I have a gas fired water heater in my garage anyway, so I already need to be careful about the fumes.

I'll check and make sure I have enough power here in the garage. My breaker panel is in my garage so getting power isn't a huge issue. Gotta make sure I have enough available power though. My house electrical really sucks.
 
Well, I think I may have to get a separate service pulled into my garage. I was looking at my panel and it is almost maxed out with spaces and I think I could easily overload it.

I only have a 150A service feeding my whole house. I think if I am running a separate HVAC in the garage and the house HVAC is running, along with the lights being on, oven on, dryer, etc and I try and run the welder/plasma/air compressor/garage oven at the same time it may just bee too much. I am using a ton of power in the garage when I am working on a big project. :lol:
 
Dude...150a is a lot of power.
I don't know what size your house is..but put this in perspective.300 60 watt light bulbs...

I mean a fridge may draw something like 10 amps...(running) dot just add up breaker sizes it doesn't work that way.

A 200 A service is standard up until around 4500 sq ft... And even then....
 
I know, if I add up breakers I have 520A in there. I know it doesn't work that way.I just meant maxed out with spaces because if I put the new heater on there I have no more spaces and I can't expand any more if I wanted to in the house. I currently need to add a separate circuit for my range/microwave because they wired it on the same circuit as about 16 other devices and if I have too many lights on in the house it trips that breaker.

I have a 2200 sqft house. 150A is fine for a normal house, but normal houses don't usually have a separate oven, welder, plasma cutter, 80gal air compressor, garage fridge, garage heater, and nine 4-ft 2-bulb fluorescent light fixtures.

150A might still be fine even with everything I do, I haven't really looked into what my draws are. I'm mostly concerned about being out of spaces and not being able to ever clean up the wiring in my house that needs to be done.
 
I'm no electrician, I just work on air conditioners but I agree blaze u prob need a larger service. Just an FYI average set of heat strips on 2.5 ton system is 10 kw which use a 60 amp breaker an pull around a constant 40 amps so shop plus house running heat strips is 80 amp continuous load then add the heat pump running defrost in the house another constant 20-25 amps so now with just both HVAC systems running heat we are more than 2/3 ur power supply at 105amps of actual load. Add a stove, dryer, plasma or welder at the right time and u can very quickly max out a 150amp service before u ever count the first light or receptacle.
 
Also I know u wanted to use the ahu because u already have it but u already have gas to shop and u can pick up a new gas furnace for prob around $1000 give or take not up to date on current pricing. I would guess that upgrading your service and running larger wire to shop if u need is not gonna be a whole lot cheaper if any. Just a thought.
 
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