(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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1answer
155 views

Which direction is the airflow through my furnace?

There's multiple lines of ductwork along the side, and up top. So what's the correct direction of airflow (red or green in the image below)?
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0answers
28 views

How to connect 4 fan coils with one wall control thermostat?

I have 4 fan coils (Sabiana sk-22)and I want to connect them with one wall control thermostat. How can I do?
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2answers
1k views

How do I cut a straight line in an installed wood floor for a flush mount HVAC vent?

At some point a previous owner installed hardwood flooring in my house. Nice. They did not however make a hole for the front entryway heating vent. The duct and duct outlet exists in the crawlspace ...
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1answer
45 views

Can I vent room air to the outside?

The building interior gets hot during the day and stays hot during the evening when it is much cooler outside. It would be a really great option to simply vent the hot air outside instead of having to ...
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1answer
858 views

Air conditioning unit sitting on the ground

We've lived in our house 11 years. Our air conditioning (condenser) unit, the big boxy thing sitting outside, is not sitting on a concrete slab. It's just sitting on the ground and we noticed this ...
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2answers
140 views

Can a 110v 3-wire thermostat be hooked up to a 110v 2-wire condo setup?

My condo that was built in 1968 has an old thermostat(rheostat type) which supplies 2 thick gauge black wires of which one is live and the other isn't. This regulator is hooked up to a blower unit(fan)...
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1answer
66 views

How to remove old A/C piping in my house?

When I had my new A/C installed I moved it to the other side of my house (right next to the furnace), so now I have a bunch of old copper piping running about 30 feet from one corner of my house to ...
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3answers
259 views

Is an HVAC license required for DIY home owner AC installation in the State of Georgia?

Does anybody know for certain if in the State of Georgia, an HVAC ("conditioned air") license is required in order for a homeowner to install their own HVAC system?
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2answers
128 views

Is the Thermostat Wiring Correct

When I moved in to the house the first thing I changed was the old mercury style T-stat to a digital one, I went wire for wire, and it has works (knocks on wood) so far. Now that I have been reading ...
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3answers
116 views

My Goodman a/c motor fails due to high voltage

I have got a brand new goodman unit. The motor kept stopping after few hours an the tech replaced the motor. It still had same issues.. I was told that the voltage coming into the unit is too high.. ...
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1answer
67 views

what is the cause whereby compressor working gets hot and stops, after cooled down picks up

My challenge was that, I have this refrigerator I'm working on and after awhile it is working and then the condenser become hot as the compressor discharges excess heat, which as time goes on ...
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1answer
107 views

Downsides to staple up radiant heat, besides cost?

I'm considering doing a radiant heat retrofit into my home and removing an older forced air system. The plumber is proposing a staple up from the basement into aluminum plates with PEX tubing with a ...
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1answer
42 views

How to control system with 2 condersors+evaporators and 1 blower

I have problem with the control the HAVC system using 2 condensors + 2 evaporatora with one blower. I used 2 thermostats (4 wires/thermostat) to control. But the problem is when i turn on (cool ...
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1answer
109 views

Can the back side of a window type aircon exhaust in an empty ceiling area?

I'm planning use a window type A/C on my little attic room. My A/C unit is just .5 HP, just enough for the small room. The problem is there's no proper exhaust area like the standard Window type. ...
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1answer
2k views

AC Blower running very slowly

I have a Ducane heat pump. When running in AC Mode, the outdoor fan and compressor kick off just fine. The blower fan seems to kick off as well, though it's not putting out very much air. I can ...
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4answers
131 views

Why is humidity high from one unit but not the other?

Two months ago, I posted about our upstairs a/c not cooling all of a sudden. I ended up replacing the capacitor for the blower fan and the contactor, which did the trick. AC cools!!! However since ...
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2answers
80 views

The house is not cooling

What would cause the outside ac motor to run than stop than start up again and continue this random stop and start cycle constantly. The house stopped cooling
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1answer
180 views

central A/C Turns back on 30 seconds after shutting off

First of all, the a/c system is probably 30 yrs old. The outside unit stays running when the inside unit shuts off. After about 30 seconds, the inside unit turns back on again, and will sometimes only ...
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1answer
63 views

How can I plug a hole cut in a window pane for a portable A/C unit?

I just moved into a room where there is a portable A/C unit. To create a vent for the unit, a hole was cut in the glass of one of the window panes that spans about 13.5 cm. I was told that the unit ...
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0answers
71 views

Smaller Footprint of new Furnace Base Cabinet

Replaced downdraft furnace in 1950's ranch house built on slab. Base cabinet of new furnace has a smaller footprint than the original resulting in a 4in. gap between the edge of the cabinet and the ...
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2answers
1k views

Temporary fix for bad contactor?

After doing some replacement for the ac, the contactor stopped working. It won't close when I turn the ac on. when I pushed it in, the compressor was able to start. I can't go out to find a new one ...
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1answer
53 views

HVAC tripping breaker - things to check before replacing?

HVAC system (we're in Houston, it's still hot here) stopped working Tuesday. A/C guy came out, determined it was tripping breaker. Would trip immediately after resetting, but after a couple of ...
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0answers
49 views

Can my A/C unit knock out my whole trailer or is it coming from the main box outside causing the problem?

I'm confused. Do you know if my air conditioner unit would blow out the main power in my whole trailer if the box inside my house isn't tripping? It keeps making a very loud popping noise under my ...
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4answers
3k views

Can a homeowner without a Section 608 EPA license legally connect his own gauges to his own air conditioner if the unit uses 410a refrigerant?

It has been suggested by at least one moderator on this site that EPA Section 608, which restricts who can purchase and handle refrigerant, including who can connect a set of manifold gauges to a unit,...
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4answers
310 views

Is transitioning to all electric heating smart?

I am in the process of overhauling my home heating and plumbing. I bought a 2600sq/ft 1980s Cape Cod in southern Maine on the coast. I've reinsulated the walls and roof and am continuing to make ...
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1answer
77 views

How to manually control HVAC without thermostat?

I would like to create a solution (Probably with Arduino) to control my AC remotelly. Opening my thermostat and doing some tests I got these values bellow: Blue (C) - Neutral (AC) Red (R) - Phase ...
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1answer
36 views

Are there testers for thermostats?

One of my A/C units was struggling to keep the temp. down to 85 three weeks ago. The pipe outside was slightly frosted so I already knew the unit was a little low of refrigerant. Called repair company ...
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2answers
59 views

HVAC breaker issue

My HVAC (Tempstar 5300XL) comes on automatically at the preset temperature. It may run cold for 45 minutes to an hour, then trips the breaker. What is the most logical problem, and solution?
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2answers
113 views

HVAC System Just Installed Yesterday and AC condenser outside is blowing cold ir

HI my just installed ac condenser is blowing cold air out side . when I put my hand over it and move it around most of the air is hot but a portion of it is cold. Is this right ?
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1answer
335 views

Help installing new thermostat

disclaimer, this is my first attempt at doing any type of electrical work, so apologies in advance for any wrong terminology :) I attempted to install a new Honeywell programmable thermostat. When I ...
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3answers
183 views

Problem- air condition- compressor and fan outside not on

I'm new to hvac. My ac was working fine but it decided to die one day. I've been able to fix my ac, but it continues to happen(the same problem), and it is not easy to get to the ac (it's on the roof)....
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1answer
319 views

Furnace is Sweating an Abnormal Amount

I noticed my furnace sweating a couple days ago. It's hot and humid where I live so I was only mildly concerned. It was a high of 74F today with humidity around 70% which is, relatively, nothing. ...
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1answer
177 views

Upstairs/downstairs cooling- leave it on or off?

It's 100+ here in Texas. My house has separate air conditioners for upstairs and downstairs. We rarely go upstairs, but I'm told that we have to account for air flow "chimney effect" up the stairway ...
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4answers
2k views

HVAC system that pulls-in cold air from outside?

My house has an existing forced-air heating system and I'm looking at getting central AC added in a few weeks' time (indeed, I've booked contractors for estimates next week). An AC system would keep ...
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0answers
48 views

Ac running but my blower will not

My ac unit stopped feed cold air from the unit outside. The main fan on top is spinning fine and my lines are freezing but the blower in the unit is just barely turning. Can someone tell me what would ...
3
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2answers
131 views

What could cause my Carrier furnace fan to sometimes stop running?

I have a Carrier system: FURNACE 58UVB080; AC 24APA530, CONTROLLER SYSTXCCUIDO1-B, approximately 7 years old. New filter, impeccable condition. I was initially told by the licensed installers that ...
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0answers
86 views

Older home with no AC plenum…replace our entire AC system as suggested?

We have an older home that has a large living-area/fireplace room; the AC unit sits over it in the attic. Earlier this year, in that room, we noticed a crack beginning to form in the ceiling sheet ...
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1answer
134 views

HVAC leaking cold air at unit: seal with tape?

I was in my crawlspace today and noticed that there was cold air leaking from a grouping of three round openings in my unit (pictured in the middle of the photo below). The outer two holes had rubber ...
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3answers
185 views

One portable air conditioner - want to use it in two rooms

I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a ...
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1answer
369 views

How can I determine the start up amps on a 3 phase 5 ton A/C unit?

I am trying to properly size a home generator and my concern is the start up amps on a 5 ton AC unit (15 years old R22 Goodwin type). My home power is unique because we have 3 phase (the AC is on 3 ...
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1answer
79 views

Can using a new evap coil on top of an older furnace cause problems?

I am getting quotes for a new R410A condenser unit/evaporator coil from several HVAC contractors. A salesperson refused to give me a quote unless I purchase a new furnace as well. He said that he has ...
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2answers
173 views

Can the A/C temperature through a vent be significantly lower than in the air handler?

Can the A/C temperature coming out a vent be significantly lower than the temperature in the air handler above the evaporator coil? If so, how does the air get colder as it comes out the vent? Or ...
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1answer
169 views

How can I prevent a secondary condensation drain line from dripping down the side of my house?

I have 2 central AC units in my 2 story house. From what I was told by the last AC repair man that visited, each of my ac units in the crawl space/attic has a main drain line that drains directly ...
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2answers
327 views

How to repair buckled duct work inside wall?

Update I think the duct is actually fine. The duct connects to a register that is shared by two rooms. When heating, one room is gets hot, while the other is cool (not too cold). I think the problem ...
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0answers
33 views

Goodman A/C unit sparks at high pressure line on furnace. Blows breaker

Got a 10 year old A/C unit and notice breaker blown. Flipped breaker and noticed a spark where the high side line goes into the plenum of the furnace and the breaker blew again. A/C repairman checked ...
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1answer
6k views

replace old furnace blower motor with a new one but the wires are different

It is an old Rheem RGAA-100C furnace, On the old motor the wires was: White, Brown, Red, Black and Blue. On the new Motor it has Brown, Brown/White, Black, Red, White, and Blue. I don't know how to ...
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1answer
125 views

Why would my house be so humid even when the A/C is running?

I live in Florida which this year has been particularly hot and humid. However, a while back I noticed mold in my closet and a very musty smell in my living room. Actually I even found mold growing on ...
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1answer
188 views

Water Heater Gas B-Vent Install

I installed a new water heater and want to vent it right. The old water heater used ABS pipe since it had a blower. Basically I have a 3" b gas vent pipe coming in and connecting to a flex gas pip ...
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1answer
75 views

Can dehumidification be achieved in a typical US residential forced-air system without dedicated components?

We have a very typical forced-air HVAC system with a medium-efficiency gas furnace and split-system central air conditioner in our house; however, latent load buildup (i.e. stickiness) is a problem ...
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1answer
719 views

Why would the condensing unit fan shut off but not the compressor?

We have an allegiance 12 unit circa 2001, model 7a2024a100a3, the fan starts up and runs for about 5 minutes then shuts off, the compressor is still on and seems to build up a bit the "flush" or so it ...