Questions tagged [hvac]
The hvac tag has no usage guidance.
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Making sense of new vs old wiring schematic
I'm hooking up a new AC condenser fan and attached is the pic of the old and new diagrams. Where should the new wires should go in reference to the old ones? They are run to a single 4 pin plug.
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HVAC control & Low Voltage Wiring (24v to 10v) [closed]
I am a GC having some exhaust fan control issues I am hoping someone on here can assist with. My mechanical and electrical contractors are stumped as well.
We have a Vari-green 2 speed controller ...
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How to average two 0-10 V signals?
For an HVAC application I'm searching for a way to average two 0-10 V signals with the ability to give a "weight" to one or another.
Example:
I have input A at 10 V and input B at 5 V.
If ...
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What is a Fast-Stat Commonmaker actually doing?
Trying to get an Ecobee thermostat to work in my old house where I only have two wires going to my thermostat. Ecobee needs a common, and the remedy they suggest is a Fast-Stat Commonmaker, which has ...
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Start heat pump (HVAC) from electric generator: AVR voltage surge issue
I'm trying to start the heat pump from the generator, and it turns out successfully...for an hour.
First of all, mandatory specs and preconditions:
heat pump: Mitsubishi Electric PUHZ-SHW140YHA
...
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Could someone help me identify a part number/brand for this surface mount diode?
I’m repairing the main control board for a HVAC unit that was damaged in a power surge. Nothing too complex, just a diode that was blown and needs to be replaced.
The problem is I’m not exactly sure ...
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Different fan size in same duct [closed]
Im trying to build pc cabinet such that there is 3 fan input to cabinet, and just one output which is the smps inbuilt fan. Then seal off all other air gaps.
Q. Will the smps fan break due to ...
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Can I use 45 uF/5 uF in place of 70 uF/5 uF temporarily for air conditioning [closed]
My air conditioning is not blowing cold air today and I found the 70 uF capacitor measures about 1 uF. I happened to have one new 45 uF/5 uF at hand.
My question is: is it ok to use this one for a few ...
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Can I replace two run capacitors with a dual run capacitor?
In this unit https://ameristarhvac.com/wp-content/uploads/pdf/M4AC3-Air-Conditioner-Installation-Manual.pdf
Can I replace the 35 uF capacitor and the 6 uF capacitor with a 35/5 uF dual capacitor? If ...
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HVAC 24VAC backfeed prevention [closed]
I have an HVAC system with a powered open/powered closed supply damper, Ultra-aire 120 V dehumidifier and ventilation damper that is powered to open. I have everything wired up and it is working, ...
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Would there be any safety issues if the input voltage on the primary coil is bigger than what the rated voltage is?
I have a neon sign transformer that converts 120 V to 12 kV which is the rated voltage. Using the 1:100 ratio would it be safe to have the input voltage be 140 V converted to 14 kV when the specified ...
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What kind of component is this, and is it damaged?
My central heating controller stopped working. It's essentially an AA battery powered device with a thermistor, some buttons, and an LCD screen, which lets me program desired temperatures for various ...
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Would retro-fitting a DC motor as the blower motor in a residential furnace be more efficient than existing 1/2 hp AC motor?
There exists DC motors of various voltages (12, 24, 48, etc) and various powers (1/2 hp, 1 hp, etc). They seem to have the necessary power and RPM to operate the blower in a conventional residential ...
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RS485 Protocol Reverse Engineering & Replay Challenges
I'm trying to reverse engineer the RS485 protocol used by my home heater/AC.
This protocol handles communications between the wired remote control (WRC)/thermostat and the main heater/ac indoor unit (...
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What are these electric components?
This is a snapshot from a single-line diagram of emergency switchboard drawn in 1984 for an oil & gas project.
What are these two components next to the motor symbol? What could ...
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How to divide 24VAC to 24VDC for use with GPIO
I'm working on a project to gather metrics from my HVAC. I need to detect the presence or absence of 24vAC on two different wires (Y/yellow/cooler, W/white/heater) relative to common - either of which ...
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Current Transformer in power meter
How to measure the total power in a 3 phase electrical system with one current transformer?
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Where do I measure the Amp draw of my motor which is connected to a centrifugal fan?
I just started my job as an apprentice technician. For the longest time, my supervisor have always been measuring the amp draws of my motor from the outgoing cable from the motor to the electric panel ...
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Can a 10uf Capacitor be used in place of a 15uf capacitor temporarily?
I am in Phoenix and it's hot. The indoor blower motor just went out on our AC unit and the wife and kids are not happy. It is just a bad capacitor.
Original capacitor is 15uf 440v. I was able to get ...
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Do 0-10V proportional valves and dampers require a sourcing or sinking controller?
A 0-10V controller can use either sourcing or sinking to set the control voltage (see Wikipedia 0-10V Lighting Control, for example). For sinking control, the controlled device provides a high ...
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