You're viewing our online Q&As related to General HVACR. Other technical categories include Commercial HVACR and Residential HVACR. You can also browse our complete list of technical Q&As, and ask a question of your own.

Q&As Related to General HVACR

Geo-thermal Heat Pump Information
Where to find geo-thermal heat pump information Read it.

Code requirements for room operating temperatures or temperature differentials between rooms
When homeowners adjust the thermostat, they expect to walk away and forget it, knowing the entire living space will be reasonably close to the desired temperature. ACCA Manuals provide HVAC contractors with the guidance needed to make that happen. Read it.

Code requirements for adjusting gas burners for high altitude locations
National Fuel Gas Code (NFGC) ANSI Z223.1 recommendations Read it.

Calculating air density at high altitudes
Formula and table for calculating air density. Read it.

Something to check out on retrofits with bypass ducts
Old Manual D designs are obsolete when it comes to bypass ducts. Read it.

High Static pressure now what?
Advice on what to do when a duct has a high static pressure measurement. Read it.

Updated flex duct friction rate chart
The new Manual D provides the information you will need to evaluate duct. Read it.

R-410A system space requirements
Unanticipated installation expenses can be minimized by first determining if the required clearance is available. Read it.

Existing R-22 indoor coils and R-410A
It is recommended that contractors proceed with caution because many older coils were not designed for the R-410A equipment’s higher operating pressures. Read it.

Drop in Refrigerant
Contractors are encouraged to not use any refrigerant unless it is endorsed by the compressor or equipment manufacturer for use in the specified equipment. Read it.

Refrigerant KDD5?
A new drop in refrigerant for R-22 systems Read it.

Can't pull a vacuum
Vacuum gauge leak problem Read it.

Blown in Foam R Value
Design guidance for structures with blown in foam insulation Read it.

Intermittent Burned Wire
Looking for an intermittent electrical problem in the compressor start / run circuit. Read it.

Balancing Registers
Advice on adjusting room supply registers. Read it.

Combustion Testing Equipment
A list of combustion testing equipment that is available. Read it.

Traversing to Measure Airflow
Brief description of what traversing is and how it is used to determine airflow Read it.

Pressure Matching Method
Brief description of pressure matching method for testing duct leakage. Read it.

Line Sets for 410A Systems
Replacing line sets when replacing R-22 systems with R-410A. Read it.

Avoid an Oil Crisis When Changing Refrigerant Types
A brief discussion of oil differences in R-22 and R-410A systems. Read it.

Converting R-22 Systems to R410A
Converting from R-22 to R-410A is not a simple matter. Read it.

The Future of R-22
R-22 is not banned, but production and availability will continue to decrease. Read it.

Manual D Duct Troubleshooting
Manual D duct troubleshooting for "losing air or supply air temperature drop /increase in the duct”. Read it.

Coil Cleaning Procedures
Advice for cleaning indoor and outdoor coils. Read it.

Cracked Heat Exchangers
What to do when a cracked heat exchanger is discovered, and why it matters. Read it.

Latest EPA Leakage Rates
Find and use the latest EPA leakage rates under Section 608. Read it.

Handling Used HVACR Oils
Removing or changing refrigerant oils. Read it.

Evaporator Freeze Up
Causes for residential and commercial evaporator coil freeze ups and some remedies. Read it.

Carbon Credits for HVAC
There currently is no way for an HVAC contractor to trade carbon credits for profit. Read it.

Caution! Shipping Refrigeration
Caution requirements for shipping refrigeration materials. Read it.

Removing or Adding Load
Sizing the correct unit when customers raise questions about costs. Read it.

Heat Pump Troubleshooting
Newly installed heat pump system in an attic shows excessive sweating of the air handler. Read it.

Leaking Vacuum Gauges
Read it.

Alternative Drain Lines
Bearing the costs of stolen materials, are there any alternatives. Read it.

Heater Troubleshooting
Troubleshooting a unit heater with no visible signs of damage. Read it.

Evaporator Problems in High Humidity
An evaporator coil freezes up every time there is high humidity. Read it.

Suspected Burned Out Compressors
What to do when a compressor won't start. Read it.

Refrigerant Replacement
What to do when replacing an unknown refrigerant when the data tag calls for another. Read it.

Brazing a Refrigeration Line
Setting the regulator pressure for the nitrogen purge when brazing a refrigeration line. Read it.

Charging Blended Refrigerants
How to charge and transfer the new blended refrigerants without altering their composition. Read it.

Clean Condenser Coils
The importance of clean coils and how to clean them. Read it.

Nitrogen Sweeps When Brazing
Nitrogen sweeps prevent copper piping from oxidizing. Read it.

EPA Rules Regarding Leak Repairs and Refrigerant Venting
The EPA hasn't changed the rules, just clarified them. Read it.

Diagnosing System Restrictions
Mistaking a restricted system for an undercharged one is common but can be prevented. Read it.

Frost on the Suction Line
Although frost may be normal in some low-temperature systems, it's best to make sure it's not a malfunction. Read it.

Suction Line Accumulators
These devices protect the compressor. Read it.

Crankcase Heaters
Heating the compressor crankcase reduces refrigerant migration and dilution. Read it.

Filter Driers
How to know when a filter drier needs to be changed. Read it.

Evaporator Size
Under- or over-sizing and evaporator can have serious consequences. Read it.

Finding Small Leaks
Small leaks can be frustrating; here's method for finding them. Read it.

Lubricants
Today's refrigerants require different oils from the ones most technicians are familiar with. Read it.

An Overzealous Salesperson
People are trying to sell customers all kinds of gadgets and fluids they say will improve performance, but they may void the manufacturer's warranty. Read it.

The Significance of Subcooling
What subcooling is, how to measure it, and what it tells you about a system. Read it.

Determining the Proper Charge
Use instrumentation to make sure a system is operating properly. Read it.

TXVs
Thermostatic expansion valves are superior feed devices, but costly. Read it.

You're viewing our online Q&As related to General HVACR. Other technical categories include Commercial HVACR and Residential HVACR. You can also browse our complete list of technical Q&As, and ask a question of your own.