Condensing Unit Too Close to House | HVAC Basics

Condensing Unit Too Close to House

Condensing Unit Too Close to HouseThis condensing unit was too close to the house to effectively reject heat. It was a bad HVAC condensing unit installation job by the HVAC installers. A mechanical inspector rejected the final for the permit until the condensing unit was correctly installed. It is recommended that condensing units have at least 2 feet of space so that it can effectively reject heat. It needs space to breathe and pull air into the coils so that there is a proper heat exchange taking place when it is running. On this air conditioner condensing unit there are four sides to the unit. By installing the air conditioner condenser too close to the house the installer effectively reduced the capacity of this unit by nearly one fourth which will cause problems with unit in the way of higher head pressures and that will cost the homeowner more money in the long run.


DX CRAC Unit Condensers | Critical Facility HVAC

DX CRAC Unit CondensersDX CRAC Unit Condensers | Critical Facility HVAC

DX CRAC Unit Condensers | Critical Facility HVAC – Most data centers do not utilize HVAC DX (Direct Expansion) CRAC units or air conditioning but instead use chilled water systems to provide cooling for the data center. In smaller buildings such as remote telecom buildings DX air conditioning systems are used to keep the equipment cool and operating efficiently. A DX CRAC Unit uses vapor compression refrigeration to provide cooling with a chemical refrigerant versus a chilled water system that utilizes chilled water from a chiller. CRAC Units or Computer Room Air Conditioners also serve telecom facilities for telephone services including cellular telephone facilities in remote locations. The CRAC units that serve telecom facilities in remote locations are typically DX CRAC Units that have utility back-up by stand-by generator so that if the utility fails to provide electricity for whatever reason the stand-by generator kicks on and provides power so that the telecom facility can remain on line. (more…)

HVAC Green Technology | Heating and Cooling

HVAC Green Technology | Heating and Cooling

First of all we need to define Green Technology before we compare it to HVAC and how the HVAC industry is working to make equipment and designs green technology friendly. Green Technology uses evolving technology to utilize methods and materials to develop techniques that are friendly or friendlier to the environment than past methods and material. HVAC is constantly evolving as new ideas about environmental friendly concepts are put into place and used to make things more efficient and friendly to the environment. It has become necessary for many people and industries to stop ignoring environmental concerns because using older methods cost more than the new methods to implement. The definition of Green Technology goes a little further in implementing a solid strategy of environmental friendly ideas, methods, and materials including machines. These strategies include: (more…)

Helping Your Air Conditioner – Beating the Heat

Helping Your Air Conditioner – Beating the Heat – The new house you just bought is not so cool and the air conditioner seems to run all the time. You begin to worry that maybe something is wrong with the air conditioner. You tolerate it for a while until your spouse broaches the subject a few hours later. Both of you discuss the matter and come to the conclusion that something is wrong with the air conditioner. (more…)

Trane Chilled Water Systems – Multi-Zone Air Conditioning Systems

Trane Chilled Water Systems – Multi-Zone Air Conditioning SystemsTrane Chilled Water Systems – Multi-Zone Air Conditioning Systems – This Trane HVAC chiller serves four different apartments. Chilled water systems offer a great way for multi-zone air conditioning. From small apartment buildings to large commercial buildings chilled water systems can serve multi-zone air conditioning systems. From one air conditioning zone to hundred the only limitation is the size of the chiller. If the air conditioning zoning system (the load) is matched up with the right sized chiller (in tons) the system will serve all air conditioning zones and keep all the occupants comfortably cool. Chilled water systems can also be integrated with the boiler system so that the same system can be used for heating and cooling. A good control system will add efficiency and more comfort to the system. (more…)

Efficiency Factors for Condensing Units | HVAC Refrigeration

Efficiency Factors for Condensing Units

New HVAC Condensers Compressor Technology

For years compressors inside the condensing unit were sized to meet the highest load demand for whatever application they were serving. Even today, many compressors, located inside the condensing unit are sized in accordance with there highest load demand even though it is unlikely they will only be needed to run for full load conditions approximately 30-35% of the time. While many systems have worked just fine this way for many years they have not been very energy efficient. So even on a mild day these compressors run full blast even though the system may only require the compressor to run at 50% capacity to satisfy the demand. That creates problems with short cycling which causes premature wear, higher maintenance costs, and reduces total compressor life span. (more…)

Dual Two-Stage Split System with a Dual Slab Coil

High Performance HVAC Air Conditioning & Heating: Ask the HVAC Man?

Dual Two-Stage Split System with a Dual Slab Coil. Huh?


Very nice site!

Dual Two-Stage Split System with a Dual Slab CoilDual Two-Stage Split System – I have a question; my home was fitted out by the previous owner with a twinned system, and a thermostat (Totaline P374-1900) which was not designed to control discreet, paired units. I confirmed this with Totaline. The result is only one unit runs, and the second unit is never activated. It functions, but not automatically.

Your website mentioned dual compressors in one systems, and mine is similar, two independent compressor/condensers. Seeing the separate condenser units, I first thought the house was zoned, and later discovered both units feed into one Aspen BHA40 4-roll coil.

Besides the issue of the wrong thermostat, I’m having problems finding an HVAC person who understands these hybrid systems and will service it. Is this configuration that uncommon?

I live very near Houston Texas, so if you know of a local HVAC person with the skills to help me out – let me know.

PS – I checked with Honeywell about the possibility of their thermostats working with my setup. They emailed me – they would only work with a HVAC professional. I thought this was strange since they sell them in the hardware stores.


York Variable Frequency Drives VFDs | HVAC Control

York Variable Frequency Drives VFDs

York Variable Frequency Drives VFDs | HVAC Control

York Variable Frequency Drives VFDs | HVAC Control – Variable Frequency Drives or VFD’s have added a whole new dimension to energy efficiency and control. These drives, or VFD’s, are hooked up to two different York VAV air handlers that have two three phase motors a piece. Each air handler has a return fan and a supply fan. Two thirds down stream from the supply fan motor is a static pressure sensor (Pressure Transducer). This is connected back to a DDC controller which will regulate the speed of the fans based on the static pressure set point. Variable frequency drives, or VFD’s, allow the system to use only the amount of air that is needed for the VAV boxes. If demand for air flow is high the drives, VFD’s, ramp up and deliver more air. If the demand for air flow is low the drives, VFD’s, slow down so less air is delivered. This allows the system to use less energy and maintain comfort levels based on temperature set points.


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