The Danfoss/Secop controller can handle powering 0.5 amps of fans and upto 1 amp for a few seconds. I'd suggest you hook up another low draw, low cfm fan to the controller to exhaust the hot air from the area and draw cooler air into it. The Fans available vary greatly in output for noise made and current consumed.

My System is working beautifully and in sub 60 degree weather it take more than 72 hours for the fridge to consume 24 amp hours. I've got a "Watts up" meter I can hook inline. Here it is next to my controller where I have a removable panel for winter time to keep warm air inside the living compartment and not draw cool air in past weak seals.


I've not reread this whole thread, and don't remember it all, but long story short, I never reversed the airflow. I did add more insulation to cabinet walls and fridge walls which allowed me enough room to move the fan to the other side of the condenser. These fans are much quieter pushing air through a restriction rather than pulling it through one.

I'd also made a cooling unit tunnel to direct all fan flow through condenser, and across compressor and controller. This air is then directed out a louvered vent behind the fridge, or into the next compartment of the cabinet where I have another fan exhausting air into the living space.

Having moved the fan makes it much easier to clean the dust off the fan blades and condenser twice a year. The cooling unit tunnel also protects the unit from installation/ removal stresses, as I do need to remove it to access the fan and condenser. 4 screws and disconnect a powerpole connector and it slides right out easy peasy

It is said that the best way to increase fridge performance is by making sure the condenser is not sitting in air it itself has already warmed. I feel that just letting it stew in its own juices with a few passive vents in the area is like a vehicle radiator with the grill blocked off and wondering why the engine runs hot.

Mine has 0% chance of running preheated air through the condenser or across the compressor, and I'm sure if the bean counters allowed the engineers to design it this way, they would, but what does a bean counter care if your fridge consumes 24 amp hours per 24 hours, or 30 A/H. There is enough wiggle room on their spec sheets, and there is no truth what so ever in advertising anyway. Besides that, they can't design the cabinet where the fridge will reside and the manufacturer making recommendations as to how to design the cabinet for most advantageous airflow for maximum efficiency will make 90% of the public thing it was not designed properly in the first place, rather than as a compromise and good enough for those who don't understand the physics.

Doing these mods is not trying to outthink the engineers, it is undoing the damage done by the beancounters to the engineer's designs, what they would do if allowed free reign, in my opinion.

Looks like they really shoehorned that cooling unit in on the back of that TruckFridge.The Danfoss/Secop controller can handle powering 0.5 amps of fans and upto 1 amp for a few seconds. I'd suggest you hook up another low draw, low cfm fan to the controller to exhaust the hot air from the area and draw cooler air into it. The Fans available vary greatly in output for noise made and current consumed.My System is working beautifully and in sub 60 degree weather it take more than 72 hours for the fridge to consume 24 amp hours. I've got a "Watts up" meter I can hook inline. Here it is next to my controller where I have a removable panel for winter time to keep warm air inside the living compartment and not draw cool air in past weak seals.I've not reread this whole thread, and don't remember it all, but long story short, I never reversed the airflow. I did add more insulation to cabinet walls and fridge walls which allowed me enough room to move the fan to the other side of the condenser. These fans are much quieter pushing air through a restriction rather than pulling it through one.I'd also made a cooling unit tunnel to direct all fan flow through condenser, and across compressor and controller. This air is then directed out a louvered vent behind the fridge, or into the next compartment of the cabinet where I have another fan exhausting air into the living space.Having moved the fan makes it much easier to clean the dust off the fan blades and condenser twice a year. The cooling unit tunnel also protects the unit from installation/ removal stresses, as I do need to remove it to access the fan and condenser. 4 screws and disconnect a powerpole connector and it slides right out easy peasyIt is said that the best way to increase fridge performance is by making sure the condenser is not sitting in air it itself has already warmed. I feel that just letting it stew in its own juices with a few passive vents in the area is like a vehicle radiator with the grill blocked off and wondering why the engine runs hot.Mine has 0% chance of running preheated air through the condenser or across the compressor, and I'm sure if the bean counters allowed the engineers to design it this way, they would, but what does a bean counter care if your fridge consumes 24 amp hours per 24 hours, or 30 A/H. There is enough wiggle room on their spec sheets, and there is no truth what so ever in advertising anyway. Besides that, they can't design the cabinet where the fridge will reside and the manufacturer making recommendations as to how to design the cabinet for most advantageous airflow for maximum efficiency will make 90% of the public thing it was not designed properly in the first place, rather than as a compromise and good enough for those who don't understand the physics.Doing these mods is not trying to outthink the engineers, it is undoing the damage done by the beancounters to the engineer's designs, what they would do if allowed free reign, in my opinion.

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3 Ways To Increase Chiller Efficiency

VFDs, parallel devices, and increasing supply temperatures all contribute to energy savings for chiller plants.

By Thomas Squillo, Contributing Writer   HVAC

OTHER PARTS OF THIS ARTICLE

Pt. 1: How To Get the Most Energy Efficiency From a Chiller Plant

Pt. 2: This Page

Editor's note: This article was previously published in and has been updated to reflect current information. 

It&#;s that time of year again &#; summer - and warmer weather brings calls to ensure that chillers are running more efficiently than ever. Though chillers may have the largest peak load of any component, it may not be the largest contributor to total annual energy consumption. Here are three things to consider when making operational changes to guarantee the efficiency of chillers all year long.  

1. Consider variable speed retrofits

Most components within a chilled water system will benefit from variable speed drives. In fact, most current energy codes require VFDs for these components in new systems and major retrofits. VFD costs have also decreased dramatically in the last several years.

As shown by the constant- and variable-speed chiller efficiency charts on page 38, there is a huge benefit to VFDs for chillers, but only if condenser water temperature relief is also implemented. 

Cooling tower fans are another opportunity to save energy with VFDs. As loading and outdoor wet-bulb temperature decrease, variable speed fan motors not only save fan energy due to fan law benefits (a fan at 50 percent speed draws 12.5 percent of the power of a fan operating at 100 percent), but also provide more stable temperature control.

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Variable speed pumping can provide an energy savings opportunity, but requires a close look at other parts of the system. On the chilled water side, a constant to variable flow retrofit may involve major and costly renovations of control valves and control sequences. Also, variable flow capabilities of existing chillers need to be reviewed. Low flow limits of the chiller may reduce the economic feasibility of variable chilled water pumping. On the condenser water side, variable flow control may be limited by chiller flow requirements or cooling tower fouling/freezing concerns. However, if pumps are oversized on a constant flow system, balancing pump flow by lowering speed versus flow restriction using a balancing value may provide good payback, even without adding variable flow during system operation.

2. More is less: Running multiple parallel devices optimizes savings

Chiller plant equipment generally runs more efficiently at part-load. Chillers, for example, can run at optimum efficiency somewhere between 40 percent and 60 percent of peak capacity. Cooling tower fans and system pumps that are piped in parallel may also benefit from a control scheme that operates more pieces of equipment at lower speeds, versus a staging scheme which allows operating equipment to increase to full capacity before staging on the next unit. For cooling towers and chillers, running more equipment maximizes heat transfer surface area at all operating points, which increases efficiency and reduces pressure drops. For pumps, taking advantage of pump law savings and running at optimum pump efficiency points is key. The pump law is similar to the fan law: When pump speed is reduced, energy consumption is cut by the cube of the reduction in speed. However, any control scheme change needs to consider minimum chiller and cooling tower flow limits.

3. Increase supply temperatures

Most commercial systems are designed with a chilled water supply temperature in the range of 40 F to 45 F. This generally allows for proper dehumidification and an acceptable supply air temperature for occupant spaces during peak times. However, these peak weather and load conditions are rarely seen.

Implementing supply air temperature reset control can save energy in several ways. First, when cold supply air temperatures are not required (acceptable humidity levels and no zones at peak load), raising supply temperatures can help prevent over-dehumidification of spaces and unneeded latent cooling. More importantly, higher supply air setpoints can allow chilled water supply temperature to be increased, substantially improving chiller efficiency. In general, chiller efficiencies improve approximately 2 percent for every degree that chilled water supply temperature is increased.   

Other design and control features should also be investigated to optimize energy savings. As noted earlier, VFDs on all or some components should be considered. Also, a close look at setpoints, temperature reset, and other simple control sequence changes are usually effective and have minimal cost.

Of course, these methods are not right for every system. Depending on budget and financial requirements, climate, expected load profile, and existing equipment limitations, your optimal solution will be unique and will likely require an engineering analysis and annual energy use calculations.

Thomas Squillo serves as technical director, mechanical, for Environmental Systems Design. 

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