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View Full Version : Are We Wasting Energy More Efficiently?







Josip
15-02-2015, 01:23 PM
An old but good article ... :)

http://www.achrnews.com/articles/89021-are-we-wasting-energy-more-efficiently


Best regards, Josip :)

chillerman2006
21-02-2015, 12:51 PM
Systems will always be incorrectly charged as so many don't charge correctly

Just a fortnight ago watched as a 'highly respected engineer' charged 13kg into a dx unit with less than 5m pipe run that should have been charged to 8kg

His justification was to raise the back pressure as the unit kept going into defrost at ! ambient 0c

After 3 defrosts in an hour the unit locks out so he had no choice [Really :D]

There was no consideration that it was a poor design issue & unable to run to spec in that ambient

Did not think about lowering the pressure that defrost kicks in at whilst in heat mode

Just over charging was the only way and said to me a return visit might be required in the summer to take some back out !

Not even response of 'no kidding einstien' would change his mind, he knew best

cadwaladr
23-02-2015, 12:29 AM
According to a maker of bus ac units said many years ago,the agent in Spain spent most of his breakdowns removing refrigerant from overcharged systems that ran great in cold climates as soon as they reached high ambient trip but his double bonus was a good free stock of refrigerant!

Glenn Moore
23-02-2015, 12:59 AM
Hi Chillerman

Interesting subject energy efficiency and refrigeration and air conditioning systems. Having been in the industry some 51 years in a service roll in both AC and Industrial fridge and in a Technical roll with a large wholesaler and then a manufacturer, I spent most of my time on sites trying to get systems up and running and training engineers on new controls and how to set them up to get the best efficiency possible from their installations. Whenever I selected new types of controllers for a customer I would if possible carry out some in house or on site training for their engineers , so that they learnt how to set up the controls to gain the best efficiency and stable control of the plant.
Very few engineers when commisioning a new system actually set up the thermostatic expansion valves as many believe they come "Factory Set". Even systems that have new Electronic expansion valves fitted often are no more efficient than a dumb TEV. Often I've gone to sites and found the Electronic controllers for the expansion valves operating with factory default settings, some even with the wrong refrigerant setting. So all these super controls are a waste of money unless engineers are trained in the set ups and benefits of these controls.
Many of the training courses I ran was on Superheat, subcooling how Thermostatic valves function and how their clever brothers the electronic valves work and why they can save the end user money and give a better product.
This is a true story :- I was at one of the larger wholesalers trade counters on an Open Day. An engineer came in who wanted to discus a problem with a compressor, I quickly sorted that one , then he wanted to discuss Expansion valves . It turns out he had fitted an identical replacement valve and orifice to a small cold room but the plant never reached temperature. I questioned him on the system charge , whether internal or external equalisation, where the bulb was positioned etc etc. I then asked how much superheat he had at the evaporator outlet. His reply was amazing. He said that he had spoken to a number of engineers who asked the same question, but told me that he had looked through all the major wholesalers catalogues and price lists but could find no Superheat listed. If I could give him a part number he would buy as much as I thought he needed. At this stage I'm thinking are you taking the P---, !!!! but he was deadly serious. The cold room was only a few streets away and I went with him and showed him how to set an expansion valve and how to measure superheat, which after we had opened the expansion valve nearly 4 full turns the room temperature dropped to the thermostats set point. He was amazed that you needed to set the expansion valve as he had never adjusted a valve before, and simply fitted a new valve if he thought it wasn't working.
If refrigeration and air conditioning plants were all installed using the the latest energy efficient type of valves,controllers and invertors,and then set them up correctly we could most likely shut down 25% of the power stations in this country with no loss of power.
From this forum alone it seems that most engineers are trying to work on equipment that they have no knowledge on and are expected to sort out various manufacturers alarm codes and error codes and this place has to be the font of all knowledge rather than manufacturers making sure engineers have easy access to their manuals and training courses.
Maybe we as an industry should be pushing all of the controller manufacturers to come up with a universal system protocol with standard alarm codes and error codes similar to the automobile industry which all car makers use identical error codes etc for mechanics to easily identify faults
This industry spends more of its time trying to find information than actually doing the job
The array of equipment coming into this country with little or no commisioning info these days makes it more and more difficult for engineers to give their customers the degree of service they would like to.

Grizzly
23-02-2015, 07:20 AM
Hi Glenn.
Wise and well written words!
You missed the bit about everything being VSD nowadays!
IE. How can you set up a chiller or large system if the water pump flows keep fluctuating or the condenser fans are set to low etc.
In fairness to everyone here on this forum!
We are all here because "WE" want to learn and I for one can never criticise anyone for that!
I forget sometimes how lucky I have been so far in having access to some very clever colleagues.
The more sophisticated the systems get the more margin for error.
Most nowadays just want it working and the cheapest costs!

Your last sentence is spot on!
Good luck to all and may you all continue to ask questions because if people are embarrassed to ask.
How are we all going to learn.

You can have the worlds most brilliant controls but without access to them they and you are worthless!
Grizzly

chillerman2006
23-02-2015, 01:21 PM
Got to agree with you both
Have had many engineers reluctant over the years to ask as they don't want to seem incompetent
My reply is always ... you only know what you know, ask and then you know
Not being an a** but meaning none of us know it all and never will
I have taken a lot of good info from this forum over the years and hopefully returned some too

Oh and why does that not surprise us cadwaladr :)

mikeref
24-02-2015, 10:01 AM
Sometimes we INHERIT poorly chosen/ installed equipment.
Might i add, The following event may have been posted in another Category during my earlier years on R.E.

An outside company mismatched 3 independently controlled Evaporators to one Condensing kit. 4 Compressors within a 12 Month period failed... Wouldn't there be questions after the first and definitely second loss? (This has a lack of efficiency written all over it.)

Company could not be contacted after the Fourth failure.

Turns out the Compressor was seriously over sized for maximum load and had to be constantly cycling on LP during part load conditions. No compressor time delay on board.
Installed a 3 Phase compressor with reduced capacity....and a 5 Minute delay timer wired in for assurance.

No more short cycling or compressor failures.:)

Glenn Moore
24-02-2015, 02:35 PM
Hi Mike
I had one where the contractor went through 7 new compressors in 2 weeks!.
The system was a simple computer room air conditioner, with a Paragon air handler inside the room with a Maneurop condensing unit just through the wall outside.
The original MT28 compressor had ran for 9 years and had then burnt out. The service company bought a replacement compressor and drier, fitted them, recharged the system and then left site with the system working. The following day they had a call that the system was running but not cooling. When the engineer got to site he found that indeed the compressor was running but not pumping ie equalised pressures suction to discharge. So he suspected a faulty compressor. So he removes the compressor and get another new one from the wholesaler under warranty.
He fits the new compressor and a new drier and away it goes. Following day gets a similar phone call systems running but not cooling . Engineer returns to site, finds the same problem, ie compressor running but not pumping. So gets a further new compressor. This goes on until he's damaged six new compressors. At this time i'm away on holiday. On the Monday I get to work and immediately i'm sent to this site in Warwick to see what is going on as we have refused to allow the contractor to start the plant until I'm on site as he is now on his 7th compressor.
The first 2 damaged machines were cut open and we found a hole through the centre of the piston in both machines. So immediately I knew what had happened to the machines.
The units operated with an LP switch and a cam motor as the control. When the thermostat called for cooling the cam motor would turn and energise the solenoid valve, the suction pressure rises and the compressor starts, when the temperature is satisfied the cam motor reverses and closes the solenoid valve and the plant pumps down and stops on the LP switch.
So when I checked the compressor contactor I found that the contacts were in a terrible state where 2 of the contacts had badly melted.
So what was happening was the thermostat would call for duty ,the cam motor would turn and open the solenoid valve, the pressure would rise and make the LP switch . the compressor would start to run but would then trip on its internal klixon. In the meantime the solenoid is still energised allowing the liquid charge to run back into the compressor and fill it to a point where liquid would enter the cylinder, and when the Klixon reset itself the compressor would re-start up and try to compress this liquid. The discharge valve would break as the liquid hits it and fall inside the cylinder, the piston would now try to compress the hard valve plate which punchs a hole through the softer aluminium piston crown,. This made it impossible for the compressor to pump at all.
The problem was the engineer had failed to fit a new compressor contactor , and the manufacturer of the original unit had failed to fit an overload to the contactor through the control circuit.
So it was a simple case of fitting a new contactor "with an overload" wired in the control circuit, this solved the problem
The contractor then expected us as the supplier of the compressors to pay for the first six compressors, as he questioned where it stated that you change the electrics after a burn out.
Unfortunateley this often happens that new compressors are fitted to the old electrics and the old electrics take out the new compressor , Then we hear the old cherry "Dead on arrival "

mikeref
25-02-2015, 09:34 AM
Glenn. It seems as though some Engineers can't see beyond changing parts.
Sure enough, components wear out but a history of the same item failing in a short time frame should trigger something in the Grey matter.

Tycho
25-02-2015, 08:43 PM
Hi Chillerman

Interesting subject energy efficiency and refrigeration and air conditioning systems. Having been in the industry some 51 years in a service roll in both AC and Industrial fridge and in a Technical roll with a large wholesaler and then a manufacturer, I spent most of my time on sites trying to get systems up and running and training engineers on new controls and how to set them up to get the best efficiency possible from their installations. Whenever I selected new types of controllers for a customer I would if possible carry out some in house or on site training for their engineers , so that they learnt how to set up the controls to gain the best efficiency and stable control of the plant.
Very few engineers when commisioning a new system actually set up the thermostatic expansion valves as many believe they come "Factory Set". Even systems that have new Electronic expansion valves fitted often are no more efficient than a dumb TEV. Often I've gone to sites and found the Electronic controllers for the expansion valves operating with factory default settings, some even with the wrong refrigerant setting. So all these super controls are a waste of money unless engineers are trained in the set ups and benefits of these controls.
Many of the training courses I ran was on Superheat, subcooling how Thermostatic valves function and how their clever brothers the electronic valves work and why they can save the end user money and give a better product.
This is a true story :- I was at one of the larger wholesalers trade counters on an Open Day. An engineer came in who wanted to discus a problem with a compressor, I quickly sorted that one , then he wanted to discuss Expansion valves . It turns out he had fitted an identical replacement valve and orifice to a small cold room but the plant never reached temperature. I questioned him on the system charge , whether internal or external equalisation, where the bulb was positioned etc etc. I then asked how much superheat he had at the evaporator outlet. His reply was amazing. He said that he had spoken to a number of engineers who asked the same question, but told me that he had looked through all the major wholesalers catalogues and price lists but could find no Superheat listed. If I could give him a part number he would buy as much as I thought he needed. At this stage I'm thinking are you taking the P---, !!!! but he was deadly serious. The cold room was only a few streets away and I went with him and showed him how to set an expansion valve and how to measure superheat, which after we had opened the expansion valve nearly 4 full turns the room temperature dropped to the thermostats set point. He was amazed that you needed to set the expansion valve as he had never adjusted a valve before, and simply fitted a new valve if he thought it wasn't working.
If refrigeration and air conditioning plants were all installed using the the latest energy efficient type of valves,controllers and invertors,and then set them up correctly we could most likely shut down 25% of the power stations in this country with no loss of power.
From this forum alone it seems that most engineers are trying to work on equipment that they have no knowledge on and are expected to sort out various manufacturers alarm codes and error codes and this place has to be the font of all knowledge rather than manufacturers making sure engineers have easy access to their manuals and training courses.
Maybe we as an industry should be pushing all of the controller manufacturers to come up with a universal system protocol with standard alarm codes and error codes similar to the automobile industry which all car makers use identical error codes etc for mechanics to easily identify faults
This industry spends more of its time trying to find information than actually doing the job
The array of equipment coming into this country with little or no commisioning info these days makes it more and more difficult for engineers to give their customers the degree of service they would like to.

AMEN!

I could write page up and page down about situations like this, where a end-user finds a cheap supplier for spare parts and doing the math in his head he finds out that he can just buy it directly and do the job himself, and then pumps down the system, making sure he has a proper vacuum on the low side before replacing a valve (because he has heard that vacuum was important), and then there is the other guy that knows that air in the system is bad, so he shuts of a few valves and then purge the line until it is "safe" to dismantle the part they are replacing, while the pressure is so low they can do it "safely"....

First guy ends up with his whole system shutting down on high discharge pressure when his condensers are full with air, and the second guy is scratching his head because he keeps loosing refrigerant... in their mind they both did it by the book...


If you ever talk to that guy again, I have five plastic bags of hotgas I am looking to get rid of, I'll part with them for the correct price :) they are great for defrosting :D

RANGER1
25-02-2015, 09:31 PM
Hi Mike
I had one where the contractor went through 7 new compressors in 2 weeks!.
The system was a simple computer room air conditioner, with a Paragon air handler inside the room with a Maneurop condensing unit just through the wall outside.
The original MT28 compressor had ran for 9 years and had then burnt out. The service company bought a replacement compressor and drier, fitted them, recharged the system and then left site with the system working. The following day they had a call that the system was running but not cooling. When the engineer got to site he found that indeed the compressor was running but not pumping ie equalised pressures suction to discharge. So he suspected a faulty compressor. So he removes the compressor and get another new one from the wholesaler under warranty.
He fits the new compressor and a new drier and away it goes. Following day gets a similar phone call systems running but not cooling . Engineer returns to site, finds the same problem, ie compressor running but not pumping. So gets a further new compressor. This goes on until he's damaged six new compressors. At this time i'm away on holiday. On the Monday I get to work and immediately i'm sent to this site in Warwick to see what is going on as we have refused to allow the contractor to start the plant until I'm on site as he is now on his 7th compressor.
The first 2 damaged machines were cut open and we found a hole through the centre of the piston in both machines. So immediately I knew what had happened to the machines.
The units operated with an LP switch and a cam motor as the control. When the thermostat called for cooling the cam motor would turn and energise the solenoid valve, the suction pressure rises and the compressor starts, when the temperature is satisfied the cam motor reverses and closes the solenoid valve and the plant pumps down and stops on the LP switch.
So when I checked the compressor contactor I found that the contacts were in a terrible state where 2 of the contacts had badly melted.
So what was happening was the thermostat would call for duty ,the cam motor would turn and open the solenoid valve, the pressure would rise and make the LP switch . the compressor would start to run but would then trip on its internal klixon. In the meantime the solenoid is still energised allowing the liquid charge to run back into the compressor and fill it to a point where liquid would enter the cylinder, and when the Klixon reset itself the compressor would re-start up and try to compress this liquid. The discharge valve would break as the liquid hits it and fall inside the cylinder, the piston would now try to compress the hard valve plate which punchs a hole through the softer aluminium piston crown,. This made it impossible for the compressor to pump at all.
The problem was the engineer had failed to fit a new compressor contactor , and the manufacturer of the original unit had failed to fit an overload to the contactor through the control circuit.
So it was a simple case of fitting a new contactor "with an overload" wired in the control circuit, this solved the problem
The contractor then expected us as the supplier of the compressors to pay for the first six compressors, as he questioned where it stated that you change the electrics after a burn out.
Unfortunateley this often happens that new compressors are fitted to the old electrics and the old electrics take out the new compressor , Then we hear the old cherry "Dead on arrival "


http://www.brainerdcompressor.com/_pdf_files/Start-Up.PDF

It's always amazed me that you can buy a new compressor & no warranty or start up check sheet supplied to fill out.
You get a re-manufactured compressor & you have to carry out lots of checks & readings (which should be done regardless).
I guess manufacturers don't want to scare the average guy away with paperwork.
If a third party was doing it for me this might be a good idea new or reco compressor.As we know changing contactor or starter gear is standard procedure after a burn out or whatever.