A technical question

Your right.... my bad.... brain going faster than fingers can type.

How hard is it to google charging charts for resi R22 heat pump systems?? that will give you a range of temps, pressures.

there's your simple answer

Do not worry about it

Bye

Simple, HVAC/R is always a reverse cycle, it is a reverse Rankine cycle. In a Rankine cycle heat engine you use a difference in temperature (Delta T) to convert heat to mechanical work, and the larger the temp difference between hot and cold the more efficient the machine is, IE more work out VS heat transferred from hot to cold.

Since refrigeration is a reverse Rankine cycle the lower the temp difference between hot and cold the more heat is "pumped" instead of just being converted (more heat transferred compared to work in).

In your/any case for the highest COP (watt-hours transferred divided by watt-hours consumed/converted) in heating and the highest EER in cooling (BTUs transferred divided by watt-hours consumed) you want as little difference as possible between suction and discharge pressures and temps.

The absolute best you could theoretically do is to have the evaporating temp be the same as its surroundings (in this case outdoor ambient) and have the condensing temp also be exactly the same as its surroundings (in this case indoor ambient.) This is obviously impossible in the real world.

Attempting to control head pressure by turning off outdoor unit fans in heat mode only makes the evaporating temperature that much lower than the building temperature, hence a higher delta T, and more energy consumed (less efficiency).

You need to find a way to slow down or unload the compressor instead, and this doesn't include suction throttling.

Those Uni chillers were large, I wish I had manage to get some or that R12. Just a few bottles would have been nice.

My experience with centrifugal chillers is very low, how ever I have done a fair bit of work with screw compressors.

The largest recips I have worked on were using ammonia, mind you although it is a good refrigerant I am not that keen on it. Some of the screw compressors also I have worked on were using ammonia.

I tend to try and not work on ammonia systems if I can avoid it.

I saw in a refrigeration magazine a long time ago where in Japan they started up a system that had 48 ton of ammonia in it.............

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Years ago I put together for my own use a self contained temprite beer cooling system.

I am not sure if they used temprites in the USA, they were in almost every hotel and bar here for instantly chilling draught beer. In Australia draught beer is the most served beer and drink in bars, almost every customer has a 'schooner' (15 oz glass size) of draught beer in front of them.

The temprites are being phase out now by glycol tank systems it seems.

Although a temprite can chill warm beer down, in most places the beer was stored in a cold room around 50 f and the final chilling was done under the bar by a temprite down to around 39 f.

Temprites were around 11 inches across and 15 inches high and connected to a refrigeration system external to the bar. The temperature of the temprite was controlled by a '750 valve' IE a suction pressure valve. Some temprites had 3 circuits in them for 3 different beers

If you are not familiar with temprites, they are a flooded system with a stainless steel coil in the refrigerant that instantly chills the beer. I have seen a 18 gallon (imperial) keg drained in 25 minutes though one of these and it chilled the warm beer down to 39 f. It was a free beer night at a construction camp.

Anyway my self contained temprite is sitting there with no R12 in it . Mind you these days I do not have keg parties, so it is not worth making it work again.

Things have change now there are no 18 gallon kegs, they are now 50 litres, or around 11 imperial gallons (around 13 US gallons)

I have not worked on bar equipment for many years now.

Just as side note. In New Zealand the bars used to have a large pressure tank in the cellar full of beer, this was filled by a 'milk' tanker full of beer which came around and filled it though a hose from the tanker.

I think they have now gone over to a keg system.

In UK in the sixties beer was stored in kegs and served at cellar temperatures (Supposedly around 56 f), their mild and bitter beers had no gas in them and those handles you see them pulling in English pubs (Beer engines) actually used suck the beer from the kegs. These days UK has gone over more to lager, which is served colder and with gas in it.

Different systems for different countries

Thank you for your input.

The controlling of the fans in this case are for simple control of the head pressure and although they will limit the amount of heat produced, it is necessary to stop the head pressure from going over the top.

It is not practical to unload the compressor as it is a hermetically sealed recip, and the manufactures do not like the idea of speed control on this compressor, maybe because lubrication problems at lower speed?

In general I am looking to make the unit heating efficient within reason, but as heating is not a big deal here (In the tropics) it is not used every day during our cooler season for heating, so in general the while plant needs to be designed as a cooling system primarily, I do want it to heat efficiently.

It seems most people here do not have any heating, as they say they do not need it, but as a person who hates the cold, I want it!!!!

What size did you say this was ? I thought you were talking hundreds of tons, etc.

On 11/8/2011 2:24 PM, snipped-for-privacy@truthonly.com.Sword of Baal wrote:

Since you mentioned tropics, it made me think of the HVAC system for the mission control center for the SDI program where I worked on the electrical, Halon fire suppression system and Liebert systems in the building. The center is located on the island of Kwajalein, the main island in the Kwajalein Atoll. It is home to The Ronald Reagan Ballistic Missile Defense Test Site and I was there working back in the late 1980's. The company I worked for had a contract for a lot of work in the atoll and building the mission control center was but one of them. The Liebert air conditioning equipment used reheat to control humidity by heating the air before it hit the cooling coils and then it could add humidity as needed with a humidifier. There was a Cray X-MP super computer and Digital VAX computer systems in the place along with an atomic clock so the Army wanted a tight control over temperature and humidity in the center. The place was cooled by a chilled water system feeding multiple Liebert air handlers which discharged conditioned air under the raised flooring and it was a darned interesting system which maintained a tight control over temperature and humidity. Of course this made me wonder about the ambient humidity where you live in the tropics and how you control your indoor humidity? Would it be possible for you the use an enthalpy wheel heat exchanger to bring in warm dehumidified air into your home without using energy for extra heat?

TDD

A few years back a customer of mine wanted a system to measure the amount of beer flowing through his bar taps. We were looking at designing a system from scratch until I thought that someone must have already done this so I started searching the net. It turns out that such systems are common in Canada where there is a tax on virtually every drop of draught/draft beer and the bar owners have to keep very accurate inventory and sales records for the tax man. I don't know if he ever installed a system but it was a lot less work and money to purchase a ready made and fully developed system. ^_^

TDD

You still don?t get it! no one can gave you that answer because!

It depends on many factors such as? Size of Condenser, Evaporator, Heat you are looking to get out of system, Thermal Expansion Valves are set for best super heat, regardless if unit is in heat or cooling mode and head can run from 200 to 350

Depend on ambient Temperature and Humidifies. And you are not EE you are dumb ass otherwise you would not be asking a such stupid question like that!!!! (The end)

The Snow white mixed you up your name is dopey.

I never said what size it was only that it was for 3 rooms.

It is 2.5 ton

Here they just tax the whole keg.

Tax on booze is high here.

Love it when in the USA and see your cheap prices of spirits.

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In some parts of Queensland, mainly in the older pubs they have a cold room behind the bar and beer taps though the wall of the cold room and the kegs are kept in the cold room and that is how the cool their beer.

Is there some sort of main way the cool draft beer in the USA?

As I have said that here draft is the main beer sold.

I sort have the idea in the US that draft is considered an inferior beer. That is not the case here.

I find that the cooling runs long enough to drop the humidity. I do have humidistats installed that can force the system onto cooling if the humidity gets too high and the cooling is not running. I have electric reheat elements in the ducts that can be used if needed. The humidistats are set a bit high to conserve power.

I did consider putting a heat exchanger on the 6 ton system and having water in it heated by the hot gas to heat a 90 gallon hot water tank I have. . It would have needed some hot water coils for reheating the air and a pump. I decided it was not worth the extra work and expense involved, and I simply use the electric elements, and they are rarely on for reheating while the plant is dehumidifying.

Here in the wet season (Summer down South) it usually gets up around 36 - 38 c ( around 97 - 100 f) during the day with the humidity up around 65%, which goes up when it rains and the temperature drops a bit when the rain starts.

I have seen a 40 c (104 f) day here once.

Records here 105 f highest 43 f Lowest.

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Someone asked how much the 6 ton R 22 system costs to run

Here is a some data I took on a 35 c (95 f) day some time back

Head pressure 220 PSI, (yes the head pressure is a bit low considering the ambient but the air cooled condenser is large and that is what I wanted.)

Suction pressure 60 PSI

This was taken 15 minutes after the system had been started and the system was pulling out almost 2 US gallons (7.2 litres) of water an hour from the air.

After a hour the rooms were 23.5 c (74.3 f) with the thermostat set down low for the test. These rooms were around 30 c (86 f) when the system was turned on.

We pay 16 cents a kilowatt for normal power.

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Yup.... more dribs and drabs....

ok... now lets try for make and model numbers of the condenser, air handler and evap coil....

I mentioned the enthalpy wheel heat exchanger because of a project I worked on for the HVAC system in some new schools in a county South of Birmingham where I live and the HVAC system in the new school was the latest technology around about 12 years ago. The monitoring was done with a dial-up modem instead of real time Internet like I see these days. The system had a huge enthalpy wheel and I'm not sure of the exact type but the system designers were striving for an energy saving system.

TDD

Lets not,

First of all they are Australian products so it would mean nothing to you., besides that they are in metric.

Second it has nothing to do with my original question.

Thirdly looking back over your remarks one can see that you are basically a stirrer.

Some of Steve's remarks :-

//Resi systems are not for the industrial hammer mechanic, its more like working on swiss watches by comparison.\\

//You wouldn't be an EE by any chance, would you??\\

//Maybe you should do a little homework on refrigerant pressure/temperature relationships.\\

//Ok.... if you had told us that you frankensteined together a system that was grossly oversized from the start\\

So Steve it is no use talking to a stirrer.

Bye Bye

Birmingham (Old Alabammy??)

The idea sounds good, but for me no practical use. I have very little fresh air being brought in and no exhaust system.

My home has a fairly low level roof and there is very little space up there now.

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On the fresh air, I have a fresh air fan yet to be started up and a timer and the fresh air fan which with come on for a short time every half hour or so to flush the air out in the house.

In a couple of the rooms there is a reasonably high internal load so there is a outdoor air thermostat and when cooling us required in these rooms and the outdoor temperature us low enough instead do cooling fresh will be brought in to combat the internal heat load.

A second fresh air fan it installed on the 6 ton system so if there are a lot of people in the house I can increase the fresh air in the living area.

That too has yet to ne started up.

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Sound like you have had quite a bit experience on lots of equipment.

Grumpy raved

Seeing I owned my company and was in charge of the installations and commissioning they worked.

It is no surprise to see someone like you come in who cannot answer the question posed and then rave on, as obviously you have no knowledge of any value.

When you are so F___ing smart why would you be asking dumb as question???