Yup.... more dribs and drabs....
2.5 ton?? those 3 rooms must be pretty good size.... maybe 1300 - 1500sqft
ok... now lets try for make and model numbers of the condenser, air handler
and evap coil....
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
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
//Ok.... if you had told us that you frankensteined together a system that
grossly oversized from the start\\
So Steve it is no use talking to a stirrer.
On 11/8/2011 2:24 PM, email@example.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?
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.
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
9 amps per phase (415 volt 50 cycles) compressor fully loaded. The fans were
not included in this amperage, only the compressor.
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
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
We pay 16 cents a kilowatt for normal power.
11 cents a Kw for off peak.
On 11/9/2011 9:20 PM, firstname.lastname@example.org.Sword of Baal wrote:
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
"The Daring Dufas" wrote in message of Baal wrote:
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
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.
Sound like you have had quite a bit experience on lots of equipment.
On 11/10/2011 2:39 AM, email@example.com.Sword of Baal wrote:
I like variety, today I'll be finishing op the installation of 42" data
and advertizing displays for a major retailer for their layaway
department. I got the network cables installed yesterday and hooked into
one of the store's network switches to verify connectivity. I have to go
back today to install two new power circuits to the darn things because
there are no spare bolt in breakers left in the lighting panels. ^_^
I suppose we get involved in various things, here I have coax and LAN wiring
all over the home for the transmission of movies to computers connected to
I have yet to set up the system so I can send Hi Definition movies across
the LAN, I shall have to look into that sometime.
Also I have 10 phones around the house.
I have a small LED display over the mirror over the bar which you can have
running message on to welcome people etc. You can program it with a
computer, or use a remote.
Darn wires everywhere, but I am not keen on using wireless for
Here we do not have cable TV, but satellite, and you lose the picture when
heavy rains fall.
There is a system being put in around Australia of optic fibre to most
houses, mind you I think it will be many years before it is competed
That will solve the satellite problem with rain, also give us high speed
internet access. At the moment internet is via ADSL though the copper
National Broadband Network
//The Australian Government announced on 7 April 2009 it would establish a
new company to design, build and operate a new high-speed National Broadband
Network (NBN). The NBN will become the single largest infrastructure
investment made by an Australian Government, accompanied by historic reforms
to Australia's telecommunications sector.\\
THE federal government is a week away from seeing the first sod of soil
turned in the construction of fibre-optic backbone links for its ambitious
$43 billion national broadband network.
Mount Isa in northwest Queensland will be the first site in mainland
Australia to have fibre-optic lines laid as part of the government's $250
million regional backbone blackspots program.
Almost 500,000 premises will see NBN construction start in the next 12
On 11/10/2011 6:18 PM, firstname.lastname@example.org.Sword of Baal wrote:
There are some communities that have fiber optic links available to
homes but with out searching I'm not sure about it in my area. I have
heard of some folks getting it but it's not advertised as being widely
available around here. ^_^
I am the designer and the manufacturer. It is a one off unit.
Balance charge has nothing to do with it as I said it has 2 TX valves and a
receiver which takes care of the correct refrigerant charge in the coils. an
extra couple of pounds of gas one way or the other makes no difference as
long as there is enough gas in the system.
.> Resi systems are not for the industrial hammer mechanic, its more like
The average residential system is a simple install of a pre-made unit and
does not require any design of the various components by the installer.
You simply stuff it in.
This a special design and all I am asking is what is the idea head pressure
for heating on R22, so far I have not had that answer.
On 11/6/2011 11:04 PM, email@example.com.Sword of Baal wrote:
What is that you're doing with your system? Perhaps a little
experimenting with data loggers for temperature and current
draw including real time monitoring. If you can adjust your
head and crankcase pressure, you may actually be able to determine
your optimum settings by watching power used in relation to
temperature and pressure. I happen to like TVX equipped systems
myself even small ones because they're not too fussy about the
amount of charge. I'm really curious as to what your application
I was figuring out a system for a two story house I was interested
in where I could use a couple of semi-hermetic compressors with
unloaders for capacity control to handle all cooling and refrigeration
for the house. I wanted a small walk-in cooler/freezer too and my idea
was to have a small rack system in a utility room that would use one
refrigerant for everything. Alas I was unable to get the house but it
was a fun mental exercise to find sources for all the parts and equipment.
"The Daring Dufas" wrote in message of Baal wrote:
In a rough general terms.
The it is a ducted system covers 3 rooms, each room has a thermostat which
besides controlling heating and cooling, it also opens and closes a damper
to that room, so if a room is not turned on, then there is no air
conditioning going into that room. This is for economy.
Pressure switches control the outdoor fans to control the suction pressure
on heating to control the head pressure somewhat.
Additional pressure switches will turn on one of the other areas if the head
pressure gets too high on heating. or if the suction pressure gets too low
on cooling, as the air quantity will vary somewhat depending on how many
rooms are turned on.
The outdoor fans are electronically controlled (Speed) while the plant is on
cooling controlling the head pressure. I like to keep the discharge pressure
fairly low, but high enough for the TX valves.
Yes, setting the system up with loggers would be OK but I was trying to get
an idea of what head pressure I should be looking at as a starter in
At the moment I am considering around 250 PSI as a starting point, possibly
300 PSI. Yes it will vary with load and conditions.
I was figuring out a system for a two story house I was interested
If it were me I would not use a single system that incorporates a cold
room/freezer and air conditioning.
Compressors that are suited for freezers are not good for air conditioning
and to a lesser extent visa visa. Using a large air conditioning compressor
to cool a freezer would work, but be expensive to run, and there could be
capacity problems. IE the compressor running down on vacuum because it is
too large for the freezer. (Yes for the trolls, the LP switch would stop
The other thing is that as soon as the air conditioning side cut in the
suction pressure would rise far to high for the cooling in the freezer.
As on a design day one could (All things being equal) can expect the
cooling would be running all day 100%, and therefore there would be no
cooling for the freezer.
One other point is that the semi hermetics would need to have some sort of
oil exchange or you could run out of oil in one of the compressors. Care
would be needed on the pipework for oil return, because of lesser velocity
when the compressors are unloaded
Unloading compressor for a 2 story house could be fine, I actually have a
Carrier 06DA818 on my home with an unloader on it. It is around 6 ton
capacity 4 cylinder unit. The house is single story. Again the system is on
The condenser has 2 x 3 phase fans and they switch from star to delta to
increase the fan speed controlled by pressure switches, it works well with 4
stages of control, as the condenser is a bit oversized and I control the
head pressure under 250 PSI on days up to 40 c (104 f), which is the highest
I have seen it here.
Originally I installed it because I had thought of adding an extension to
the house, but that is not going to happen, however it works well as it is.
I am not altogether happy with the unloading as it does not shed anywhere
near half the power when unloaded.
I did design and install a multiple fan coil system in a home using a
Carrier 6D 6 cylinder unloading compressor years ago, it worked well. That
one had 2 unloaders on it. IE 100%, 66% and 33%.
Ok.... if you had told us that you frankensteined together a system that was
grossly oversized from the start, that would have made a huge difference. If
this 6 ton commercial unit is only feeding 3 rooms, this begs questions...
how big are the rooms?? Where are you dumping the excess air when the
dampers are closed?? Where is the house located? How big is the house? Is
this system cooling the entire house? or just the 3 rooms you mentioned?
What are your average power bills while running this beast??
Steve, the 3 rooms reverse cycle system is not part of the 6 ton system I
mentioned. The six ton system does 2 very large rooms It takes around a good
1/2 an hour to pull it down to temperature and is not 'grossly oversized'.
My house is in the tropics, and I could have gotten away with maybe a 5 ton
system, but this works well, and I would not change it.
The six ton system is a different system altogether and has nothing to do
with the reverse cycle system.
I would not design a multiple fan coil system to work on reverse cycle with
an unloading compressor, too many problems could occur.
As a matter of fact I am not at all keen on larger reverse cycle systems
(5-10 ton and up).
I asked a simple question re head pressure on reverse cycle and am not going
to get deeply involved in the whole design of two separate systems.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.