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a standard dimmer switch like you use on a light does reduce the voltage. they do make varialbe speed controls for ac motors that change the hertz to control the speed ,but they are not called dimmers.
a light dimmer will harm the motor, should have said reduces current
you are correct I also think the coil is adding too much load.
Modern dimmers dont work that way either Walt:
http://home.howstuffworks.com/dimmer-switch.htm
Regards
John.
Don't get me started on what a motor can and cannot do. Motors are my hobby! I've rewound motor stators that have burned out i've replaced sleeve bearings with ball bearings and more I even own the second edition Fourth Impression, Fractional horsepower electric motors By Cyril G. Veinott. And i've seen ceiling fans that use a dimmer switch and if thats not enough take a look at the pic below. Nuff Said! :owned:Quote:
Originally Posted by wdrzal
you won't see the voltage drop on a standard multimeter because the sample rate is to slow. however you will see the voltage drop on a scope meter or ocillascope
I asked my boss at work that question and he agrees with me that the tubing wrapped around the compressor won't effect the temps in the loop since the compressor coil is after the loop so most of the gas has already boiled off in the loop section before it even reaches the compressor coil. So I still tend to think that the compressor is too small for stage 1. Prove me wrong.Quote:
Originally Posted by pythagoras
I wasnt denying that there will be momentary voltage drops, you would have to precisely control the switching time to the ac cycle to avoid an off period at the top of the cycle, I'm just pointing out that modern dimmers modus operandi isnt to vary the voltage as part of the operation.
_HL4E_HalfLife_ We dont own people in here, we have discussions sometimes we are right sometimes wrong, its not a competition ;)
Regards
John.
every ceiling fan I ever installed that had a dimmer had a rectifier and used a dc motor.
dimmers that drop the voltage are also still in sold, usually the cheaper ones
Well I dont think thats true, when you add heat the pressure in the coiled section increases-----That is definately fact.
Now if the pressure is increased in this section and its directly connected to the evap the pressure there will increase. If the pressure in the evap increase the evaporating temperature of the refrigerant also increases.
In these systems the only major pressure differences are across the expansion device. There is minimal pressure difference between compresor discharge and expansion device entrance, and a similar minimal pressure difference between expansion device exit and compresor suction.
Regards
John.
Actually this is very easy to demonstrate: Stick a hairdryer on that coiled section and watch your evap temp rise ;)Quote:
Originally Posted by pythagoras
as far as the loops even if it alreadly boiled off it can still asorb load in vapor form. thats why you insulate suction lines.
I know ill have to insulate but that still don't account for the roadblock i've run into. My suction pressure was around 10Psi now for R402A that should make the loop somewhere around -35~-45c and yet im nowheres near there and the sight glass is full.
If thats 10 psig thats equates to an evap temp of between -10 and -12 Centigrade, pretty close to what you have.
Regards
John.
Oooops :( 10 psig for 402a, thats what you have right? Is -32C.
Now if you have a pressure of 10psig and an evap temp of -15C, one of those readings are wrong. What are you using to measure the temps, if you have already said, I apologise I will read the thread carefully now.
Regards
John.
I looked this up to be sure I was correct, this is from copland: heat entering the suction line from ambiant air can cause capacity losses from 10% to 15%.this is why its cost effective to insulate a suction line. thats just a uninsulated suction line in ambiant air, you have it wraped around a hot compressor.that could be over 1/2 your capacity or more gone. you only should have about 10 to 15 degrees of superheat to prevent liquid return,thats it.
back to using dimmers, even a modern dimmer that uses a reostat and a triac will harm a ac motor. a ac motor controler uses the same triac, thats where dimmers got the idea from,but because a light dimmer only controls a single filiment the reduction rate doesn't matter. In a ac motor the commutator is divided into many sections for the number of armature windings.Without getting to complex , When the motor is turning, a speed controllor senses these breaks in the commutator and matches the rate at which the motor is turning and supplies even power to each winding. A light dimmer can not do this,and a unbalanced load codition will exist.
I really don't think expensive speed controllors would sell if a dimmer was all that is needed.
Pythagoras- Im using a UEi Digital thermometer. As for my gauges i know there giving an accurate reading. So I would say something else isn't right,couldn't it be because the compressor simply isn't pumping enough fast enough to get the temps any lower?
wdrzal- As i said earlier i've been using dimmer switches to control motor speeds for 10 years now and have never had a dimmer switch die or have a motor on a dimmer switch burn out! thats gotta telling you something.
remember the pressure/ temp relationship is only if both liquid and vapor are present.
also a full sight glass apears clear , so does a empty one. they look the same you have judge which it is.
that compresor is designed to run on one speed why would you want to slow it anyhow?
as to dimmers , you can't getto rig stuff in the real world or it will hang you someday. Overloaded stuff causes more fires than anything,don't you think if it could safely slow a ac motor that way the manufacturer would say so!!!!
read up on how a variable speed controlers work, similiar to a triac dimmer but with a very important differance. those triac's were used in motor controllors long before dimmers started to use them.
1st of all who said anything about slowing the compressor down???Quote:
Originally Posted by wdrzal
and 2nd the sight glass i have has a FULL word in it that can only be seen when its full.
BTW Please stop treating me like im a rookie at this!
you did say condensor motor, thought you said compressor motor. my mistake. never seen a sight glass that says full, what I said about them is true . .
I could take a pic of it if u want to see.Quote:
Originally Posted by wdrzal
I beleive you, I,m more courius on how it works, what happens to make the word "full" appear. could you explain that.
whats with all the valves?? why so many
http://www.xtremesystems.org/forums/...chmentid=31856
Take that suction line off of the compressor.. :stick:
I love your experiment with the captubes :clap: Cool Idea :cool: - I hope it works.
read back a page or 2 its all explained there.Quote:
Originally Posted by kayl
Thx runme :woot:
Its kinda hard to explain so ill just post some pics of it empty and full.Quote:
Originally Posted by wdrzal
thats neat, but I never seen a glass like that.No idea how it works. LOL
just a thought, most sight glasses have a moisture indicator, is that telling us its full of liquid or full of moisture? No, since you got a pic in both positions I sure its saying full of liquid.
Is there a manufacturer mark on it?
does the flow of liquid make it flip up or what, if you have bubbles,say half gas and half liquid is it half way up?
I use a electronic sight glass so I rarely buy visiual ones,
all thats on it is made in USA and M.B. CO.Quote:
Originally Posted by wdrzal
My guess is that the liquid changed that second glass inside from being cloudy to clear making the "FULL" word clear to see.Quote:
Originally Posted by wdrzal
Does anyone know how many Psi this waterblock could withstand?
did you buy that locally or get it on ebay?
talkig about the sight glass
I got it at the shop where i work. Its a gold mine there :DQuote:
Originally Posted by wdrzal
Ok today i removed the compressor loop and my temps are the same AS I SAID ALL ALONG THE COMPRESSOR LOOP WON'T EFFECT TEMPS IN THE EVAP!! :slapass: :slap: :nono:. I still think the compressor is too small.
What about the waterblock?
a water block is not a evaporator. and the loops did definely affect system temps. a given compressor and condensor can oly handle so much load, adding any heat to the system increases that load.
Still think the compressor is too small..........
Quote:
Originally Posted by _HL4E_HalfLife_
I read the last 2 pages where you had the pic of the valve assembly (in particular post 79 onwards, too much to read before)
There doesn’t seem to be an explanation on how it is meant to work.
Are the valves used for the secondstage? or first stage? and is that pipe the HX they are all connected to?
I did read 50” of capilaary line used, I also read that it didn’t get cold.
If you remove any plastic parts and braze the water block together (if its brazed already just pressure test it)
And it holds the pressure that you tested the valve assembly to, it should work fine.
Kayl the valves are attached to 5 different lengths of cap tubing i did this so i can change the cap length without having to braze it and can be done while the system is up and running.
U really think that waterblock could withstand 250Psi??
BTW kayl if ur following this thread u really should be reading it all :nono:
Well I had a bit of a setback today my rotary vacuum pump has stoped pumping it still spins but no pumping action. So tomorrow im gonna build a duel compressor vacuum pump. If everything goes ok ill have pics of it on here by tomorrow night. :D
that's exactly the reason why I buy a brand new vacuum pump.Quote:
Originally Posted by _HL4E_HalfLife_
2.hand or used compressors has a limited capacity to remover the air and moist from the system.
Like i promised heres a pic of my new duel compressor vacuum pump. Mannn does she ever pull a vacuum quick :D
ok i seen now, didnt realise they all just capubes.
the daul vacuum pump will work well.
try compound system, series compressors.
im not hope full now a second look at that evap.
maybe test it under water just in case splits.
i think i have to stop drinking on the internet not see properly :toast: and not reading properly :slapass:
It looks as if parralel compressors (yours) will only evacuate to a certain lvl faster. Compressors in series should give a better vacuum though.
Well i finally switched compressors the 1hp rotary is on stage one now i ran out of gas so ill have to wait till monday to get a new jug of 402A. I also might try using 402A as a 2nd stage gas too because at 20hg it will be at -80c ill just have to see how things go with stage1.
I also finished making some touch-ups on the vacuum pump.
UPDATE!!
I picked up a brand new jug of R402A at the shop yesterday :D. also I decided to remove the receiver mainly because those things will hold soo much liquid its not funny and its kinda of a waste and if i have to let the gas out of the system because of a problem (unless i recover it) ill just have to refill the whole receiver again.
Today I finally the system going on the new compressor and I was right the other compressor was too small and yet noone agreed with me on that :nono: :slap:
Also today I also reached a goal i had set way back when i first started building this to hit the -40c mark on 1st stage. :D Now i'm gonna start insulating the evap im hoping to get another 5 to 10c by doing this and making small tweaks to the charge and adjusting the fan speed to find the sweet spot.
Comments suggestions on other improvments would be appreachiated.
ANOTHER UPDATE!! :D
Just finished my first layer of insulation. Im gonna go to the hardware store to see what i can use as a second layer. Once i finished the first layer i turned the system on again and it went right down to -49c than for some reason it slowing came up to -25c than slowly when down -45c and stayed there. I think the reason it came up is because the thermometer probe moved and wasn't in good contact with the copper tube.
Nice job on the insulation. :toast:
From the look of it its under charged judging on low side pressure compared to pressure charts, you are gonna need more capacity for second stage. Whats the temperature of suction line first stage out of the hx?
Looks really nice... keep up the good work. Like kayl said; nice insulation :)
The sight glass is full so i don't think its low on charge.Quote:
Originally Posted by kayl
As for the temps i ran it again tonight and this time it didn't come back up in temp so it was the probe out of place. :D and also it went past -50c unfortunitly thats the limit of the thermometer with the probe on it anything lower than -50c just reads as LO. :( I dono what im gonna use now i can't afford a $200 thermometer :mad:
I'm low on options for a 2nd stage gas to use im on a very limited budget so i can't afford any 1150 or Co2. :( Has anyone tried using R22 and adding a small amount of helium or another extremely cold gas to lower the boiling point? Would it work?
Quote:
Originally Posted by _HL4E_HalfLife_
sight glass does come in handy no guessing.
mainly say that casue ya had low pressure with not good temps.
but a loose probe does it to ya. i found 8degs on the autocascade attacked right.
i had the same problem when i did my first cascade temp probe only going to -50c, unless you can make one ya really forced to get one other wise guessing temps. look on ebay that not too dear if order them from the US. Under 140us.
how expensive is c02 in your country, the welding stuff is normally dirt cheap.
really all the cascade gasses are expensive except c02. what about really low grade of 1150 like the 99% stuff is cheap compared to 99.5? after that it gets way more expensive.
I have no clue what it costs here kayl and i wouldn't know where to look for 1150 or the co2.
As for the thermometer is it possibile to remove a low temp limit? like im sure the probe would read below -50c but its just that the thermometer isn't displaying it below -50c
run over to canadian tire and grab a paintball co2 cannister. a 20oz one is about $60 and to fill it is about $10
Yes its a lot of fun trying to source cascade stuff in your own town.
I know im the only person in Australia doing cascades so no one to help me source stuff.
Its a lot lot harder than ppl think. Have to get account etc and enquire etc.
Some places they wont even let you get 1150.
Gkiing is from Canada and he got a bottle of c02 for his autocascade project.
http://www.xtremesystems.org/forums/...2&page=1&pp=25
From memory stuff in Canada and Australia is similar prices what gkiing said. I think he rented his bottle, give him a pm or something more info if helps.
You should be able to get most gases needed (well at least ethane, co2 and ethylene) from aire liquid or boc gas, they are located all over the word in different countries.
Im getting mine from boc gas, just get an account and order what you need over phone, can even have it delivered to your house.
I wouldn’t buy regulators through them, cost too much, get them through a torch store and just an industrial one, a lot cheaper.
Also with the temp gauge, the sensor may read lower temps, but you will need to map the voltages to relate to a given voltage.
The reason why they limit the meter to -50c as not read that accurate. The -50c meters arnt always accurate anyways.
You only need one good gauge, then get xtra probes and its like you have several metres
Hmm that all sounds interesting. This co2 cannister for paintball guns how would i connect it up to the gauges? would i have the braze a check valve on it?
Well i got alot of stuff coming in over the next week or so, 2 more A/C's with 12000Btu rotarys and i got this compressor today (in pic) no cost 11300Btu's 115v 50LRA.
where are you getting all this stuff from? it took me 3 months to find two good compressors for my cascade.
as for a c02 bottle. go to your local air liquid supplier/ welding supply shop. they can definetle hook you up with some c02. if im not mistaken, a regulator is about $90/ bottle $200 (i think)/ and a fill is about $50 for small personal bottles.
i made my co2 paintball adapter from one of those propane torch thingys. i got a fitting for the paintball bottle, brazed it onto the bottom of the torch thing, trimmed the central shapft down a couple of mm, and brazed a shraeder onto the top
Hehe at the shop where i work its a gold mine theres compressors there that range from being brand new to being 20 years old and 20 year old compressors weather they have been used or not won't installed in a system anytime soon such as the compressor i got today its ment for a window A/C and nowadays you won't see a window A/C with a recipricator compressor you'll see a rotary. Next time im at the shop ill take a few pics and post them here.Quote:
Originally Posted by f00t
I've already went to a gas store and to buy co2 from there u need to start a contract which is $80 and u have to pay that each year to get the tank serviced so im not doing that i think ill look up on the paintball co2 cannister because thats all ill need.
you can purchase a tank, then just pay for contents. I own every tank I have and thats quit a few.
Still buying a tank u need a contract from them i asked and thats what he said.Quote:
Originally Posted by wdrzal
I just found this so this is what im gonna get. :D
http://www.canadiantire.ca/assortmen...romSearch=true
Today i got those 2 A/C's i mentioned in a previous post. I had to replace the run cap on 1 of them to get it going but other than that they both work. There both identical 12000Btu 1hp rotarys 62 LRA 12 RLA 115v they both have the exact same rotary as the one i got on my first stage :D.
I just got a 20LBS bottle for about 150$ cnd @ BOC GAS they probably have a store near by. The bottle is mine and when I need to fill it up, it will only cost me 35$. I had no contract or anything else to do with thems just passed by and asked for 20 lbs co2. He even gave me a nice cga320 to cga 580 adapter for free...
What oil should be used with co2 anyway?
Edit: What do you guys think about this oil separator? would it work?
CO2 doesn't catch any oils, that's why it's better to use R134a/R22/R290 for oil transporting
I don't think that idea should work fine :
- it's horizontal, the power of gravity works weakly
- too small area for dropping droplets (only two pipes)
- the flow of refrigerant should transport droplets which layed on bottom of this wide pipe to separator's outlet
I would go to classic oil separator, vertical and wide pipe filled by metal wool
So why would i want to use an oil separator if co2 doesn't carry any oil? Again what oil should be used?
This is the thing man...you don't need an oil separator in a co2 auto-cascade. You need one in a co2 cascade because the carbon dioxide dosen't carry the oil well. You can use hydrocarbon and fluorocarbon based oil.
But why would u want to carry the oil? all the oil is for is to lubricate the compressor not to travel through the system. What is hydrocarbon and fluorocarbon based oils? MO? POE? AB?Quote:
Originally Posted by Cr@sh_D1n3r
You wand oil to be carried in the part of the circuit that oil is required, your compressor. Therefore you want the oil to be carried:
Out of the compressor --> to the oil separator --> back to the suction line --> and into the compressor.
This will ensure complete lubrication of the compressor as the oil is dispersed in the refrigerant in the 'oil circuit'.
If you had oil that didn't freeze up and block the system, an oil separator would be unnecessary, and in single stage systems the temperature isn't cold enough, so oil sep's aren't used.
As for compatibility of oil, I'm curious myself, as I'd like to use R22 and 508b in an autocascade, and I'm unsure if they are fine using the same oil. POE was the oil I'd planned to use.
Gray
On a normal phase-change system there's no oil separator because the refrigerant carry the oil by it self. I guess you will use r290 so just make your phase sep and propane will take care of the oil transportation. If you want to build one go ahead dude but I'm telling you, you don't need one. You can use mineral and poe oil with it.
Hmm from what i know compressors are self-lubricating at least recip ones are they pick up the oil from the bottom of the shell and up through the shaft to the bearings just take a look at the video i posted in another thread heres a link.
http://binary-side.net/tmp/opencompressor.avi
ok then, build a system and fill with propane and let it run for 2 hours. Then make all the gas leak from the discharge and you'll end up with an messy oily pipes.
Youve got nice ac units there. Hope you will make it!
Dude i know oil travels in any regular system im not stupid and i think ur misunderstanding what my point is. My point is if co2 doesn't carry any oil like u say than an oil separator shouldn't be needed because all the oil will remain in the compressor.If u watched the video i posted u see that recip'sQuote:
Originally Posted by Cr@sh_D1n3r
are self-lubricating im just not 100% sure if rotarys do the same thing. Im gonna cut the top off my old rotary compressor i used as a vacuum pump and find out of they do self-lubricate.
sorry I didn't meant to piss you off...lol dunno why I thought it was a autocascade for a moment sorry :P. If you use co2 as 2nd stage then you need to put some propane in it because you will end up with a clogged evap because dry ice will form in it. I'm not sure that under pressure the compressor isn't blowing oil through the discharge. Some expert could help us on that one.
I don't have any 290 will some 402A be fine?
r420 will do the job but from what i have heard berkut say r22 is the best and r290 is supposed to be pretty good too.
ps: r290 = propane
what is r420? or do u mean 402a?Quote:
Originally Posted by f00t
Im wondering if 402a would work since it boils colder than R22 does so it would be less likely to effect the temps the co2 reaches.
Also, oil must be cooled, probably that's why a traveling through whole unit is needed, it cools at evaporator and suction
Don't forget that the gas return is what really cools the compressor. Also having oil in the evap reduces cooling efficiency because its coating the walls of the copper tubing. Like i say im gonna cut open my old rotary vacuum pump this evening and see if its self-lubricating or not i think that will help resolve this issue. On another note how would u build an oil separator?Quote:
Originally Posted by Tonic
lol yeah i ment r402a. not enough sleep
I cut open the rotary compressor and there is a hole in the middle of the shaft possibily for the oil but ill have to do further cutting to get a better look at the bottom. Heres some pics of it.
UPDATE!!
I drilled some holes and mounted the second compressor in place, it just fits :p:. I also brazed a desuperheater to the discharge of the compressor and ran it around so its mounted behind the fan thats on the condensor for stage one so an extra fan is not needed here :cool:.
Can only upload 5 pics at once :mad:
I pumped some R11 through the condensor for the 2nd stage to remove the moisture in it. Thats R11 in the icecream container in liquid form cool huh?
really nice :banana: ! I was wondering why is your hx made that way? I mean why you didn't put simple pipe insulation? Hurry I want to see the temps so we can compare each others system :D (I made a cascade and auto-cascade yesterday but I can't tune it yet because I have no probe that goes lower than -55c) Good luck on that "thing" !
The cascade is really coming together nicly, should see some noce temps with that.
Quote:
Originally Posted by _HL4E_HalfLife_
they should make fine compressors, unless been used too much.
they look like old r22 ones (what refrigerant are they?)
more than likly mineral oil i would say. just drop the oil and replace it with new stuff, also give ya an idea of what work it done.
those 2 compressors are capable of -100c with a co2/r290 cascade. ;)
as for oil separator i would just use one just in case to be safe.
the r290 will carry some of the oil to the separator and then back to the compressor when return valve opened. and ya dont want oil in capillary line to add to blocks second stage.
i think that r402 does actually consist of some r290 r22 and something else.Quote:
Originally Posted by _HL4E_HalfLife_
Google search on it and find composition.
Just try it and see who ya go
its expensive stuff though, $38kg compared to r507 $18 i just need a frigin license, unfair.
r22 / r125 / r290 ratio : 38 / 60 / 2 . I think r125 is mainly a firefighting agent.
Man you guys post quick lol and yes they are R22 compressors im not sure about the oil in them heres a pic of them the clear oil (one on the left) is the oil that came out of the rotary i got on 1st stage. So what the heck is it? AB? Ester? Synthetic?
my bottle of mineral oil have the same oil color as the one on the left if that help you.
btw imo the oil color you have mean your compressor is in perfect condition! I mean not even a bit dark! that's great!
O yea i almost forget this clear oil seems to carbonated as well it was making bubbles for quite some time after i removed it from the compressor. I've never seen mineral oil do that before so im not so sure that it is mineral oil. Any idea what color AB,Ester, and Synthetic oils are?Quote:
Originally Posted by Cr@sh_D1n3r
:D :D :DQuote:
Originally Posted by Cr@sh_D1n3r
I once removed the oil from a rotary compressor with mineral oil in it and it did it :) lol we are flooding the forum :P do you have msn ? would be cool to have each other address :)
This isn't flooding, were providing useful information for rookies out there.Quote:
Originally Posted by Cr@sh_D1n3r
Ps.yes i do have msn.
On a side note for those of you that are wondering what im using for a torch...
Quote:
Originally Posted by _HL4E_HalfLife_
Indeed, it's nice to read your coversion
Acetylene/Air torch, if you can, shot photos of torch at action :)
LOL sure np next time i braze something ill take a pic heh.Quote:
Originally Posted by Tonic
Again about the type of oil i should use i didn't really get a direct answer on this so since some 402a is gonnna be added anyway which has R22 and R290 in it i decided to just leave the MO in the compressor since MO works best with R22/R290 this shouldn't be a problem should it?
Ps. where would i find copper/steel wool?
You can buy those wools in markets/supermarkets/hipermarkets. They're used to wash the dishes :D
About oil, sorry, at the moment I can't understand, I'm to sleepy.. :PMaybe tomorrow I'll read a few late
pages and try to answer
Ahhh i was wondering about those dish washing wools i just wasn't sure if it was the same thing as what you guys were using. So what do you guys use to keep the wool in place in the oil separator?Quote:
Originally Posted by Tonic
Heres that pic u requested tonic. :D :woot:
Just a thought..is there any reason not to use manifold gauge hoses to connect up the evap? I know they would have to be tightened alot to prevent leaks but they would be perfect since there designed for high pressure.
Yes there's simple one : it's not made for such low temperature. The hose will freeze up and will get incredibly hard to bend so all vibration will go to the cpu :P
deigned for high pressure but not cold. if your gonna be at -70 some with a rubber hose the slightest abrupt bend could crack it