Purging air from system?

[mswinman]

Firstly I am not a refrigeration engineer, however as an electrical engineer I do encounter air con control systems in various environments. During the recent hot weather I bought through ebay a split unit and having partially deciphered the installation procedure (quite fun actually it refers to a flare nut as an enlargement nut!!) it says to purge air from the high pressure line to the evaporator and on to the low pressure pipe work back to the outdoor unit by "loosen big enlargement nut by 1/4 to 1/2 circle for 10 or so seconds", Now I'm not asking anyone what this means as I think I've worked that out but surely this cannot for certain remove all the air, moisture, and contaminants from the system, for one thing I'm sure refrigerant content after the operation could not be right. I invite any comments you guys may have even sarcastic ones, I do have a vacuum pump that I could use but I see no way it could be connected.

[Cary]

There should be a 1/4 access valve stem on the service valve of the larger of the two pipes to conect your guage manifold and then you vacume pump.
You are not allowed to refrigerant purge as it breaks many EPA laws and was never effective anyway as you pointed out, it was a method for less reputable A/C manafactures to market their units to the DIYers who figured saving a buck on the install was worth it even if it ment the A/C didn't work properly.
Here in Aus. our regulatory body has at least succeded in having all manafactures remove instruction on air purging with refrigerant removed and replace with vacumeing instructions
lol with your install

[guapo]

Hi,
Just install a good filter drier to remove moistur from the system,

Regards,
Guapo

[Peter_1]

Hi,
Just install a good filter drier to remove moistur from the system,

Regards,
Guapo
And the air in the lines then?

[A/C student]

Theres some bad logic in the filter drier to remove moisture. Over time the filters get bashed internaly by the high pressure of the refrigerent going through them. This causes a blockage. So the tedious routine of decanting, removing the filter, re brazing pipework, pressure testing the system, vacing out and finaly regasing the system, hoping that the right amount of gas was recorded in the first place or that you rememberd to way the recovery bottle before and then after decanting the system.

It'd be easier to vac the system out completely.

[Brian_UK]

Firstly, welcome to the site and THANK YOU for asking this question before you did the deed.:)

No, you are breaking the law by purging with refrigerant. There are no other answers than that.

As others have said that type of purging was never totally effective but sometimes seemed to work.

Cary mentioned that there should be an access port on the larger of the two service valves. That is the point you should connect your manifold set having made off all of the pipework connectors.

You should then perform a pressure/strength test using oxygen free nitrogen before evacuating to at least 1000 micron.

Only then should you open the service valves on the condensing unit to release the entrapped refrigerant into the evaporator section.

Just being nosey but what make of unit did you buy, is it new or second hand and what refrigerant is it using?

[guapo]

And the air in the lines then?
Any better Idea? My sugestion is if the system is running already, but ofcourse you have to do the very good installation from the very start, good vacuum, nice welding etc. if you had better idea share it pls.

Regards,
Guapo

[US Iceman]

Theres some bad logic in the filter drier to remove moisture. Over time the filters get bashed internaly by the high pressure of the refrigerent going through them. This causes a blockage.


I'm not sure where you heard this, but I take issue with the whole statement. The purpose of the filter drier is to remove moisture from the refrigerant.

Even if we assume the system is completely evacuated and dehydrated by pulling a deep vacuum, the drier is always a good idea to ensure very low levels of moisture content.

I have yet to see a drier get "bashed" by the normal high-pressure encountered in any common liquid.

I'm going to need more information, before I sign up to agree with this.

[mswinman]

Well I've certainly come to the right place. What an amazing response from you all, I'll include more info that has been asked for.

The system has not yet been installed.
system manufacturer is Fonko ( did I hear a snigger just then), Model no FO0918WF Refrigerant r407c all new.
Yes there is an access point on the low pressure connection this has a cap on it.
All the valves are closed and no pipe work is connected.
In short all I've done is take it out of the box.
The vacuum pump I have is new and was bought as a replacement for an oil degassing plant some years back.I have a manifold set on order as I am determined to do this install but obviously it has to be done correctly. Another question comes to mind does this access point have a non-return valve? The reason I ask is that with the pipe work connected I would have to remove the cap on the access point to fit the vac pump I take there would be no refrigerant loss, then having drawn a vacuum The vac pump could be removed with no loss if vacuum. With this done I open the service valves first the high pressure valve (smaller) and then the Low pressure (larger) Connect the supply then go and put my coat on because it's going to get cold round here!!!

Now then does anyone see a flaw in my plan. I have seen on ebay complaints from buyers that they have experienced refrigerant loss probably due to faulty installation, Keep up the good work and I hope to hear from you soon.

best regards Paul.

[leftjobrunning]

Paul,
The access on the high side valve should be a schraeder connection, so apart from the gas released when putting your guage line on and taking it off there's no problem there. With the valves closed you have access to the installed pipework and indoor(evaporator), this should be pressure tested before being evacuated properly as already pointed out.
Most a/c manufacturers recommend not installing a filter drier an these systems as your high side pipe is not a liquid line, there should be factory installed driers inside the condensing unit.
The condensing unit if precharged with refrigerant will have been pressure tested and vacuumed already so you don't have to worry about this.
When properly vacuumed just open the valves and you're away. Very simple when done properly.
I think we'll all have to go and find alternate employment if splits are the way forward in a/c.

[A/C student]

I'm not sure where you heard this, but I take issue with the whole statement. The purpose of the filter drier is to remove moisture from the refrigerant.

Even if we assume the system is completely evacuated and dehydrated by pulling a deep vacuum, the drier is always a good idea to ensure very low levels of moisture content.

I have yet to see a drier get "bashed" by the normal high-pressure encountered in any common liquid.

I'm going to need more information, before I sign up to agree with this.

I encounterd the filter problem on a system which is being used solely for cooling a comms room. The continual high pressure caused the filter dryer to make a blockage, which then neded to be removed etc

That is what I ment. This happened twice on the same site on two units of the same model etc

I understand that if a drier is fitted on a unit used for comfort cooling then the dryer would not cause the same problem. Thank you for your interest in what I said. Sorry it look like i was talking utter b*ll**ks lol

[Brian_UK]

..., then having drawn a vacuum The vac pump could be removed with no loss if vacuum. With this done I open the service valves first the high pressure valve .....Hi Paul, yes shut off the valves to the vacuum pump but do not disconnect the hose from the access port.

If you do you may let a small amount of air into the pipework as you remove the connector.

Open the service valve and as soon as your pressure gauge shows a positive pressure you can disconnect.

[Peter_1]

Any better Idea? My sugestion is if the system is running already, but ofcourse you have to do the very good installation from the very start, good vacuum, nice welding etc. if you had better idea share it pls.

Regards,
Guapo
Sure, because it was a new unit, vacuum is the only good method: remoevs non-condensables and mositure in one time.

[US Iceman]

The continual high pressure caused the filter dryer to make a blockage, which then neded to be removed etc


My guess is this is caused by something other than high pressure. Now, when I say high-pressure I mean something close to what is the normally expected pressure, not something extreme.

However, strange things have been know to happen right?:rolleyes:

[mswinman]

Hi guys.
Brian when you mentioned the pressure gauge showing a positive reading it was like someone turning on a light, all became clear it's obvious really. What I really liked about your post was what not to do and why. All I have to do now is get adapters made for the vac pump they look like 1/2" BSP on the pump, I'll wait for the manifold to arrive and match up the threads. This pump is capable of pulling down to 5 microns (so I'm told) so you may hear the evaporator imploding as you're only a few miles away. I'm pretty sure I'm going to post more questions here so thanks to everyone I've got something from all of your posts.

Best regards Paul.

[A/C student]

My guess is this is caused by something other than high pressure. Now, when I say high-pressure I mean something close to what is the normally expected pressure, not something extreme.

However, strange things have been know to happen right?:rolleyes:

Yeah I know lol Well I was on site the day we found out what the problem was dude. Don't want to argue lets agree to disagree on what was actuay wrong there.

Least mswinman finaly knows what he has to do lol

[greamegferguson]

Theres some bad logic in the filter drier to remove moisture. Over time the filters get bashed internaly by the high pressure of the refrigerent going through them. This causes a blockage. So the tedious routine of decanting, removing the filter, re brazing pipework, pressure testing the system, vacing out and finaly regasing the system, hoping that the right amount of gas was recorded in the first place or that you rememberd to way the recovery bottle before and then after decanting the system.

It'd be easier to vac the system out completely.no such word in refrigeration bashing(u mean choked)

[Makeit go Right]

Firstly I am not a refrigeration engineer, however as an electrical engineer I do encounter air con control systems in various environments.

I do like your attitude and willingness to go for it. That is very good indeed and 10 out of 10.

However (I’m very sorry if I sound like a party pooper), I think you should get a skilled refrigeration engineer to install the system. There is, or should be, a great deal of training and apprenticing that goes into making a skilled refrigeration engineer (as many will tell you here) and getting some info over the internet just is not quite enough to cut it. It’s a long way off.

Simply pressure-testing the pipe system can be extremely dangerous. Then there is the gas itself, which must not be released to the atmosphere. High-pressure gas bottles, etc. And then, if there are leaks inside the building, people using the building may suffer with their health. That’s not even talking about the possible damage to the equipment you are trying to install, which likely will need some repairs (by a qualified engineer) before too long.

DIY should be restricted to the push/clamp–on connecting pipework and associated units, the B&Q stuff. BUT, no DIYer should be encouraged to install a custom fixed system.

However, I know you will hate me for saying it but it is not okay IMO that you start in on this fridge install. It is a professional task. It is similar to someone asking you over the internet how to replace a consumer unit while live – you’d scream the place down and tell him to get an electrician.

[US Iceman]

Don't want to argue lets agree to disagree on what was actuay wrong there.


No problem, dude...

As they say, everyone is entitled to their own opinion.:rolleyes:

[A/C student]

No problem, dude...

As they say, everyone is entitled to their own opinion.:rolleyes:


Thats true, you say choked thats not a term that I have ever came across in the trade. I didnt know any other way of putting it realy. It's just what i remember happening. lol And my phrasing was poor lol

[mswinman]

Hi Guys.
I've been quite busy lately so the air con has taken a back seat. I read the post from "makeit go right" and have to say you're absolutely correct, the analogy you put forward summed up the case. The advice you all put forward was sound such as where to connect what and what procedure to follow etc., when I got hold of a manifold I was clearly in unknown territory. I could say now "what pipe do I connect to what fitting and what knob do i twiddle do you mean red or blue" NO!!! it stops here. I will fit the indoor unit and I will fit the outdoor unit I'll run in the pipe work I may connect the pipe work to the indoor unit and I'll get the other end close to the outdoor unit. I think the electrical connection should be the last thing I do, then a phone call to the proffesionals I may watch them just to see if I would have been OK. At the end of the day my original post reflected concern at potential refrigerant escaping to atmosphere and should remain my only concern. It's a great site some stuff makes me cringe so you guys must spend most of the time on the edge of your seat.

Best regards to all Paul.

[Brian_UK]

Thanks for the update Paul, I'm sure all will go well and don't be afraid to ask your 'professional' if you can watch the important bits.

I've found that most people have no objection to someone watching and asking questions as long as they are allowed to get on with the job.

[mswinman]

Hi everyone.
Installation went ok, pipework had to follow a rather tortuous path and a lot tougher than MI even with a former. Did a pressure test, all seemed OK. Eventually found someone prepared to come and do the final stage.

Thanks all.

Regards Paul.

[A/C student]

Hi everyone.
Installation went ok, pipework had to follow a rather tortuous path and a lot tougher than MI even with a former. Did a pressure test, all seemed OK. Eventually found someone prepared to come and do the final stage.

Thanks all.

Regards Paul.

Good for you amigo, hope it didnt cost too much for the engineer to come out to it XD

[Sledge]

Hi

My first question is: How were you able to purchase an a/c unit, *****, or refrigeration tools, without the necessary licences? It is against the law in Canada to sell any of those products to anyone who is not licenced.

My second question is: why would you want to? Release of refrigerants into the atmosphere causes global warming and ultimately jeopardizes life on earth. This is not a job where you "wing it" and see what happens.

The post about filter driers plugging up and rupturing; I have seen that a few times. I think that in my situations it ws caused by systems being very dirty (either during install or due to a burn up). The filter did its job, collected all the debris, and became plugged. Add to that a high head pressure, due to a dirty condenser and it blew apart. I am not certain whether installing an oversized filter would have helped, or if it would have delayed the inevitable, in my situations

I have installed a filter drier on every system I have touched in the 20 years I was on service, and have only seen them rupture 3 or 4 times.

[Brian_UK]

My first question is: How were you able to purchase an a/c unit, *****, or refrigeration tools, without the necessary licences? It is against the law in Canada to sell any of those products to anyone who is not licenced.We haven't yet reached that level of legislation here in the UK, it's coming, but slowly.


My second question is: why would you want to? Release of refrigerants into the atmosphere causes global warming and ultimately jeopardizes life on earth. This is not a job where you "wing it" and see what happens. That's why he asked the question in the first place, he wants to act responsibly and he has.

[mswinman]

A little inter-trade negotiation and natter over a coffee saw the deed done. Having done the pressure test and drawn a vacuum it was just a case of opening the service valves and that was done today. He also explained the general reluctance in doing the job. In short, I have to say I agree, nobody, myself included, wants to do half a job and accept responsibility for the whole job. Some very pertinent points were examined during this thread, particularly environmental issues. I hate the term DIY, it conjures up images of **** Emery in one of his many sketches, but for every elegant DIY electrical installation I've seen, I've seen a hundred that are total crap. If I'ts the same ratio for this type of install the planets F****D.

[Brian_UK]

Glad to hear that you are up and running, just in time for winter :D

That sigh of relief when it all started running was heard half way across the country :cool:

As you said, the problems of responsibilty when a job is split does raise it's own problems in lots of fields.