beginer questions

[steve_k]

I am new to air conditioning and this forum,

been a plumber and electrician for a long time now, moved over to Spain (from UK) 3 years ago, my only AC experience is fitting about a dozen split units, dakin, hitachi, verhal, nothing complicated.


so to my beginners questions

1st brazing
this is embarrassing as a plumber, but i have never braised, though with over 25 years in the trade i have seen my share, I will only be working on domestic units with a max 5/8" pipe
Do you use flux?
I assume you clean the joint prior to brazing?
I have only seen you use ex panders to make the joints, I cant find ex panders for 1/4" pipe?
can you use pre made joints?
I have seen locally (only on 1/4")just map gas being used, I had always assumed you needed a small oxy kit to braise?


How do i determine if there is enough gas in the unit?
not new units, pre installed units, I had a leak on a unit, not a joint but a duff o'ring on a gauge hose, I had no idea how much gas had been lost so i just added more gas until it started working properly (here's you all cringe)
I have bought 3 books on AC/Refrigeration but none give any real info on this (for a modern split unit)

any info on this would be appreciated, maybe a good book recommendation

thx
Steve

[marc5180]

Hi Steve,

1) Flux isn't needed when braizing copper to copper pipe, i only use it when trying to braize copper to brass or things like that.

2) You can buy a little kit that expands 1/4 but i tend to use the 1/4 sockets, much quicker in my opinion.

3) Mapp gas will work fine on braized joints up to 7/8th if you have the double ender then you can go up to 1 1/8th.

4) To determine if there is enough gas in a unit, you need to take temperatures at different points around the system and work out your subcooling and superheat. Just topping a sytem up will reduce efficency, as more than likely you will have added more gas than necessary and if that is the case then you will be filling up the bottom of the condensor with overcharge thus reducing the capacity of the sytem.

Edit... Also with regards to a good book, a friend of mine has just got two books from amazon that he reccomended;
Air Conditioning and Refrigeration Repair and Arco Air Conditioning & Refrigeration Toolbox Manual

[Brian_UK]

Add to Marc's no.1 , You must have oxygen free nitrogen flowing through the pipework to prevent oxidization within the pipe.

As regards 'how much to add?', do a search here on 'Superheat' and 'sub-cooling'. That will get you started,

You should perhaps be getting a Refrigerant Safe Handling ticket if they operate one in Spain - they should because it is EU regulations.

[steve_k]

You should perhaps be getting a Refrigerant Safe Handling ticket if they operate one in Spain - they should because it is EU regulations.

they have very strict rules and very lax enforcement, so you get some very bad

practices

, I fitted the first unit because the

original

fitter

didn't

use (

didn't

own) a vac pump,

kinked

the pipe 3 times (

didn't

have any benders either) in a 3 m run, and all the gas leaked out anyway

You must have oxygen free nitrogen flowing through the pipework to prevent oxidization within the pipe

obviously i have seen this in the

UK

, but here in

Spain

on domestic nobody flushes the system with nitrogen, on 2/3m

installations

how important is it?

Mapp

gas will work fine on

brazed

joints up to 7/8th if you have the double

ender

then you can go up to 1 1/8th.

whats a double

ender

?

[frank]

whats a double ender?

Excuse ME!!

This is a refrigeration forum - not a SEX forum

[Brian_UK]

Well, there's a difficult post to read, however...

Without nitrogen flowing the inside of the pipe will oxidize. When the system runs the oxides will wash off the pipe into the compressor where they will break down the oil and cause acid.

The acid will then attack the motor windings until it shorts out.

If it fails during warranty and the manufacturer checks to find oxides then the warranty is void.

A double ender is a brazing torch with two nozzles.

[Brian_UK]

Nice one Frank

[Brian_UK]

Also, Steve, have a look at this thread from earlier....

http://www.refrigeration-engineer.co...ad.php?t=13832

[steve_k]

thx for the quick replies

don't know what happened with my above post, very strange

your previous thread link was very informative thx

plenty of info on this forum will be spending some time reading over old posts

[steve_k]

After Brian_UKs recommendation i have today purchased a nitrogen set, here in Spain you have to purchase your first bottle, then just pay for the refills, the bottle cost 580e and the refills are 35e (11ltr) how does that compare to the UK?

so I have my nitrogen what do i do with it?
flushing how much do i push through the new pipework?
pressure testing, what pressure do you fill to? how long do you leave under pressure?
vacking, i presume i have to vack the nitrogen out of the pipe before gassing up

All this sounds very amateurish, and you may be thinking that i have no business fitting AC units, I have over 25 years in the trade (plumbing and electrical) I have 95% of the skills required, I only intend to fit domestic precharged split units, I have no intention of calling myself or becoming a service engineer, I just need to put in good practices to ensure my fitting has no detrimental effect on the unit, 4 compression fittings on 3m of pipework is hardly rocket science, with a bit more patience and guidance you may help me become more competent

Steve

[nike123]

This is article for arc welding of steel tubes, but could be considered also for copper tube brazing and nitrogen purging:
http://files.aws.org/wj/2006/12/wj200612/wj1206-38.pdf

[Brian_UK]

Pricing in the UK..

We pay about 76Euro for a 10l bottle which includes the bottle deposit; sorry no idea how much the gas is.

[Electrocoolman]

Steve....Nitrogen set?...presume (hope) you are referring to pressure regulator?

You will in fact need two different pressure regulators....one low pressure (150 psi) which will allow you two get a small psi for small flow whilst brazing.
The other one will be high pressure (500 psi) which you need for pressure testing on modern R410 systems.

Under NO circumstances do you connect nitrogen cylinder directly to system without regulator.

[steve_k]

Steve....Nitrogen set?...presume (hope) you are referring to pressure regulator?


Under NO circumstances do you connect nitrogen cylinder directly to system without regulator.

lol see I am coming across as an armature, not ac or plumbing related, but i am a scuba diving instructor, and i have a gas blending ticket o2 and helium to 300 bar

back on topic
yes I purchased a regulator, it has 2 gauges for the cylinder and secondary pressure, and it looks like i can set the secondary from 0 to 45bar


you say

Under NO circumstances do you connect nitrogen cylinder directly to system without regulator

out of interest what is the working/test/fail pressure of refrigerant copper pipe?

[steve_k]

electrocoolman
you are from the UK and you are using psi, is this standard for the trade? i thought it was just the Americans using psi nowadays, maybe its just my scuba training.

[nike123]

yes I purchased a regulator, it has 2 gauges for the cylinder and secondary pressure, and it looks like i can set the secondary from 0 to 45bar

That is pressure regulator for pressure test with nitrogen and for blowing.
For air purging you need pressure regulator with flow regulation!
That mean you need two regulators!

[steve_k]

OK back to my diving background, if on my rebreather (yes another ticket i have) if i don't have my flow rate correct i die, its that simple.
back to ac, whats wrong with cranking open the regulator a bit to flush the system? we are talking about flushing out the o2, how accurate do you think the flow rate needs to be?

please remember i am doing small runs of un brazed pipework

[nike123]

OK back to my diving background, if on my rebreather (yes another ticket i have) if i don't have my flow rate correct i die, its that simple.
back to ac, whats wrong with cranking open the regulator a bit to flush the system? we are talking about flushing out the o2, how accurate do you think the flow rate needs to be?

please remember i am doing small runs of un brazed pipework

After flashing 0.2-0.4 l/min.

[steve_k]

After flashing 0.2-0.4 l/min.

I have no idea what you

are

on about, do you mean

flushing

?

[paul_h]

When brazing they are saying you need a regulator that has very fine control, feeding a certain flow rate into the system while brazing with a low pressure regulator, rather than using a high pressure regulator which is just for pressure testing as you can't set them to an accurate low flow rate.
Pressure testing disconnected pipework should be done to at least 2000kPa, as the units run themselves at 3500kpa when on heating.
2000kPa is the minimum, I normally pressure test to the whole 3500kPa if I suspect a leak.
When pressurizing a assembled unit though, standing pressure across the valves is usually only 800kPa, so if you go over that limit, you run the chance of your nitrogen getting past a leaking valve and ruining the precharged gass.
Search for threads here about that possiblity, as it's already been discussed.

If you are just going to be split bashing, odds are you won't be brazing that much and you can just use your service gauges to limit flow IMHO.
It's mainly in repair you need to do a lot of brazing (replacing components, repairing leaks etc)
But if you have to supply warranty to your own unit's, you may need to repair and be more qualified.

[nike123]

I have no idea what you

are

on about, do you mean

flushing

?

Sorry for mistyping.
With flushing I mean prepurging process to lower O2 amount in pipes to acceptable level. For that, you need to adjust flow to 20l/min for some time depending on pipe diameter end length. When flushing (prepurging) is done, you need to reduce flow to 2-4l/min (I was wrongly said in previous post 0,2-0,4) to be able to braze without disturbing brazed joint.
For that purpose, I use Co2 regulator for MIG welding.

[tony--1]

I know every 1 needs help . but this guy has gone out and got sumthing that could kill him with no idea how to us it . every 1 starts sum where but a little training would be good . you would not let your boy thats just left school loose with the nitrogen on a job you were on .

[nike123]

I know every 1 needs help . but this guy has gone out and got sumthing that could kill him with no idea how to us it . every 1 starts sum where but a little training would be good . you would not let your boy thats just left school loose with the nitrogen on a job you were on .

I think that you are overprotective! He is big boy now!

[steve_k]

I know every 1 needs help . but this guy has gone out and got something that could kill him with no idea how to us it . every 1 starts sum where but a little training would be good . you would not let your boy that's just left school loose with the nitrogen on a job you were on .

thx for the vote of confidence

I have an O2 and helium handling and blending certificate, and i can assure you that can kill you much more than nitrogen will (not sure how you could be killed more though lol)

thx for the info on prepurging

re brazing, I have had a lot of contact in my career with air conditioning, mainly commercial, I have seen hundreds of installs by different companies and have never seen nitrogen being used in conjunction with brazing, do you all use nitrogen when brazing?

Training
what training could i do? my Spanish is not good enough to go on any Spanish course, so it would be back to the UK, any hvac course is just too much for my intended use and i would never use 95% of the course content, there are some specific 4/5/7 day courses, but again 90% of the content would be telling me how to suck eggs, I had been seriously considering the gas handling certificate, but its tailored for the UK regulations and is worthless in Spain,

In my area of Spain there are lots and lots of people who fit AC (domestic) and most have no training, I only know of 2 companies that use nitrogen and they do mainy commercial, I know of more than a few that don't even have a vac pump,

I want to provide a proper service, i want to know that it is fitted correctly, I am here asking for you help because I know I have a shortfall in my Knowledge and skill base


last week I went to quote for a central heating system, weighing all the factors up I knew that hot/cold AC split units where a much better option for the customer,
Do i just stick to the central heating to get the work?
do i tell the customer about the AC option and loose the work? or do i fit the AC?
work is much harder to come by in this area of Spain and i am finding i need to expand my services to keep me in work.

Steve

[dogma]

Steve. If you're just planning on fitting Split system A/C units up to 14KW on a restricted A?C ticket then you will need the following tools.


R410a Flareing Block

Spring benders and Rachet type Benders For 3/8, 1/2, 5/8, 3/4, 7/8.

A vucuume Pump

A vuccustat

Scales

Digital Leak detector

Recovery Unit and Bottle

R134a/R22 Manifold Guage set

R410a Manifold guage set

Rotary Hammer drill

Turbo Tourch (mapp Gas) (cig turbo Tourch braises up to 1 1/8")

Expanders

And your basic Hand tools


... You Can buy Copper unions for 1/4" but I just use 5/16" tube and make my own unions.


....My advice to you Steve is go into your local A/C and Refrigeration wholesaler and Have a chat. Look around at what you think you might need and ask them for some advice... I don't know what it's like over there but the wholesalers are usually retired from the trade and know what they are on about.



_DOGMA-

[steve_k]

the wholesalers speak Spanish, getting the correct size copper can be hard enough

I don't see the nitrogen bottle on your list :-)

I have all the tools apart from the recovery unit, digital leak detector, and proper scales,

not sure i would get to use the recovery unit, but again i don't know do i

[Peter_1]

You have pressure regulators and flow regulators.
A flow regulator gives you a certain flow/minute and can't build up a pressure where a pressure regulator regulates a certain pressure.
I've done a lot of tests and we use these extensively while doing the test for the EU certification and you will need 3 to 1 bottles if you don't use a flow regulator while brazing.
They look the same but the working principle is completely different.
The smallest flow of nitrogen is enough is OK and we set it to 5 l/hour.
Make sure that where you connect the OFN or insert it in the tubes you blank it off with tape so that you don't suck air together with the OFN.

or

[Peter_1]

On the outlet, you can install a small SV and control it by a small and cheap remote control so that you can stop the flow when you stop with brazing.
Saves you a lot of OFN.
Something like this.

[dogma]

Thats a bloody good idea peter_1. It's such a simple solution for saving OFN.

...Sry Steve, I fogot the OFN and regulator(s).


______ Have a look at this Product Catalouge... BTW If you want to purchace any of this stuff from Australia due to the value of our dollar atm $1.00 US = 65cents Australian, send me a pm and I'll put you on to my supplier.



http://www.airzone.com.au/index.cfm?...Price%20Guides

[Testech]

Good on you mate for getting out there and actually doing something...
I have just finished working for a cowboy in the UK with 15 yrs experience who still didn't have a clue.
I would write down the actual processes in fitting the units and write a small but concise training manual.
Why not try doing it right from the start ? - If you want to purge whilst brazing then that will set you apart from the others.
The internet is a great source of information, as is the install manuals for each unit.
We all know that pre-charged units are only up to a certain distance of pipe run, so if you have to add refrigerant then your going to need a good set of scales.
My advice : Do your best safely, and remember your customers are trusting you to do a good job. Never put yourself or others at risk, and NEVER be afraid to ask questions.
Good luck my friend

[Testech]

I have just had a thought : Why not get old pieces of pipe and use them as a guide when buying copper pipe ?.
Better still get a good Spanish plumber to translate the sizes into Spanish.
Note : Rather than overfill, would everyone suggest, reclaiming, then re-charging to the correct capacity as per manufactuers instructions ?.

[steve_k]

I have just had a thought : Why not get old pieces of pipe and use them as a guide when buying copper pipe ?.

Note : Rather than overfill, would everyone suggest, reclaiming, then re-charging to the correct capacity as per manufacturer's instructions ?.

I am just about getting buy at the merchants, I am now very good at sketches I have just printed out the merchants entire product page, and that has nice little pictures for me to identify what to ask for,

the reclaiming and recharging may be a good idea, I don't have a unit at the moment, would i be able to use my 410 bottle if reclaiming and recharging 410?

and thx for your positive comments, I knew i would be opening myself up for some flack admitting to my level on here,
you are right the Internet is a fantastic source of information and an invaluable learning tool

Steve

[steve_k]

not sure what is going on with some of my posts? I back arrowed then checked and re posted changing nothing and everything is now fine?

I cant see an edit button?

[nike123]

not sure what is going on with some of my posts? I back arrowed then checked and re posted changing nothing and everything is now fine?

I cant see an edit button?

It looks like some glossary crosslinking!
Check in user CP on Edit options that Glossary Crosslinking is unchecked and that enhanced interface is selected as Message Editor Interface

[Testech]

What part of Spain are you in ?.

[steve_k]

Javea
Its aproximatley halfway between Alicanti and Valencia, about 40mins north of Benidorm

[icecube51]

Yo Steve,
i would not recommend to reclaim it together whit the fresh refrig because its blend can be wrong. it is a mix from 2 gases,and there is always 1 lighter than the other.you can keep a old bottle and remove the flow back valve,so it can be used as a recovery bottle.

Ice

[cookster]

last time i saw pipework being purged with ofn was at college

[Brian_UK]

last time i saw pipework being purged with ofn was at college

Well, me thinks that it is time you upped your game to improve standards

[Electrocoolman]

electrocoolman
you are from the UK and you are using psi, is this standard for the trade? i thought it was just the Americans using psi nowadays, maybe its just my scuba training.

Grew up with psi.....a bar is where I go for a drink!

With regard to Copper sizes.....most copper used is still in imperial sizes 1/4, (5/16), 3/8, 1/2, 5/8. These are the sizes that you will come across for a/c.
You might find that metric sizes are used in spain, but the flare nuts on the a/c units are normally sized for imperial (at least in UK), so this could present you with a problem area? (i.e. leaks) (poor flare joints are one of the major areas for leaks).

Can you get pre-insulated coils of soft copper over in spain - often co-joined pairs of the two sizes i.e. 1/4 and 3/8.
You do not then need to braze, as you run a continuous length of pipe, and just flare join at each end.
Its worth investing in a decent eccentric flaring tool suitable for R410 joints. You should also invest in flare nut torque tools so joints are not overtightened.

[The MG Pony]

Yes all ways purge while brazing any thing ells is an epic fail frankly.

One thing he didn't mention is that the oxides all so turn the oil into liquid sand paper!

[frank]

Did someone mention BAR & DRINK??

[monkeydoug]

I applaud you for efforts Steve.

If I'm honest we only really use OFN whilst brazing on our VRV installations, this is because their can be dozens of brazes and therefore alot of potential crap in the system. For splits, especially in domestic installs, its usually only ever one or two small brazes. We use soft rolled copper in 15 or 30 metre lengths so can often have one whole pipe between indoor and outdoor, no brazes required. Also, we use MKM german copper and in 10 years have never had a problem.

We ALWAYS use OFN for a leak test, saves alot of screwing around. You should test to 1.5 times running pressure, so for R410A it is about 550 psi or whatever that is in bra.?

[steve_k]

http://www.youtube.com/watch?v=tUH-5vAYCx8&NR=1

thats in appreciation of your help

[expat]

so for R410A it is about 550 psi or whatever that is in bra.?

I think it converts to about double D cup

[steve_k]

I have come onto this forum and been completely honest in my skill level and lack of skills,
I expected quite a lot of flack, because it is easy to pick on the new plumber ac wannabe,

you have been very kind to me, given me information, you deserve credit and thanks for this,

this could of so easily been a slanging match telling me i have no business even looking at ac units,

as a direct result of the comments on this forum, I now have a nitrogen rig, proper scales and recovery unit on order,
I am getting my head around concepts i had not even hear of 1 week ago

Thx for your helpful posts, you may make a competent installer out of me yet

Steve

[steve_k]

I think my head is going to pop I ave read that much in the last week,

I have some more questions,
Pressure testing, on a domestic 410a split, am i supposed to have the pipework disconnected from the outside unit? this would mean i am not testing the joints to the compressor (50% of the joints) obviously i would vacuum test it afterwards,

Superheat, yes I know stop trying to run before I can even walk,
anyhow, I have been trying to get my head around this, All the article's and posts say to take a temperature reading with your gauge connected to the suction line,
I have a dedicated 410a gauge, it obviously reads pressure and not temperature, If i got a reading of say 15bar or 220psi do I then use a PT chart to obtain the temperature, so for 15 bar I would have 58 Oc, if this is correct what are the R410a marking for on my gauge? they are at 0 at 100psi and then marked in +- around the gauge,

sorry if this is all a bit basic
Steve

[dogma]

Hi steve, I like to pressurise after I connect the pipes to the outdoor unit. If I find a leak and it's in the service valves, leaking ofn back into the outdoor unit, I call the OEM and let them know their service valves are leaking.


Also I llike to cut the flare connectors off of the indoor unit and braise my pipes. Make sure you use 15% silver solder. 5 % is cheaper but should not be used with R410a pipe work. I find it's safer to cut and braise... I also take out the philips head screws from the electrical side and service valve cover and replace with safty screws which you can't undo with a normal screwdriver.


I know of installers that won't flare at all and braise all their pipes, even to the outdoor unit so the system is hermetically sealed and can't be tampered with...



_DOGMA-

[just chilling]

writing on forums is new to me. so see how we go?

1. flux is not needed when brazing copper to copper if you are using correct rods.
2. if you are welding/brazing dis similar metals e.g brass to copper or brass to steel etc you will need flux or ready fluxed rods.
3. the only type of expander/swager for 1/4 ids manual flaring/swaging block type. imperial eastman make them you can get the at fridge wholesalers. but it is far easier to use a piece of 3/8 copper and sleeve it like a welded union/connector.
4. i live in australia now but worked as a fridgie in the UK. i expect you have to be licenced some how to handle refrigerant in spain. or most likely you will face heavy fines/imprisonment.
split air conditioners are critically charged with exactly the correct amount of refrigerant weight. useing digital scales and charging to the specified weight on the equipment label.
5.if you did not evacuate after the repair with a vacuum pump it is most likely the unit has moisture in it and will most likely suffer a burn out and render the whole system acidic.
6. a good book to buy and read is modern refrigeration and air conditioning written in america by Althouse Turnquist and Braccianno ISBN number
1-56637-300-x

[just chilling]

i am so new i did not see more than a week of discussion.
another tip i have for you now i have read all the above.
if you look at your refrigerant gauges you will notice different colours of scale incremements around the crcumferance of the gauge the different coulours repesent different refrigerants and they will be wrote on the gauge for each colour e.g blue = R 134a and red may be = R407c etc. the pressure corresponds to the satuated temperature.
you will see R22 = 0 degC at 400KPA or 60 psig
also R407C = 0 degC at 400kpa or 60 psig. this will save you having to get a pressure temp table out all the time.