Superheat and subcooling

[marc5180]

is there any where that i can get a chart from that shows troubleshooting a system so that when i take my superheat and subcooling readings and Lp and Hp pressures i have a chart to look at.. i.e if my superheat is high but sub cooling is low it would be this..... and if my superheat is high and my subcooling is high it could be this etc etc

[lana]

You have to take a training course for trouble shooting.
Also you can buy a book and CD which are for training and it is called Kotza.

Very good training material, but it is not a single chart. First you have to understand every possible fault and the symptoms.

Cheers

[marc5180]

which is the one that i would need first of all, iv been on the website but dont fancy spending 700+ on all of the software even if it is worth it.

[lana]

In my opinion first you need the Ref Repair book not the CDs.
The CDs are for exercising and teaching.
The book is very good, starts from the basics and covers almost anything you need in the field.
I am not sure if they sell the book alone though.

Cheers

[marc5180]

In my opinion first you need the Ref Repair book not the CDs.
The CDs are for exercising and teaching.
The book is very good, starts from the basics and covers almost anything you need in the field.
I am not sure if they sell the book alone though.

Cheers

just looking through the site now but can seem to find the price for the book and one of the cds? Any idea Lana

[lana]

Go to the price list and all prices are there.
Ref repair manual is 93.84 EUR exc VAT.

Cheers

[marc5180]

what about for 1 cd and the book?

[lana]

Check their site.

One software + one manual = 299 EUR exc VAT.

I suggest you get the RefriDiag software + RefRepair manual.

Cheers

[marc5180]

thanks Lana, much appreciated

[Brian_UK]

Marc, you could try the Tech Method books.

Check member 'Gary', view his personal details and you can link to his website.

[marc5180]

Marc, you could try the Tech Method books.

Check member 'Gary', view his personal details and you can link to his website.

Yes iv been looking at that for a while now but im unsure about it due to the negative comments from some people. I know the kotza has a fault simulator that i can use on my PC but for one book and 1 cd its 250pounds which is ridiculous... How do garys book differ you dont get a cd like you do with kotza do you?

[lana]

Hi Marc,

Don't make any mistake. The fault simulator is a training tool and you can not create your own faults and expect an answer.

It shows a DX system operating with a fault in it and user can measure every parameter on it like temperatures and pressures. Then the user must find the fault.

Cheers

[marc5180]

Hi Lana,

I understand about the kotza programme and the fault simulator and i know that i cant make up my own faults, though this would be good.
Thanks
Marc

[Andy W]

There is no subsitute for practical experience, the knowledge that us older engineers have amassed in our heads over the years is priceless, with experience you can diagnose a problem by looking, listening and touching the pipework.

[marc5180]

I agree but a little bit of help along the way must surely be a good thing

[BigJon3475]

I agree with Lana completely. However here is a chart for when you completely understand the refrigerant system.

http://www.hvac.amickracing.com/Trou...leshooting.pdf

[Andy W]

I once had one of those charts on a wheel shaped comparitor type of thing when I started in the fridge trade in 1978.

[marc5180]

I agree with Lana completely. However here is a chart for when you completely understand the refrigerant system.

http://www.hvac.amickracing.com/Trou...leshooting.pdf

Thats just what i was after John, thanks very much

[taz24]

I once had one of those charts on a wheel shaped comparitor type of thing when I started in the fridge trade in 1978.

I had one on a disk aswell.
It was from J E Halls and I thought it was a very useful piece of kit at the time.
It would compair temps and pressures and give fault diagnosis too.

Long gone now unfortunatley.

Cheers taz.

[The MG Pony]

practical? Get three old beat up A/Cs and have at it. Technical lititure? Well you got answeres for that. Best way to learn is buy just doing it in your living room and stumbling around, you may kill a fiew systems but once you learn the wrong ways the right way makes even more sense!

So with that book I strongly sugest you grab some old beaters to play with when your at home with not much to do!

[nevgee]

Get the Kotsa demo cd its got some basic work in there that you can make use of. It will give you some guidance on principles of sh and sc then you can make your choice.

[Magoo]

forget the books and cd's. superheat is checked against system TD (air on versus evaporating temp ), the superheat should be 60 to 70% of system TD, can be checked at design or during pull-down, wait 15 minutes if TXV has to be adjusted and re-check superheat.
Write in your head for future reference.
regards Magoo

[Pooh]

Marc
what about using a PH chart that would give you all the answers you need, just plot the discharge and suction pressures and the temperatures and bobs your uncle there is the answer.

Ian

[BigJon3475]

http://efficientcomfort.net/ACanalyz...alyzer_Web.jsp


It's American so you may have to convert....

[marc5180]

Thanks for all your help guys, i understand superheat and subcoling pretty well now. I use it a lot more these when checking a system for problems but mostly for commisioning a system.

[Brian_UK]

Well done Marc, another convert

[marc5180]

one last thing whilst we're on the topic, can you calculate superheat and subcooling on VRV/VRF's when there is more than one indoor unit?
Would all the indoors have to be working 100% to get a correct reading?

[Brian_UK]

Tricky subject on VRFs I think, you really need to be able to interrogate software to get system readings.

Some machines you can use dip switches and display but I'm not 100% on that.