Deep cold well

[jeff5may]

Akbrant,

Welcome to the forum! You seem to be eager to accomplish something, but viewers of this thread have been given a scatter-gun blast of information to try to make sense of. I will attempt to answer some of your basic questions.

1. Will R134a work in a unit designed for R410a? Kind of, but not well. The only real element that is nearly the same is the compressor's compression ratio. The metering device and heat exchangers are designed to run at much higher pressures than you can run R134a in the same system. If you try to make it work, the capacity of your 410a unit will be seriously decreased at 134a pressures. Your best bet with this unit is to fix the leak and have it recharged with R410a. That said, other members have had decent luck recharging their units with R290 or R1270.

2. They use R410a because it's more efficient? Nope, they use it because the good ol' refrigerants are either ozone layer destroyers or flammable gases or both. Also, Honeywell has a patent on R410a, and R12 and R22 both have targets on their backs. R410a was chosen as a temporary residential-market replacement gas until the mfr's can decide what refrigerant to use next. It and the other HFC's will be next on the phaseout list due to their high global warming potential. Meanwhile, industrial/commercial entities will continue to use whatever they want to as long as they can afford to. Check out http://www.gas2010.com for the current state of disarray the refrigerant market is in, as well as what refrigerant will work in what systems and the pressures and temperatures that they are designed for.

3. How can I piece together something that will work with what I have to charge and recover? That all depends mostly on your skill and patience levels, then to a lesser extent, your tool set. Most older auto and residential systems were plumbed with standard acme fittings, AKA 1/4 inch SAE flare fittings. With the introduction of R12 and R22 replacements, this all changed. Newer automobiles have completely different fittings than home systems, and newer home systems have different fittings depending on what gas they use as refrigerant. MOST (NOT ALL) home R410 systems use 5/16 inch SAE flare AKA 1/2 inch acme fittings. MOST (NOT ALL) R134 systems use 3/8 inch SAE flare fittings. For industry standard parts, their names, cool pics, etc. check out ITE-Tools.com - Home . Click on "Product Line" and dig for treasure.

Hope this helps,
Jeff

[akbrant]

Thanks Jeff,

I Just found your reply as I didn't realize the second page of this thread existed! Sorry about the scatter gun, I get excited about projects and don't do the best documentation.

As far as the r135a in a r410a designed unit I've been proving your comments correct over the past few days. I ended up charging the system with 22oz of walmart auto r135a I didn't really run the unit before I killed it so I don't have a base line but the 1 ton unit seems to put out lots less heat than the r22 half ton.

Here is my hacked 1 ton unit, I cut the evaporator off and built a tube in tube with 20 feet of 3/8 copper and 17 feet 3/4 inch poly. The good news is my refer brazed connections held up to the bubble test bad news the I melted out the 3/4 low temp brazed water connections!

On the tag on the back the 1 ton reads 20oz of 410A with a suction pressure of 236 and discharge pressure of 523. In my testing with 135A in a 65F garage with 45F cooling water I hit around 25 psig suction and 125 psig discharge. The water heat exchanger never really had a delta temp of over 3F so I didn’t seem to be pumping much heat.

I'm about to get some help from the local HVAC guys in town to recover my r135a mess and charge up the system with the r410a.

Thanks for the help on the fittings, its good to see that information in once place in writing.

Thanks again!

[jeff5may]

Not bad for a first test! From the pic, it looks like you're going water to air with this unit. If the unit was evacuated well before charging, the numbers you posted for your pressures are on the low side for R134a. Without any temperature readings, it's impossible to know for sure. But if the unit blew any warm air, it can be judged as proof of concept that it will work better when refilled with R410a.

At this point, I will offer some friendly advice to ensure your next revision will operate reliably. Taking time to make sure you do the best plumbing job possible now will save you tons of head scratching and problem solving later.

Before you have the system recharged with refrigerant, have the R134a recovered and the unit filled to atmospheric pressure with inert gas. Take apart your coaxial exchanger and rebuild the ends with new parts, this time avoiding sharp bends or extra fittings. Sharp bends cause pressure drops that will kill your efficiency and concentrate stress from vibration that end up causing leaks.

Extra fittings can be avoided by making your own adapters with a swaging tool. Sharp bends can be avoided by using a tubing bender. If you are planning on doing much hacking, these two tools will be priceless and pay for themselves over and over. Here are a couple of examples on ebay:

3 SIZE TUBE BENDER BRAKE, A/C, PIPE BENDER, FUEL LINE TUBING BUY 2 - FREE SHIP

Swaging Punch Tool Kit - 3/16" to 5/8" - New - 5 Sizes

HVAC Tube Working Tools Tube Cutter Flaring Tool Tube Bender Swaging NIB | eBay

Once you have everything fitted, braze everything up with silfos rod. Not tin solder, not silver solder, but copper phosphate rod with added silver which acts as flux. At R410a pressures, regular plumbing solder will not hold up for long. Silfos is actually stronger than the copper pipe it holds together. It is available in different brand names at welding and A/C supply houses everywhere. I found some in a pinch at Tractor Supply Co., Hobart brand looks just like silfos. Another ebay example:

http://www.ebay.com/itm/SILVER-SOLDE...item51ada4317e

This is the point where a little added work will make or break your homemade unit. A little prevention will be worth years of trouble free operation and few surprises. Trust me when I say that Murphy's Law bites hard in this realm. That's why air conditioning guys charge so much.

While you're at it, make sure to take lots of pics. Let us marvel in your accomplishments. The refrigeration industry in general has attached a stigma to activities such as you are performing, saying even if it could be done it shouldn't. So any information added by those of us who know better is good information IMHO. It seems to me that you have the skill and mindset to add a lot to the forums.

Wishing you success,

Jeff

[Mobile Master Tech]

Thanks for the third tool link in your post. $35 shipped for ALL of that, it doesn't hurt to have multiples of certain things!

Craig

[Daox]

Any updates here?

[akbrant]

Hi Guys,

Sorry about the no updates, I put this project on hold for the summer. Working on a boat project now that sucks all my time.

-brnat