HVAC gurus, HELP!

[HvacN3wb]

Ok, so first time poster long time listener. I've recently built a little variable speed (up to 5000 btu) DC hvac system and it is not operating at all like I expect.

1.) I have a masterflux hermetic compressor that runs on r134 and 12 volts.
2.) because of lack of funds and completely custom nature of this project I've cobbled together the condenser and evaporators using a busted up 5000 btu window unit I disassembled.
3.) because it is what the previous window unit used, I am running 1/4" line from the high side into the condenser. The condenser (not parallel flow as far as I can tell) then has some sort of small diameter coiled metering device back out into 1/4" line after the expansion. This then runs through 1/4" evaporator line back into the suction side that is expanded out to 1/2" to accomodate the pre brazed fittings to compressor. This expansion to 1/2 line happens about 8 -10 inches away from the accumulator near the compressor.

Now heres the problem, it isnt cooling anything. The only portion that is even relatively cool is the portion of the suction line right before going back into the compressor. I assume because there is quite a bit of room for the gas to expand. Is my whole problem that my evaporator lines arent large enough?

Also i was told that it does not matter where the low side service port is mounted as long as its on the low side, however the low side service port is also mounted right before the accumulator in the 1/2" tubing. I could never get the pressure above 12 psi and I had it filled with 20 oz of r134. With the system off, the pressure would rise well above the low side guage reading.

I assume the pressure reading is because of the expansion of the tubing dropping the pressure in that section.

Please help me, I'm a year invested into this build and this is a major setback. I suspect I need to run larger evaporator lines so the gas can properly expand but I'm just guessing and would appreciate any advice you guys can give me before I set out to reconfigure the whole thing. Id rather not waste any more time or money than I already have.

Thanks for any help you can give me.

[jackintheboxtec]

I don't think you will get much info in here. Site rules says no DIY.

[HvacN3wb]

Well I considered that and I'm not asking someone to show me how to hook up the system, only asking what my problems could be.

I thought DIY was a step by step guide on how to do something. Id just like advice on how to make my system better based on what I outlined earlier.

[jpsmith1cm]

You've got a mismatch going on most likely.

The compressor, I'll *assume* is properly rated for R134a. Possibly a poor assumption, but let's run with it.

The coils you are using are from an old window unit which used R-22.

There is a 40% capacity difference between the 2 gasses.

Good luck with your project.

[HvacN3wb]

Ahhhhh, I see. Your assumptions were correct. So are you saying that the condenser AND evaporator lines are too small to accomodate the capacity difference?

[rogerk]

Its funny how all these home owners come on here trying to play the pitty card saying they have no money, yet they obviously have money for computers and internet service. I aint buying the "I dont have any money to call a pro". They're just cheap ***es.

[HvacN3wb]

Its funny how all these home owners come on here trying to play the pitty card saying they have no money, yet they obviously have money for computers and internet service. I aint buying the "I dont have any money to call a pro". They're just cheap ***es.

For your information, I've tried calling 5 different companies around town and none of them would even give me the time of day. As soon as I mention what I'm trying to do they clam up and tell me they dont do that.

Whats with this attitude? I dont understand it. I thought the purpose of a forum was to discuss ideas and help likeminded people?


I appreciate the little bit of advice that was given but you guys are just ridiculous. Get over yourselves, and help people. It will return dividends far exceeding your protectionist attitudes.

[Diceman]

lets see some pics.

[beenthere]

For your information, I've tried calling 5 different companies around town and none of them would even give me the time of day. As soon as I mention what I'm trying to do they clam up and tell me they dont do that.

Whats with this attitude? I dont understand it. I thought the purpose of a forum was to discuss ideas and help likeminded people?


I appreciate the little bit of advice that was given but you guys are just ridiculous. Get over yourselves, and help people. It will return dividends far exceeding your protectionist attitudes.

If you piped it to run the way you described it running.

It will never work.

Go to a HVAC trade school, and then you will know why.

This is not a DIY site. So no, we won;t tell you how to fix your Frankenstein thing.

[Wendo]

For your information, I've tried calling 5 different companies around town and none of them would even give me the time of day. As soon as I mention what I'm trying to do they clam up and tell me they dont do that.

Whats with this attitude? I dont understand it. I thought the purpose of a forum was to discuss ideas and help likeminded people?


I appreciate the little bit of advice that was given but you guys are just ridiculous. Get over yourselves, and help people. It will return dividends far exceeding your protectionist attitudes.

Okay, I'll give you the time of day. It's 10:13 PM. The reason you can't get any info from your local companies is because they are using their heads. Can you imagine what fun the lawyers would have in court if, after your homemade device blew up in your face, you sued the poor HVAC contractor for giving you advice? Also, a little humility would go a long ways. It's a bad idea to knock us guys when you're trying to milk us for some info. Maybe you could try giving your EPA Refrigeration Handling Certificate number to one of them to prove you are legally doing this.

[jpsmith1cm]

No and I can't give too $uch more info without running afouk of the no DIY rules on this site.

It isn't the line sizes I don't think, though,

[billygoat22]

sounds like a computer chiller.


no one wanting to touch it is not protectionist, they just don't like gum in their hair...

[shwung79]

Well said about the epa cert.