The Homemade Heat Pump Manifesto

[Xringer]

Benson Airconditioning | Wall Split Systems

These Downunder guys really like R-290!

[AC_Hacker]

Originally Posted by Xringer

"Here's a guy who re-charged his home Air Conditioner with propane (R-290). He got it working again...
no surprise. Also has information on the environmental benefits of R-290...also way cheaper.
"

I watched his vids and read his blog with great interest..
I also noticed his youtube chat about possibly using R-290 in an R-410a system..


As you know, I have a broken R-410a outdoor system and could buy the indoor side for about $500.

Please comment..

Thanks,
Rich

You'll need to make some kind of modification to the metering device, and also change out the compressor lubricant.

-AC_Hacker

[AC_Hacker]

Originally Posted by Xringer

Benson Airconditioning | Wall Split Systems

These Downunder guys really like R-290!

Yeah they do, and they also sell flammable gas monitors, just in case.

Did you see this page?

-AC_Hacker

[Xringer]

Originally Posted by AC_Hacker

Yeah they do, and they also sell flammable gas monitors, just in case.

Did you see this page?

-AC_Hacker

I did see that page. And "Refrigerant losses are calculated at 2% per year." Seems pretty high..
Are they saying that all systems are leaking? Or is it those that fail completely, causing the 2% ?

[Xringer]

Originally Posted by AC_Hacker

You'll need to make some kind of modification to the metering device, and also change out the compressor lubricant.

-AC_Hacker

The 'study' implied that R290 could be a 'Drop-In' replacement for R410a,
and that R290 would cool better and use less power..

It seemed like they didn't have to make any mods..
But, the last part does recommend a change be made to the capillary tube..
To avoid very high "evaporating temperature"..



"
For further discussion, even the optimum charge is
found from the experiments, the evaporating
temperature found to be very high 14.6C,

`For air conditioning application the temperature for
evaporation is 5C and condensing temperature is
45C.

`For the result above and requirement stated show that
there is an accurate result due to system setup.

`Even the manufacturer claim that R290 is suitable as
direct replacement for R22 andR410A (in the case of
this experiment), we found that minor modification
need to be done on the system.

`Suitable capillary tube should be change and follow
with further investigation.
"

[AC_Hacker]

Originally Posted by Xringer

The 'study' implied that R290 could be a 'Drop-In' replacement for R410a,
and that R290 would cool better and use less power..

It seemed like they didn't have to make any mods..
But, the last part does recommend a change be made to the capillary tube..
To avoid very high "evaporating temperature"..

That would be the mod I had in mind.

I don't know if your unit has the cap tube or the TXV valve metering device. If it's the TXV, there is a possibility that the screw adjustment would do the trick. The screw will adjust over some range, don't know if swapping R-410a to R-290 would fall within that range.

Originally Posted by Xringer

`Even the manufacturer claim that R290 is suitable as
direct replacement for R22 andR410A (in the case of
this experiment), we found that minor modification
need to be done on the system.

`Suitable capillary tube should be change and follow
with further investigation.

You might want to do a little more research into refrigerant lubricant compatibility.

I do know that mineral oil lubricants are not soluble in R-410a, that's why the synthetic lubes.

I suspect, but I am not completely sure if the synthetic lubricants are soluble in R-270. My suspicion is that they are not.

If it was my project, I'd find out for sure.

-AC_Hacker

[Xringer]

http://i46.photobucket.com/albums/f1.../referFlow.jpg
Dual tubes.. And, an electronic expansion valve

http://ecorenovator.org/forum/applia...ion-valve.html

Since it uses a temperature sensor as feedback, maybe that electronic expansion valve will allow for using other refrigerants.?.


I've read R290 has good versatility in the type of lubes that can be used.
In the study, they flushed the unit out completely.
I think they didn't want any R410a lube in the system.

If I was going to do this, I would find some R290 compatible lube..

[AC_Hacker]

Originally Posted by Xringer

[IMG]I've read R290 has good versatility in the type of lubes that can be used. In the study, they flushed the unit out completely.
I think they didn't want any R410a lube in the system.

If I was going to do this, I would find some R290 compatible lube..

R-290 uses a mineral oil lube, same as R-22 & R-12.

It is the easiest to find and cheapest refrigerant lube available, you should have no problem getting it.

You'll want to be careful when you flush out the old lube, affixed to the input side of your compressor is a filter/dryer that could 'hang on' to old lube, you'll probably want to flush the system a few times.

Also be careful to add the proper amount of lube back in. If you over-fill it, it can cause the compressor to seize and possibly damage the system.

Boy, if your house was set up for low temperature hydronic, the uber-cool setup would be to hack your outside unit to heat water for your house. This would really be the ultimate hack as it would significantly boost COP above what you are now enjoying.

As it is, with the hydronic radiators you have, the feed temp would be just too high.

BTW, perhaps a bit off topic, here's a chart of COP v Air Temp for ASHP. This is for a particular brand, but the trend is interesting to see.

-AC_Hacker

[Xringer]

The oil doesn't sound too hard to find. Just getting the amount right..

I'm surprised at how well my hydronic radiators work at lower water temps.
If the water is above the room air temperature, there is some heating going on.
If it's 100f or higher, it works pretty well to supplement other heat sources.

Interesting plot. Still getting a COP of 2 at 10F.. I've noticed the power use
can get up to around 700-900w when it's 10-12 F outdoors.
Compared to right now, it's 35F (and raining) and we are using 600w (ave).

~~~

Firstly, I need to find and repair that leak.. Which I think is under the sensor tube.
http://i46.photobucket.com/albums/f1...r/NCL/r027.jpg
It's in a tight spot..
http://i46.photobucket.com/albums/f1...eakysilver.jpg

This is a job that's going to have to wait for warmer weather.

[AC_Hacker]

Originally Posted by Xringer

The oil doesn't sound too hard to find. Just getting the amount right..:

Xringer,

What do you think about starting another thread to move this worthy dialog to. I fear that it is diluting the GSHP information I'm trying to create.

We can copy this dialog and paste to the new thread.

-AC_Hacker