The Homemade Heat Pump Manifesto - Page 91

Xringer · 08-18-11, 10:55 PM

Thermal Properties of Metals, Conductivity, Thermal Expansion, Specific Heat - Engineers Edge

I was looking at the heat conductivity of Aluminum,
and it seems like a copper-to-copper HX would give a lot more heat transfer.
My old Solar hotwater system used a copper-to-copper double-walled HX.
The problem was the clean-out access started leaking too much.

But, I still like the high pressure (and BTU) rating of this one..
20 Plate Cu Brazed Heat Exchanger SS304 1" MPT B3-32 | eBay
For a mere $175USD, that's one sweet HX..

It seems like a good choice for my old Sanyo unit, and it's small enough to easily package up inside a well insulated box..

Cheers,
Rich

AC_Hacker · 08-19-11, 07:45 AM

Quote:

Originally Posted by Xringer

It seems like a good choice for my old Sanyo unit, and it's small enough to easily package up inside a well insulated box..

I hope you have better luck than I did keeping the high-pressure refrigeration gases from leaking out from MPT fittings. The refrigeration gasses are going through very large temperature cycles, to say nothing of the HX being subjected to vibration.

What you want on the refrigeration side is a "sweat fitting". Don't let the name fool you into thinking that it implies sweat soldering, that would be a mistake. You need to braze your refrigeration tubing, in order to withstand the temperature cycling and vibration... Or else use a compression fitting, which this is not.

The HX you linked to is a water-to-water HX.

-AC_Hacker

Xringer · 08-19-11, 08:56 AM

Except for those connections, it sure 'seems' like a good fit for a 2-ton ASHP water heater.

I was thinking that 1" MPT Screw-on Flare adapters for the 1/4" & 5/8" OD lineset,
might work for R290, and maybe even R410A..

It seems like a heating only app would not require "very large temperature cycles".

What if the HX was always kept above 40F, to avoid freeze damage,
and the maximum upper range was 120F to 170F ..?.
(How high does your Sanyo go)??

This seems very close to the normal temp range, of my current forced hot water baseboard system..
The largest extremes might occur during the Defrost cycles.
Depending on the way it was implemented.

If Propane was used, (outdoors of course) and the threads leaked a little,
I have to wonder if it would be a big deal, topping-off the charge once in a while.?.

Design pressure 3.0 Mpa (435 psi)
Test Pressure 4.5 Mpa (650 psi)
Design Temperature -195°C to +220°C (-319°F to 430°F)
Refrigeration Capacity 5-25KW (17,000-85,000 BTU/hour)

Applications:
SVO conversions, Heat pump system, household type central air conditioning,
after heat recycling, refrigeration equipment, industry cold water machine,
cooleroil and so on

AC_Hacker · 08-19-11, 09:56 AM

Quote:

Originally Posted by Xringer

Except for those connections...

I was thinking that...

It seems like...

What if the HX was always...

This seems very close to...

If Propane was used... topping-off the charge once in a while.?.

Well, there's certainly nothing to stop you from actually trying it...

Then again, there's nothing to stop you from finding & ordering the correct heat exchanger either.

-AC_Hacker

launboy · 08-20-11, 01:26 AM

I know there has been talk of hacking an inverter minisplit in this thread. AC Hacker I believe you mentioned it. It's always been talked about in a way with the OD Unit still in tact and hooking it just to a Plate exchanger with no ID unit. The problem with that being the electronics. Why not just use the whole thing and replace the evap coil inside with the plate exchanger, then elecrtonics are not an issue. Does anyone know how the minisplits choose a fan/compressor speed? Is it just a computer logic thing, does it look at pressures, incoming/leaving air temp, coil temps, etc? Some of those would be easy to modify to still work without an actual evap coil, others wouldn't as much.

Adam

Xringer · 08-20-11, 07:31 AM

Quote:

Originally Posted by launboy

I know there has been talk of hacking an inverter minisplit in this thread. AC Hacker I believe you mentioned it. It's always been talked about in a way with the OD Unit still in tact and hooking it just to a Plate exchanger with no ID unit. The problem with that being the electronics. Why not just use the whole thing and replace the evap coil inside with the plate exchanger, then elecrtonics are not an issue. Does anyone know how the minisplits choose a fan/compressor speed? Is it just a computer logic thing, does it look at pressures, incoming/leaving air temp, coil temps, etc? Some of those would be easy to modify to still work without an actual evap coil, others wouldn't as much.

Adam

I was thinking of just buying a new indoor unit to use with my spare outdoor unit.
Not too expensive. Sanyo KHS2472 Heat Pump Indoor Wall Unit

But, I found my Sanyo OD unit has a test mode (T-Run), where it will run stand-alone.
http://ecorenovator.org/forum/geothe...html#post12206

So, if I can repair my OD unit and get the right HX hooked up, I might just
be able to warm up a lot of hot water..

Anyways, my point is, maybe some or all inverter type OD units have some
kind of stand-alone test mode, that might be useful to DIY hackers..

Xringer · 08-20-11, 08:06 AM

Quote:

Originally Posted by AC_Hacker

Well, there's certainly nothing to stop you from actually trying it...

Then again, there's nothing to stop you from finding & ordering the correct heat exchanger either.

-AC_Hacker

Hey, for a measly $175, it comes in 1/2" copper sweat..

B3-32A 20 Plate Heat Exchanger [HX3220] | DudaDiesel Biodiesel Supplies

Have not seen this version in their Ebay store..

AC_Hacker · 08-20-11, 10:38 AM

Quote:

Originally Posted by Xringer

Hey, for a measly $175, it comes in 1/2" copper sweat..

Now you're talking.

This configuration will allow you to braze your refrigerant side and get a permanent seal, so no problem there.

The other side will constrict your water flow a bit but it should not be a problem, if you braze your water connectors (what ever they may be) to the outside of your fittings.

I have written to Dudadiesel & another ebay seller, inquiring about being able to order HXs with water pipe fittings on one side and sweat fittings on the other, but I have not heard back from either seller. Maybe if enough people inquire, they will be more motivated.

-AC_Hacker

okpiddler · 08-21-11, 09:21 AM

I was short one brass fitting and tried to use a copper one and it leaked so had to get another brass fitting. I used plenty of teflon tape and a lot of torque. When I silver soldered the copper to the brass fitting I used a lot of heat and ran water over the wrench flats of the brass fitting. It has been running since last fall with no leakage. I even submersed the whole unit in water to verify no leakage and I use a sight glass in the liquid line. THe unit only holds about a pound of r 22 so if it were leaking performance would drop off quick. BUT, if I were going to do it again I would do as Hacker has said and stay away from the pipe threads at least on the high side.
Sorry I have been gone so long! Have been doing lots of other things.

AC_Hacker · 08-21-11, 12:30 PM

Quote:

Originally Posted by okpiddler

Sorry I have been gone so long! Have been doing lots of other things.

Welcome back!

-AC_Hacker

08-21-11, 09:21 AM	#909
okpiddler Lurking Renovator Join Date: Feb 2011 Location: NE Oklahoma Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	My one inch pipe threads are not leaking I was short one brass fitting and tried to use a copper one and it leaked so had to get another brass fitting. I used plenty of teflon tape and a lot of torque. When I silver soldered the copper to the brass fitting I used a lot of heat and ran water over the wrench flats of the brass fitting. It has been running since last fall with no leakage. I even submersed the whole unit in water to verify no leakage and I use a sight glass in the liquid line. THe unit only holds about a pound of r 22 so if it were leaking performance would drop off quick. BUT, if I were going to do it again I would do as Hacker has said and stay away from the pipe threads at least on the high side. Sorry I have been gone so long! Have been doing lots of other things.

08-18-11, 10:55 PM	#901
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Thermal Properties of Metals, Conductivity, Thermal Expansion, Specific Heat - Engineers Edge I was looking at the heat conductivity of Aluminum, and it seems like a copper-to-copper HX would give a lot more heat transfer. My old Solar hotwater system used a copper-to-copper double-walled HX. The problem was the clean-out access started leaking too much. But, I still like the high pressure (and BTU) rating of this one.. 20 Plate Cu Brazed Heat Exchanger SS304 1" MPT B3-32 \| eBay For a mere $175USD, that's one sweet HX.. It seems like a good choice for my old Sanyo unit, and it's small enough to easily package up inside a well insulated box.. Cheers, Rich

08-19-11, 08:56 AM	#903
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Except for those connections, it sure 'seems' like a good fit for a 2-ton ASHP water heater. I was thinking that 1" MPT Screw-on Flare adapters for the 1/4" & 5/8" OD lineset, might work for R290, and maybe even R410A.. It seems like a heating only app would not require "very large temperature cycles". What if the HX was always kept above 40F, to avoid freeze damage, and the maximum upper range was 120F to 170F ..?. (How high does your Sanyo go)?? This seems very close to the normal temp range, of my current forced hot water baseboard system.. The largest extremes might occur during the Defrost cycles. Depending on the way it was implemented. If Propane was used, (outdoors of course) and the threads leaked a little, I have to wonder if it would be a big deal, topping-off the charge once in a while.?. Design pressure 3.0 Mpa (435 psi) Test Pressure 4.5 Mpa (650 psi) Design Temperature -195°C to +220°C (-319°F to 430°F) Refrigeration Capacity 5-25KW (17,000-85,000 BTU/hour) Applications: SVO conversions, Heat pump system, household type central air conditioning, after heat recycling, refrigeration equipment, industry cold water machine, cooleroil and so on

08-20-11, 01:26 AM	#905
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	I know there has been talk of hacking an inverter minisplit in this thread. AC Hacker I believe you mentioned it. It's always been talked about in a way with the OD Unit still in tact and hooking it just to a Plate exchanger with no ID unit. The problem with that being the electronics. Why not just use the whole thing and replace the evap coil inside with the plate exchanger, then elecrtonics are not an issue. Does anyone know how the minisplits choose a fan/compressor speed? Is it just a computer logic thing, does it look at pressures, incoming/leaving air temp, coil temps, etc? Some of those would be easy to modify to still work without an actual evap coil, others wouldn't as much. Adam