The Homemade Heat Pump Manifesto - Page 64

mrd · 03-09-11, 06:09 AM

It looks like a pressure control similar to what piddler linked to is in the control panel for a huge system shown in this video.

YouTube - Control Panel From Large Semi-Hermetic Refrigerant Compressor

AC_Hacker · 03-16-11, 07:05 PM

I found a line-level thermostat, one that will switch 120 v power according to the temperature on the dial.

...hooked up the thermostat in-line with the hot wire...

...put it all into an insulated box...

...here's a graph of it regulating my GSHP in the basement.

...works just fine.

Regards,

AC_Hacker

* * *

S-F · 03-16-11, 08:39 PM

I did this several years ago to turn a light bulb on and off for regulating the temperature inside of an incubator for making fermented foods. Was easy as pie.

AC_Hacker · 03-16-11, 11:38 PM

Pie is an art, this is a hack.

...but you're right, very easy to make.

-AC_Hacker

AC_Hacker · 03-18-11, 06:41 PM

On the first heat pump, I tried to utilize as much of the original structure as possible, but on this one I decides to make new structure where it made sense to do so.

Since I'll be using a TXV metering device, I had to swap around a lot of the original layout so that the build would go together easier.

So I'm bending copper tube for the envisioned layout.

Here is my collection of bending tools:

Lowest in the picture is a spring bending tool, it's also lowest on my list of bending tools that work. The idea is that the tube goes into the spring and then the spring is bent with the tube inside. Never worked well for me at all.

Next up is a small, single-diameter bending tool that actually works pretty well and is quite cheap to aquire. You'll need one of these for each diameter of tube that you bend. The nice thing about this tool is that it will bend a narrow "U" bend. Of course, you can bend less than a full "U".

Upper on the list, and my most used tool, is a multi-diameter bending tool. Although it looks like it would be awkward to use, once it is positioned and 'snugged-up' on the tubing, it works very well. Down-side is that it will not do a narrow "U", only 90 degree bends, but it will do two 90 degree bends pretty close together. All of the bends I needed to do on this project were two 90 degree bends pretty close together, so it worked out just fine.

Here's a shot of how I used this tool to do a long "U".

A lot of the process of doing bends has to do with estimating just where the components will be and how to position the bends so that things will line up as well as possible.

I needed to install a Schrader valve in both the high-side and the low-side tubing. Here is a detail of how I installed the valve in the low-side tube. First I drilled a hole to match the OD of the Schrader valve (they come in various sizes). Note that I cleaned up the surface of both pieces of tubing with a small wire brush, this removed oxide and made brazing a snap.

...then I brazed it on using Sil-Phos brazing rod. I just love this stuff, no flux required and it flows like a dream.

I'm using 5% silver here, the HVAC trade seems to prefer 15%.

NOTE: Inert gas was used throughout the brazing procedure to prevent copper oxide flake contamination.

NOTE #2: Remember to remove the Schrader valve core before brazing. Only replace the valve core when the brass body is cool to the touch. If you smell burning rubber when you are brazing, you screwed up... (voice of experience).

Regards,

-AC_Hacker

* * *

AC_Hacker · 03-20-11, 01:47 PM

I have been using my new data logger (which currently has just one '1-wire' temperature sensor) to monitor the air temperature variations resulting from the line-level thermostat.

Here is a chart of about 36 hours of performance:

The thermostat is regulating, after a fashion, apparently keeping the temperature level within a four-degree window.

While I wasn't expecting lab-grade performance from a thrift store part, There is simply too much fluctuation to be very useful.

So it's back to the workbench.

-AC_Hacker

S-F · 03-20-11, 01:58 PM

Before you go and rethink everything you might want to consider that once in production it will be operating on much more mild materials than air. Your radiant slab, or whatever it is you end up doing, has a lot of mass to buffer such fluctuations and on top of that your living space is certainly insulated better than your basement. It might be just fine.

Why not just get a relay and use a regular domestic thermostat?

AC_Hacker · 03-20-11, 06:29 PM

Quote:

Originally Posted by S-F

Why not just get a relay and use a regular domestic thermostat?

That was my next step...

-AC_Hacker

AC_Hacker · 03-21-11, 01:48 AM

Quote:

Originally Posted by S-F

Why not just get a relay and use a regular domestic thermostat?

Hey S-F, I have a couple digital thermostats...

I have a transformer too, and a solid state relay, but the solid state relay wants to see a DC control signal input.

Do the digital thermostats need AC to work or will they also work with DC?

Please advise.

-AC_Hacker

electrostunt · 03-21-11, 03:26 AM

A suggestion for a different approach:

What about reading the temperature with ex. a 1-wire tempsensor as you are used to and using an arduino board to control the solid state relay.

This way you could also add a sensor for outdoor temperature and add this into account for calculating the running of the compressor.

combine this with a web interface: arduino.cc/en/Tutorial/WebServer
And you have flexible and scaleable temperature control.

03-16-11, 07:05 PM	#632
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Line-Level Thermostat... I found a line-level thermostat, one that will switch 120 v power according to the temperature on the dial. ...hooked up the thermostat in-line with the hot wire... ...put it all into an insulated box... ...here's a graph of it regulating my GSHP in the basement. ...works just fine. Regards, AC_Hacker * * * Attached Thumbnails __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker... Last edited by AC_Hacker; 03-16-11 at 07:08 PM..

03-16-11, 11:38 PM	#634
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Pie... Pie is an art, this is a hack. ...but you're right, very easy to make. -AC_Hacker __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...

03-18-11, 06:41 PM	#635
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Bending Copper On the first heat pump, I tried to utilize as much of the original structure as possible, but on this one I decides to make new structure where it made sense to do so. Since I'll be using a TXV metering device, I had to swap around a lot of the original layout so that the build would go together easier. So I'm bending copper tube for the envisioned layout. Here is my collection of bending tools: Lowest in the picture is a spring bending tool, it's also lowest on my list of bending tools that work. The idea is that the tube goes into the spring and then the spring is bent with the tube inside. Never worked well for me at all. Next up is a small, single-diameter bending tool that actually works pretty well and is quite cheap to aquire. You'll need one of these for each diameter of tube that you bend. The nice thing about this tool is that it will bend a narrow "U" bend. Of course, you can bend less than a full "U". Upper on the list, and my most used tool, is a multi-diameter bending tool. Although it looks like it would be awkward to use, once it is positioned and 'snugged-up' on the tubing, it works very well. Down-side is that it will not do a narrow "U", only 90 degree bends, but it will do two 90 degree bends pretty close together. All of the bends I needed to do on this project were two 90 degree bends pretty close together, so it worked out just fine. Here's a shot of how I used this tool to do a long "U". A lot of the process of doing bends has to do with estimating just where the components will be and how to position the bends so that things will line up as well as possible. I needed to install a Schrader valve in both the high-side and the low-side tubing. Here is a detail of how I installed the valve in the low-side tube. First I drilled a hole to match the OD of the Schrader valve (they come in various sizes). Note that I cleaned up the surface of both pieces of tubing with a small wire brush, this removed oxide and made brazing a snap. ...then I brazed it on using Sil-Phos brazing rod. I just love this stuff, no flux required and it flows like a dream. I'm using 5% silver here, the HVAC trade seems to prefer 15%. NOTE: Inert gas was used throughout the brazing procedure to prevent copper oxide flake contamination. NOTE #2: Remember to remove the Schrader valve core before brazing. Only replace the valve core when the brass body is cool to the touch. If you smell burning rubber when you are brazing, you screwed up... (voice of experience). Regards, -AC_Hacker * * * Attached Thumbnails __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker... Last edited by AC_Hacker; 03-18-11 at 06:50 PM..

03-20-11, 01:47 PM	#636
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Bi-Metallic, Line-Level thermostat revisited... I have been using my new data logger (which currently has just one '1-wire' temperature sensor) to monitor the air temperature variations resulting from the line-level thermostat. Here is a chart of about 36 hours of performance: The thermostat is regulating, after a fashion, apparently keeping the temperature level within a four-degree window. While I wasn't expecting lab-grade performance from a thrift store part, There is simply too much fluctuation to be very useful. So it's back to the workbench. -AC_Hacker Attached Thumbnails __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...

03-16-11, 08:39 PM	#633
S-F You Ain't Me Join Date: Nov 2009 Location: Northampton MA Posts: 662 Thanks: 6 Thanked 71 Times in 58 Posts	I did this several years ago to turn a light bulb on and off for regulating the temperature inside of an incubator for making fermented foods. Was easy as pie.

03-20-11, 01:58 PM	#637
S-F You Ain't Me Join Date: Nov 2009 Location: Northampton MA Posts: 662 Thanks: 6 Thanked 71 Times in 58 Posts	Before you go and rethink everything you might want to consider that once in production it will be operating on much more mild materials than air. Your radiant slab, or whatever it is you end up doing, has a lot of mass to buffer such fluctuations and on top of that your living space is certainly insulated better than your basement. It might be just fine. Why not just get a relay and use a regular domestic thermostat?

03-21-11, 03:26 AM	#640
electrostunt Lurking Renovator Join Date: Jan 2011 Location: Norway Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	A suggestion for a different approach: What about reading the temperature with ex. a 1-wire tempsensor as you are used to and using an arduino board to control the solid state relay. This way you could also add a sensor for outdoor temperature and add this into account for calculating the running of the compressor. combine this with a web interface: arduino.cc/en/Tutorial/WebServer And you have flexible and scaleable temperature control.