The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by MN Renovator

"MN Renovator's comment is not correct."

Model FM12R
KW of elec. heat 1.7kw
8.9amps*230v=2047 watts

Are you sure? The numbers don't seem to add up but they aren't putting in the BTUs of heating either but 1700watts of heat output would be 5800BTU. If it produced the same amount of heat as it would cold, it would be a COP of a little over 2 but they aren't claiming that anywhere.

Yes, I am sure.

The model you choose is an air conditioner only and uses an electric resistance element as it's heat source.

Your chosen model has a 1700 watt resistance heater and at 115v the element would draw 14.78 amps.

Your chosen model uses 17.7 amps total when heating.

That would leave 2.92 amps to do something else with... I bet that is to power the fan... don't you think?

If you look further down the chart you will see that some model's cooling current use is much closer to the heating current use which indicates that the compressor is operating in heat pump mode and also notice that being figured into heating amps is current draw when BOTH the heat pump AND resistant heat is being used simultaneously.

-AC_Hacker

[Thumper]

I agree with AC. Making something do what you want it to do by re-purposing it for a few dollars is a wonderful thing. It's just that seeing these marine units with all the parts already there for a medium cost is exciting. Using old ACs or water coolers to help heat a shop or some other living space is cool (sorry - I couldn't resist).

[Thumper]

We were lucky to get a hold of a Trane water source heat pump for $1200. 24000BTU unit with top discharge air handler.

http://www.climas-trane.com.mx/docum...a%205%20TR.pdf

I'll post pictures of HP later. it won't suffice for our size house but we look forward to the challenge - being our first time doing this. Hopefully I can post updates of project as it progresses.

[AC_Hacker]

Originally Posted by Thumper

...It's just that seeing these marine units with all the parts already there for a medium cost is exciting. Using old ACs or water coolers to help heat a shop or some other living space is cool...

It looks like an interesting project you have there ahead of you...

But this thread is actually about re-purposing or refashioning existing HVAC units for your particular purposes. In fact that is why it is explicitly named Homemade Heat Pump Manifesto. The Homemade part of the name really says it.

If you wish to share the installation of your Trane water source heat pump, you should start another thread at the 'Geothermal' level of the forum tree. Starting a new thread is very easy, just click the 'NEW THREAD' button, and you are on your way.

There have been lots of other folks who have created their own thread(s) and shared their install projects. Many of our users have found this contributed information to be of great interest and in some cases, imminently useful to their own related projects.

Good luck to you with your new thread and your new project.

Best Regards,

-AC_Hacker

[Thumper]

Fair enough. Keep up the excellent work demystifying geothermal technology and sharing your experience so others can be inspired and and also share.

Thumper

[AC_Hacker]

BradC a HVAC hacker from Australia posted this great information on another thread... I didn't want it to go unseen.

Ok, some practical experience.

In Australia we don't have "heat pumps" (we do, but we call them reverse cycle air conditioners).

I have 2 Window A/C units (both reverse cycle) and my car A/C running on R290.

The car A/C is actually running a 60/40 mix of Propane and Iso-Butane (pressures are close to R12).

Both window A/C units are running on straight Propane.

I've not taken detailed measurements, therefore my evidence is strictly anecdotal. Both window A/C units run as well on R290 as they did on R22. I changed them over for the "because I can" factor, not because they needed it.

I removed the R22 by using a thermal vacuum. I vacced out a propane bottle down to about 200 microns. I then placed it in an esky (cooler, chilly-bin..) packed with dry ice and filled with methylated spirits (denatured alcohol). I did this as the vapor pressure of R22 at ~-70 Degrees C is below atmospheric an therefore it would reliably suck all the R22 out of the system (and I did not own a recovery machine back then).

I then charged the systems up with nitrogen, cut the end of the process tube off and brazed on schraders.

Both systems were charged loosely by monitoring the suction line temp where it leaves the evap (in cooling mode) with my calibrated finger and charging them up until it was "about right". Both systems have done in excess of 18 months service and are going strong. I did not filter or otherwise modify the straight BBQ propane I fed into them.

Since then, I've obtained a couple of proper recovery tank Y-valves and put them in some locally obtained propane tanks. I've also bought a recovery machine and some other assorted fruit to allow me to recirculate propane through a filter and sight glass to clean it up proir to feeding it into my ducted A/C which is sitting in the garage to be installed next weekend.

If you are mixing up gas for your car, you want iso-butane not butane. I went and bought one of every kind of camping gas disposable cylinder I could get my hands on, put them all in the freezer and then measured the pressure at the valve output. Iso-Butane retains higher pressure at 0 Degrees than Butane so it's easy to see which is which.

I then dumped 4 cans into an empty (vacced to 200 microns) propane cylinder and then weighed in the propane on top of that. You need to give the bottle a good shake and roll before you charge it in, and you need to charge it in as a liquid to prevent it fractioning off as it evaporates. I used my gauge set as an expansion valve to dump liquid from the bottle, but charge it into the system as a vapor. The gauges get *really* cold.

There.. now the thread has some real experience.

Hopefully after next weekend, when I hook up my new 7KW ducted system I'll have some more to post.

<edit> Charging scales are REALLY handy. I found some *cheap* shop scales on e-bay that do 30kg with a resolution of 5g. They were about $35 delivered and have a rechargable battery in them. Brilliant for mixing gasses and weighing in and out charges.

-AC_Hacker

[MN Renovator]

Originally Posted by Thumper

We were lucky to get a hold of a Trane water source heat pump for $1200. 24000BTU unit with top discharge air handler.

http://www.climas-trane.com.mx/docum...a%205%20TR.pdf

I'll post pictures of HP later. it won't suffice for our size house but we look forward to the challenge - being our first time doing this. Hopefully I can post updates of project as it progresses.

How big is the house? I've got 2200sq ft that had a heat load that matched the output of that heat pump at nearly -30c(-20f) and I've got R13 in the walls with 3/4" XPS wrap on the outside and my air sealing and insulation was barely started at that point, that was with 7" of cellulose overhead a little under R30. If you could boost your insulation it would do it for heating. Cooling would need the help of added shade, extensive air sealing, and probably triple pane low-e reflective tinted argon gas windows to work out depending on your solar exposure. I digress, have fun with that unit!

[AC_Hacker]

Originally Posted by MN Renovator

How big is the house? I've got 2200sq...

You are off-topic...

Please start a new thread for this conversation...

This conversation is not relevant to the homemade heat pump topic.

-AC_Hacker

[AC_Hacker]

This was just too good to pass up...

I have one of these... It works just fine. Probably will not hold up to professional use, but for experimenter's use it is just fine.

With fresh oil, mine will go down to 60 microns.

Good enough for me.

Print this coupon...

-AC_Hacker

[BradC]

Originally Posted by AC_Hacker

With fresh oil, mine will go down to 60 microns.

Never underestimate the value of fresh oil. Another thing I stumbled on recently is running the pump in under heavy load. (I didn't know they needed to be run in, or could benefit from it).

Mine pulled to just under ~200 microns. I'd used it on and off over an 18 month period, but never for more than 4 or 5 hours at a time and always pulling a high vacuum. Recently I learned that vane pumps need running in, and need to be run *hot*. I put a ball valve on the input and throttled it back to just a trickle of air and let it run for 24 hours. I then changed the oil, did it again, closed the valve completely and let it run another 24 hours (total of 3 days). It now pulls a 37 micron vacuum.

If you want to pull a good vacuum, run the pump for about 1/2 hr loaded with a trickle of air to get it good and hot before you hook it up to the system. More so if the system has moisture in it as the hotter the oil, the less it loads up with moisture.

(Tried to respond to your PM AC_Hacker, but I don't have enough posts yet. Thanks for the message. More to come!)