The Homemade Heat Pump Manifesto

[ThomSjay]

Hi all! I found this thread, I believe, through a link from "Build it solar" which in my mind is a mine of information. I just wanted to say that this thread is very, very intriguing because I have wanted to have GSHP since I learned about it probably ten years ago or more. It took me over a week to read the whole thread!
AC Hacker, thank you for starting this up. I do have a question at the moment...how warm do you keep your house during the winter. I like mine at 70degF/20degC. I live in Sarnia, On. Canada
One more question for the group before I go to sit on the side-lines,(and this probably belongs elsewhere) .....would a radiant wall work as well rather than to do heavy mods to a floor? And perhaps one could point me to the proper location for that discussion.

[AC_Hacker]

Originally Posted by electrostunt

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.

electrostunt,

Welcome to the discussion.

What you are suggesting is the 'missing link' in this project. The features you have suggested are all very well thought out, however I would add to your feature list a two or three minute power-up time delay feature to protect the compressor.

[* EDIT (11-11-11): Since this post, an inexpensive controller with a web interface has been found. Xringer has posted a thread where he gives a pretty good introduction to the controller including sources of interface devices that make it very useful. *]

I have my hands full with the mechanical aspects of this project and also tending to this project thread (and I am also re-modeling my house and I am the workforce).

I have the skills to develop the controller you are envisioning, but not the time.

If you want to start a Heat Pump Controller thread, it would be very helpful to me and to the many thousands of people who are following this project.

An Arduino Open Source Controller project would be super useful.

If you choose to initiate such a project, I can guarantee the gratitude of at least one person...

-AC_Hacker

[AC_Hacker]

Originally Posted by ThomSjay

AC Hacker, thank you for starting this up. I do have a question at the moment...how warm do you keep your house during the winter. I like mine at 70degF/20degC. I live in Sarnia, On. Canada

ThomSjay, welcome to the conversation...

I am anticipating an indoor design temperature of 65 degrees, when the radiant floor is in operation, and all the insulation measures have been completed (this includes upgraded windows). I spent a weekend in a house with a radiant floor recently and this was the temperature, and it was wonderfully comfortable.

To answer your question in the present tense, I'm currently using a small mini-split which uses air convection and the temperature level I dial in changes between 66F and 70F, probably due to my own metabolic variations, I suppose. But 95% of the time, I have it set on 68F.

Originally Posted by ThomSjay

One more question for the group before I go to sit on the side-lines,(and this probably belongs elsewhere) .....would a radiant wall work as well rather than to do heavy mods to a floor? And perhaps one could point me to the proper location for that discussion.

The real topic here is hyper-efficiency heating even though the thread is called 'Homemade Heat Pump Manifesto', but the combination of very large area radiant heating and GSHP is such an excellent combination that it is not easy to separate all the parts and continue a coherent conversation.

Since you carefully read the entire thread, you probably understand that to get the maximum efficiency of such a combo, you need to run your heat pump at the lowest possible temperature.

You also probably understand that to do this, you will need to have the largest possible radiant area AND hydronic piping spaced much closer that is needed for a fossil-fueled boiler, AND radiant floor construction techniques that spare no effort to maximize efficiency.

With all that as a basis, when you look at radiant walls, you have to consider the area you want to be radiant, and also look at the possibility that if you choose outside walls to be radiant, a considerable amount of your heat will be going to heat nature.

There is also the ratio of wall area to floor area... wherein a large, low room would have a large floor-to-wall ratio. This situation would definitely favor radiant floors. If your rooms were small, your floor-to-wall ratio may not be as favorable to radiant floors, and a radiant wall approach may make the best sense especially if most of the walls are interior walls.

(* the impact that building proportions have on heating efficiency is well understood in the Passive House world *)

I did some power-Googling a few months ago on this subject and found that in Europe the practice of heating walls is not unheard of, and that hydronic wall board is being made and utilized.

To your last point, regarding where such a discussion should take place, there is a thread on DIY Radiant Floors, which has some interesting information for you.

I think that what is actually needed is a new thread on Low Temperature Radiant Heating (AKA: Low Exergy Heating), which would belong in Renovations and New Construction. Press HERE to start a new thread in that area.

Best Regards,

-AC_Hacker

[rhino 660]

at last i finally finished all 65 pages, what a great resource thanks for the documentation

[AC_Hacker]

In post # 631, I documented how I made a temperature controller from a line-level bi-metallic controller. It served it's purpose as a cheap and reliable temperature controller, but it seemed to have an excessive amount of 'wander'.

I had a nice non-programmable Honeywell electronic thermostat that I got at the thrift store for $3 and decided to try it as a temperature controller instead to see if it reduced or eliminated the wander.

The electronic thermostat is battery powered and can switch up to 36v AC. I have a few Solid State Relays laying about and wanted to use them. They require DC for the input. I wasn't sure if it would switch DC, so I eventually did a test using low voltage DC (6V) and it worked just fine.

I decided to put the sensor of the new controller outside of the enclosure for the power switching device, to further improve accuracy.

I downloaded the schematic for the thermostat to see how to wire it...

I saw that I can also wire it to control both heating and cooling, so a subsequent mod will be reserved for warm weather months. I also noticed in the instructions, that when the unit is used in cooling mode, a time delay of 5 minutes is built in, to prevent damage to a air conditioning compressor. Since heat pumps are becoming more wide-spread, I would think that thermostats with a time delay in the heating cycle must also be available.

I decided to use a cell phone charger which are flooding into the thrift stores are cheap, efficient and reliable.

Doing a drawing always helps me anticipate problems...

Next I did a physical parts layout to see if it would be possible to enclose the parts (not including the thermostat) in a dual-duplex handybox...

I made an error in the wiring which I corrected in reality and in the photo at the top...

... otherwise, it was all a tight fit, but it did fit. The Solid State Relay was screwed to the Handybox so the box serves as the heat sink. I considered soldering wires to the power supply plug prongs, but thought better about it as it would probably conduct heat into the plastic and electronic parts. I used small machine screws to attach crimp-connectors, but after it was all done, I realized that Pop Rivets would have worked even better.

The top chart is the bi-metallic controller, the bottom chart is the electronic controller.

The improved consistency of the electronic thermostat is pretty obvious...

Regards,

-AC_Hacker

[S-F]

That's frik'n awesome.

BBTW, new thermostats are designed for heat pumps. Might want to sink the $15 to get one. They can control many aspects of heat pumps. Including backup heat.

[AC_Hacker]

Originally Posted by S-F

...new thermostats are designed for heat pumps. Might want to sink the $15 to get one. They can control many aspects of heat pumps. Including backup heat.

Great info... thanks S-F, for that one!

-AC_Hacker

[AC_Hacker]

The Homemade Heat Pump Manifesto thread has hit a respectable milestone, by receiving over 100,000 hits!

First of all, I would like to thank the folks who run the overall EcoRenovator blog, that would be Daox and Piwoslaw, that I know of and others that I don't know about. Your work is successful when we don't even notice it. You work in the background, you deserve our thanks.

Then, thanks go out to to everyone who has who has stopped by to read, who has asked questions, who has contributed their knowledge, experience and enthusiasm. Your presence is the 'oil' that allows the wheels to turn.

And the most important thanks of all goes out to those who may have been inspired by some of the imperfect efforts, presented in these pages. Those of you who have used some of the ideas in the 'Manifesto' thread to create your own solutions to energy problems. It is for you that this thread began...

Best Regards,

-AC_Hacker

[Piwoslaw]

You are the one who should be thanked, AC!

By detailing your ups and downs many people see that building a heat pump does not require a fat wallet and/or black magic.

[pachai]

I have a quick question - a few of you on this list have the Sanyo or other Mini-split. I am almost finalized on my thought to install a quad mini-split on my second floor, which will give me heating and cooling while I work on the DIY....

What I would like to know is, can you tell if the outside unit would lend itself to conversion to Ground source?

In other words, is it suited for a hacking by adding
chilled water piping, or clipping on additional cooling
fins that could then be connected to a ground loop?

It seems silly to have 2 systems, but my idea is to
leverage the mass market volume pricing of an ASHP,
and with it the "sealed" system.

My understanding is, using stock pipe lengths
does not require special tools (does it?).
And it is much easier to plumb in a 3" cable
than a 4x10 duct.


Thanks
Seth