The Homemade Heat Pump Manifesto

[jeff5may]

AC,

Congrats on 400.000 hits!

Thank you for starting this thread. I never would have built any of my creations if it wasn't for this forum. You deserve a ton of recognition for your support of so many people and their projects.I'm certain I'm not alone.

Here's a tip for a quick ballpark charge of small, self-contained ac units:

1. Pull a deep vacuum, make sure your unit doesn't leak and has enough oil.
2. With unit stopped, connect refrigerant tank and let in charge until the flow stops.
3. Close the tank valve, start the unit. Watch frost build on your evap coil.
4. Slowly let in charge. Watch more frost build on evap coil.
5. When frost starts to recede, stop charging.
6. If frost returns, especially at end u-turns of coil, slowly add charge until the frost melts.
7. Repeat steps 5 and 6 until no frost forms on evap coil.
8. Feel the liquid line leaving the condenser. It should be warm to the touch.
8.5 You should be able to touch the compressor discharge line without burning yourself. It should be hot to the touch.
9. Close up, you're done. Without proper test equipment, this is the best you can do.

Note: If something doesn't happen as described during this sequence, stop what you're doing and figure out what's wrong. Don't just keep adding charge hoping for the best. A quart-size bottle of refrigerant should contain more than you need to get to this point. A 5000 btu unit or dehumidifier should take less than a pint to fill from a vacuum. For safety's sake, always be ready to unplug the unit and clear the area.

I can't wait to see how things turn out for everyone. People are making progress in so many different ways here.

Yours truly,

Jeff

[thumperoo]

jlaw,

We run our WSHP on an open loop approach - the most efficient approach. We have a well drawing from a sandpoint and rejecting into a very thirsty weeping field (our cottage sits on 30-40' feet of sand). In your case flowing water can exchange heat way more than trying to use the ground loops. You should consider using the water straight from your stream. The temp differentials will be way better than trying to exchange it through many feet of pipe in the wet ground. Your discharge can go straight back downstream from where you suck it out. Of course, you'll have to ensure its filtered/strained so that no nasties go into your coil heat exchanger.

[thumperoo]

jlaw,

Our system runs with a 24,000 BTU/Hr Trane WSHP that uses well water from a sandpoint with a1/2HP shallow well pump set for flow rather than presuure. Our water temp is at ~47-49 degF in winter and exits the HP at about 38-39 degF (well above freezing). Looking at the performance charts for this model Trane we are getting approximately 4.5 to 5.0 GPM thru the unit. Closed loop systems stink. You have a gold mine for heat source! Flowing water that never freezes. Your only concern is that you remove as much heat from it and still leave enough so that it doesn't freeze before you return it to the stream. You'll need to find out what stream temps are seasonally.

[Vlad]

AC here is my reply for you and others....:

Sorry about ignorance... Got super busy and have no time for my project. I used city water (I know bad bad boy.....) for cooling my HP in summer time. The HP I built is office type water to air HP. Remember one I converted from cap tube to TXV. It works just fine on propane (distilled regular car fuel type sold in Canada). My main goal was fresh air heating/ cooling. Because of this I took office water source HP replaced weird 165V compressor (normal thing for commercial buildings). The rest of components were 24V so I only needed transformer.

Winter came and I got super busy and didn't have time to connect my outside loop to HP. 2 pipes are about 1 foot away from my foundation wall also the weather was a big demotivator. So I ended up using city water (only when needed) for heating air.

My radiant floor loop gets heat from DHWT through HX. This winter was very mild and my floor was always cool but this was enough to heat up house. I think the hottest water in underfloor loop was 90-92 degree this winter. Also I made some adjustments to system.

My current HP is a bit to small (1 ton) for cooling in summer time. I have 2 monster computers and 6 monitors in my office and they just boil my office. This summer my goal is to build one more HP bigger one. I have one more office water to air HP (165V). I found 2 ton scroll compressor for it. Need to get TXV's (currently HP has cap tube and I hate it). Smaller HP will be used is the other portion of my house. Also I will connect my ground loop to the rest of my system. I just don't want to deal with foundation drilling when it rains outside.

I think the best heating system from efficiency point will be radiant floor and air heating both using heat pumps. In this case you don't need high temperature in your underfloor loop because air heating will compensate heat loos and add extra BTUs to house heating. Also air part will be used as AC in summer time (this will also pump heat back to your ground loop) and bring fresh air for your health benefits....

[BradC]

Super interesting (well, I think so anyway) article on long term corrosion of BPHX when used in an open loop geothermal application (like mine is).

http://geoheat.oit.edu/pdf/tp41.pdf

I've noticed a little extra pump head I assume is from light fouling, and my filters have certainly gone rusty brown lately. It'd be interesting to get a water test for H2S and NH3. Have no idea where I'd get that done though.

Looks like I'll be doing an Oxalic acid flush as part of the winterizing procedure.

[scottharrison]

In recent years, the solar water pump usually used for water pumping from river and ponds for irrigation. What are the benefits of this solar water pump and how does it affect in our environment? I need some justification in regarding this.

[AC_Hacker]

Originally Posted by scottharrison

In recent years, the solar water pump usually used for water pumping from river and ponds for irrigation. What are the benefits of this solar water pump and how does it affect in our environment? I need some justification in regarding this.

You are in the wrong place my friend.

You have posted to the wrong thread.

If you are interested in an informed response, you should POST HERE.

-AC

[Ormston]

Hi Guys

I've been lurking on here for a while now picking up some useful ideas and think it's about time to say hi and ask a question or 2.
I will probably start my own thread in time to discuss the whole project but for now this seems like the best place to seek advise.

My wife and I (mostly I) are in the process of renovating a 58 year old house, we've finished gutting it and are starting to put things back together whilst waiting for planning permission for an extension.
The house was heated by an ancient oil fired boiler, however as it had been unoccupied for 5 years before we bought it all of the plumbing was shot (rusted radiators, burst pipes etc).

The Plan

Rewire of all electrics (I'm an electrician so got that covered)

Get mains water as it was fed by a bore hole. (Done although the borehole will have it's uses)

Replace all plumbing and heating system. Currently installing underfloor heating throughout (My dad is a plumbing and heating engineer which will keep costs down)

Insulate everything in site before re-plastering and decorating.

We have an architect drawing up some plans for an extension, assuming all goes to plan we will have planning permission to start building the extension around June. The extension will house the utility/plant room where the heat pump will live.

We (My dad and me) have some training and experience in the installation of heat pumps, we fitted a large 11KW ground source heat pump, and several air source heat pumps.


Even with experience of installing heat pumps and being able to purchase at trade prices i find the cost of a commercial heat pump excessive, which is why i'm here.

The idea is to convert 2 or more portable air conditioners into ground source heat pumps. I will install 2 x 200 meter ground loops (Horizontal), we have around 100 meters from the back of the house to the end of the garden so 200 meters is a practical consideration not calculated for heat output.

I want to use multiple heat pumps for several reasons.
Small portable air conditioners are cheap and easy to source.

As this will be our primary heating source, i like the idea of a pre-installed backup.

More importantly the first thing we were taught about installing heat pumps is not to oversize them as an oversized heat pump will never be efficient at any time of the year. By using multiple heat pumps of differing sizes i can run 1 or more at a time to meet the heating demand.


So, working on the basis that i will sometimes be using 1 heat pump, sometimes 2 and possibly even 3 at the same time(to meet the heating demand when it's -20C outside, very rare here but did happen 2 years ago for 2 solid weeks).
What is the best way to link 3 ground source heat pumps to 1 buffer tank, in series or in parallel?

Thanks Steve

[AC_Hacker]

Originally Posted by Ormston

...What is the best way to link 3 ground source heat pumps to 1 buffer tank, in series or in parallel?

It looks like you have thought this through pretty well, and you have a good set of skills and resources at your disposal.

Not knowing what the degree day situation is of your area or what your house configuration is or the overall heat loss, it's not possible to comment on or predict the success of your undertaking.

However, the idea of using smaller homemade heat pump is good and the idea of using several is brilliant.

To my mind, a parallel arrangement would be better, because if it is arranged properly, it would have less fluid friction than if the same size tubing were arranged in series ( a lesson I painfully learned). Also, having multiple compressors offers better reliability, since the probability of two or three going down at the same time is quite remote. And lastly, if one did go down, you could switch it out of the system while you rebuilt it, and the others could carry the load in the meanwhile.

One of our heat pump hackers, named randen had a heat pump failure in the dead of a Canadian winter, but luckily he had kept a previously-built spare at the ready, so he was able to plumb it back into service in a reasonable amount of time. In your case, if it was properly done, it would simply be a matter of turning a few valves and your crisis would be over.

Please keep us informed about the progress of your project... that way we'll all benefit from the sharing.

Best,

-AC

[Ormston]

Originally Posted by AC_Hacker

Not knowing what the degree day situation is of your area or what your house configuration is or the overall heat loss, it's not possible to comment on or predict the success of your undertaking.

Thanks for the input AC

The heating degree days for this area is around 2400 average over the last 5 years.
The rest is a bit of a guess due to the house being a work in progress with some of it still being designed/drawn.
Will be approx 150 meters2 floor area over 3 floors, the existing ground floor which is having the single story extension on 3 sides, the existing first floor and the attic being converted to provide additional bedroom and office space.

At the moment we're guessing on around 7KW maximum heating load but will have a wood burner to help out when it gets really cold.

Cooling isn't really needed in the UK, maybe 2 weeks a year if we're lucky.

I've almost finished laying the last of the insulation ready for the underfloor heating pipework to go in this week and maybe get the floor screed down by next weekend.


Steve