Improving a heat pump????

[FONT=Arial][size=2] I have a Mr. slim heat pump and it does most of the heating and all of the cooling for our home .
I was talking to a geothermal guy about increasing the efficiency and also having it work in real cold weather .
I think the heat pump quits at -13 °C or 10°F .
I talked about putting in BIG O to feed the unit .
He loved my idea and even offered to help for a much reduced rate as he like me loves to think out side the bubble .
He told me of a winery who has a 14 inch pipe I think buried to bring air into their wine storage 500 feet I think and the temp from summer to winter is only two ° different Cost to run this is extremely cheap.
He recommended 75 feet of 2 …6 inch big O ( 3 might be better )down about 4 + feet and he said try and keep them about 7 inches apart .
He said Clay is the best to cover them with Never gravel or sand .
I mentioned in line duct fans and he said pushing air is far more efficient then pulling .
I said I was going to feed the ducts from under my Deck as it is cooler in the summer and warmer in the winter .
I stated I was thinking of bringing the pipes up in a Insulated pipe to the heat pump from down 4 feet . He liked that and suggested a XXX to turn the duct fans on after the heat pump fan started .
His best guess was my efficiency could go up over 40+% both summer and winter .
In my area the soil temp is about 55°F ~ all year at 4 feet .

Any thoughts good or bad appreciated.
This web site has More info


Home Inspectors are great people with lots of Knowledge and Ideas.
I am surprise over 100 have visited this post and nobody has made a post .
I was hoping for your ideas on what I think .
Do you think Is it good bad idea or Do you think it can work .
All thoughts appreciated.
Thanks for reading I will try and Keep all posted what I will be doing .

Maybe nobody knows what a BIG O is? There is a discount tire chain that goes by that name in my area.

Thanks James I should have thought about that .
We in Canada use it for Long buried electric , Water lines and when it is perforated to drain water from the farm fields we also use it to take Water away from the home from the down spouts .
Thanks for the reminder… Roy


Hi Guys,

Not sure I follow your logic here. Are you suggesting modifying an existing heat pump with some geothermal components?

Certainly, as time goes by, geothermal will find increased market share.

Tell me more.


Supplying the Heat pump in post #1 with air from 5 feet below the ground .

Remember what I said about Roy being a vindictive old fool?

I see Michael the Bully man with no friends is following me again he stopped for a while .He is showing how jealous he is of me he even sends me email .

----- Original Message -----
From: Michael Larson
Sent: Friday, June 22, 2012 9:29 AM
Subject: ignore list

good morning you old bastard.

At least you started to call out KEVIN on his bull****.

When you start it up Roy I will respond.

Funny how Roy’s profile shows no friends at all

In my opinion, don’t waste your money.

It is recommended that geothermal glycol systems installed on the horizontal are buried 8 ft. below ground, spaced 8 ft apart and that 400 ft./ton (more if buried in sand) is provided and you’re talking about a big-O forced air buried 5 ft, 75 ft in lenght!!!

Isn’t the idea here to just warm/cool the air slightly by passing it under ground. Am I assuming correctly that the air will enter one end of the tube somewhere else? Or is it just going to draw the air directly from the ground?

Yes I the open end feed will be from under my closed in deck it is slightly warmer in winter and a lot cooler in the summer then the out side air .
A friend who does Geo thermo tell’s me one of his clients is a winery and he has a large long run of pipe and it does his wine warehouse with the underground pipe only and the difference from summer to winter is only two ° F . He says it’s down 4 feet ~ in our area .
I will be talking some Ground temp samples this week to get some Ideas .
Thanks to all,appreciate any thoughts .
I expect doing most of the work myself will bring this in under $1,000;00 . I expect I will end up with at least two possible three Big O’s and 100 feet .getting clay in my area for coverage will be the hardest to find .

Reminder: that is not your utility bill savings.

I have seen this done with water and it works well.

As for air, I have built heat recovery systems in New England by taking the discharge heat from computer cooling ventilators and passed them over the heat pump coils located inside the ducts. But I had a significant source of heat from the computers.

  1. Air is an insulator so it does not transfer heat well.

  2. There is a large by-pass factor with air coils. You loose a lot of your underground air effect to the ambient air without achieving anything. As this is not a closed loop, you get one chance at what heat transfer there is.

  3. What would be the recovery time for your open loop system? If it gets really cold where you are at, the amount of air required by the Heat Pump may not collect much heat when your sucking in sub-freezing air from one end. In this case, you got the same thing going on without your contraption.

My wild-*** impression is that it may not get all that hot where you live (for a long enough period of time/yr) to make it worth while to increase the capacity of your heat pump for the short period when the weather is above the design temps of your equipment. In effect, your savings will only be realized when the weather goes to extremes.

The design temps for your area seems to be -9F Heating, 86F Cooling.
So your contraption will only help out on the times where it gets above 86F.
I don’t really think it will do anything in Heating with an open loop.

So your 40% savings, divided by the number of days over 86F is about all that you are looking at.

NACHI Message Board Disclaimer: As most here can argue as to if the sun is shinning or not, this is just a general observation with No Facts considered. After all, I wouldn’t want to clutter this place up with anything factual…

There you go, unit is inside just connect your big O.

Thanks for your post and info .
I am in over my head and have no idea how to prove or disprove how well this system would be.
Or how good it is if I get it working .
I will like to try this next winter with using heated air mixed with out side air from my garage to feed the heat pump to see what happens .
I have been extremely Fortunate ( Lucky) over the years with my many thoughts and ideas .
I do not rush into things I know little about .
But do enjoy planning and trying .

Attached are formulas to determine heat conduction and convection and ability of a material to conduct heat for your information.

Notice that air is at bottom of chart for thermal conductivity!

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Scan 1.jpg

More information on Earth Tube Ventilation here.

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Hey Marcel,

We seem to have very much the same reference files and I have a lot of credibility in them…