Ground Source Tempering Of Incoming Fresh Air.

[AC_Hacker]

Originally Posted by Phantom

AC_hacker are you going to be using two or one pump with the two loops? I figure if you are using two pumps depending on the demand needed it might be useful to be able to run one or both reducing the energy requirements when there is demand but demand is low.

Thanks for the input. To answer your question, one pump.

But the plan is to run the loop ends into an input mainfold and an output manifold, that will give me the low-velocity I want at the flowrate I need, and also the reduced pump power. I'm figuring a 60 watt pump should do it.

So, I figure I'll buy or braze up a couple of copper manifolds with capacity for three loops. If you look at the loop field diagram, I left space for eight more holes (actually seven, I'll have to find a home for the eighth one).

I may opt for a multi-speed pump at some point, too... It would be cool to have the pump speed auto-selectable, depending on demand. But there is a lot to do before refinements.

-AC_Hacker

[ThomSjay]

Originally Posted by AC_Hacker

Yeah, I'm speaking from experience on this one...

So, it is shovel time for AC_Hacker.

I will have plenty of time to contemplate on 'how much easier it is to do mathematical calculations than it is to dig a ditch'.

Best Regards,

-AC_Hacker

LOL, that's funny. I'm glad that your sharing this info so that the rest of us hopefully don't make the same mistake.

[Xringer]

This guy didn't do the math, but ended up doing pretty well with his "Earth Air Tubes".

Earth Air Tubes | Sugar Mountain Farm

Got me wondering if this idea is applicable to ASHPs? If you had your ASHP sitting on
the side of a hill, and had some buried air pipes coming up the hill, to emerge from the ground,
Right beside the air intake of your ASHP?
Maybe have a damper on the end, so the Geo-warmed air wouldn't flow, until the fan in the ASHP came on..
The cold air port at the downhill end, would suck in cold air, to be warmed up.
As the warmer air tended to flow uphill, to the output, it would still cool the tube..
But, if the HP was turning on and off, there should be some recovery in the tube, Back towards normal ground temp.

If the air picked up 10 or 20 degrees of warmth inside the tube,
it would give up that heat to the coil in the ASHP.


Some more..
301 Monroe» Blog Archive » Earth Tubes

[Ryland]

So more or less turning an air source heat pump in to a ground source heat pump?
Talking to the friend of mine who in is charge of this house project, he seemed to think that earth tubes had issues, issues that you can fix by tossing money at them, but issues all the same and a $500 coil of PEX 700 feet long seems cheap compared to the issues that you can have with sticking chunks of culvert in the ground and trying to keep water, rodents, mold and dirt out of them, altho the same idea of an earth tube fed air source heat pump has crossed my mind as well.

[Xringer]

If ask yourself, where does warm air come from at midnight? (to feed the ASHP)
It's likely warmth from leftover solar warming during the day, (stored energy)
much of it being released from the pre-warmed ground, rocks & man-made junk.

And, we all know what's sitting a few feet below the grass,
it's geothermal (80% nuclear) heat, just trickling up to the surface.

I'll bet that earth tubes would allow an ASHP to work better at low temperatures.
So, on those days when it was 4.2deg F outdoors, a source of warmed up
air coming into the ODU coil, could really help efficiency.

Around here, where the lowest temperatures normally occur just before sun up,
that little boost of warm air might keep the back-up from coming on..

Screens can keep out the squirrels and a little mold wouldn't do much harm.
If the tube was built right, (all down-hill) it could be flushed out with water.
Or, you could leave a line in it, to drag a cleaning brush, end-to-end.

C
X

[vmike]

I have a couple of thought projects I've given much consideration to, but not much physical labor. The chances of putting 6' deep trenches for cool tubes in mostly sand stone is highly unlikely. The forest on the north side of my currently under construction retirement home is on a down hill slope of 35' to the north. Well shaded, and in the depths of summer, quite cool comparatively. What I've been considering is just laying a couple of 12" tubes, side by side on the floor of the forest and drawing the air for my condenser through them. In time, the tubes will be covered with earth.

The other thought project is to build a solar chimney above the condenser to draw in cooler air. Possibly used with the cool tubes. The idea being the air close to the house stagnates and also heats/cools the house while the unit is running.

mike

[Xringer]

That solar chimney-earth tube might be hard to implement.
I'll bet it would be hard to keep it from just sucking up the cool air from the ground tubes.
Maybe better to use a small PV w/ fan to haul up cool air..

X

[vmike]

The solar chimney was primarily considered for the unit next to the house without the use of the cool tubes. Simple placing the condenser away from the house is also a consideration. The primary drawback to that is the falling forest debris, a canopy of some sort will be required.

mike

[AC_Hacker]

Originally Posted by Xringer

And, we all know what's sitting a few feet below the grass, it's geothermic (80% nuclear) heat, just trickling up to the surface.

I think this statement gives a false impression.

The sources I have come across indicate that the percentage that geothermic heat contributes to total ground heat is about 3%... the rest is solar, unless there is a hot geothermic area under your location (see below).

So the 3% areas would be in white on the map.

Massachusetts, for instance, would not be a geothermic hot area.

Xringer, you measured your basement floor temp a couple of years ago,

• Is it still the same temp?
• Is it getting hotter?
• Is it getting cooler?

What does your basement air temp read?

What does your basement floor temp read (measured with the same thermometer)?

-AC_Hacker

[Xringer]

Originally Posted by vmike

The solar chimney was primarily considered for the unit next to the house without the use of the cool tubes. Simple placing the condenser away from the house is also a consideration. The primary drawback to that is the falling forest debris, a canopy of some sort will be required.

mike

During the heating season, having a Mini-split ODU out in a windy open area will affect the performance (negatively).
They make baffle shields that can be mounted on the air input.. I hear they help.

Close to the house is good. Facing away from the house, it's going to blow
exhaust air away from the house, while pulling air into it's intake.

A tree crashing on it would be a real problem. Plus, I don't want to
have dig a snow path out to middle of the yard, so I can shovel off the Sanyo!

One of the neater pre-heat/ASHP ideas floating around here,
is to stick the ODU at the end of a long greenhouse.
Cold air comes into one end, picks up solar heat, on it's way to the ODU on the other end.
The Extra cold air exhaust is send off into the air, to fight global warming!

The far-end air input could be low to the ground, so warm air inside the
greenhouse wouldn't be escaping wholesale, while the system was in idle.