Total Home Automation

GreenTip: Airflow - A Waste of Energy

The practical reality of every home, and the truth behind the challenge of energy efficiency, is that what a manufacture says savings will be, and what happens once something is installed are two different things.  Low refrigerant in home air conditioning systems and poor airflow are two big issues in home energy usage.

My house, as many homes do, uses the space between the floor to bring air back to the air handling system.  In 1960 it was a nice cheap and effective way to build a HVAC system.  With today's concerns about air quality and material out gassing, return air is brought through a duct system.

The contractors arrived today to remove my old air handling units, and install the rest of my geothermal.  They ripped out one of the current air handlers.

It did not take long to find the first issue.  The supply air duct which comes down to the back of the green air handlers (Silver duct to the left and behind in this picture). has an obstruction in floor joist area.

Looking up into the duct, that has been cut out, you can see another grey/silver duct running across above the vanes coming down.  This is hard to see, but essentially the duct blocks 80% or the return air flow.

 

These are 5 ton air handling units, so the blowers for 40 years have been operating with the added burden of drawing a lot of air through a space the faction of intended design.  You cn bitch and scream about the idiots who made the mistake, but this is not a surprising revelation.  These units for years have been running with a lot more load to attempt to make up the desired temperature in the zone.

When undertaking these kinds of projects it is super critical to have a contractor with the integrity to point these kinds of problems out.  It could have been real easy for them to have masked this issue and I would have been left wondering why I was not getting the right performance from my system.

Geothermal Project: What is going away....

Since I am replacing my heating and cooling system, all the interior air handling units need to be replace, along with the exterior compressors.  My current system is made up of 3 big old air handlers....

These units have heat exchangers in them fed by a boiler and outdoor air-conditioning units.  The Boiler feeds 5 units all together, these three green ones in the basement and two newer units in the attic.  The Boiler was built the year I was born and probably is only about 70% efficient if that.

The part my wife really likes is that all the outdoor compressor units go away.  With that goes the related noise.  These units are stacked in the back end of the house out of the way a bit from everything, but just below our bedroom window.

 

The green colored air handlers, boiler and out door compressor units are all being replace with the white unit shown in the picture (Note its size vs one of the old green colored air handlers).

 

The air handlers in the attic are modern variable speed units, so we are keeping them.  They also use the new 410A refrigerant systems, so we can install what is called a split system.  Essentially, the big white thing includes a compressor, ground loop water pump, and an air handler.  With a spit system, it deletes the air handler - passing hot and cold refrigerant to the air handlers in the attic.  We wanted to save space in the basement so we mounted them in a rack (I stole this idea from President Bush's ranch where he did the same thing for his Geothermal system).

Geothermal Project: Horizontal Boring is realy cool......

I placed the Geothermal wells in my lower driveway.  The primary feeders need to come up from the driveway, around the front of the house, and into a corner of the foundation.  Unfortunately we have some nice old trees in front of the house in the way of where the pipes needs to go underground. 

 

So, the contractor proposed something called horizontal boring.  With a horizontal bore, they can go under the trees, horizontally, without damaging the trees.  Not only can they go under, they can actually steer the bore left, right, up and down in various ways to dodge the foundation, water pipes, natural gas, etc.

The Horizontal Bore machine, made by Vermeer, is about 15 feet long by 4 feet.  Unlike a bore that uses a spinning bit, a horizontal bore essentially pushes through the ground using hydraulic force.  The end of the bore has a asymmetric wedge.  the wedge can be turned 90 degrees, more or less, to cause the bore to move left, right, up or down as it is pushed through the dirt.

 

A technician follows the bore head, as it moves through the dirt, with a hand held device (an advanced metal detector) that tells him how deep the bore head is, and its general location.  With that information, he helps the operator decided how to run the bore. 

 

The bore was pushed some 90 feet to a hole the contractor dug at a corner of our foundation.

 

Once the bore pushes through at the far end, they attach a cutting bit(About 6 inches in diameter) to the end.  The bit has a swivel, that is then attached to the pipes that needed to be pulled back through the hole.  The bore machine then rotates the bore and pulls the drill bit back through the hole, expanding its size from 3/4" to 6 inches, dragging the pipes along the way.

Geothermal Project: Connecting the Wells....

With the wells drilled, the next step is to link the wells through a "header pit", the bring the wells into the house.  Essentially the 20 wells are integrated into 2 supply lines and 2 return lines going into the house.  The back hoe dug 6 foot deep channels adjacent to each well, and toward the central location where the header pit will be placed.

 

With the channels cut in, the well pipes are laid down towards the header pit.

 

Each of the wells are integrated into the header pit into these long plastic pipes.  The end of the pipes feed into the set of 4 larger pipes that feed into the house systems.

 

Geothermal Project: Video of Geothermal Well Drilling Process

Here is a video of them drilling a well and then feeding the pipe down the well.

Geothermal Project: Drilling Holes

Installing Geothermal can be a mess.  In my case, they are drilling 18 - 250 ft deep holes in my drive way area.  The holes are about 6 inches in diameter.  So, imagine how much material comes up when you have a 250 ft x 6 in hole.  For those that have never seen this done, they use a big portable rig on a truck that looks like.....

   

To get a sense of the mess from materials pulled out of the ground, our yard and driveway now have mud all over them.  This is the Driveway....

 

This is the yard just below the driveway....

 

Once they drill a hole, the put down pipe.  The pipe looks like this.....

 

If you look carefully just to the left of the picture, you can see a plastic return for the water loop.  These use to be installed in the field, but now come out of the factory fully tested so that there is less chance of a leek occurring through field installation.

The pipes are fed into a drilled hole and basically look like this once done...

 

They then scoop as much mud as they can down the hole, and in some cases inject a gunite like material, so it looks like this....

 

Once they put all the pipes in, they will clean up the residual mud, then sometime this week they will backhoe a channel through the drive way (5 ft deep) to run all the wells back to a header section that will then feed back into the house. 

Geothermal Project: Heating, Cooling and Energy Usage

So, I have decided to replace my HVAC system with a geothermal system.  They just started drilling the other day.  I will get some pictures up soon.  I have decided to use the Water Furnace product line.  They are drilling 18 - 250 ft vertical bores in my driveway area.  These will be tied into 5, 5 ton units.  2 of those units will be split systems (that means just the compressor for the refrigerant and tie into existing air handlers), the other 3 will be complete integral units to replace my three air handlers in the basement.

Estimates are that my heating and cooling costs will drop about 60%, more if electricity costs go up in the Midwest with the introduction of Cap/Trade.  So, the payback looks like it will be about 6.5 years.  I also get a 2K tax credit for going to geothermal, but given the size of this system that does not pay the bills......

In the end I am a bit of a geek, so I am buying my units with BacNet controllers.  These controllers will let me gather more data and store it for trending purposes.  The controllers are Johnson Controls (JCI) FX10 units, which are oddly not shown on their website.  These are part of the Facility Explorer product line. The FX10 is a standard feature for the Waterfurnance commercial units.  I am guessing I will feed them all into an FX20/40/60, which is the JCI version of the Niagra/Tridium framework for aggregation.  I really wish I could just buy these parts on line rather than pay a controls company to come in and do what I already know how to do.

I will probably use a standard thermostat to operate the units. My Crestron system has all of the programming for manipulating their thermostats, but crestron and BacNet don't play well together, so I will use a conventional crestron thermostat using R/G/Y/B type connections to the units. 

Geothermal units don't have a lot of "Recovery" compared to a boiler.  So they can't pour out BTU's to heat a house quickly, so it does not make sense to do dramatic setback schedules.  For extra and quick heat, these units have electric elements.  For efficiency reasons, we don't want those electric elements to go on often, so setbacks are a bad idea especially on the heat side.  I do want to investigate the notion of some form of anticipator - essentially building a real heat transfer model for the house that over time can determine that on a 25 degree winter day with no moon, the compressor units need to come on 2 hours ahead of time to achieve a certain temp without use of the electric elements.

I am also installing a Shark Meter at my primary utility box.  I have an 800 amp service.  The shark has a lot of data storage and is easy to get to (modbus or Ethernet).  That will let me more precisely understand overall load.  Correlated to the bacnet data I will be able to get a very precise breakdown of HVAC vs. other loads on a minute by minute basis.  I will probably install a Veris meter system for each circuit breaker load.  They have a great unit that has 40 or so C/Ts in a row that easily fit in a conventional circuit breaker box.

Making my home use less energy

I have a house that is about the size of Al Gore's.  I know he has been getting a lot of grief about how much energy he uses.  Recently he apparently upgraded a lot of systems to "Walk the Talk".  I have looked on the web to see what he has done, but really can't seem to get any really good information.  Maybe I can provide some answers by doing things to my own home though, that others might benefit.

I am in the planning phase for my energy conservation project.  I want it to:

• Save energy
• Ease maintenance
• Have a near term payback
• Be resilient to future upgrades and technology

My general plan is to:

1. Implement a monitoring solution so I can measure performance
2. Switch to geothermal
3. Consider solar thermal and electric
4. Improve insulation and windows
5. Increase automation/conservation

My house is large enough to almost be a commercial property, but small enough not to be - so there are a lot of complexities to how best to balance out my systems, recover energy, etc.  Some of these questions include.....

1. Should I replace my 5 5-ton AC units with a single chilled water plant?
2. If I replace my 5 air handlers with geothermal, should I still use my boiler to supplement heat, or use electric re-heat coils as often recommended by HVAC vendor
3. Geothermal has a slow "Recovery Phase" (that means if you set back your thermostat in the winter, the system can produce enough peak heat in the morning to get back to proper temperature in time for breakfast).  So, does the improved efficiency of geothermal make up for a setback strategy - what is the payback?
4. I can fit a lot of solar thermal on my east facing roof.  Not a perfect direction, but is it worth augmenting my system with some of that heat?
5. I need more insulation in my attic.  I have 2 air handlers and my second floor ducts in that space.  Should I instead insulate the underside of the roof?  What is the real science behind vented and un-vented roofs?
6. If I super insulate the attic, how much tonnage reduction will I have, and how will that effect cycling of my Geothermal system.  If my load is 25 tons during the summer now, and it goes to lets say 20 tons with super insulation, will those larger units cycle excessively?
7. I get most of my energy from Coal (the power plant).  Natural gas is going up in cost.  New power plants will have more natural gas.  There is a high loss rate in electricity distribution, so with increased energy cost will I be better positioned to heat with natural gas or electric (via heat pump)?  What is the cross over point in the business case for this?

If anyone has answers or thoughts please comment.....