OVER-the-MOON.us





SEPTEMBER - OCTOBER 2008

September 25, 2008
Getting the locksmith to complete customizing our front door lockset literally took months. But we were so busy with everything else, the delay wasn't important.

Now that he has the finished product in his possession, Greg has been tinkering off and on with the installation.

Today it was a quick trip to the local hobby shop. Greg needed a thin metal sheet to act as a strike plate for the front door.

September 26, 2008
Greg began working on designing our HRV system back in June. Nearly three months later, he is still installing it.

Once Greg finished the training, sized our unit, and designed the ductwork system, he began to order the materials.  Most of the ductwork can be obtained locally through any HVAC company, especially long pieces.  He found unusual fittings were available on the web.

Installation of these residential systems usually follows a general path.

You want to install all the rigid systems first: systems with ducting of larger rigid tubing, i.e., HVAC, HRV, central vac, plumbing drain/vent lines, rigid copper plumbing, and so on.  Then systems that are a little more flexible like PEX water lines and radiant tubing.  Installing the most flexible systems, electrical wiring, low voltage, speaker wire, etc. comes last.

So the installation process goes from larger rigid systems to the most flexible systems.  You can see what a headache it would be if you reversed the order.  It is easier to run romex around and over a 8" metal duct than trying to run the 8" metal duct through the romex.  Most codes require the mechanical systems and electrical installed and inspected before you can get your framing inspection.  This is to make sure that any framing compromise created by these installers is corrected and repaired.  It is not uncommon for an installer who needs to get his pipe from Point A to Point B, to cut right through a structural member.

If you aren't installing any of these systems yourself and are relying on the local subcontractor, then follow this advice:  tell the subcontractor that rather than cutting through joists or beams, to come to you so you can determine if a soffit or raceway could solve the problem rather than cutting.

As the rough install follows a path, so does the finish.  For instance, in a room that has hardwood floor to be sanded, which would be completed first? The sanding and finishing of the hardwood floor or the finish painting of the room?  

I will try to describe as best I can some of the process of installing the HRV, but I can't really give a blow by blow.  Every job would be different.  However, I can say that if you are thinking of installing your own HRV, then at least go through the training or have the manufacturer provide the layout based on your plans.  This is similar to installing you own radiant.  The starting point for radiant is having the proper tools to create a Heat/Loss analysis of your home.  It wouldn't be wise to proceed without one.

What follows are some of the specific points about the HRV installation Greg learned in his training, conversations with techs, online info, and his own installation experience.

1.  First and foremost, a properly designed and calibrated HRV system is designed to run continuously, 24/7.

To some contractors, the HRV is just a unit that pushes air through ducts.

While it is probable that your local HVAC contractor can provide installation of an HRV, the question is: do they know what they are doing?

Sometimes the person selling you the job, and coming up with the bid, is the is most knowledgeable.  He sells you the system; but he isn't the guy involved in the installation.  Often times they're two 18 year old kids who don't understand what they are installing, just that they have to have it in by the end of the day.

As an aside, since the HRV and radiant heat go together, some radiant contractors are now providing the HRV installation as well.

2. Sizing.

Some will size the unit by the old "rule of thumb" formula they use to size a typical HVAC unit. For instance, in sizing an air conditioning system, some contractors use nothing more than a guestimate by using 1 ton (12,000 BTU/h) of air conditioning to cover 400 square feet of building area.  Square footage times a rate of BTU/h (BTUs per hour) is all that concerns them.  But his formula doesn't account for many factors:  altitude, location, humidity, insulation, and construction of home, windows, doors, and so on.  This often leads to an undersized unit.

Knowing this limitation, some HVAC contractors will still use the rule of thumb, arrive at a unit size and then go up one size larger.  This approach has its problems, the least of which is added cost to the client.

Some justify this to the homeowner by telling them the larger unit won't have to run all the time, thus, saving money.  That's not how it works.  Remember the purpose is to continually introduce filtered fresh air into the home.

So you'll want to know how the contractor arrived at sizing your HRV.  After Greg had installed the system and he revisited the American Aldes website, he saw they now provide system sizing and layout.

3.  To work effectively, the system must be as tightly sealed as possible.

Most contractors use sticky aluminum tape to wrap the joints of the system.  Depending on the installer, it's easy to be sloppy creating voids and air spaces as the aluminum tape is smoothed down.  The best method is to use duct mastic; a thick porridge that can be brushed on with disposable bristle brushes.  (Be sure to wear latex gloves.) And most HRV manufacturer's specifications will usually state that mastic on the joints is the "preferred" method. In this image you can see the duct mastic not only where sections have been joined together, but also along the lengthwise seam of the duct.  

If you are running a section of duct work that has some straight ducting, then an elbow, and so on, it may be easier to assemble the ductwork "on the ground".  Greg developed his own system. He would dry fit a section, apply the mastic, set it aside, and then work on another section of the ductwork.  He may have three or four sections drying and then install them the next day.  Greg just followed the manufacturer's specifications on duct work installation.  Obvious, but often discounted.... "When in doubt, read the instructions".

The manufacturer strongly recommends that you mastic all joints but since this isn't a code requirement, it's considered "code plus". Yes, it's very time consuming but Greg felt it was worth this extra time in the end because he saved time by putting pieces together which allowed him to get the mastic in tight places that would be impossible to reach once installed.

In addition, if the manufacturer's instructions are followed, should there be a problem, with the use of dampers and mastic, you will be able to rule out dampers and mastic and other details to hone in on a problem with the system.

For ducting that is already installed, brush on the mastic as best you can, even if you have to use your latex gloved hand to get into those areas the brush won't fit.  For areas that have larger gaps - over 1/4" - use a fiberglass tape around the seam and then mastic over it.  This tape is not unlike the mesh tape used for drywall joints.  Using the mastic system adds much more labor than the sticky tape.  You're probably asking, "if the mastic is a better way to seal the ducting, then why don't all contractors do it"?  The answer is: they don't have to.  This is not a code issue, especially with the HRV.  Also the HRV is basically just an air exchanger.  It doesn't create heat or cooling.  When a unit provides that function and consumes energy to create it - electrical or gas - then the inspection is a bit more detailed.  So keep this in mind: if you have an HVAC contractor who knows that mastic is superior, he also knows he won't be competitive because he's bidding against time-saving sticky tape. 

4.  When connecting the straight duct lengths to one another or to fittings, small sheet metal screws are used to secure these sections.  Typically, Greg would use 3 screws at connections of 6" or less, and 4 screws for larger ducts.  The straight sections of ducts are cut to whatever length is needed and then snapped together along a pre-made seam.  This locks the seam, but Greg usually installed screws about every 2' to make sure it wouldn't come apart.  This seam will get the mastic as well.  Straight ducts and all fittings slide one into the other.  So there is a "tapered" end to fit into the duct or fitting.  This taper is referred to as the crimped end.  If the duct needs to be cut down and a new crimped end needs to be created, then there are
sheet metal hand tools to create that taper. The key thing to remember:  the crimped end is always pointing in the direction of air flow.  

5.  The duct work is
supported by strapping; either standard ol' perforated plumbers tape or some approved strap for this purpose.  Greg used a mixture of the metal plumber's tape and a fabric strap.  Since he was working alone, Greg used temporary wood supports to get the ducting up and then he could strap it later.  In cases where the ducting was going to block the spot the strapping needed to attach to on the joist, he would put the strap in first on that one side, install the duct, and then complete the strapping.  The code requirement on HVAC strapping is one every 54".  However, keep in mind something done to code is the only the bare minimum for safety. Greg usually had a strap at every 42".  He would also strap any fitting that needed extra support.  

6.  In some cases, you just have to make your own small ducting to solve a problem area.

In our case, it was usually small pieces of straight duct work.  This is easily completed with a tin snip, crimp tool, and what is called a "break".  This is just a hand tool that will fold the sheet metal into a predetermined straight line.  Home Depot sells a small 12" break, but larger ones are available online.  This tool can be extremely helpful.  For instance, when the ducting finally reaches the place where it exits the wall, there is a transition of the 4" round duct to a plastic 90 degree fitting.  This fitting is designed to slide over a 4" round duct; but the plastic has an oval shape.  Try as he could, Greg could never get this connection to work.  So he made a transition piece from the round duct to the oval connection.  For larger, more complicated bends, you should utilize a local HVAC contractor who has a shop.  One of the local lumber yards realized long ago that creating custom sheet metal parts was a good income stream and they have a well equipped shop to create custom flashing, ducting and sheet metal parts.   

7.  Most HVAC contractors will tell you that by installing an HRV, it eliminates the need to install bathroom exhaust fans.

But when Greg spoke to the manufacturers and techs of HRVs, they told him that in most cases you should have a separate bathroom exhaust system.  Depending on the size of the home and the HRV design, there will be a number of exhaust registers installed and a number of fresh air registers within the home.  Again, rooms that produce bad or stale air (bathrooms, kitchen, laundry) and those receiving fresh air (living rooms, bedrooms, office) will have a register.  You don't put one of each in the same room.  The theory is that as the exhaust register is pulling out the bad air, fresh air is being drawn into the room from an inlet in another room.  Once calibrated for individual rooms, the airflow for these would be about 10 to 20 cubic feet per minute (cfm).  The basic bathroom exhaust fan starts at about 50 cfm but usually a minimum 100 to 150 cfm unit is installed.

With the concern for mold these days, you can see that pulling even 20 cfm continuously would not evacuate the moisture as fast as a regular bathroom exhaust fan.

Also, if you use an HVAC contractor to install the unit and he doesn't brief you on the workings, then you may just end up turning it off.  Especially if you were told that it doesn't need to run all the time - or doesn't run well because it wasn't calibrated properly which would cause an amount greater than 25 cfm of cold air to blow into the room.  Naturally, you'd turn off the unit.

The problem is, you now have no way to remove even a minimum amount of moisture from a long, hot shower.  One friend had an HRV unit installed in addition to his radiant heat system. Unfortunately, he took the contractor's word for it that he wouldn't need a separate exhaust system; the HRV would be sufficient.

Well, he moved in and three months later he was up on his roof tearing off brick tiles to install vents for his "new" exhaust system because his bathroom walls were continually damp.  He was not happy.

American Aldes also provides these units and designed our basic system based on Greg's input.

8.  The American Aldes website,
http://www.americanaldes.com/, and the Lifebreath website, http://www.lifebreath.com/ both have extensive documents on installation.  And they have great information on what you should and should not do.

One of the other components of a HRV system is the calibration.  Simply said, the unit is bringing in air and exhausting air.  These two streams should be made as equal in airflow as possible.  Calibration is done on the warm or house side of the HRV.  To set up for the calibration, a damper must be installed as part of the ducting along with ports to attach a calibration meter. This image shows the damper handles and the ports. These should be at least 30" away from the unit in both the fresh and exhaust ducts.  This damper allows you to manually control the flow of air.  To determine the flow of air, use a Magnehelic Differential Pressure Gauge for the calibration.  At least with American Aldes, this tool with complete instructions can be purchased with your order, or even rented.  This gauge connects to an "airflow measuring station" or pressure taps.  Again, complete instructions come with the tool. And since checking the calibration will need to be done occasionally, purchasing the tool wouldn't be a bad idea.

Here's a picture of the entire system - minus the addition of ports and dampers.

Here are two websites that can help you scratch the surface, but remember, this is a bit more of an advanced DIY and all manufacturer instructions and input should be followed.  

http://healthandenergy.com/heat_recovery_ventilators.htm

http://healthandenergy.com/installing_a_balanced_ventilator.htm

October 13, 2008
On another out-of-town foray, I ran through the local Big Lots. We had one in our town here but it closed about a year or so ago and it was a big loss to all of us (no pun intended). They had wonderful - and cheap - stuff, especially figurines, columns, architectural elements, and big candlesticks made of resin that we plan on reworking to create the facade of our livingroom fireplace. There are companies which make either hand carved or machine carved components such as this, but they can run into the thousands of dollars.

At any rate, this Big Lots at least was a big disappointment; filled with uninteresting, same old same old. I'm glad I had the foresight to buy when I did.

October 16, 2008
Greg begins installing the front door lockset and the first step will be boring the holes. With a 6" thick door, it was necessary to have our locksmith length the original.

This is one of those steps that can only be done once and it must be done to perfection. If our front door were painted, a mistake could be camouflaged.

But that is out of the question with this front door.

October 21, 2008.
Today was our electrical inspection for the HRV. We passed. With Greg at the helm, there was never a doubt.

and...

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