HRVs, Part 2 of 3: Maintenance & Operation

Last time I blogged about why houses need HRVs.  This time I'll write about maintenance and operation of HRVs, and I'll try to cover the stuff you should know if you own one.  The information in this blog is general - every manufacturer will have their own set of instructions and their own maintenance schedule.

Maintenance

• Every three to six months the filters should be cleaned by vacuuming to remove as much dust as possible, then washed with warm water and mild soap.  Some filters can also be washed in the top tray of a dishwasher, but this may tarnish the aluminum finish.  The filter below should have been cleaned a long, long time ago, and this is what I find at almost every home inspection - way more than dirty furnace filters!

• Every three to six months Clean the condensation tray with damp cloth.  The condensation tray is the area where water will collect in the bottom. The condensate drain should be checked, and replaced if needed.  The drain tube usually consists of clear plastic tubing with a little loop that creates a trap to prevent odors from the floor drain or wherever else from getting sucked in to the HRV.

• Every three to six months Check the intake grill at the exterior of the home to make sure it's clean.  These get very dirty, as there is a fan constantly pulling air in.

• Every six to twelve months the core should be cleaned by removing it and letting it soak in a mixture of lukewarm water and mild soap.  Rinse the core thoroughly when done.  If you own a summer core, don't get it wet, as you'll cause permanent damage to it.  Summer cores can be cleaned by vacuuming with a brush attachment.

• Every one to three years the fans should be cleaned.  This typically requires removal of the fan assembly.  Check the owner's manual for specific instructions, or hire a professional to do this.

Operation

Operating an HRV is usually quite simple.  If the HRV has a switch located on the unit itself, it will typically have a couple of the following settings, but not all:  On, High, Low, Off, or Remote.  If your HRV has a "Remote" setting, you'll probably want to use that one. This will allow the HRV remote controller, usually mounted on the wall next to the thermostat,  to turn the HRV on and off.  This remote will also typically have a dehumidistat, which controls how much moisture is in the air.

If the bathrooms in the house have funny little wall buttons instead of bathroom exhaust fan switches, it typically means that the HRV system has had ductwork installed in the bathrooms.  This is an acceptable alternative to bathroom exhaust fans.  When the wall button is pushed, this will turn on the HRV for somewhere between 15 - 60 minutes, or will kick the HRV in to high gear for 15 - 60 minutes.

Every HRV should also have a defrost cycle, and the HRV should go in to the defrost cycle automatically when it gets too cold.  The defrost cycle is actually quite simple; the exhaust fan just runs for about five minutes, which forces a bunch of warm indoor air through the core without bringing in any cold air.

If you plan to operate your HRV during the summer, check your owner's manual to see what the manufacturer has to say about it.  If your HRV is designed to run during the summer, you'll probably need to remove the standard winter core and install a summer core.  The difference is that the summer core is designed to remove moisture from the air coming IN to the house, rather than the air leaving.  If there is no mention in your owners manual about running your HRV during the summer, you probably shouldn't.

That's about all for maintenance - for any more specific instructions, you'll need to check your owner's manual.  Next time I'll talk about installation defects.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minneapolis Home Inspections

HRVs, Part 1 of 3: Why Houses Need Them & What They Do

Many months ago I wrote a blog about how houses can often havemoisture problems when old furnaces are replaced with high efficiency furnaces. The fix that I mentioned at the end of the blog was to install a Heat Recovery Ventilator, or HRV.  The character in that blog finally got around to installing an HRV in his house, and solved all his moisture problems! For the first time since he installed his high efficiency furnace, he no longer has condensation on his windows during the winter, and he couldn't be happier about it.

Today I'll share some basic information about how HRVs operate and why they're needed in today's newer, tighter houses.

New Houses Don't Breathe As most people know, new houses are constructed much tighter than they used to be - they don't leak air all over the place.  I've heard a lot of old-school home inspectors and building contractors complain about this, and you probably have too.  The rant goes something like this: "We build houses so damn tight that they don't breathe, and they end up rotting from the inside out!  Things were a lot better when we didn't have all these stupid house wraps."

These cranky doom sayers are only partially right - yes, we build houses tighter today, but we've also figured out how to prevent mold and moisture problems, and how to improve indoor air quality.  This is where HRVs come in.

HRVs Provide Fresh Air An HRV works by constantly bringing fresh air in to a house and exhausting stale air.    The air that gets brought in to the house gets passed through a screen at the exterior, then through a filter inside the unit, then through the HRV core, which is actually a heat exchanger.  The heat exchanger allows the fresh outdoor air to get warmed by stale indoor air right before the indoor air gets exhausted to the exterior.  This allows about 60 - 80% of the heat in the air to be re-captured.  The diagram below illustrates this principal.

To understand how an HRV works, interlock your fingers together and picture warm air flowing through fingers in one hand, and cold air flowing through the fingers in the other hand.

HRVs Remove Moisture Besides providing fresh air, HRVs also remove a lot of moisture from the air.  Old, drafty houses get dry in the winter because they're leaky, and the moist indoor air is always getting replaced with dry outdoor air.  Not so with newer houses - they stay humid during the winter, and HRVs are often needed just to get rid of all the excess humidity.  As the warm, moist air passes by the cold air, the moisture will condense.  This is why HRVs have a drain running out the bottom.

 

HRVs Lower Radon Levels Because HRVs constantly change out the air in a house, an HRV will reduce radon levels when working properly.  During a recent Eden Prairie home inspection that I also performed aradon test at, I had the HRV running during the majority of the radon test, but I tripped the GFCI outlet for the last hour of the radon test during my inspection.  Look at the jump in radon levels at the house from NOT having the HRV running!  Any time a radon test is performed, if there is an HRV present at the house, it should be up and running throughout the duration of the radon test.

HRVs Have Many Names If you hear any of these terms, someone is probably talking about an HRV:

• Air-to-air heat exchanger
• Air exchanger
• Whole house ventilator
• Big square thingy in the furnace room
• VanEE system (brand name)
• ERV

The last one, ERV, stands for Energy Recovery Ventilator.  These are similar to HRVs, but ERVs are pretty rare here in Minnesota - I think I've seen two of them, ever.  They're designed for more humid, southern climates.

If you don't have an HRV at your house and you think you need one, you could always just turn on an exhaust fan and leave it running.  This will be very inefficient, but it will change out the air in your house.  I call this the Poor Man's HRV.

Next week I'll talk about the maintenance needs of HRVs, and the week after that I'll discuss installation defects.

Reuben Saltzman, Structure Tech Home Inspections - Email - Eden Prairie Home Inspections

New Windows Are Nice... But You'll Never Get Your Money Back.

I've heard some pretty outrageous claims from window replacement companies.  The most common 'hook' for selling replacement windows is that you'll get a Return On Investment  (ROI) because of all the money you'll save on your heating bills.  In the real world, the idea that you could ever come close to breaking even on your investment for new windows is impossible at best, and borders on downright dishonesty.  Unfortunately, a lot of consumers believe the window company's claims - I hear this myth repeated many times while doing home inspections throughout Minnesota.


To prove this, I decided to figure out how much money I would need to save every year if I just wanted to break even on the investment of new windows at my house, assuming the windows could last thirty years... although the average life expectancy for replacement windows is actually twenty years.   I've already replaced nine of the twenty-two windows in my house with newer energy-efficient windows.  If I replaced the remaining thirteen windows with incredibly energy efficient windows and I only paid $500 each, I would have to save 46% on my heating bills every year for the next 30 years just to break even!

I arrived at this number by pouring over my gas bills for the last six years, and figured out how much gas I use to heat my house on average every year.

• I use an average of 520 therms per year to heat my house.
• The average cost of gas is $0.90 / therm, which makes the average cost to heat my house every year $468.
• 
  
  
  

  

  Reuben's Gas Bill

A few details about my house:

• Built in 1939, 1500 finished sf, 1 1/2 story.
• 2x4 construction, most walls have about 2" of rock wool insulation.  This means the walls are very poorly insulated, so a lot of my heat loss is happening through the walls.
• Basement is completely unfinished and uninsulated.
• Attic / 2nd floor is insulated with about 3" of closed-cell spray foam.
• Thirteen original single pane windows with removable storm windows installed during the winter.
• Nine newer Low-E windows (the kind that are supposed to save energy)
• I keep my house at 72 degrees during the winter, and I use a setback thermostat.

.
Assuming each new window costs $500, replacing thirteen windows would cost $6500.  To save $6500 over a period of 30 years, I would need to save $216 per year on my heating costs, or 46% or my average annual cost, which is $468.  In reality, I might end up saving somewhere around 5%.  I've already replaced almost half the windows on my house, and I haven't noticed any significant savings on my heating bills.


I'm not writing this to discourage anyone from replacing their windows -  I love new windows, and I dislike my old windows with a passion.  They're a huge pane to maintain, and I'm slowly replacing them... but every time I replace a window, I do it because I like having new windows, not because I think I'm going to save any real money on my heating bill.  A $1500 tax credit still wouldn't even get me close.

ps - when it comes time to sell your home, a house with new windows will sell for more money than a house with old windows.  Home sellers in the Minneapolis area can expect to recoup about 70% of the cost of new windows.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspections

Bad Chimneys Don't Always Need Repair

Most homes in Minneapolis and Saint Paul are old houses with masonry chimneys.  When these masonry chimneys go bad (and they all go bad) the repair can be very expensive.  If you call up a chimney contractor to see what can be done about it, they'll tell you the chimney needs repair, just like an orthodontist will tell you your kid needs braces.  Repair is just one option. The other option is removal.



When chimneys are badly deteriorated, sometimes it just makes more sense to tear the chimney down below the roof line instead of repairing the section that sticks up above the roof.  The benefits of doing this are lower repair costs, less exterior maintenance, and less chance for leakage at the roof.  Chimneys are notorious for leaks, both through the top and at the roof flashing.

If you're thinking about tearing a chimney down below the roof line, the chimney must be located in the middle of the house.  If the chimney is located on an outside wall, the fix wouldn't simply involve removing the chimney below the roof line - it would require complete removal of the chimney, which might be cost prohibitive.  I counted houses around my neighborhood in Minneapolis (Bryn Mawr), and about three out of four houses has a chimney in the middle of the house.

To remove the chimney below the roof line, the chimney must also be abandoned, or only be used to vent gas appliances that are connected to a metal flue liner.  If the chimney is completely abandoned, it's a no-brainer; it's not doing anything, just get rid of it.

If the chimney is being used to vent gas appliances such as a furnace /  water heater / boiler, that vent will still need to penetrate the roof to carry the exhaust gases to the exterior.  Just make sure that all of the gas appliances are properly connected to the vent!

It used to be common practice to connect the furnace to a metal vent that ran inside the chimney, while the water heater would be connected only to the chimney, where it would use the annular space around the furnace vent to carry exhaust gases to the exterior.  If you see the water heater vent connector entering the chimney separately from the furnace or boiler, this is probably what is happening.  That's what you're seeing in the photo below - the smaller vent connector that I outlined in red comes from the water heater.

The diagram below shows the same thing - click for a bigger version.

If you have an installation that looks like this, you should have it fixed, whether you plan on tearing down your chimney below the roof line or not.  Allowing the water heater to vent in to the annular space in the chimney will allow the corrosive exhaust gases to damage the chimney walls, and water heaters usually don't draft properly when they're installed this way... but I digress.  More on this topic another day.  Back to the chimney.

If the chimney is removed down below the roof line, be sure to seal up what's left of the chimney inside the attic space, to prevent the chimney from doing what it does best - bringing warm air up!  If the chimney ends below the roof line, it will act like a huge attic bypass, allowing heat to escape in to the attic.  If the chimney is abandoned, seal off the top completely.  If the chimney is still used as the chaseway for a gas vent, seal off the area between the chimney and the vent with sheet metal, and use high-temperature caulking to make it airtight.

No more chimney maintenance!

Reuben Saltzman, Structure Tech Home Inspections – Email – Bryn Mawr Home Inspections

Forget Code, Bathrooms Need Fans.

For the last 800 years, building codes have allowed bathrooms to be built without exhaust fans.
Exhaust fans aren't even a requirement here in Minnesota!  This is a great example of how building codes are only minimum standards. I thought about this while doing a home inspection at a rental home in Minneapolis.   The outdoor temperature was about 45 degrees, and every single window in the home was covered with condensation, which was also dripping down the walls.



Oh, and there were no fans installed.

Bathrooms need exhaust fans to help eliminate moisture problems, plain and simple.  When people take showers and baths, moisture gets pumped in to the air.  During the winter, this moisture condenses on windows and walls, and often makes it's way in to the attic space through attic bypasses, where it will create frost.

Minnesota requires windows in bathrooms that provide a total glazed area of at least three square feet, and half of that must be openable.  The exception to this rule comes when a bath fan is installed that will exhaust at least 50 cubic feet per minute, or a continuous exhaust system such as a Heat Recovery Ventilator exhausts at least 20 cubic feet per minute.

The idea of someone actually opening a window on a cold winter day in Minnesota to help reduce moisture in the bathroom is ridiculous.   If you live in a house without an exhaust fan in a bathroom that gets used for showers or baths, install one.  Your house will thank you for it.

If you're going to install a fan, here are a few tips to make sure your house is happy with the fan.

• Choose a good fan. You'll want to balance noise level, performance, and price.  If you buy a cheap noisy fan, you probably won't even want to turn it on.
• Make the exhaust duct short. A proper exhaust duct will be as short as possible and take as few turns as possible.  The longer the duct and the more twists and turns it takes, the less air flow.  A fan rated for 80 cubic feet per minute (CFM) assumes the fan has no duct.  As soon as a duct gets added, the actual CFM goes down.  I've inspected hundreds of houses where there is barely any air flow at bath fan exhausts.  If the bath fan is located in the basement and the duct runs up to the roof at the second story, air flow will be pretty pathetic.
•  Insulate the duct where it passes through unconditioned spaces, such as the attic.  If you don't, moisture will condense it the duct, and might drip down and stain the ceiling. I once inspected a house in Richfield where the exhaust duct was uninsulated in the attic, and so much moisture had accumulated in the duct that it was completely filled with water!  The photo at right shows me holding my flashlight up against the duct - this is one of my favorite photos ever.  Click the thumbnail to see the full version.
•  Don't use a standard switch to control the fan. When a single switch controls the fan, people turn the fan on while in the shower or maybe after the shower, and turn the fan off when leaving the room.  The problem is that the fan doesn't run long enough to remove enough moisture.  A better solution would be to install a timer that runs for at least a half hour, or install a humidity sensing fan.

Reuben Saltzman, Structure Tech Home Inspections – Email –Minneapolis Home Inspections
RELATED POSTS:

• A Common Problem With Bath Fan Exhausts
• Kitchen Exhaust Problems

Ground Fault Circuit Interrupters (GFCIs), Part 2

Last week I gave an overview of what GFCI outlets are for - the long and short is that GFCIs are life safety devices; they prevent lethal shocks.  This week I'll talk about the different types of GFCI devices, how to test them, what drives me crazy with them on home inspections, and what some of the newer features are.


The two most common types of GFCI devices are circuit breakers and outlets.  A GFCI circuit breaker gets installed at the electric panel, and protects the entire circuit.  This is a handy way to make sure everything on the circuit gets protected, and there is no need for individual GFCI outlets anywhere in the circuit.  The other type, which everyone has already seen, is an outlet.  The most common type of outlet is a duplex receptacle, which is shown below left.
 
One GFCI outlet can protect several other non-GFCI outlets when wired properly.  Every GFCI outlet has screws behind the outlet labeled "line" and "load".  The current coming in to the outlet must always be connected to the "line" side of the outlet.  If more outlets are going to be protected by the GFCI, they can be wired to the "load" side of the outlet.   Many houses built in the eighties will have the exterior outlets, garage outlets, and basement bathroom outlets wired downstream from a GFCI outlet in the upper level bathroom.  Today it's common for a GFCI outlet at the kitchen countertop to protect several other outlets.  This saves money.



A redundant way to wire  GFCI outlets is to wire one GFCI downstream from a second GFCI outlet.  This is wasteful, pointless, annoying, and it makes things difficult for the home inspector and anyone else that might trip the outlet, especially if the first GFCI outlet is hidden! Please don't do this.

GFCI outlets should be tested every month because they can go bad, and a defective GFCI outlet doesn't provide any life safety protection.  To test a GFCI outlet or circuit breaker, simply press the test button.  Here are the possible outcomes you can have by testing a GFCI outlet with the test button:

• Acceptable - The reset button pops and the power goes off.  The GFCI device is functioning properly.  Simply press the reset button to restore power.
• Unacceptable - The reset button doesn't pop.  This means the outlet is defective and should be replaced.
•  Unacceptable - The reset button pops but the power doesn't go off.  This means the line and load are reversed at the outlet. This should be corrected.  Newer "SmartLock" GFCI outlets that have a little lock symbol on the front have a built-in safety feature that prevents the outlet from getting energized if it's incorrectly wired.
• Unacceptable - The reset button is already popped, the power is off, and the reset button won't go in.  This can happen on the newer "Smartlock" GFCI outlets if they're improperly wired or the outlet has gone bad.
• Acceptable, but annoying - The outlet loses power when tested, but the reset button doesn't move.  This means someone wired the GFCI outlet downstream from a second GFCI outlet.  Shame on them.

Another way to test GFCI outlets is to buy a tester.  This is a great way to test standard outlets that are wired downstream from a GFCI device.  Just plug it in to an outlet and press the test button.  If the power goes out, the GFCI device is working properly.  If the power stays on, it doesn't mean the GFCI device is defective - sometimes GFCI testers won't trip GFCI outlets.  If this is the case, try the test button at the outlet.

Why do GFCI outlets go bad? I honestly don't know, and if anyone reading this blog can tell me, I'd be interested in hearing about it.  From my own experience, I've found that after a GFCI outlet has had a lot of power running through it, it will often fail.  For example, any time I'm working on a remodeling project and I'm running a bunch of power tools through a GFCI, it goes bad within about a month.  I've heard of home builders wanting to put all of their GFCI outlets on the inside of the house because there's this idea that cold Minnesota weather makes GFCI outlets go bad, but I haven't experienced that myself, and a study on GFCI outlets has shown that temperature doesn't have any effect.

RELATED POST:  GFCI Outlets, Part One


Reuben Saltzman, Structure Tech Home Inspections – Email – Home Inspector Minneapolis

Ground Fault Circuit Interrupters (GFCIs), Part 1

For this this week and next week's blogs, I'll be waxing on GFCI outlets.  I'll talk about what they do, why they're so important, what you need to know about them, and how to test the outlets in your own home.


First, a quick refresher. In my blog about reversed polarity outlets, I explained that there are two wires that conduct current - one get connected to the earth (grounded) and the other doesn't.  The grounded conductor should always be white, and is referred to as the "neutral" wire.  The ungroundedconductor is usually referred to as the "hot" wire, and it can be any color besides white or green, but it's typically black.  Because the neutral wire is connected to the earth, any time you're in contact with the earth and you touch an ungrounded wire, you'll complete the circuit and you'll get a shock.  The general, technical name for this event is a ''ground fault", because current is getting back to the ground in a way that it shouldn't (it's using you!).

Not all shocks are the same. Here's where we'll get in to a little more detail about what happens when a human comes in contact with an ungrounded(hot) conductor.

• No shock. If I could magically levitate and grab on to a ungroundedconductor, I wouldn't get a shock.  I'm not providing a path back to the earth, so the electricity doesn't have anywhere to go.  This is why birds can sit on power lines without getting a shock.  No ground fault.

• Small shock. If I were working on the second story of my wood-framed house, wearing rubber soled shoes, standing on the carpet, and then came in contact with an ungrounded conductor, I would probably receive a relatively mild shock.  The current has a difficult time traveling through my skin, through my body, through my shoes, through the carpeting, through the wood framing in the house, and eventually back to the earth.  I say 'relatively' mild because this has happened to me several times, and I'm still here to tell about it.  It still hurt like hell every time, and it's always dangerous. This is a ground fault.

• Severe / lethal shock. If I were holding on to the kitchen faucet with a wet hand and I touched an ungrounded conductor with my other hand, which was also wet, I'd probably get killed.  Having a wet hand will make it easier for electricity to pass through my skin.  After the electricity passes through my body, it has a very easy time getting back to the earth; it will pass through the kitchen faucet to the water pipes, which are directly connected to my electric panel.  This ground fault could easily be enough to kill me.

To prevent lethal shocks through ground faults, special electrical devices called Ground Fault Circuit Interrupters, or GFCIs, are required in homes.  If a GFCI device detects a ground fault, it will shut off (or 'interrupt) current within a fraction of a second.  It won't be fast enough to prevent a painful shock, but it's enough to keep you from getting killed.

GFCI devices were first required near swimming pools in 1971.  Today they're required in areas where lethal shocks are most likely to happen - typically at areas that are wet and have good contact with the earth.  These areas include the exterior, garages, kitchen counter tops, bathrooms, unfinished basements, crawl spaces, and outlets within 6' of laundry sinks, utility sinks, and wet bar sinks, among other places.  For an excellent one-page chart that lists all the locations and shows when the specific requirements went in to effect, click here.

That's enough information on GFCIs for this week.  Next week I'll talk about the different types of GFCI devices available, the difference between new and old GFCI outlets, how to test them, how they irritate me, and how to save money while installing them.

Reuben Saltzman, Structure Tech Home Inspections – Email – Home Inspector in Minneapolis