If you've been following our Facebook Page every day for the past four-and-a-half years, you've already seen most of these photos. Halloween seems like a good time to re-share these. Unlike most of our blog posts, this one has no educational value whatsoever. These are just for fun.
Warning: Some of these photos have a high 'yuck' factor. If you don't want to see a floating mouse, don't scroll down.
Baby bunny trapped in a window well. Yes, we rescued her.
Spotted Salamander trapped in a window well. Yes, we rescued him. I think. This was many years ago.
This was a squirrel living in the wall of a vacant Category II property in Saint Paul. I extended my tape measure and poked it just to be sure. It was definitely living.
Aww...cute! A baby squirrel in an attic. Now GET OUT.
We found this albino squirrel keeping warm inside of a chimney.
This squirrel skeleton made me wonder why I don't find more skeletons.
Yep, it's a bat in a bedroom. We encountered this bat while doing a TISH evaluation in Minneapolis at a bank-owned property with a broken window. Our inspection of this room was very brief.
Why did this owner keep animal jaw bones in their kitchen cabinet? Good question.
When I told the buyer about the chipmunk remains in this knee-wall attic, he quickly 'shushed' me to make sure his wife didn't hear. Good plan.
We find mice getting stuck in the darndest of places.
Is this mouse not the fattest, happiest mouse you've ever seen? There was a huge bag of spilled, half-eaten bird seed in the garage.
Lots of home buyers ask us how often they should clean the moths out of their light fixtures, and we tell 'em "as needed". Ok, nobody has really ever asked us that. But still. We think it's good advice.
Creepy white spider in a crawl space. What makes this happen? No idea.
Finally, here's a super creepy video that Milind took.
I'll get back to something more educational next week.
Author: Reuben Saltzman, Structure Tech Home Inspections
At my house, we say "Go Big or Go Home." Bigger is better when it comes to a lot of stuff: snow forts, leaf piles, power tools, computer monitors, towers made out of Duplos... but not furnaces. When it comes to sizing a furnace, there are a lot of reasons to not go bigger.
Earlier this year in a blog post warning consumers about cheap AC tune-ups, I mentioned how a hack service tech / salesman tried to convince me that a bigger furnace would be good for my house because it would "heat my house better". Now that we've officially reached the 'heating season' in Minnesota, it's time to take a closer look at over-sized furnaces.
A perfectly sized furnace will probably run almost all day long on the coldest day of the year, and it might not get the house up to 70 degrees about 1% of the time during the winter. No joke. That would be a perfect system. For 1% of the time during winter, you might need to put on an extra sweatshirt. No big deal. For us in the Twin Cities metro area, that would be any time the temperature drops below -11. Old-school folks will say -20, but that's the old number.
An undersized furnace will work fine for the majority of the time, but every once in a while it won't get the house quite as warm as desired. How bad would this really be? You'd need to wear an extra sweatshirt sometimes. It's coldest at night, and people that have a programmable thermostat already turn the temperature down at night, so would this really be a big deal? No, probably not.
An over-sized furnace will keep the house warm no matter how cold it gets outside, but it does so at a cost. First, it will probably make the house less comfortable. When the furnace kicks on, some areas may warm up very quickly, so much so that they get uncomfortably warm before the thermostat has even been satisfied. In poorly insulated, drafty houses, this heat can be quickly dissipated, causing the furnace to turn on and off frequently. Many people run the furnace fan 24/7 to help even out the heat.
An over-sized furnace will also be less efficient. A furnace is least efficient when it first fires up, and doesn't reach its peak efficiency until the temperature of the air coming out has reached a steady value. When a furnace is over-sized, it spends a large portions of its running hours in the 'warming up' phase. Once it reaches a steady temp, the thermostat has been satisfied and the furnace shuts back off.
When a furnace constantly cycles on and off, the life of the furnace is dramatically reduced. The best analogy I can think of is a car with all city miles and no highway miles. City miles involve a lot of starting and stopping, which is what puts a lot of wear on a vehicle. Heat exchangers on furnaces fail from the metal heating and cooling repeatedly; when a furnace is over-sized, the furnace turns on and off constantly, putting all 'city miles' on the furnace. This is not a good thing, and will lead to premature failure of the furnace. Guaranteed.
Besides premature failure, an over-sized furnace will be prone to short cycling, which is a term that refers to a furnace shutting down before the thermostat has been satisfied. Furnaces are equipped with a safety feature that prevents them from overheating. When a furnace is over-sized, it will run hotter than it should, which puts it closer to the temperature at which it will shut itself off. Throw in a dirty furnace filter, and it will probably be enough to push the furnace over the edge. When a modern furnace short cycles too many times in a row, it will go into shut-down mode to help prevent further damage. This is most likely to happen when it's extremely cold outside, which is the time when you really don't want your furnace to quit working.
The same stuff applies. Most boilers are oversized, and it's not a big deal if a boiler is slightly undersized. An oversized boiler will make the house less comfortable, will be less efficient, and the constant turning on and off will shorten the life of the boiler and probably cause unexpected breakdowns.
From my own experiences and from everything I've heard from everyone in the know, a large portion of the older furnaces out there are over-sized. HVAC contractors who are passionate about their trade love to talk about this stuff, and when they do, I listen. I've learned a lot about this topic from a couple of local, passionate HVAC contractors; one being Enviroworld USA, and another being Chris Jirak of Neighborhood Plumbing Heating and Air.
Chris estimates that at least 75% of the furnaces that he replaces are over-sized. As furnaces get more efficient, the trend should be to install furnaces with lower BTUs, not higher. Many HVAC contractors are reluctant to go smaller because they don't want to deal with homeowner complaints about the house not heating enough, but just a little bit of client education is really all it takes to prevent this. A furnace that takes a long time to heat a house is probably sized properly.
When a furnace is replaced, the HVAC contractor should perform a Manual J calculation (or the equivalent) to help them determine what size furnace the home really needs. This is a calculation that requires several of a homes variables to help determine the proper heating and cooling requirements. If a calculation isn't done, the contractor is just making a guess at the size of the new furnace, which means they'll probably go big, then go home.
Author: Reuben Saltzman, Structure Tech Home Inspections
I hear a lot of the same home inspection myths repeated over and over. I've blogged about most of these, but there are a few topics here that I haven't blogged about yet.
The seller doesn't need to fix squat. Home buyers can ask sellers to fix things or pay for things to be fixed, but I can't think of a single defect that a seller would be required to fix.
Many cities in Twin Cities metro area have Truth-In-Sale of Housing evaluations (TISHs) that might identify required repairs, but those are separate from the home inspection. Even if the home inspector identifies a defect that was missed by the TISH evaluator, the seller has no obligation to fix anything.
There is no such code requirement. This misunderstanding comes from section R308.4 of the International Residential Code (IRC). The IRC requires special glass in hazardous locations, and goes on to give a list of hazardous locations. One such example is glass in a location that meets ALL of the following conditions:
- Exposed area of an individual pane larger than 9 square feet.
- Bottom edge less than 18 inches above the floor.
- Top edge more than 36 inches above the floor.
- One of more walking surfaces within 36 inches horizontally of the glazing.
When only one, two, or three of these conditions are met, it's not considered a hazardous location and tempered glass is not required. My oldest code book is the 1988 UBC, which basically had the same requirement.
For more detailed information about safety glazing, check out Douglas Hansen's article: Safety Glazing.
Buyers will probably get the most out of the inspection if they do what the home inspector prefers. If the home inspector prefers to have the buyer show up at the end, the buyer would do best to show up at the end. If the home inspector prefers to have clients attend the whole thing (like we do), the buyer should try to be there the whole time.
We inspect a ton of new construction homes, and we find a ton of defects. Click here for some examples: new construction inspections.
Minnesota's requirement for CO alarms has nothing to do with real estate.
The physical size of that thing at the outside of the house won't tell you anything about the cooling capacity. It has a lot more to do with the efficiency of the unit; larger units = more surface area = higher efficiency. The cooling capacity is measured in tons. To figure out how many tons your unit is, look at the model number and find a number usually between 18 and 60 that's a multiple of 6. Divide that number by 12, and you have the number of tons your unit is.
For example, the unit pictured below is a 2-½ ton unit.
For more info on sizing air conditioners and a nice explanation of why air conditioners are rarely undersized, check out this article on Air Conditioner Capacity that was published in the ASHI Reporter.
There are several blog posts about AC sizing at the Vanguard Energy Blog. Here are a few:
Replacing a water heater won't correct backdrafting unless a new powervent water heater is installed. If a water heater backdrafts, there's a problem outside the water heater. Sometimes it's a problem with the vent, sometimes the vent connector, and sometimes it's a more complicated problem that requires evaluation of the entire house.
For more detailed information on this topic, click this link: backdrafting water heaters.
Old stucco is fine. It's just the newer stuff from the early 90's on that should be a concern. What went wrong with this stucco? Joseph Lstiburek calls it the "perfect stucco storm." We recommend invasive moisture testing when buying a newer stucco home.
There is nothing in the building code that requires a closet. An appraiser might want to see a closet... so what's a closet?
This is one of the most common electrical defects that home inspectors report on, but the repair for a double tapped circuit breaker is usually quick and easy. When compared to most of the other electrical defects that home inspectors find, the safety risk posed by a double tapped circuit breaker is quite low. So what's the big deal? Probably fear of the unknown.
This is one of the topics I'll be covering in an upcoming continuing ed seminar for real estate agents on October 23rd. It's free and breakfast is included. Click here for more info: https://cecreditbreakfast.eventbrite.com/
Author: Reuben Saltzman, Structure Tech Home Inspections
In last weeks blog post about backdrafting water heaters, I mentioned that I might someday follow up with a blog post attempting to explain how to use section 501.3 of the Minnesota Mechanical Code (MMC), which is the code section that describes how to supply makeup air to dwellings. Well, there's no time like the present. This isn't the most exciting topic, but it's certainly a misunderstood topic.
There's a general consensus among those 'in the know' that makeup air is needed any time a kitchen exhaust fan rated over 300 cfm is installed, however, that's not exactly true. The real requirement is that makeup air must be provided if it's needed. If an exhaust fan rated over 300 cfm is installed, makeup air might be needed and a calculation will need to be done.
The Minnesota Mechanical Code is a combination of chapters 2 to 15 of the 2006 International Mechanical Code and Minnesota's amendments. The amendments can be found online here: https://www.revisor.mn.gov/rules/?id=1346 . Minnesota has amended section 501.3 in it's entirety, which means that this entire section is available online: https://www.revisor.mn.gov/rules/?id=1346.0501. Nice.
The MMC has very specific language about makeup air that basically says makeup air must be installed when it's required, unless it's not required because of an exception. Yes, that's how code language is written. Clear as mud.
I'm going to paraphrase this code section to hopefully make it a little easier to understand, because it's written in a very confusing manner. The easiest way to break it down is by the age of the home. There are five age categories, but the requirements for two are identical so I lumped them together under number 2:
New homes require a calculation for makeup air using table 501.3.1.
To complete this calculation, you'll need to know the number and type of combustion appliances (power vent /direct vent / fan-assisted / atmospherically vented / solid fuel ), the conditioned floor area square footage, and the CFM rating of exhaust fans. Once all of these numbers are plugged into the table and a little math is done, the final number will be the amount of makeup air needed.
If the number is negative, nothing has to be done. If the number is positive, table 501.3.2 determines how makeup air should be supplied. Footnote "K" at this table says that if flex duct is used (and flex duct is almost always used), the diameter of the makeup air duct needs to be increased by one inch.
Any time a vented combustion appliance is installed or replaced, or an exhaust system is installed or replaced, table 501.3.1 needs to be used to determine if makeup air is needed. This means that if an 80 cfm bathroom exhaust fan is replaced with a 90 cfm exhaust fan, yes, a new calculation needs to be done to determine if makeup air is needed.
When a solid fuel appliance is installed, use table 501.3.1. One exception is if the appliance is a closed combustion appliance and combustion air is installed in accordance with the manufacturers installation instructions.
When an exhaust system with a rated capacity greater than 300 cfm is installed, use table 501.3.3(1). One exception is if powered makeup air is electrically interlocked and matched to the airflow of the exhaust equipment.
When a solid fuel appliance is installed, use table 501.3.3 (3). One exception is if the appliance is a closed combustion appliance and combustion air is installed in accordance with the manufacturers installation instructions.
When an exhaust system with a rated capacity greater than 300 cfm is installed, use table 501.3.3(2). One exception is if powered makeup air is electrically interlocked and matched to the airflow of the exhaust equipment.
There are two exceptions to all of the above makeup air requirements. One is if a test is performed in accordance with ASTM Standard E1998-02, Standard Guide for Assessing Depressurization-Induced Backdrafting and Spillage from Vented Combustion Appliances, and it's proven that makeup air isn't needed. I don't know what those standards look like because I don't own them and I'm not going to buy them. The other exception is if a test is done that's approved by the building official which verifies proper operation of vented combustion appliances.
Just for fun, lets go through a sample calculation. Lets say I have an old house in Minneapolis and I want to install a 600 cfm kitchen exhaust fan. This is an exhaust system with a cfm rated greater than 300 cfm and the home was built before 1994, so I'll need to use table 501.3.3(2) to determine if makeup air is necessary.
The house has a high efficiency, sealed combustion furnace, which is a 'direct vent' appliance. The water heater is a powervent, and the fireplace has a sealed combustion gas insert (direct vent). There is a total of 2,000 square feet of floor area in the house, which includes the unfinished basement.
To start, I need to figure out which which column I'm working with. The first column on this table lists "one or multiple power vent or direct vent appliances or no combustion appliances." That's what I have, so I'll use this column. To determine the estimated house infiltration, I can either use the conditioned floor area or use the results from a blower door test. If extensive air sealing has been done on an old house it would be wise to use the results from a blower door test, but we'll use floor area instead to make it easy.
I plug in the numbers and get 500 cfm for my estimated house infiltration.
Section 2 says to plug in 80% of the largest exhaust fan, which will be the 600 cfm kitchen fan, which gives me 480 (600 x .8).
Section 3 subtracts part 1 from part 2 (480-500), giving me a negative number. When the number is negative, no makeup air is required. So there you have it. Makeup air isn't always required when installing a big kitchen exhaust fan, but the calculation is always required. The calculations are shown below.
On the other hand, lets say I'm working with the same house but I have an atmospherically vented water heater and a wood burning fireplace. In that case, I would need to use the column at the far right. Once I plug in all of the numbers, my makeup air quantity would be... 380 cfm. That's some serious makeup air. Next, I use table 501.3.2 to determine the size of my makeup air duct, which would be a 9" rigid duct with a motorized damper, or a 10" duct if I use flex material.
In that case, a 600 cfm kitchen fan would just be a stupid choice, dontcha think? Hopefully I've taken a little mystery out of the makeup air requirements for Minnesota homes.
Author: Reuben Saltzman, Structure Tech Home Inspections
If a water heater backdrafts, it means that potentially hazardous exhaust gases are coming back into the home. Last week I blogged about how to determine if a water heater is backdrafting; that's the easy part. The tough part is determining why it's happening and fixing it. There are many potential causes for a water heater to backdraft, so I'll cover as many as I can think of. In many cases, it's a combination of conditions.
The one guaranteed fix for all of the issues that I'm going to discuss is to install a new powervent water heater that typically vents through the side of the house. Powervent water heaters won't backdraft, but they cost more money, they're more work to install, there's more that can go wrong with them, and they won't operate if the power goes out.
A vent connector is the thing that takes the exhaust gases from the top of the water heater (draft hood) to the vent. If a vent connector isn't properly installed, the potential for the water heater to backdraft increases.
One of the most common installation defects with a vent connector is improper pitch; the vent connector need to pitch upwards towards the vent with a minimum slope of 1/4" per foot, and there should be no sags or dips.
Insufficient rise in the vent connector can contribute to backdrafting. While the code requires a minimum pitch of 1/4" per foot, if there is a quick 90 degree turn right at the top of the draft hood and the vent connector only has the minimum pitch, there's a good chance that it won't draft properly. There needs to be more of a rise created in the vent.
Most atmospherically vented water heaters come in two shapes - tall and short. Short water heaters are a couple of inches wider and nearly a foot shorter than tall water heaters. Replacing a 'tall' water heater with a 'short' gives the vent connector almost an extra foot of rise, which will increase the potential for the water heater to draft properly.
Another common defect with a vent connector is too long of a horizontal run.
The longer a vent connector runs horizontally, the greater the potential that it won't draft properly. Section 503.10.9 of the Minnesota Fuel Gas Code says that "a vent connector shall be as short as practical and the appliance located as close as practical to the chimney or vent". The photo above shows a water heater installed much farther away from the chimney opening than it should be. That water heater could certainly be moved closer to the chimney.
Another thing that can be done to help with a long horizontal run is to replace a single-wall vent connector with a Type B vent connector. This will help the vent to heat up faster, which will help with draft.
Mid-efficiency furnaces have an induced draft fan that is designed to pull the exhaust gases out of the furnace's heat exchanger. This fan ends up ‘pushing’ the exhaust gases up the vent, and if the water heater vent connector is located directly across from where the exhaust gases are directed, the exhaust gases from the water heater get pushed right back down. Most water heaters will not draft properly with this configuration.
One way to fix this is to re-arrange the common vent so the water heater vent connector is offset from the furnace.
Here's a common scenario for water heater draft problems: an old 80% efficient furnace is replaced with a new, high efficiency furnace that vents through the side of the house, leaving the water heater vent an orphan. The illustration below, provided by the Minnesota Department of Commerce, Division of Energy Resources, shows what this looks like.
The relatively small burner on the water heater may not generate enough heat to warm up the chimney or vent, which can lead to backdrafting. In many cases, a new vent liner will be installed to allow the water heater to vent into a smaller space.
The text in the image above also mentions adding a power vent to the existing water heater. Tjernlund of White Bear Lake, MN makes such devices; one is a powervent conversion kit for an existing water heater, and another is a chimney stack assist kit for an existing water heater.
An obstructed chimney or vent will almost certainly cause backdrafting. I've heard stories of leaves, acorns, and squirrels in chimneys and vents; I once even found a dead bird blocking the draft hood at a water heater. To help prevent the possibility of that happening, a listed cap should be installed at the vent terminal at the exterior.
A proper cap will help to prevent debris from falling into the vent, keep rain out, prevent downdrafts caused by strong outdoor winds, and is required by the Minnesota Fuel Gas Code (section 503.6.6).
For a water heater to draft properly, it needs to have plenty of available air. Some water heaters will be right on the brink of backdrafting even with a proper installation, and all it takes is a single bathroom exhaust fan to pull enough air out of the house to make the water heater backdraft. Even in a home with a water heater that drafts very well, just throw in a big 600 cfm kitchen hood fan and it's almost a guarantee that the water heater will backdraft with the fan running.
Insufficient combustion / makeup air is a condition that many plumbers and HVAC folks seem to have a tough time diagnosing. They get called out to correct a backdrafting water heater and they head right down to the basement to diagnose the problem. They see that the venting is all installed to code, there's a nice rise in the vent connector before the chimney, there's a combustion air duct installed, and there are no signs of previous backdrafting. They get the water heater to fire up, and it drafts perfectly for them, so they proclaim there are no problems.
Hmm... did they miss any steps in testing for draft? 'Fraid so.
According to Steve Schirber of Cocoon, LLC, BPI standards for testing water heater draft are extremely similar to the steps that I listed in my blog post last week. I won't go into all of them, but they involve closing all windows and doors, turning on exhaust fans, and only running the water heater.
If a water heater backdrafts under a worst-case scenario test like this, open a few windows or a door to see what happens. If the water heater starts drafting properly right after doing that, it's obviously a problem with insufficient combustion air or makeup air.
The fix for this is to hire a savvy plumber or HVAC contractor with a holistic understanding of houses. If there is already a combustion air duct installed, they'll make sure the intake is clean at the exterior and the duct is not obstructed. If that all looks good, they might install a makeup air duct; it's pretty much identical to a combustion air duct. They might just guess at the size needed and do a performance test when they're done, or they might use Minnesota Mechanical Code Section 501.3 to find a formula for the amount of makeup air needed. Some day I might follow up with a blog post attempting to explain how to use Section 501.3 to figure out a formula for makeup air.
That's everything I can think of.
Author: Reuben Saltzman, Structure Tech Home Inspections