The Range Hood Exhaust–as Air Intake

Modern tight houses can easily become depressurized when exhaust fans are turned on. What this means is there is no place for the air to come into the home to replace the air that is trying to leave. If there are gaps around door weather-stripping, or gaps around window sashes or similar locations, the air will come into the home at these locations.  Sometimes even chimneys might be the path for this air.

If we operate and exhaust fan in a bathroom the house becomes depressurized, or an area of “lower pressure.” Areas of higher pressure will tend to make balance with areas of lower pressure, so the air outside the building literally “pushes” its way into the area of lower pressure.

Most houses are not tight enough for the air to not find its way in somewhere, and general infiltration was once allowed to be the source of this air replacement.

This small condo unit was too tight for general infiltration to be the source of make-up air, as was evidenced by its finding a path through the range hood exhaust.

Most range hoods have a back-draft damper in them, but there should also be one in the cap at the exterior of the building as well. You can see in this picture there is no damper—but there is a screen.

Exhaust fan vent termination with no back-draft damper

With two bathroom exhaust fans and the laundry exhaust fan running, the purple/violet colors of the thermal image of the chase and microwave/hood shows cold air cooling the chase and the area around the microwave.

  

The screen at the exterior cap location did hold a tissue paper to show that indeed air was pushing its way through the microwave/hood.

So, let’s say we “fix” the cap at the exterior with a proper back-draft damper. Where will replacement air come from? General infiltration may still be adequate, it is just easier coming from where it is now. If it is not adequate, the functionality of the exhaust fans will be reduced. In other words, they will make noise but not exhaust enough air from the room. It is like turning a 100-cfm fan into a 50-cfm fan.

For exhaust fans to do their job, replacement air is necessary and is required by modern codes when houses get to a certain point of air-tightness. This one may be at that point, even though it is an older home in that respect.

Some “positive” means of allowing exterior air to enter the home may be indicated if exhaust fans do not function properly after the exterior cap is repaired and its back-draft damper installed.

By Charles Buell, Real Estate Inspections in Seattle

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Telling the difference between a gate and a wall

There are lots of metaphors related to the paths our lives can take.  There are even metaphors of metaphors.

nowheregateWe like to think that we can pretty much do whatever we want.  The reality, for most of us, is that our choices are limited by where we have been–where we have come from–and the many restrictions our culture places on us.  Most of the time it is difficult to tell, except in retrospect, that we have truly chosen.  If the outcome turns out “OK” we take credit.  If the outcome is less desirable we are not quite so willing to take responsibility for what has happened.

Our “choices” more closely resembles our being driven–as opposed to our choosing.

Sometimes the road blocks are obvious—sometimes not.  They are mostly of our own making but often there are limits based on the culture we grow up in.

Freedom beyond being a “state of mind” is very difficult to pin down.

Ultimately, that is all it can ever be.

Some paths appear blocked, we know they are blocked.  We may even know they are supposed to be blocked and yet we still look for a way around or through them.

Such is the case with the gate in the above picture.

Why do we waste time–sometimes our whole lives–on paths that are obviously blocked?  Sometimes we have to look very closely to tell the difference between a gate and a wall.

While some obstacles along the way are meant to be pushed out of the way, climbed over or even ignored–sometimes we need to learn when it is more efficient to go around.

By Charles Buell, Real Estate Inspections in Seattle

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What’s a little raw sewage between friends?

OK–nasty subject–I get that, but what is an inspector to do?

These sorts of issues are considered life/safety issues and the purpose of modern plumbing is to keep “stuff” where it belongs.  We like it when the drinking water stays in the pipes, the waste stuff stays in the pipes and the two don’t get mixed together.

ejectorpump1This sounds like a good plan.

I don’t like sewage ejector pumps–but they exist so I have to deal with them occasionally.  They are common whenever you have plumbing fixtures that cannot drain by gravity.  The effluent has to be pumped up to a level where it can drain by gravity.

Homeowner installation of these devices is almost always obvious and tragic.  At a recent inspection I found one in the basement of a home where a non-conforming kitchen and bathroom had been added.  The bathroom properly drained to the sump below the surface of the basement floor.

The kitchen sink drain however was tied into what amounted to the vent pipe for the unit (the lower pipe that runs off to the right).  However, because there was a big hole cut in the sump cover, no vent was really necessary for the pump to function.  The vent is there because under normal operation a vacuum would be created if it was not there.  A vacuum could suck the water out of the traps of the fixtures it was servicing.  The hole in the cover eliminates any possibility of there ever being a vacuum created.

There also has to be a check valve to prevent water that has been pumped out from draining back into the sump.  There also has to be a gate valve and unions so that the unit can be taken apart to be serviced.  Most importantly there HAS TO BE A SEALED LID!

ejectorpump2

Without a sealed lid the sewage could flood the basement if the pump were to fail–not to mention the likely continual odors of sewage that would be present.

I can only guess why anyone would destroy a perfectly good lid to create this health and safety issue.

The installation needs a new lid—but more importantly it needs a licensed plumber.

By Charles Buell, Real Estate Inspections in Seattle

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