HRV Maintenance

I returned to a Nashville residence for my 1 free maintenance call on a heat recovery ventilator I installed in the summer. I had wanted to return anyway, because I wasn't crazy about the zip ties I had used to secure the ducting to the unit. They had been to short for the 8" diameter sleeves, about 24", so I picked up some 36" heavy duty zip ties at Home Depot on the way over. This is the Fantech SHR-2004 model:

Air intake vent through the outside wall

Looks like the screen on the intake vent is pretty dirty!

Exhaust Vent showed plenty of outflow.

Duct tape for cleaning the vent screen

A little debris from the intake vent screen

36" zip-ties are plenty long for a secure grip for the ducting

This duct is securely held in place for life!

Time to open the unit itself

Flip the latches down and out to open the door.

The HRV Core

Slide it out.....

Vacuum the screens, or "soak in soapy water for 3 hours" if super-dirty

The ever-present dead insect population

Slide core back into place after cleaning

Slide door on the hinges on top from left to right

Close latches

Good for another year of radon removal

Core Drilling

Often I have requests to drill under the concrete section of a house from the outside. Here is how it is done:

Sealing Your Crawlspace

I thought I was finished with radon work for 2011, but I had a follow-up visit to a home where the radon levels have stubbornly remained above 4.0. This time I concentrated on sealing the existing vapor barrier in the crawlspace. After about 4 hours of taping and sealing, I got the vacuum gauge to show a slight increase in suction for my efforts:

Manometer/Vacuum Gauge at the Start 

Sand and gravel helps seal difficult areas around cement pillars

Leftover tile pieces serve to seal the perimeter 

Specialty seam tape for sealing tears and other openings 

Gravel for sealing openings around the water heater 

Bricks circa 1910 seal off the sloppy edges 

A hair-increase in vacuum is actually significant for this size area!

Crawlspace Radon

I had to return to a property recently, because our post-radon test showed radon levels in their basement apartment to be about .7 above EPA safe limits, although upstairs levels tested safe. The apartment is next to the large crawlspace, and I was to attempt to dig under the basement concrete slab horizontally, from the crawlspace.

Unfortunately, I could find no gravel layer from the outside, so I have to return again tomorrow, to attempt to drill directly through the concrete floor from inside the apartment to find that gravel layer. If we find that there is no gravel layer, the only alternative will be to install a heat recovery ventilator.

Digging below the foundation 

Nothing but concrete - on dirt 

Current vacuum levels 

Sealing loose sections with sand raised vacuum levels a bit.... 

Our original opening was sealed back up 

Some loose tile helps seal the edges 

Sand is also good for sealing loose edges of the vapor-barrier 

Sand seals around the base of the A/C unit 

A pillar is a leaky spot until we pour sand around it. 

Placed a trim ring around the pipe exit

Wasted Wednesday

I traveled up to Goodlettsville today, to install a basic radon mitigation system. Of course I had to do the standard diagnostic testing for adequate airflow under the basement concrete slab before I began installing the main system. In this case the house failed the test, so it was a complete wasted morning-no installation occurred.

I think from now on, I will charge $75.00 for the diagnostic part, applicable towards the original estimate if the house passes the test, otherwise I lose that amount on travel expense and labor.

In this particular case, the concrete was about 10" thick and directly on dirt, so there was no crossflow of air to work with:

 Concrete Basement

 Client wants the pipe to come through the concrete wall to the outside, here.

 Time to christen my new and improved Bosch hammer drill

 The pilot hole from the outside comes through the basement wall at a good spot and luckily not into that black pipe there.

 We'll need a 3 5/8 diameter hole, here.

...But first we have to check beneath the concrete floor for a gravel-layer. X marks the spot. 

"Ready for Radon" 

This time, a 1 inch bit will be needed. 

My small industrial vac with a big motor. 

The work area. 

 So far, 10" of concrete and no sign of gravel. Maybe we're too close to the wall? The new Bosch hammer drill performs amazingly well in concrete and it doesn't try to tear my arm off, unlike the el-cheapo hammer drill I used from 2008 through last month.

5" further in should get us away from the footer. 

This time we hit some hard-packed dirt at about 8", but no gravel to be found. I will recommend a heat recovery ventilator. A subslab ventilation system will likely fail.

Concrete in a tube to patch the test-holes. 

 And some foam backing-rod filler.

We were never here......

I also patched the smaller hole to the outside.

Wasted trip. At least the dog was friendly.