Lessons learned: 1st floor ventilation

We have a special friend. His name is Erv, and he brings us fresh air into the house year round. Other people have the same friend, but they call him ERV, or sometimes by his full name: Energy Recovery Ventilator.

The ERV is a well appreciated equipment. Because our house is almost completely airtight, we need mechanical ventilation to remove the stale air and bring in fresh air. The ERV does just that, assures good indoor air quality, and in the process keeps us comfortable with the enthalpy wheel. It acts as a heat exchanger and removes excess moisture.

I like to put it this way: Using the ERV is like keeping windows open during the winter to get fresh air in, with the exception that it doesn’t get cold. It works so efficiently that it helps us to delay our heating season by up to four weeks.

The fresh air is distributed across our 1st floor apartment through a system of ducts, supplies and returns. I was about to embark on the ductwork installation project for the 2nd floor. But before doing so, I wanted to review our 1st floor ventilation system: What worked, and more importantly, what could we have done better?

Stale rooms (with a lowercase s)

The 1st floor ventilation system has fresh air supplies in key rooms to assure fresh air distribution across the apartment. A series of undercut doors, ‘indoor pressure balancers’ and ‘between room vents’ help move air from room to room and to eventually to the returns in the two bathrooms.

We can easily flush stale air out of the apartment by cranking up the ERV. However, if we run the ERV on the low setting (low airflow), the library and living room remain somewhat stale for longer than any other rooms in the unit.

In other words, the fresh supply air is not mixing sufficiently with the room air. The velocity from the fresh air supply in the foyer is good, but too slow when moving on to the library and living room.

To avoid something similar on the 2nd floor, I plan on adding a fresh air supply to the library and living room.

Noise transmission

The first time we fired up our first floor ventilation system, it sounded like a roaring jet engine. That problem was quickly solved with two three-foot pieces of insulated flex duct connecting the ERV to the rigid ducts. I made sure we had a 90 degree bend in each flex duct, and our ventilation system fell completely silent – almost.

While the noise transmission from the ERV is under control, we still had some transmission from room to room. For example, the fresh air supply of the office and foyer are connected by a six foot duct. The noise transmission through this short duct is as such that two people – one in the office and the other in the foyer – could have a conversation with each other. The longer the duct between supplies, the more faint the noise transmission.

To minimize the room-to-room transmission on the 2nd floor, I plan on using a three foot piece of insulated flex duct with a 90 degree bend right after every supply to act as a sound muffler. This will also increase friction and reduce velocity, but I will try to make up for it through more generous duct sizing.

2nd floor ventilation layout

The plan below shows the 2nd floor ventilation layout with the improvements mentioned above:

  • Using flex duct at each supply as a sound muffler to reduce room-to-room sound transmission
  • Adding fresh air supplies to the library and living room to improve mixing with the room air and a more efficient flushing of the stale air, even at lower airflow rates.

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Putting a frame on the kitchen ceiling

My to-do list for the second floor is long. Two items at the top of that list are the ventilation duct work and the electrical installation. Before I could get to those two items, I had some ceiling framing to finish.

In preparation for the roof insulation, we removed the ceiling joists in the back third of the second floor. This was so we had enough room for the insulation and the ventilation duct work.

My friend Rubani and I had begun to rebuild drop ceilings in the bathroom and guest bed room. It was now time to tackle the framing of the kitchen ceiling.

When we removed the ceiling joists, I put them to the side so that they could be reused for the drop ceiling. These are old growth two by six, meaning they actually measure two inches by six inches, compared to the nominal lumber which measures one and a half inches by five and a half inches.

That matters because I have to use joist hangers. And joist hangers are made for nominal lumber.

I was in no mood to carve the ends of the old growth studs to fit the joist hangers. It turns out that you can find joist hangers for old growth lumber online. Ordering them took a little longer than picking the up at the store, but it saved me time and a headache.

 

Thanks again to Rubani for helping me to lift the old growth two by six into place!

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Pot rack

Let me try something very different today: This is my attempt to write up a recipe using only leftovers.

We have a very nice and useful collection of cooking pots and cast iron pans, but they’ve begun to clutter up our kitchen. That sparked the idea for a recipe with left-overs. Here we go:

Ingredients:

  • Salvaged old growth stud scraps (preferably close to a 100 years old)
  • Leftover 5/8 inch poplar dowels
  • Leftover wood glue
  • Leftover VOC free lacquer

Preparation:

Carefully place the old growth scraps on prepared saw horses and clean them (some people refer to this process in a rather rough and tumble way as de-nailing).

To assure the most delicious surface texture, I recommend rubbing the old growth studs with 60 grit sandpaper first, followed by 120 grit. For the gourmets among us, keep rubbing with 200 grit.

Core the cleaned and prepared old growth scraps at the desired intervals. For the best possible presentation, it is recommended to match the core size exactly with the size of the leftover dowels.

Next, chop the leftover dowels into the appropriate lengths. Shorter pieces feed into the old growth scrap connection. Longer pieces stretch across.

Carefully marinate the short pieces in wood glue and immediately insert into the prepared old growth scraps. Only marinate the ends of the long pieces and immediately place into the prepared cores.

Carefully clamp the ingredients and let rest for at least 12 hours.

Remove clamps and glaze with two coats of the leftover VOC lacquer. It is recommended to let each coat bake at room temperature for about four hours.

Et voilà, a wonderful pot rack entirely made from leftovers!

  

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Winterizing the rain barrel

Did you notice that jumbo ice cubes for cocktails are all the rage? How about a 250 gallon mega ice cube? That would be my full rain barrel frozen solid.

Well, maybe not. I would like to keep using it next season and rather not have it burst because it froze. To protect it from any winter damage, I went through the task of winterizing in early December before freezing temperatures settled in for good.

Come springtime, I’ll basically reverse the winterization steps and have it back in operation in no time.

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Minisplit winter operation

Our minisplit kept us cool during the dogs days of summer this year, and without having our electrical bill going through the roof.

But the minisplit can do more! Because it’s an air-source heat pump, it also can heat the building during the cold season. And that was something I wanted to put to the test when it recently was really cold outside.

Like I mentioned in the video, I simplified my explanation about how the system works. If you would like to read a more comprehensive and accurate description, you can find it in a previous blog post with the title “Mini what?

The morning after I took the video, our outdoor temperature had dropped to -5F, the specified minimum operating temperature. I turned the minisplit on and indeed, it still was putting out heat.

While the outdoor unit was almost inaudible during the summer when we ran the minisplit in cooling mode, it was humming away pretty good in the heating mode, as you can hear in the video. I assume that the compressor has to work harder at these cold temperatures, thus the increased noise. Not that it matters. All windows are firmly shut anyway, keeping the noise out.

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