Heating & Ventilation - Part 1

It's been too long since I last wrote about the adventures of building this passive house. March I believe. When we passed our first blower door test. Most homes could be built in the length of time since my last post, but not Casa Tortuga. I joke that maybe we should have named the place Puma Palace and things may have happened much faster around here. But where's the fun in that?

 

Much has happened here since March. We have actually moved into the house and Priscilla has
left Turtle Falls for her next adventure. Will we miss her? Yes. And NO! The camping memories with
family and friends will always be a highlight of the Priscilla years. The cramped quarters, the leaky
roof, the outhouse...in the middle of the
night, the ants, black flies, mosquitos and deer
flies, the lack of showering and laundry facilities,
the mice, the mice and...THE MICE! These are
just a few of the things we will not miss.

Moving on...

Recently someone asked us what has been the
most challenging or difficult part of the building of this house. Unequivocally, it has been the heating and ventilation system. Not because it is a difficult thing to do, but because we are building a house that no one in the building department in this township has ever seen. Mass confusion and misunderstanding ensued!

To back up a little, we originally were going to install an EcoLogix cold climate heat pump. After going through the whole process of having the heat/ventilation system designed for Casa Tortuga we were advised that maybe EcoLogix wasn't quite ready to offer the customer service we would want in the future. The product is apparently quite awesome, the support...not so much. Then we got jostled around from a ducted Daiken multi-split heat pump/Zehnder ERV (energy recovery ventilator) system to a ducted Mitsubishi multi-split heat pump/AirPohoda ERV system and finally to two individual ductless Fujitsu mini-split heat pumps/Zehnder ERV system.


Zehnder ComfoAir 550 Luxe ERV (L) with the
ComfoFond Brine Loop (R) option.

The move to a local HVAC company rather than the original company chosen by our architect makes for the first change for our system. The second, the heat pump we wanted was not available yet and the ERV was not on the approved list. And finally we settled on the best available cold climate heat pump and ERV options available to us for the least amount of grief. All the best laid plans of mice and men...

Too many mice may have been our problem, I think.

Or it could be said that the building inspector has been the main reason for so much of the jumping around from system to system. AirPohoda, virtually unheard of here, has not yet made it to the list of approved ERVs for Canada and as much as we fought to get this incredibly efficient system in our house, the inspector was making the hoop-jumping impossible for us. Our last option was to go with something that was on the approved list. The Zehnder products are recognizable and approved here in Canada. And even though the efficiency of the AirPohoda trumps the Zehnder by a few percentage points, this machine is also pretty impressive.

Having a tightly sealed house requires good ventilation. The ERV runs silently in the background 24/7 exhausting the stale air and replenishing with filtered fresh outdoor air. Within the confines of that darker gray box hanging on the wall, like magic, the majority of the heat from the warm exhaust air gets transferred (with no cross contamination) to the incoming fresh air. Efficiency at its best.

Sometimes more details are just not necessary. It's kind of like electricity for me...flip a switch and a light comes on. I don't need to know how it works, I just need to know it will work. Same goes for the ventilation. Plugged it in. It works. I'm happy. Finally! It sure was a long haul getting to this point.

The brine loop option (the light gray box) bumps up the efficiency of the ERV even more by pre-heating (pre-cooling in summer) the incoming fresh air. There is just under 500 feet (152m) of glycol-filled 3/4" Pex tubing buried in the ground on the north side of the house. While air temperatures can occasionally go below -30°C (-22°F) here in the winter, the ground temperature stays fairly constant at around +10°C (50°F) past 4' (1.22m) below the surface. The ground loop will temper that -30°C (-22°F) outdoor air so the ERV will work more efficiently. This will also work in reverse in the summer time when air temperatures are +30°C (86°F). The ground loop will help to lower the temperature of the incoming fresh air before it even reaches the ERV.

With limited space for the ground loop, the 500' (152m)
was installed in layers with a minimum of 2' (0.6m)
of fill separating each layer. The top layer of tubing
 is 4' (1.22m) below the surface.



The 2 smaller grey vents are the intake and exhaust for the ERV. At the 
time of this photo, the spray foam around each pipe and cutting pipes to
length is yet to be done. These need to be tightly sealed to maintain our
super tight air seal.

The two units sitting on the stands in the photo above are the mini-split heat pumps. I will talk about those in the next post since I've probably already bored you to tears with this post. Lucky for you...there will not be a 7 month wait for the next post.

And for those thinking of building a passive house, fear not! Our experience building a passive house is by no means typical. Far, far from it. Although we may not have approached this project with the simplest of ideals and plans, the resulting house is proving to be completely 100% worth the seemingly never-ending grief and gargantuan effort. As I write this, the morning sun is streaming in the gorgeously large east windows, gently warming the interior...for free. Life is good.

We remain grateful to the ever expanding league of extraordinary gentlemen helping us breathe life...and fresh air...into this labour of love known as Casa Tortuga.

Happy Thanksgiving to all the Canucks out there.

Thankfully,
Mimi