Friday, January 8, 2016

Interior Pictures Prior to Move-In

It's been nearly two years since my last post and I've been meaning to follow-up with some passive house post construction articles--as I believe that sort of information is lacking online.

Now that Lisa and I have a good number of years under our belt living in our passive house, I will be posting some additional stories based upon our real-world experiences.

I continue to receive questions from readers interested in passive house (or energy efficient) construction and I would hope these upcoming articles can answer some of them.  I am open to suggestions for other topics that may be of interest.

Topics planned, include:
  • Real-world heating/cooling performance
  • Electricity monitoring with SiteSage (formerly eMonitor)
  • Earthtube status update
  • ERV performance & maintenance
  • Development cost analysis versus house appraisal
In the meantime, I realized that I have not shared any pictures of the interior of the house.

As I indicated at the outset of our project documentation, we wanted to design a luxury house that looked more conventional and less like a science project.

We think we hit this design goal.  Below are some pictures and videos of the interior of the house shortly after construction and before move-in.

Foyer, South Facing

Custom exotic wood staircase

Bridge railings

Dining room, 1st floor

Guest bathroom 2nd floor

2nd floor master bathroom jetted tub

Master bathroom 2nd floor walk-in shower

Master bathroom shower backlit stained glass

Master bathroom 2nd floor walk-in shower

ERVs, earth tube outlets, heat-pump water heater

Triple water filtration system, softener, UV treatment, RO unit

Office entrance

Foyer powder room

Breakfast room adjacent to kitchen

Great room, North facing


Minisplit 1st floor

Office 1st floor

Basement pet room & pet shower

Friday, February 28, 2014

Improving Passive House (Passivhaus) Temperature Performance

Having taken the steps of cleaning both mini splits and the ERVs, identifying appliances of high phantom loads, temperature variances at the intake side of both mini-splits, one mystery remained to be solved: how to figure out a way to extract the greatest efficiency of the mini-splits as we could as we believed our placement was compromising their performance.

I could not understand how a house could maintain an interior temperature of 62F (at its lowest point) when we experienced an extended power outage that lasted 36 hours which spanned two evenings of temperatures in the single digits.  Nor could I understand how the home's interior temperatures could rise to as high as 75F in certain rooms when sunny outside regardless of the outside temperature and yet we struggled to raise the temperatures about 72F when the minis were operating.  .

Since we already determined a connection between our Stiebel Eltron heat-pump water heater and the mini-split located in the basement, I decided to install some foam material--that we had used for insulating our basement slab-- between the floor joists located in the ceiling directly above the mini-split.  The hope was that by preventing the cooler air in the mechanical room from supplying the intake of the mini-split, its temperature sensor would be more accurate than before and hence the heating performance would be more accurate and eliminate the need for installing a remote thermostat.

I am pleased to report that this effort was successful.  The temperature setting of the basement mini-split is now more inline with the actual temperature of the entire basement.  Furthermore, no longer does the mini-split kick on whenever the Accelera's heat-pump engage.

Having corrected the basement, the next area that we needed to address was the family room mini-split.  This one was especially important because this was the unit that provided heating for the 1st and 2nd floors.  The solution turned out to be very simple.  What we did was create essentially a vent that connected the closet area of the 1st floor master bedroom--an area located directly behind the curved staircase leading up from the foyer to the 2nd floor bridge.  The temperature of the air there is more along the lines of the temperature of the rest of the house.

I cut a small rectangular area into the drywall of about one inch in height and as long just above the intake of the family room mini-split.  I was thrilled to find the the supply temperatures of the air that were now being supplied dropped to within 2F (down from 12F) and set temps are much closer now to actual rooms temps.

I also determined that the apparent COP increased from a low of about 1.85 to approximately 2.45 at a given outside and interior temperature.  The reason for this was the mini-split was no longer being asked to raise the temperature from 82F but a more realistic 68F.  Looking at the performance chart of the Fujitsu RLS2s it is clear that heat production, in terms of BTUs, noticeably drops as the interior temperatures rise and hence heating efficiency as well.

At a low last night (Feb 16th, 2014) of about 18F (very nearly at the temperatures used for determining heat-loads) throughout the night and a high of 24F with overcast conditions, the day earlier, the observed improvements have been dramatic. No longer are the temps falling to 66-67 in the family room through the night regardless of the mini-split temperature settings.  Family room set temperature was 70F.

Following are the temperature profiles of the rooms taken at 7.00-7.30 with an outside temperature of 18F at the time of readings.

Family room set temp: 70F
Average nightly usage: 1400 watts

Master bathrom (1st floor): 69.2/48%
Master bedroom (1st floor):  69.4/48
Family Room: 71.7/45%
Kitchen: 70.8/45%
Laundry: 69.4/47%
Bird Room: 69.0/47%
Dining Room: 70.5/48%
Study: 70.1/46%
Bridge: 71.9/44%
Master bedroom (2nd floor): 70.8/47%
Master bathroom (2nd floor, south facing): 68.3/49%
Back bedroom (2nd floor, north facing): 68.9/47%
Front bedroom (2nd floor, south facing): 69.6/48%
Shared bathroom (door closed): 68.9/50%

Basement mini set temp: 66F
Nightly usage:  ~700  watts continuously

Basement: 68.0/39%
Mechanical Room: 67.8/42%
Pet room 67.1/41%
Bar Room: 67.6/41%
Movie Theatre Room: 68.0/42%

Total average about 2.2kw between both units.


Family Room:

According to Fujitsu, electric consumption of 2000 watts results in approximately 17,000 BTU/hr at a COP of 2.49 (improved over 1.8 historically) at the temperature conditions experienced.

Therefore, at about 1400-1500 watts this equates to about 12,300 BTU/hr or 12,000 BTUs--its nominal heat production rating.


Electric consumption of  700 watts equates to about 6,000 BTU/hr.

Consequently at about 18,300 BTU/hr production to maintain or slightly raise temperatures throughout night suggests a heat-load of about 2.8 (per square foot).  Our PHPP modeling predicted a similar number, which goes to show how accurate and thorough the PHPP modeling software is.

These results also suggest that we actually did have the heating capacity to handle the entire conditioned interior space (TFA: 6600SF) with only one mini-split (even with the heat-pump DHWH robbing some interior heat from us).  All we need to do is take install a blown ducting connection between the first floor and the basement (which could be reversed during the summer months), which is our next project to undertake.

The observed results also suggest that room-to-room temperature variation has noticeably improved and we do not appear to need the supplemental heating coils installed in the ERV supply ducts as we had believed we may.

I am kicking myself for having not discovered our design "flaw" earlier as we have now been through two summer and winter seasons.  Perhaps had it not been for the fact that this winter has been the coldest one in thirty years and one that has given us plenty of days and evenings below the design temperatures of our climate, we may not have caught this.  Without question, eMonitor (now called Sitesage) has played an integral part in assisting us in our resolution.

Tuesday, February 18, 2014

Passive House Electricity Consumption: Reducing Electric Use

Current Electric Consumption

I am pleased to report that I have solved some of the issues that I have been experiencing of late during this especially cold winter season. 

In a previous article, I had indicated that I had received a higher than expected electric bill for the month of December.  As a result of this, I began to investigate where and what I needed to address to bring future bills more into line with what I was expecting.

To summarize, I undertook several corrective actions:

1) Cleaned both Zehnder ERVs to return their efficiencies in heat exchange to specified levels.  By cleaning thoroughly cleaning the enthalpy unit and the filters the temperature deltas between the supply and return were significantly improved.

2) Cleaned both mini-splits' filters and condenser units--that were absolutely cruddy--with a vacuum cleaner, toothbrush, and some water misting.

Both of these steps made substantial improvements to performance and in the case of the mini-splits the high level of work they had to do (energy consumed) to do very little was rectified.  They are now running using significantly less energy on average, producing better air flows, and are providing more consistent temperature performance at a higher COP.

These experiences have taught me that it is extremely important to perform routine checks and cleaning (when merited) to ensure tip-top performance .

Also in the case of the mini-splits, I experienced on one occasion a loss of some coolant early on.  Speaking with someone who installs these, I learned that this occurrence isn't entirely uncommon.  Furthermore, the mini-split in the family room (providing heat to the majority of the house--1st and 2nd floors) needs a replacement fan blade.  It is partially broken which is probably hurting heating and cooling efficiency somewhat.

Both of these remaining issues will be resolved when my HVAC contractor comes out to service them.  I would suggest that owners of minisplits routinely have their units checked.  I understand that the fan blades can often pick-up "crud" from accumulated dust and debris coupled with some moisture.  If the condenser, blades, and/or the condensate lines get gunky or clogged things can go sideways.  Take my advise and have them checked routinely (perhaps as frequently as twice a year).

Our eMonitor (now called SiteSage) system is continuing to prove its worth to me.  Using it, I have been able to confirm some of the problems mentioned above by their impact upon energy consumption.

I have since unplugged a wine cooler because it was a electricity hog, consuming about $24 per month alone in electric, placed some electronics on separate power switches, and identified three appliances consuming relatively high levels of phantom power--both Fujitsu mini splits and the Grundfos well-pump.  Between them they are consuming about 350 watts of electric continuously.  I will be looking at inserting a water pressure switch to cut-off electric to the pump controller when not in use and am considering manual toggle switches of some sort to cut the power to both minis when they won't be needed.

The minimum draws I have been seeing or about 620 watts.  Losing another 330 would get me below 300 watts nominal draw for the whole house--amounting to about a 50% reduction over current levels.  That amounts to up to another $20-$40 month of reduction in electric costs, potentially.

I can't stress enough how important it is to research the phantom loads of any electronics that you incorporate into your project.  While the Grundfos well-pump is certainly efficient when it runs, the overall efficiency is reduced because of such high levels of standby power consumption.  Speaking to Grundfos technicians, they themselves were not entirely knowledgeable of this fact and as such have taken my feedback to hopefully affect some changes.  In the meantime, I am on my own to come up with a solution.  The newer Fujitsu RLS2hs I understand have even a higher level of standby power consumption than our RLS2 models.  I am pleased to report that our Miele kitchen appliances are good stewards as is the Stiebel Eltron Accelera heat-pump hot water heater.  The Zehnder ERVs are also incredibly small consumers of electricity when running.

The next area of tweaking has positively affected the temperature performance and overall comfort levels in the home.  I will be covering this in my next article.

Monday, February 3, 2014

eMonitor: Passivhaus (Passive House) Whole House Electric Energy Monitoring System

eMonitoring the Heartbeat of a Passivhaus/Passive House

eMonitoring refrigerator power consumption over time
Ever since I saw a presentation at the PHIUS convention in Maryland some years back, I had considered implementing a whole house energy monitoring system for our home as I am a stickler for obtaining real-world performance data regardless of projects I work on.  But the events of the last six weeks--as documented in the of the previous three part series of articles--have prompted me to implement a comprehensive whole house energy/electric monitoring system.

I opted for Powerhouse Dynamics eMonitor.  They are not inexpensive and require a minimum of a two-year "cloud-based" monitoring contract, but I believe this system will more than pay for itself.  You are able to run an extensive amount of reporting of the data which is "continuously" collected.  You can even use your smartphone to access the data real-time as there are apps for both the iPhone and Android systems.

A quick snapshot of the top five consumers of electricity

The older system (which I purchased) is the eMonitor24 24 circuit CT monitoring system.  Unlike the newer eMonitor4-24, the eMonitor24 requires direct CT clamping via a wired connection to the base control unit, meaning the panels have to be exposed.  This isn't a problem in our case as they are isolated in the mechanical room.

eMonitor base control module and CT clamps
I didn't even need to read the manual as installation and configuration was a snap.  Once the control module is connected to your network via its ethernet connnection, it quickly phones home and downloads any software updates required.  Configuration takes place on the Powerhouse Dynamics web portal

eMonitor phoning home to retrieve software updates automatically

Already I have found some pigs of energy usage (some of which I already suspected) and unnecessary phantom/vampire loads. As you can see in the below image, the wine cooler is continually sucking 200+ watts (it doesn't appear that the compressor is shutting off).  That's costing me nearly nearly $24 a month in electric, alone.  I have since pulled the plug and will be looking for a more energy efficient appliance.  (Note: You'll also notice some spikes in electric exceeding 1000 watts.  That's because our plumbed super-automatic Miele Espresso maker also shares the circuit.)

eMonitoring Wine Cooler: $0.78/day or $23/month
Without eMonitor, I was only able to take brief snapshots of electric usage with an amp clamp.  With eMonitor I am able to get a two dimensional picture over time (just like an EKG).  I absolutely love it.  eMonitor enables me to observe patterns of compressor operation for the refrigerators, the mini-splits, and the heat-pump hot water heater.  The system can also be configured to alert you to particular set conditions--for example, a power failure (through loss of connectivity). 

I also found the our refrigerator as configured was using a more power than what was otherwise suggested on its EnergyStar label.  Granted it is the largest side-by-side shipping and we programmed the coldest freezer set temperature, but we were a bit surprised to see its impact on consumption.  We have since tailored back the temperature to a more reasonable -18C for the freezer and +1C for the refrigerator.  We feel getting the extended storage capacity of food with colder freezer temperatures are worth the trade off.  We have already seen a modest reduction of compressor operation.

Using coldest temperatures comes at a cost and blows the EnergyStar estimates out of the water

As stated in my previous article, it helped me identify a configuration shortcoming with the placement of the mini-split in the basement in the proximity of the hot water heater.  And now that the minis have been cleaned and are operating more closely to what they should, their power consumption has been largely tamed.

Estimated Monthly Cost of Family Room Mini Split: A Wonderful $28 for February ($0.154/kWh)

Over time, I will be able to get a handle on how the house is actually performing relative to the design goals expressed in the PHPP model and coupled with a whole house room to room temperature monitoring system, I should be able to get a complete handle around our real-world energy consumption.

If we ever decide to incorporate an active grid-tie photovoltaic system, I should be able to now accurately size one according to our actual power consumption requirements.  I will publish more data as I collect sufficient amounts.

eMonitoring usage from Jan 31st, 2014 - Feb 3rd, 2014 of circuits
I have found the eMonitor system a thoroughly well-sorted out and refined whole-house energy monitoring system.  Every home owner, builder, retrofitter of super energy efficient buildings such as a Passivhaus (Passive House), should include one in their arsenal of tools.  It is a wonderful feedback mechanism to your actual accomplishments and can also point to areas where you can improve/tweak your designs.  It is one heck of a teaching tool and it enables you to effectively manage an track your overall energy consumption before you get the bill from the utility company.

Part III: Importance of Mini-Split Placement for Whole House Heating and Air Conditioning

Current Configuration Short Comings of our Two Minisplits Requiring Remediation

While Lisa and I made a bunch of progress improving the temperature performance of our home, one final mystery remained.

When the ERVs and mini-splits were properly cleaned the interior temperatures quickly recovered but once we reached an increase in about four to five degrees, we found it became increasingly difficult to raise temperatures further.  For some reason it appeared that we struggled with raising the temperature of the family room in the evening beyond 70-72F and I was at a loss to understand why.   With potentially 16,000Btu on hand (with these outside temperatures) with two units, I couldn't understand how they could so effective at quickly increasing the temperature from 66F to 71F and yet they couldn't seem to raise the temperatures further even after an extended amount of time having the minis set to 76F.

Sure we were experiencing some stratification in our open two story family room and foyer (ceiling fan was not on) and our 2nd floor tended to be warmer as a consequence, but I was still at a loss to explain what was going on.

Speaking with Jason Morosko of UltimateAir he did some quick calculations of how many more BTUs--than we were generating--that we would need to raise the temperature of the house taking into account the heat loss of the ventilation system at a given flow (air exchange rate).  It appeared that all we needed was an additional 3600 BTUs to do the trick during these super cold nights (of -1F).  But 3600 BTUs over what exactly?  How much production were we actually producing?  Between both units I figured we had a total capacity of about 32K BTUs given these outside conditions.  Which would mean we would need a total of about 36K BTUs, but that was assuming these units were always running at maximum capacity (which they were not).

Upon measuring their energy consumption, it appears that their nominal power consumption is about 585 watts each or about 2.7A at 240v.  Assuming a COP of about 1.85 at these low outside temperatures that would mean that each was producing about 3900 or a total of 7800 BTUs combined.  Surely we had another 3600 BTU potential between both of them without then need for yet another unit.

Yet even if we cranked the set temperature to 80F the family room would not get beyond 71.9F.  Something was up. But what was it?  After some serious head scratching and a couple of discussions with our Fujitsu installer, John, the potential answer became clear.  John had suggested that we take a temperature reading on the high side of the unit, the intake side, to measure the temperature.  I knew there was some temperature stratification going on (on the 2nd floor), but I wasn't expecting anything at eight feet off the floor.  Well was I wrong.  As it turned out we measured temperature differences as high as 12F or more above the unit!

I didn't realize how serious this situation could be until I had the mini-split set to AUTO instead of its heating/cooling/dry function.  By happenstance one evening before I was going to bed, I turned the temperature down a couple of degrees C (about 4F).  About 10 minutes later I walked by the unit on the way to the bedroom and was surprised to feel "cool" air blowing out of the unit.  It occurred to me that the unit actually was going into air conditioning mode!  Clearly this was a mistake on my part.  Here I was expecting the unit to go in standby monitor mode, but instead it went to cooling mode to lower the temperature.  Clearly during the Winter season, the minis should be on HEATING mode only.  That was my first lesson.

The second lesson came from the temperature monitoring of the intake side of the minis.  I finally realized that the overhang of the bridge and the nature of its ceiling (recessed as it is) was acting as a trapping mechanism for the heated air that was blowing out of the unit!  This is why the unit peaked and stopped heating even with high set temps.  We measured air with temperatures in excess of 82F that was being trapped.  This could also be accounting for the seesawing or the rapid cycling ramping up and ramping down of the minis.  This hurts power consumption because when the units ramp up, they ramp up with a lot of power before settling down to their nominal operating range.

Fujitsu 9RLS2 mounted in a "pocket" close to bridge overhang

Delving deep into the technical manuals we come across a temperature correction function setting for both cooling and heating modes.  While not documented well the Fujitsu minis have the ability to have their temperature readings altered.  The programming functions to do so are FUNCTIONs 30 and 31.  Each function has four values.

Cooling Mode (FUNCTION 30):

Value 1: 00 - No correction (default)
Value 2: 01 - Slightly cooler correction -4F than indicated
Value 3: 02 - Cooler correction -8F than indicated
Value 4: 03 - Slightly Warmer correction +4F than indicated

Heating Mode (FUNCTION 31):

Value 1: 00 - No correction (default)
Value 2: 01 - Slightly cooler correction -4F than indicated
Value 3: 02 - Slightly warmer correction +4F than indicated
Value 4: 03 - Warmer correction +8F than indicated

At a setting of 02 for FUNCTION 31 this would mean that the unit would allow for a temperature of 76F measured before ceasing heating with a room set temperature of 72F.  In our case the temperature deltas have been as high as 12F.

This really limits are ability to use this feature.  The better option for us is to install a wired thermometer and control panel somewhere in the room away from the overhang.  This is our next step.

In the basement, the opposite situation was going on.  The basement mini split was mounted high to our ceiling on the wall adjacent to the mechanical room.  Once again I was befuddled with another mystery.  The room was consistently warmer than the set points of the mini.  I couldn't understand why the 9RLS2 would continue to heat when the room was quite a bit warmer than its set point.

I didn't figure this out until last night with the help of a Powerhouse Dynamics eMonitor24 whole house energy monitoring system (more on this in a future article).  Just before the Super Bowl, I took a shower.  As I began watching the game, I took a quick look on my iPhone's eMonitor app.  What I noticed was as the Stiebel Eltron heat-pump hot water heater was running, so was the mini split at maximum power.  How could this be?

The room was at its set point temperature and yet the unit is cranking out the BTUs.  Looking at both power charts--those of the DHWH and the basement mini--I saw the correlation.  As the Accelera 300 was running, it was cooling the mechanical room by as much as four degrees.  The problem was that the location of the mini-split put its intake on directly on the other side of the wall and sure enough I discovered the intake temperature  was being artificially lowered as the hot water tank's heat pump was blowing cooled air from its exhaust towards the wall that where the mini split's intake and thermostat was located.  In fact it is appearing, every time the hot water kicks on, so eventually does the mini split.  Once again a correction needs to be made with the installation of a remote thermostat and control panel.

Fujitsu 9RLS2 located high on the wall adjacent to mech room
Stiebel Eltron Accelera 300 Exhausting Cooled Air Toward Min Split

Current room temperature in excess of 69F while set temp is 64F
Remediation Solution

So there you have it.  While I may have made some poor choices in location of our mini-splits (in part for the aesthetic value), I would recommend that any builder/designer of an energy efficient home--be they Passivhaus, LEED, or Builders Challenge--that plans on using ductless mini splits choose their locations carefully and install a remote located controlling thermostat.

Part II: Importance of Maintenance and Upkeep for Maintaining Optimum Passive House Temperature Performance and Minimal Electricity Consumption

Maintaining Peak Mini-Split Heating and Cooling Efficiency
Having made some substantial improvements to our ventilation system we looked to our heating system.  I had suspected that our Fujitsu 9RLS2 ductless mini-splits were not performing as they should and had initially been under the impression that there may have been something going on with our outside units, but instead what I found was something vastly more simple that was to blame.

Just like I had been remiss with my upkeep of the ERVs, so it was with the mini splits.  Opening the covers up, I was shocked to find that the filters were completely "clogged" with dust build up.  I knew these things acted like vacuum cleaners for the air, but even I was floored when I saw how much these systems collected.

Dirt Filters Kill Mini-Split Heating and Cooling Performance
It was no wonder then why these units were performing so poorly, both with their heat output and with their air flow.  Here I was believing that I would need additional supplemental heat either by adding another mini-split (costly), an ERV post heating system (somewhat costly), or a number of space heaters (inexpensive) when all I really needed to do was to do some simply housecleaning maintenance of my minis!  I felt like an idiot that I didn't think to look at this possibility earlier.

One dirty filter!
Filter cleaning is very simple.  Once the replacement filters were put back in them supply temperatures returned to 120-130F and flow rates were way up.  Within a couple of hours the temperatures of the house rose 3-4 degrees.

Vacuuming the Condenser Unit with the Filters Removed
Here we were going through one of the coldest winters in recent memory and we weren't even bringing our A-game and our comfort and our wallet were paying the price.  No longer were the minis cycling frequently nor consuming 1500-2000 watts for extended periods of time without giving us much in return.

Big power consumption, little heat output!
Beyond the cleaning of filters, I noticed the condensers also appeared pretty gunky.  When these units were originally installed the home was still going through its finishing construction.  While the dry wall had been up, painting and sanding was under way and our on-site custom built stair case and railing system had been underway.  The amount of saw dust that was generated was staggering and even with the mini's filters in place plenty got past them.

I decided to disassemble wall units and give them a thorough cleaning.  I found a small toothbrush was every effective at cleaning the units along with spraying a blend of Clorox and water.  Fujitsu told me that it was not uncommon for the blow unit to get a build up of gunk, but I was unsuccessful at getting to this component.  I will leave that to my HVAC contractor.  Perhaps leaving that to an annual checkup.

Having completed my cleaning, I can say the units appear to be running much more efficiently and effectively.  They may even be operating at a level where I actually do not need any supplemental heat at all, even with temperatures below our design thresholds.

Both of these experiences have taught me the importance of system upkeep.  Passive houses certainly can have less complex mechanical systems in place that need servicing, but the ones that are there clearly require constant attention to ensure they are operating at peak efficiencies.  Having a house full of pets certainly adds to the dust factor and while the air is being "scrubbed" by the MHVR and the mini-splits, there is an increased stress on the filtering systems as a consequence.

Part I: Importance of Maintenance and Upkeep for Maintaining Optimum Passive House Temperature Performance and Minimal Electricity Consumption

Maintaining Peak ERV Efficiencies

As I indicated in my previous post, December's electric bill was higher than we had expected.  This Winter is proving to be especially cold and outside conditions have frequently exceeded our heat-load design parameters.  We have a had a couple of days where our temperatures were below that of International Falls and more than a couple of days where we were below those of Nome, Alaska.  This morning it was -1F. 

We also running a number of computer systems here 24x7x365.  I recently got a Kill a Watt meter and have gone throughout the house identifying and eliminating unnecessary phantom loads from equipment left on that do not need to be.  We have moved some of our entertainment equipment off to a power switch and have turned them off and we are being mindful of turning off the two laser printers that we have in our home office. 

Beyond the higher than expected December electric bill, we had been finding that we were experiencing some room-to-room temperature variances that were greater than expected and we also began questioning the performance of our two mini splits.  Both units felt like they were working hard(er) but not really delivering the heat that we desired.  I was beginning to believe that perhaps we had been experiencing a coolant drop in our heat pumps.  Yes the COPs drop when temperatures get really low, but even at these super low evening temperatures, the Fujitsu RLS2s should have been producing a good amount of heat.  What I instead was finding that when they were running, the supply temperatures were only in the 90s not the 120s or 130s.  Clearly something was amiss and the temperatures in the house suffered as a consequence.

On January 4th at 07.35 we took spot readings throughout the home.

South Laundry Room: 65.3F/46%
South Bird Room (Door Closed): 63.8F/48%
Mud Room: 64.4F/48%
East Kitchen: 65.3F/47%
North Family Room: 66.3F/44%
West/North Master Bed 1st Floor: 66.3F/46%
Master Bath 1st Floor: 66.2F/47%
South Dining Room: 66.2F/43%
South Study: 66.2F/43%
Powder Room 1st Floor: 66.2F/42%
South Foyer: 66.5/43%
Bridge: 69.8F/39% 
West/North Master Bed 2nd Floor: 69.2F/40%
West/South Master Bath 2nd Floor: 65.4F/45%
North Facing Bedroom 2nd Floor: 64.2F/41%
South Facing Bedroom 2nd Floor: 64.5F/43%
Basement: 66.5F/43%
Media/Movie Theatre Room (Basement): 66.5F/43%
Mechanical Room (Door Closed with Stiebel Eltron DHWH): 66.2F/41F
Bar Room (Basement): 66.3F/42%
Dog/Cat/Pet Laundry/Grooming Room (Basement): 65.6F/42%

I first looked at both of our Zehnder ERVs and took temperature/humidity readings at each of the four ports of each.  This is what I found.

Zehnder Novus 300 (Paul)

Intake (EAT Supplied): 46.4F/38%
Exhaust: 51.2F/44%
Return: 66.7F/42%
Supply: 62.7F/41%

Zehnder Comfoair 200

Intake (EAT Supplied): 48.9F/35%
Exhaust: 52.8F/31%
Return: 67.2F/43%
Supply: 57.5F/30%

As you can see the 10 degree temperature delta between the supply and return temperatures of the Comfoair 200 was indicating something was awry and could be accounting for rooms of the house (supplied by it) that were noticeably "colder" than others, especially when their doors were closed.

The very high heat-exchange efficiencies of the Zehnders (92-93%) should be allowing for a greater amount of heat recovery (temperature) between the supply and return.  In the case of the C200 we were off six additional degrees than the Paul unit.

Examining the duct connections, I found some areas where leaks were occurring which could account for some pressure imbalances.  Using special duct tape, I sealed those areas.  Next I examined the filters of each unit.  Sure enough, they needed cleaning and with several of them, I outright replaced them with new ones.  I then took off of the covers of each ERV and removed the enthalpy units.  They were an absolute mess!

I used a vacuum cleaner and a brush to clean them off thoroughly.  I even sprayed a little bit of clorox and water blend onto the grills of each.  Fortunately both Zehnders are easy to disassemble and clean.

Once everything was back together and running I retook my measurements.

Zehnder Novus 300 (Paul)

Return: 67.6F/44%
Supply: 63.1F/45%
Exhaust: 51.2F/47%

Zehnder Comfoair 200

Return: 68.0F/43%
Supply: 63.6F/42%
Exhaust: 52.8F/53%

Clearly one can see that we got our expected efficiencies back, picking up more than six degrees on the supply side of the C200! 

Later in the day without any other changes we retook most of our readings through out the home:

At 13.35

East/North Facing Bedroom 2nd Floor (Door Open): 69.6F/41%
East/South Facing Bedroom 2nd Floor (Door Closed)  70.3F/38%
East/South Facing Bedroom 2nd Floor (Door Open): 71.7F/38%
Bridge (overlooking family room): 71.4F
Bridge (overlooking foyer): 73.1F
West/North Master Bedroom 2nd Floor: 71.2F/40%
West/South Master Bath 2nd Floor: 72.3F/40%
East "Shared" Bathroom: 71.0F/40%
South Dining Room: 71.2F/39%
South Study: 71.0F/39%
North Family Room: 71.0F/39%
West/North Master Bedroom 1st Floor: 69.4F/42%
Powder Room 1st Floor: 69.8F/43%

Beyond the heat gains of the morning and early afternoon sun, the temperature variances dropped from 5.7F pre-cleaning to 2.7F post-cleaning.  Clearly not only did we improve our heat recovery performance from the ERVs (ie; retaining of heat during fresh/stale air exchange) we also reduced room-to-room temperature variances.

It is easy to forget those trusty ERVs since they quietly just do their job, but our experiences absolutely underscore the importance of performing routine checks and cleaning of them.

Next, we looked at our point-source ductless mini splits...