Featured Article

Taylor CERV2+Ducted Mini Install (2.5 Year Follow-up)

It’s been two and a half years since I installed a CERV2 in my home located in Western New York. I wrote an article for the newsletter back then: Taylor Home CERV2 Testimonial. My original article covered the analysis of my home, retrofitting the install of the CERV2, and early performance results of the system. I found many of my assumptions to be true and a few that were slightly off. I’d like to share the lessons I’ve learned and to showcase some of the changes I’ve made.

Let’s start with changes that I have made. My house has always been fully electric but I have made it a priority to upgrade outdated mechanicals. I started with the HRV to CERV2 upgrade. I then made a financial commitment in an electric vehicle (EV). It then made sense to take advantage of solar incentives and net-metering to install a roof-mounted solar array to achieve a net-zero home. I replaced the 18 kW/h tankless water heater and 5 kW/h dryer for a heat pump water heater and a heat pump ductless dryer. During a remodel of my master bathroom, I ducted the CERV2’s return directly into the shower exhaust fan so that heat and moisture can be intelligently exchanged rather than lost.

 

Nissan Leaf, Solar Array, Heat Pump Hot Water, Heat Pump Dryer, Duct Work to the Attic for Shower Fan

 

These upgrades have reduced my yearly energy usage by more than 2,000 kW. That same amount of energy can propel my EV more than 6,000 miles. These savings will free up more capacity on my solar array and ultimately set me up to trade my last conventional vehicle for another EV.

The last change needed was to reduce my dependence on the 5 kW/h auxiliary duct heater in the winter. I accurately calculated that the CERV2 could alone heat the house at an outdoor temperature greater than 45° F. However, the indoor temperature would reach a little on the cool side for my preference. I found that it would level out around 62° F. I find myself to be more comfortable around 67° F.

 

Indoor/Outdoor Temperature April 2020

 

In the deep winter months: Dec – Feb, the auxiliary duct heater is running nearly constantly. I set the output temperature to 113° F. This was to balance comfort, solar capacity, and energy consumption. On a sub-20° F week it will pull nearly 3 kW/h to maintain an indoor temperature near 62° F. I could push it harder but didn’t want to tip the scales past what my solar would generate for the year. I significantly under-estimated my comfort level and the house’s heating load. I believe a more accurate heating load for my house is in the 15-20k BTU/h range.

 

Indoor/Outdoor Temperature February 2021

 

The summer months are generally well handled by the CERV2. However, the number of abnormal stretches of 80-90° F weather is becoming more common. The CERV2 can maintain reasonable temperature through these stretches. However, less under control are elevated indoor humidity levels, which can reach as high as 70% RH. Unfortunately, indoor air at 74° F and 70% RH makes for uncomfortable sleeping conditions.

 

Indoor/Outdoor Temperature July 2020

 

Indoor/Outdoor Relative Humidity July 2020

 

What can be done to help solve these energy and comfort problems? The solution I preferred was to integrate a mini-split to reduce the energy consumption in the winter and add more conditioning in the summer. I will be honest, I wasn’t in love the idea of maintaining equipment that resides outside, in the elements, in the blizzards, in the rain storms. But, in order to obtain the surface area necessary to deliver 15-20k BTU/h of air-to-air heat transfer, an outdoor unit is the only practical way. Luckily heat pump adoption is increasing across the country, modern refrigerants are less damaging to the environment, they operate amazingly in extreme temperatures, parts are relatively easy to find, maintaining the outdoor unit is simple, the Cost vs. ROI of the unit is highly favorable, and it’s a surprisingly easy DIY.

 

Fujitsu Low Temperature Ducted Mini-Split

 

I opted to go with a ducted mini-split and integrate it directly into the CERV2’s indoor air stream. I will share the story of my DIY install and the preliminary results from the tail end of the summer. Before I jump in, I want to point out that many great articles have already been written on the topics of mini-split selection, mini-split integration, and humidity management. I highly recommend you check out these articles if you haven’t already:

I am installing the ducted mini-split with Build Equinox’s Magic-Box Mechanicals. The CERV2 has built in algorithms for both Mitsubishi and Fujitsu low-temperature heat pumps. Both manufactures offer comparable products and I ultimately went with the brand I could find at the lowest price. That turned out to be a Fujitsu 1 ton (12k BTU/h cooling, 16k BTU/h heating) unit. It’s rated for full capacity at 20° F and can operate down to at least -5° F. It has a rated Coefficient of Performance (COP) of 3.60, which means 1 kW/h of input power will result in the equivalent of 3.6 kW/h of resistance heating. The resistance duct heater often used 75-100 kW/day, while this mini-split should use less than 30 kW/day and obtain similar heating capacity.

 

Thermostat Control in CERV2 Software

 

I started with relatively little knowledge about how to install a mini-split. I found a super helpful video that I will link here (available as-of Nov 2021): Full Installation of Mini Split Ductless Unit. Ty Newell from Build Equinox also wrote a great tech guide here: Installing a Ductless Mini-split. The number of tools involved can be fairly daunting. I made sure to pick up a torque wrench, gauge set, vacuum pump, flaring tool, and a R410a vacuum port adapter. Please note, depending on your jurisdiction, you may be required to complete a refrigerant certification course or have a certified professional present.

 

Assortment of Tools Used for Installation

 

With the help of my dad, we installed an electrical disconnect box and ran conduit through the wall. The electrical requirements for this model are 240V with 15A protection. We mounted the outdoor unit on a wall bracket several feet above the ground so that it will remain clear of snow. Lastly, we fit a 3” pipe through the wall so that the line set and indoor wiring can passthrough and connect to the indoor unit. We then sealed the openings and tidied up the install.

 

Cutting Holes and Mounting Equipment

 

Electrical Hookup

 

Final Outdoor Installation

 

Next, we started working on the indoor ducted unit. I decided to mount the unit vertically, directly over the CERV2 to both save space and limit the amount of ducting rework. The original vertical duct work and duct heater were removed. We used bolts and rubber vibration dampening washers to mount the indoor unit to the wall. I went a little fancy and ordered plastic insulated plenums with round duct adapters. The alternative is to craft something of your own out of duct board or sheet metal. After a little bit of alignment, the indoor unit ducted in smoothly. We attached the drain line and made the final electrical connections. The line set was cut to a final length, the flaring tool and some Nylog made the copper connections tight, and all the locknuts were torque wrenched to the specifications. We successfully pulled a vacuum in the line set for several hours and felt confident to let the refrigerant flow!

 

Insulated Plastic Plenum Attachments

 

Duct Heater Removed and Ducted Unit Installed

 

It was time to commission the mini-split, I used the included Fujitsu thermostat to run it through some tests. For the CERV2 integration I was provided a CERV-IR device that communicates wirelessly with the CERV2 and connects to the mini-split’s thermostat controller. This thermostat controller (purchased from Fujitsu separately) takes the signals the CERV2 sends and converts them into a digital language only the Fujitsu understands – it’s basically a digital middle-man. Both these units need power which I pulled from the CERV2’s transformer panel. An additional temperature sensor is inserted into the ductwork after the indoor unit and is connected into the CERV2’s motherboard. This sensor allows the CERV2 to optimize it’s heating and cooling algorithm alongside the mini-split’s.

Connections to CERV2, CERV-IR, and Thermostat Controller

 

Closeup of CERV-IR and Thermostat Controller

So, how well did it work? Let me show you the results using the CERV2’s graphing data. The graphs show the 2nd half of August 2021. The solid red line shows when the mini-split was turned on. The top graph is temperature and the bottom graph is relative humidity. As the outdoor temperature rose the indoor temperature reached 74° F and 72% RH. After the mini-split was activated, the house settled down to 68° F and 64% RH. This might not seem like a big difference, but it is. The dew point was lowered from 66° F to 58° F and there was 30% less absolute humidity (measured in g/m3) – the actual amount of moisture in the air. This was achieved with the mini-split using between 10-15 kW/h per day.

 

Indoor/Outdoor Temperature August 15-31, 2021

 

Indoor/Outdoor Relative Humidity August 15-31, 2021

 

I am pleased with the combined summer-time capacity of the CERV2 and the ducted mini-split. I think it is worth spending the extra kilowatts in the summer to keep the house cooler and less humid. The kilowatts saved in the winter will far outnumber those used in the summer. We are now into the transitional months where additional heating and cooling are needed less frequently. I will have to end this article with a teaser… to be continued once the winter results are compiled. Next year, I will follow up with a new article to analyze how the combined system performed in the winter.

I want to thank the Build Equinox team for all their help, support, and advice. Ty visited me for a CERV2 checkup last year when he was passing through my area. And this summer, I was able to make a stop by the Build Equinox workshop to meet Ben and Alex. I was given an excellent tour and got to see their assembly lines, mini-splits, dehumidifiers, solar array, rain water collection, and chickens in action!

- Matthew Taylor

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November 15, 2021 Events – Two Talks in One Night at ASHRAE Madison (Dec. 13, 2021, CEUs available!) 20211115
November 15, 2021 Featured Article – Taylor CERV2+Ducted Mini Install (2.5 Year Follow-up) 20211115
October 25, 2021 Events – PHMass Passive House Virtual Symposium (Nov 3, 2021) 20211025
October 25, 2021 Review – The Role of Global Air Pollution in Aging and Disease, by Professor Caleb Finch 20211025
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September 29, 2021 Events – Virtual Metro Denver Green Homes Tour 20210929
August 17, 2021 Opinion Article – ASHRAE, You’re Making Us Sick! 20210817
August 17, 2021 Featured Article – CERV2 Smart, Integrated, Supercharged Dehumidification 20210817
July 19, 2021 Events – CERV2 Smart-er Ventilation New Features & Product Demo (Video & Slides) 20210719
July 19, 2021 Review – 5 Steps to Net Zero Multi-family Residence Renovation: Toronto 20210719
July 19, 2021 Featured Article – Test Chamber Pt. 2: VOCs! 20210719
May 20, 2021 Tech – It’s Springtime and Aprilaire is in the Air! 20210520
May 18, 2021 Featured Article – Alexa, Meet the CERV 20210518
April 19, 2021 Spotlight – Illinois ADAPTHAUS Wins 1st Place in Comfort & Environmental Quality 20210419
April 19, 2021 Events – Register for Building Energy Boston (Online)! May 5-7 20210419
April 19, 2021 Featured Article – Broken Clocks Work Better than Today’s Ventilation Standards 20210419
April 19, 2021 Events – Upcoming Online Webinars and Conferences! 20210419
March 11, 2021 News – New Video, Booklet, and CERV2 Smart Options! 20210311
March 10, 2021 Spotlight – CERV Installed in the UofI ADAPTHAUS 20210310
March 10, 2021 Events – Re-Opening Schools and Beyond Safely Webinars (3/23, 4/21, 4/22) 20210310
March 10, 2021 Featured Article – Human Value: Thinking Beyond Energy 20210310
February 26, 2021 Spotlight – Dar-Lon Chan’s Journey to Sustainable Living 20210226
February 26, 2021 Featured Article – Covid Safe Space Calculator 20210226
January 29, 2021 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 2-4) 20210129
January 29, 2021 Spotlight – University of Illinois ADAPTHAUS becoming Reality 20210129
January 29, 2021 Featured Article – CERV2 Installed in Equinox House! 20210129
December 21, 2020 Spotlight – Tour Bill Spohn’s New Modular Net Zero Home (CEUs available!) 20201221
December 21, 2020 Special Edition – Ventilation, Vaccination, Infection, and Luck. Covid-19 and the New Year 20201221
December 21, 2020 Featured Article – AWE: Air, Water, Energy 20201221
November 17, 2020 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) 20201117
November 16, 2020 Spotlight – New Lungs for a 101-Year-Old Home Pt.3: Heat Pump Water Heater! 20201116
November 15, 2020 Featured Article – Equinox Meets the Needs / ASHRAE Solar ZEB Article 12 20201115
November 12, 2020 Special Edition – Stay Safe this Holiday Season! 20201112
October 29, 2020 Spotlight – New Lungs for a 101-Year-Old Home Pt.2: Total HVAC Replacement! 20201029
October 28, 2020 Featured Article – Equinox House Performance / ASHRAE Solar ZEB Article 10 20201028
September 22, 2020 Events – Michigan Residential Net Zero Energy Conference (Oct 20-22) 20200922
September 22, 2020 News – CERV-UV Now Available for New Orders! 20200922
September 22, 2020 News – CERV-ICE Now in the iOS and Android App Stores! 20200922
September 22, 2020 Featured Article – Solar Collection & Use / ASHRAE Solar ZEB Article 10 20200922
August 17, 2020 Special Edition – Build Equinox Groundbreaking Research into COVID 19 20200817
August 17, 2020 Events – SEDAC Webinar: Considerations, Best Practices, and Energy Implications for Reopening Critical Community Facilities in the Pandemic (Aug 18, 2020) 20200817
August 17, 2020 Featured Article – Comfort Conditioning & Indoor Air Quality / ASHRAE Solar ZEB Article 9 20200817
August 17, 2020 News – Building Science Podcast: “Ventilation & Virus Transmission Prevention” 20200817
August 14, 2020 News – New HVAC School Podcast: “Advanced Ventilation w/ CERV2” (Watch/Listen) 20200814
August 12, 2020 Events – Free CEU Webinar: Can Building Science Help Us Slow COVID-19? (Sep 2, 2020) 20200812
July 10, 2020 Tech – Ultimate Ultraviolet! 20200710
July 10, 2020 Special Edition – Covid-19 Update: Airborne Means AIRBORNE! 20200710
July 10, 2020 Featured Article – Appliances Power EVs / ASHRAE Solar ZEB Article 8 20200710
June 29, 2020 Events – Free New Webinar: Guidelines for Protecting Against COVID-19 (PDF + Slides) 20200629
June 25, 2020 Featured Article – Designing a Thermally Massive Home/ASHRAE Solar ZEB Article 7 20200625
June 25, 2020 Special Edition – Covid19 Status Report: We are at the Beginning of the Pandemic, Not the End 20200625
May 29, 2020 Spotlight – CERV Retrofit: New Lungs for a 101-Year-Old Home 20200529
May 29, 2020 Special Edition – Covid19 Status Report: Guidelines for Homes & Businesses 20200529
May 29, 2020 Featured Article – Ground Heat Transfer/ASHRAE Solar ZEB Article 6 20200529
April 16, 2020 Events – Free CEU Webinar: Covid-19 Characteristics, Transmission, and Control (April 29th) 20200416
April 16, 2020 Special Edition – Battling the Spread of Covid-19 20200416
April 16, 2020 Featured Article – Infiltration & Sealing/ASHRAE Solar ZEB Article 5 20200416
April 16, 2020 Spotlight – New Projects: 1930s CERV Retrofit & Mitsubishi Hyperheat 20200416
March 13, 2020 Featured Article – Light and Delight/ASHRAE Solar ZEB Article 4 20200313
March 10, 2020 News – CERV Voted One of the Top 16 Coolest Things Made in Illinois! 20200310
March 5, 2020 Special Edition – Fighting COVID-19 with Fresh Air 20200305
February 24, 2020 Featured Article – Walls and Roof/ASHRAE Solar ZEB Article 3 20200224
February 24, 2020 Tech – Magic-Box Mechanicals 20200224
February 24, 2020 Events – Designing Exceptional Homes for Exceptional People Webinar (Video + PDF) 20200224
January 30, 2020 Events – Visit us (Booth 17) at Energy Design Expo in Duluth (2/25-26) 20200130
January 14, 2020 Tech – Designing Exceptional Homes for Exceptional People 20200114
January 14, 2020 Featured Article – Designing for Zero/ASHRAE Solar ZEB Article 2 20200114
December 19, 2019 Events – Free Webinar: Smart Ventilation & Air Distribution (Video+PDF) 20191219
December 19, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) 20191219
December 19, 2019 Spotlight – Acorn Glade: 2019 NAPHC Awardee! 20191219
December 16, 2019 Featured Article – Equinox Origins/ASHRAE Solar ZEB Article 1 20191216
November 19, 2019 Events – Visit our booth at 2019 NAPHC in Washington DC! 20191119
November 19, 2019 Spotlight – Equinox House Turning 10! 20191119
November 19, 2019 Featured Article – Handling Humidity Pt.4 Putting it All Together 20191119
October 16, 2019 Events – Mechanical Systems for Passive Buildings (Chicago, Oct 16) 20191016
October 16, 2019 Featured Article – Handling Humidity Pt.3 Methods for Managing Moisture 20191016
October 16, 2019 Events – Free Webinar: Handling Humidity (Video + PDF) 20191016
October 16, 2019 Events – Free CEUs: Building Green & Beer at Founders Brewing (Oct 28) 20191016
October 16, 2019 Spotlight – Inter House Wins Solar Decathlon Africa!!! 20191016
September 20, 2019 Featured Article – Handling Humidity Pt.2 Climate Moisture Variations 20190920
September 20, 2019 News – Brand New Release: Colorfil VOC Absorbing Filters! 20190920
September 20, 2019 Tech – From CERV to CERVEZA: a Quest for Smart Beer 20190920
August 27, 2019 Events – Earn Free CEUs with the Handling Humidity Webinar (Aug 29) 20190827
August 27, 2019 Featured Article – Handling Humidity Report Series 20190827
August 12, 2019 News – Listen to the Building HVAC Science Podcast, ft. Ty Newell! 20190812
July 29, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Aug 27, 2019) 20190729
July 29, 2019 Featured Article – Poor Home Maintenance = Increased Health Risks 20190729
July 29, 2019 Tech – Say Hello to Our New Server! 20190729
June 19, 2019 Featured Article – Watch out for Cranky Heaters! 20190619
June 19, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (July 10) 20190619
June 19, 2019 Spotlight – Marrakech Express! CERV2 Heading to Africa! 20190619
May 13, 2019 Featured Article – Taylor Home CERV Testimonial 20190513
May 13, 2019 Events – 7 Steps for Designing an Economical Net Zero Home (Video + PDF) 20190513
May 13, 2019 Tech – AeroBarrier Demonstration 20190513
April 15, 2019 Events – Indoor Air Quality Metrics Free Webinar (Apr 24, 2019) 20190415
April 15, 2019 Featured Article – CERV2 Geo–Boost 20190415
April 15, 2019 Review – 2019 National Home Performance Conference 20190415
April 15, 2019 Tech – CERV2 Sketchup Model Now Available 20190415
March 28, 2019 News – Visit us at the Chicago 2019 National Home Performance Conference 20190328
March 28, 2019 Featured Article – Happy Equinox, St. Patrick’s Day, and Super Moon! 20190328
February 27, 2019 Events – Free CEU Webinar: Smart Ventilation & Air Distribution (Mar 12) 20190227
February 27, 2019 Featured Article – Smart Ventilation and Smart Air Distribution Reports 20190227
February 27, 2019 Spotlight – El Salvador NZEB Update 20190227
February 25, 2019 Events – CERV2 Smart-er Ventilation Product Demo (Video + PDF) 20190225
January 22, 2019 Events – Smart Ventilation & Smart Air Distribution Webinar (Video & PDF) 20190122
December 26, 2018 Spotlight – Progressive Canada 20181226
December 26, 2018 News – Happy Holidays from Build Equinox! 20181226
December 26, 2018 Review – CERV2 at Greenbuild 2018 20181226
November 26, 2018 News – CERV OEM Filter Store is OPEN!!! 20181126
November 19, 2018 News – Check Out Our Social Media! 20181119
October 24, 2018 Events – Free CEU Webinar: Duct Design & Performance (PDF Download) 20181024
October 24, 2018 Featured Article – CERV2 is UL Approved! 20181024
October 24, 2018 News – Stop by Our Booth at Greenbuild Chicago (Free Tickets!) 20181024
October 24, 2018 Spotlight – University of Illinois Students Visit Build Equinox 20181024
July 23, 2018 Featured Article – Happy 10th Birthday, CERV and Sunflower! 20180723
July 23, 2018 Spotlight – Good News from El Salvador! 20180723
June 22, 2018 Tech – Installing a Ductless Mini-split 20180622
June 22, 2018 Featured Article – Mini-split Mania! 20180622
April 30, 2018 News – Now offering on-demand webinars for CEUs! 20180430
April 30, 2018 Events – Free CEU Webinar! (May 2, 2018) 20180430
April 30, 2018 Featured Article – Ductology Part 2 20180430
February 19, 2018 Review – 2018 Better Buildings by Design Conference, Flu and Colds 20180219
February 19, 2018 Featured Article – Hot Water! 20180219
January 22, 2018 Events – Visit us at BuildingEnergy Boston! (March 7-9, Boston, MA) 20180122
January 22, 2018 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 7-8) 20180122
January 22, 2018 Featured Article – Ductology (Part 1) 20180122
November 20, 2017 Featured Article – Heat Pump (Hybrid) Clothes Dryers are Coming! 20171120
October 31, 2017 Featured Article – CERV2 Measures IAQ at NAPHC & NAPHN 20171031
September 25, 2017 Featured Article – Introducing CERV2 20170925
August 21, 2017 Events – Free CEU Webinar! (Sep 27, 2017) 20170821
August 21, 2017 Featured Article – Quiz 20170821
July 27, 2017 Events – New IAQ Metrics Webinar (Video + PDF) 20170727
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May 22, 2017 Events – Economical Net Zero Design Webinar (Video+PDF) 20170522
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April 28, 2017 Events – 7 Steps for Designing an Economical Net Zero Home (May 25) 20170428
April 28, 2017 Featured Article – Engineering Net Zero Homes 20170428
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February 14, 2017 Featured Article – February Flu 20170214
January 20, 2017 Events – HRV, ERV and Smart Vent Systems, Free CEU Webinar (Feb 15) 20170120
January 20, 2017 Events – NESEA IAQ Metrics Presentation (Mar 9, Boston, MA) 20170120
January 19, 2017 Featured Article – The Perfect Dust Storm 20170119
January 12, 2017 Events – Efficiency Vermont Better Buildings by Design Conference (Feb 1-2) 20170112
December 26, 2016 Featured Article – Happy Holidays from Build Equinox! 20161226
November 29, 2016 Featured Article – Geo-Boost 20161129
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October 28, 2016 Featured Article – Comparing ERV, HRV, and CERV 20161028
October 28, 2016 Spotlight – Net Zero Eco-House (Monticello, IL) 20161028
October 28, 2016 Spotlight – Forty Under 40 20161028
September 28, 2016 Events – Free CEU Webinar (Oct 5th): Why are new Indoor Air Quality metrics needed? 20160928
September 28, 2016 Review – 2016 North American Passive House Conference 20160928
September 28, 2016 Featured Article – New CERV-ICE IAQ Analytics Released! 20160928
September 28, 2016 Spotlight – CERVs in Passive Homes, pt. 2 20160928
August 18, 2016 Featured Article – Understanding the House as a System 20160818
August 18, 2016 Spotlight – CERVs in Passive Homes 20160818
August 18, 2016 Review – “What is IAQ?”, P. Ole Fanger 20160818
August 18, 2016 Tech – CERV CO2/VOC Library 20160818
July 19, 2016 Events – September North American Passive House Conference 20160719
July 18, 2016 News – CERV Website 20160718
July 18, 2016 Featured Article – VERMOD CERV Report Released 20160718
July 18, 2016 Review – LBNL report: “Houses are Dumb Without Smart Ventilation” 20160718
July 18, 2016 Spotlight – Professor P. Ole Fanger (1934-2006); IAQ and Comfort Pioneer 20160718
July 18, 2016 Tech Note – Airflow Calculation for Ventilation Systems 20160718
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