Multiple Zone Retrofit Carrier Infinity Residential HVAC System

I upgraded my residential central heating system three years ago with a new variable-speed Carrier Infinity Greenspeed 4 ton heat pump and fan coil. The previous system was about 22 years old, and had some upgraded components, but ultimately, the 22 year old fan coil developed a refrigerant leak in the coil, and replacements were no longer available. I looked at having a custom coil fabricated, but ultimately, decided to go with a full variable speed system for efficiency, low temperature capability, and greatly reduced outdoor noise with the variable speed heat pump.

Close duct - basement supply. Far duct - main floor supply with Belimo Damper Actuators

My house has three levels - main floor, basement and first floor. The house was originally constructed with three ductwork branches, one for each level, and each branch had a bypass damper installed. The bypass dampers allow excess air from any one zone to recirculate within the mechanical room back to the furnace. In my case, the bypass was open to the room and not ducted, for this reason, the large mechanical room in the basement was always very warm in the heating season, or very cold in the cooling season - a tremendous waste of energy.

At one time, the dampers were controlled with an industrial PLC which was also connected to thermostats on each level of the house. By the time I purchased the house, the PLC controller was no longer functioning and the system was operating as a single zone system, however, the thermostats were still installed on the walls, and the dampers could be controlled manually with toggle switches on the original PLC panel.

Manual Damper Controls on Legacy PLC Panel Cover

With the Covid-19 lockdown, my wife and I were working from home full time, from our office in the basement. In the summer time, the basement was too cold, and I began manually modulating the dampers to heat the basement in the summer for better comfort. This was laborious, especially considering the dampers had a 45 second full cycle time - you had to manually hold the spring loaded control switch for 45 seconds to make the damper position change. I quickly scrapped this idea and thought about upgrading the Carrier Infinity system with its Damper Control module and retrofit damper actuators. 

Components required for the retrofit - 2 Zone Thermostats, 3 Zone Actuators and the Zone Control Module

Researching how the Infinity Damper Control module controls its dampers, I learned that it expects the damper actuator to have a 15 second cycle time from full open to full close. If the Damper Control module needs to modulate damper position partially open or partially closed, it will simply actuate the damper for a fraction of 15 seconds - for example, half open - it will power the actuator for 7.5 seconds from full open or full closed. It also has a current limit of 1A at 24VAC. My Belimo dampers would not be compatible, so I would have to replace them. Carrier sells two damper actuators which are compatible with the Infinity system - standard damper actuators complete with the damper for new installations, and a retrofit damper actuator designed for round shaft dampers - in two versions - 90 degree rotation and 45 degree rotation. I needed the 45 degree versions. 


New Carrier Retrofit Damper Actuator DAMPACT45DEG-R on the Left - Old Belimo Actuator on the Right

So - I ordered all the parts and got started. The first order of business was replacing the actuators. I could take my time with this without affecting the normal system operation. 

First step before removing old actuators - mark shaft with damper blade orientation

And for each damper - mark the blade orientation - Damper Open and Closed

In my case - the damper opened with counter clock wise (CCW) rotation, but the markings on the Carrier actuator are for clock wise (CW) opening. So - I simply relabled the actuator cover with open and close positions reversed, both for the electrical connection and for the orientation sketches. Not only does this help yourself keep things straight during installation and cabling, but it will really help the next guy that comes along sometime in the future and has to figure out what you've done. 

Carrier DAMPACT45DEG-R Damper Actuator Cover Relabelled for CW Opening

I expected this to be fairly quick and straightforward and it was - until I tested the actuator with 24VAC. The actuator could not supply enough torque to move the damper for the basement or main floor dampers which were installed horizontally. The first floor damper, which was installed in a vertical duct, was properly balanced and the Carrier actuator had no problem with it. 

Measuring torque required to move damper blade
So - to check to see how much trouble I was in, I took a pair of vice grips and gripped the damper axle. Then, I took a digital fish scale and hooked it on the vice grips at a measured distance from the axle (8") and pulled the damper open - careful to keep the scale oriented exactly 90 degrees to the radius to the axle. I measured approximately 2lb of force required at 8" - which works out to 16 in-lb of force. The Carrier Actuators are rated for 10 in-lb of force, and the old Belimo actuators were rated for 133 in-lbs. So - the new Carrier actuators were 13 times weaker than the Belimo actuators, and half as strong as what I needed. What to do now..... 

The axles did not protrude from the other side of the duct, so I would have to come up with a solution on the actuator side of the axle. I checked out counterweights - some are available online, and the principle is that you have a weight on an arm that is fixed to the axle at a particular orientation - with the weight at a particular distance from the axle to balance the damper blade. I didn't have enough space to use a balance weight because I had ductwork above each actuator installation - I only had about 3" of clearance above the two horizontal duct actuators. 

I thought about using springs to assist with opening the actuator, to reduce the torque required. Luckily, I had a mixed kit of Power Fist extension and compression springs from another project. I realized that I could simply replace the short shaft lock screw with a longer lock screw - the screw thread is 5/16" diameter, and I had some 2" bolts in my hardware stores. 

Damper actuator assist first attempt - extension spring attached directly to 2" bolt

First I tried connecting an extension spring directly to the 2" bolt - however, very finicky to retain the other end, and I found that the spring yielded easily because of the relatively long travel of the head of the lever (2" lock bolt) compared to the relative short length of the extension spring (about 3" compressed). So, I selected some additional extension springs and cobbled together a spring assembly using zip ties. 

Prototyping an assist spring for the damper

I ran out to the local home improvement store, and found some 3" fully threaded 5/16 bolts to allow me to use a washer and nut to attach the spring assembly near the head of the lever bolt. 

2nd Try - 3" fully threaded lock bolt with spring assembly

Upgraded with small turnbuckle for Tension Adjustment

I was able to get these adjusted to reliably assist the opening and closing of the dampers. In my case, if the furnace fan was running - it greatly impacted the torque on the axle. I adjusted the dampers to reduce the opening and closing effort without the fan running, because I expected that the Damper Control module would only actuate the dampers at a reduced fan speed. I turned out to be correct. 

With damper actuators resolved, I moved onto installing the remote thermostats. You have the option of installing 2 wire thermocouples, or 4 wire communicating thermostats. I went with the thermostat option, which Carrier calls a "Smart Zone Temperature Sensor", Carrier part number SYSTXCCSMS01. Luckily, I had a 4 conductor cable already in the wall from a Legacy home automation system - so I just reused the existing cable. 

Smart Zone Temperature Sensor baseplate and 4 wire communicating cable connections

Smart Zone Temperature Sensor installed in the upstairs master bedroom

With the actuators and zone thermostats installed, it was now time for installation of the Zone Control module. Before undoing any connections, shut power off to the furnace, fan coil and thermopump, to ensure that the 24V control transformer is powered down. 

In my installation, I had a Carrier Network Interface Module installed to control my whole house air exchanger. This ended up greatly simplifying my installation, because all system cables already ran to a location just above my fan coil, so I didn't have to move any cables. 

Carrier Network Interface Module

As I removed the cables from the Network Interface module, I labelled each cable with 6mm Brother TZ tape, with clear heat shrink to protect the label. This provides a durable label that won't fall off or become illegible over time. Helps avoid errors during installation, and greatly assists the next guy that has to come along and maintain or modify the system. 

As I disconnected cables from the Network Interface Module, I labelled them

The new Zone Control module installed on the ductwork above the fan coil in place of the old Network interface module. I labelled all the new thermostat and damper actuator cables and brought them into the Damper Control module enclosure. Zip ties help keep the cabling neat. In my case - the master thermostat (what Carrier calls the "User Interface") connects here, as well as the 4 wire communication cable to the fan coil. 

Damper actuator cables connected to the terminals on the Damper Control module

Cabling complete - Thermostats, Damper Actuators, Air Exchanger

Once all the cabling is complete, double check all of your connections, and then reapply breaker power to the fan coil and thermopump, this powers up the 24V system transformer and powers up the User Interface (Master Thermostat) and the Zone Thermostats (Smart Zone Temperature Sensors).

The first thing you need to do is program the Smart Zone Temperature Sensors with the correct zone number. This is done at the Zone thermostat - because it is a communicating device and the commications cable connects to a common interface ABCD bus, and not a particular terminal on the control board. 

Program the zone number on the Smart Zone Temperature Sensors

With the zone sensors programmed, you then need to reset the installation at the User Interface. This will force the User Interface to query the Carrier communication bus and identify all connected components - the fan coil, the thermopump, the two smart zone temperature sensors, and the zone control board. 
Carrier User Interface queries the communications bus and identifies connected equipment

Carrier User Interface identifies the Zone Control Module, and 2 Additional Zone Thermostats

With all equipment identified, the system automatically starts a duct assessment, and checks the flowrate (duct sizing) of each zone.

Duct Assessment in Progress

When the duct assessment is complete, it displays the results. In my case, I have relatively high leakage and I later realized that the humidifier bypass duct is open - this will cause air recirculation that appears as a leak. I intend to redo the duct assessment with the humidifier bypass duct closed and see what effect this has. 

Results of duct assessment

Then - the setup process finishes, and you can now control all three zones independently from the user interface / main thermostat. You can control the remote zones using the Smart Zone Temperature sensors as well. This worked perfectly from initial startup, and I really like the new capability. 

System status - temperature control screen - shows setpoints and temperatures of all zones

System status - temperature control screen on the Carrier iPhone app - Same information

System has been running for 2 days now - I've programmed the the first floor where we have our bedrooms for cooler temperatures at night to promote better sleep, and the basement during daytime hours to be warmer for comfortable working temperature from home. I'll be fine tuning the programs going forward to optimize energy consumption. Stay tuned for an update once I have some operating experience and data. 











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Quickjack Hydraulic Fluid Contamination and Quickconnect Fitting Failures

I had the BMW wagon in the garage up on the quickjack for a few weeks at the start of September, fixing a Low Boost Pressure code, oil pan leak, replacing rear drive axles, and treating some underbody and rear bumper corrosion

I've had the Quickjacks for two years now - they've been a great tool, really useful to quickly get all four wheels in the air for doing seasonal tire changes, or drivetrain maintenance. Halfway through the last job, the hydraulic hoses began to get difficult to reconnect, there was residual hydraulic pressure in the hoses. I was in a hurry, so I tried forcing the connectors onto the pump. The next time I hit the lift control, I started losing a lot of hydraulic oil from the quick connector. 

Quickjack hydraulic pump releasing its schmoo

It didn't take long to figure out the problem - forcing the connectors cut the o-rings in the face of the connectors. I trashed two connectors of the four female connectors. 

Notice the protrucing piece of O-ring left of the center pin

I was in the middle of raising the car and I wanted to get the next step of the job done, so I simply removed the bad connectors and made fixed hose connections, using 3/8" NPT unions, and a 3/8" bulkhead fitting to replace one of the pump male quick connectors. However, I had lost a lot of fluid. I went to my automotive fluid bin and grabbed a bottle of brake fluid. Big mistake. The spec is for automatic transmission fluid, and I added about a pint of brake fluid and got back to business. 

Two days later I went to lower the car - and the cylinders wouldn't hold the car raised without the buttons pressed. I had difficulty removing the lift locks so that I could lower the car. Fluid was bypassing the check valve that holds the car in the air when there isn't any button input. I removed the check valve, and found little bits of white plastic jamming the check valve open. 

Quickjack check valve - marked with a CV on the valve body.

Not good news - but I immediately realized the contaminated fluid was the probable cause. Once I was done with the Quickjacks, I drained all the fluid from the system - removed the reservoir, removed the quick couplings from the hoses, and stood the jacks up to drain the cylinders by gravity. 

Draining fluid from hoses and jack cylinders by gravity

When I opened the reservoir, that's where I encountered the real mess. Bits of white plastic suspended in hydraulic fluid. Larger chunks in the bottom of the reservoir. The inlet strainer was detached from the inlet elbow, and just lying in the bottom of the reservoir.  

Inlet strainer (round) detatched from inlet elbow.

Bits of white plastic in the reservoir

Inlet strainer missing its attachment hardware (likely made of the white plastic which dissolved)

White plastic in the inlet port of the pump

More white plastic in the pump inlet port

I don't have a replacement inlet strainer yet. I have seen all metal inlet strainers and inlet elbows on the internet - but I'm having difficulty getting my hands on them. For now, I've replaced all the fluid with clean ATF and I'm running the jack without the strainer, just the inlet elbow. I'll drain and flush the fluid a second time once I have an inlet strainer to install. 

A few recommendations from what I've learned the hard way.

1.    Put a label on your quickjack hydraulic reservoir near the fill port - "ATF Only"
2.    Always hold the "down" button for 5 to 10 extra seconds when descending the quickjack, to release as much pressure as possible from your hoses before disconnecting them. This helps prevent residual pressure buildup in the hoses. 

Not my finest hour - but hopefully the information in this post helps someone else avoid the same issue in the future. 




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BMW E60 / E61 Rotor Repair - COVID Lockdown Parking Rust and Brake Vibration

 When the COVID lockdown hit back in March, daily commuting stopped, kids were pulled from school, shopping essentially stopped except for weekly trips to the grocery store, and the BMW wagon went from use 4 to 6 times a day to a couple times a week. The drop in use was dramatic, and one result of this was a couple of instances of the brake pads bonding to the rotors with corrosion. You would go to use the car, all the brakes would be stuck, and after a few seconds of throttle, eventually the corrosion bond would break and the car would start rolling normally. 

BMW E61 535xi Front Rotor
Use of the car has gradually returned, and we did a local road trip in August. The brakes in the car were completed replaced when I did the turbo project 2 years ago, since then the car has only travelled about 20,000km. During the road trip I noticed minor brake pedal vibration - more apparent during light braking, less apparent with a bit more force on the pedal. 

When I brought the car into my garage in September to look at the low boost pressure issue, this was on my list of issues to repair. 

Rust ridges on front rotor left from pads freezing to rotor
I thought about purchasing new pads and rotors to sort out the issue, but 20,000km is next to no use, and I wanted to avoid the cost and the waste. I got onto google and looked for brake rotor turning services. At one time this was common, now, almost impossible to find. There was one machine shop in east Montreal that gave me a reasonable quote for turning the rotors, but when I went to drop them off, the machinist had sufferred an accident and would be off work for a month. No go. 

Frozen brake pad prints on the front rotor

So - if a part is broken, you can't really break it any more trying to fix it. I decided to try sanding the rotor surfaces with a Dewalt 5" orbital sander with 200 grit paper, to try to remove the ridges. 

Frozen brake pad prints on the front rotor

I sanded the complete surfaces, front and back, of both disks. I did two passes, not wanting to remove too much material and creating a bigger problem than I already had. I was careful to spend the same amount of time and pressure as equally as possible around the surface of the disk, just spending slightly more time on the ridges left by the various brake pad prints on the rotor surface. I didn't try to completely remove the brake pad prints, but smooth them out and hopefully reduce the pedal vibration. 

Front disc following sanding - pad outlines are still visible.
The sanding removed some of the ridges left during the pad bedding into the rotors. I knew that the pads would have to bed in again, so I was patient for the last month and tried to modulate my brake pressure to allow that to happen gradually. 

I would say that this has largely solved the problem, although, with very light application of the brakes there is still a slight vibration. With normal stopping pressure, the vibration is not apparent. It seems to have improved the braking feel, but it's not perfect. It seems to be improving with time however, so I'll let it go for another month or two and report back whether the problem resolves itself. For now - I've saved the cost of a pair of rotors and pads. So far, so good. 


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BMW Underbody, Suspension and Rear Bumper Rust Repair with POR-15 System

While I had the BMW wagon in the garage replacing the rear axles and sorting out the turbo control vacuum issues, I noticed the start of some corrosion in critical areas - on the steel body near the rear subframe and brace mounts in particular. 

Rust bubbling the paint near the spare tire well - frame stiffener mount

I had some time so I decided to take action now to avoid larger problems further down the line. Two years ago, when I did the turbo replacement project, I also dropped the differential to give it a thorough cleaning, replace all the seals, and paint the steel body. At the time, I used Tremclad spray paint. After 2 years, 2 winters on the road, the rust was coming back and I was almost back to where I started. From some research on the internet, I found the POR-15 system - a polyurethane based prep and paint system that seemed to be much more durable, so I decided to give that a try. 

Rust returning to the differential case - 2 years after Tremclad application

The first component I cleaned up and painted was the right front bearing carrier. I had the drive axle out of the car to repair the oil leak, and some of the suspension components disconnected, so this was a good time to access the part and get it done. 

Bearing carrier - loose rust removed, degreased, and treated with the rust conversion primer.

The POR-15 system is comprised of a few basic steps:

  • Remove loose rust
  • Degrease using the POR-15 degreaser
  • Prime using the rust conversion primer
  • Paint - at least two coats - using the polyurethane paint.
Bearing carrier painted with POR-15 Black Paint

What's interesting with the system is that the degreaser and primer are both water based - and the paint required humidity to cure. This allows you to perform the steps fairly quickly one after the other. You don't need the part to be perfectly dry before painting (although you don't want any standing water on the part which may affect curing by causing bubbling under the paint). 

Surface rust on the rear bumper

More surface rust on the rear bumper


Rust on right side rear bumper mount

I had pretty substantial rust on the rear bumper, trailer hitch and bumper mounts. Large areas of paint were flaking off the trailer hitch, and large areas of the rear bumper were rusting badly. 

Loose paint and rust removal with 3" carbon steel wire cup brush on grinder

I pulled the rear bumper and mounts from the car, and the trailer hitch. I used a 3" cup brush on my Dewalt 20V grinder to remove loose paint and rust from the parts. It took about an hour to do all the parts - there was substantial rust and the cup brush worked fantastically. What a tool, highly recommended. 


3" Wire Cup Brush - great tool for cutting through paint and rust

With the parts cleaned, I washed them with soap and water to remove all the loose scale and grinding dust, prior to degreasing. 

After loose paint and rust removal, rinsed and ready for degreasing.

To degrease the parts, you use the POR-15 degreasing solution, diluted 4:1 with hot water. I use a plastic brush to scrub the parts and get into hard to reach areas. When complete, rinse the parts with hot water. 

Immediately after rinsing, you can do the rust conversion primer since it is water based. Apply the rust conversion primer to all bare and exposed rust and metal. I use a 1" paint brush to scrub it in as good as possible. The instructions suggest you leave the surfaces wet for at least 20 minutes, I went back and reapplied the primer about 5 times over the course of an hour to ensure a good application. 

POR-15 Metal Prep and Degreaser


POR-15 Rust Conversion Primer applied - it's slightly foamy - keep it wet for the entire treatment time

Once the rust conversion treatment is complete, rinse the parts off with hot water and allow to dry before the paint application. 

Bumper surface following rust conversion primer treatment. 

The POR-15 coating comes in a limited number of colours for various applications. There is Gloss Black, Semi-Gloss Black,  Silver,  Gray  and Clear. In addition, there is a high heat caliper paint available in Black,  Blue,  Red,  Silver and Yellow. I have the Silver, Gloss Black and Silver caliper paints. For touchups on the underbody steel, I used my silver paint, just so that it wouldn't contrast too badly with the seafoam green factory color. For the suspension parts, rear bumper and hitch, gloss black obviously from the photos. 

POR-15 Gloss Black applied to the trailer hitch

POR-15 Gloss Black applied to the rear bumper and mounts, and trailer hitch

The paint application is pretty straightforward - I use disposable brushes so I'm not bothered with cleaning them. You need a minimum of two thin applications, applied before the coating cures completely. You can recoat once the initial application is dry to the touch with a slight finger drag (stickiness). If you allow the first coat to cure completely, you need to sand before the second coat - it's important to time your work. 


POR-15 Silver applied to rust touchups on the underbody (battery box next to suspension compressor)

I wasn't able to get up around the rear suspension mounts with a tool to remove loose paint, there is not a lot of access in those areas. I've ordered a dremel flex extension - will see if that allows me to get at the flaking paint in those areas and I'll post an update when I get that done. I really wanted to get all the corrosion protection done before this winter. 

Gloss Black POR-15 on the rear differential case. 

I painted the rear differential in the car. The Tremclad provided some protection, so I didn't have massive pitting and flakes of rust, so prep was pretty quick and easy. The differential is exposed to road salt and grit, so I'm looking forward to how well the POR-15 holds up over time. 

Reinstalling the bumper and hitch components - spacer washers for bumper held on by masking tape

It was totally worth removing the hitch to treat the rust on the hitch - there is no way I could have done a proper job of it on the car. It's common to see rusty hitches - but I hate seeing the rust on my car. If I'm going to keep it, I want it to look good. 

Ready to lift the trailer hitch back onto the car

Reinstalling the hitch was fairly straightforward. I treated all the hardware by soaking it in the POR-15 primer overnight. Once everything was reassembled, I coated all the fasteners with the black POR-15 coating. 
I didn't completely disassemble the hitch, so I needed to pull the crossbar into position with a load strap

Rear bumper and hitch installed. Looks great in gloss black - will mostly be covered by the bumper cover.

So - another job done. Looking forward to seeing how well the POR-15 holds up over time. The final step was to apply fluid film in critical areas - around fasteners, where there is metal to metal connections, and inside the rear bumper cavity that was inaccessible for painting. One other comment - removing the rear bumper cover on the E61 is really quick and straightforward, much simpler than removing the front bumper cover. It only takes about 10 minutes, and it's probably worthwhile removing it periodically just to clean out the road salt and grime that collects within the rear bumper that caused a lot of the corrosion in the first place.

Sources


Some POR-15 products are available at Canadian Tire at a reasonable price. For everything that Canadian Tire didn't carry - I simply ordered from the POR-15 online store - quick delivery in a couple of days. Real simple.

Let me know if you have any comments or questions below. 









 

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