Showing posts with label HVAC. Show all posts
Showing posts with label HVAC. Show all posts

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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Filtering Pollen from Air Exchanger Intake Duct

My son has Asthma, and it's aggravated by seasonal allergies. We've taken steps to limit allergens from entering the house - we keep the windows closed most of the time, we've sealed air leaks and we've added a mechanical air exchanger with heat recovery. I wanted to improve the filtration of incoming air to try to ensure we're removing pollen and other potential irritants. I decided to to add supplemental filtration of the air exchanger intake duct.
Fantech FB6 Inline Filter Box - Designed for 6" Round Duct
This is a fairly simple project. Find a location on your incoming air duct where you can remove approximately 26" of the round duct, and mount the steel filter box. Ideally, locate the filter box close to your other air handling equipment, so that it is easily accessible for filter changes during routine servicing. The specifications of the FB6 are as follows, check to see if these are appropriate for your installation or if you require a different size.
• Airflows up to 176 cfm
• 6" diameter plastic duct connections
• Beige powder coated
• Neoprene door seal
• Access door removed with thumb screws
• Weight - 10.6 lbs
• Filter compartment dimensions - 19 1/2 x 10 x 8
• Filter size - 20 x 10 x 1"

Filter Box located close to HRV to simplify servicing and filter changes
One thing to note about this filter box is that it's not insulated, so if you're operating this in cold climates, you'll get condensation on the box. In my case, I wasn't too concerned about this because the box is located above a concrete floor in the utility room, about 24" from the floor drain. I've considered insulating the box, but haven't gotten to that because the condensation doesn't cause too much of a problem.
Data Plate on the Filter Box
Once I installed the external filter box, I removed the smaller incoming air filter from the air exchanger, because there is no need to filter the air twice. You can select your level of filtration depending on your needs, in my case I'm using MERV 11 filters which I find is a good balance between filtration and pressure drop. I also want to maximize the airflow, because my air exchanger is a bit undersized for the size of my home.

Conclusion

Works fine, condensation on the box doesn't cause any problems in my installation, and I can tell the filtration is working well by the amount of crud the filter pulls out of the air. I change filters four times a year. 

Sources and Links

I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to Amazon.com in the United States.

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Solving slow clothes drying performance with an inline duct booster fan - Fantech DBF4XL

Since moving into our new house - we've seen our clothes drying times double. The clothes dryer gets very warm, but due to a long duct run to the exterior of the house - airflow is reduced. The duct run is about 30 feet, not including losses due to elbows and fittings. Large loads would take 2 hours to dry.
The Fantech DBF4XL Dryer Booster Fan with Pneumatic Sensing Control
Some research lead to inline dryer duct fans - which improve dryer performance by overcoming the duct loss due to the length of the duct. I have a standard clothes dryer with 4" diameter round ductwork. The ducts were all sheet metal ducts, with only a short length of flexible at the dryer connection, so the ductwork was already optimized by being as smooth and as short as possible to reach the exterior of the house.

Fantech DBF4XL - Serial Number Plate - On the Pneumatic Timer Control Box
I decided to go with a Fantech model with a pneumatic switch that automatically detects the change in air pressure in the dryer duct when the dryer is activiated, then turns on the booster fan in 10 minute timed periods. At the end of the 10 minutes - the booster fan switches itself off - and if the dryer is still operating - the pneumatic control turns the fan back on for another 10 minutes. I found the Fantech DBF4XL on eBay - previously installed but never used - for a good price.

Reading the installation instructions for the fan - they recommend the installation of a secondary lint screen upstream of the fan to help protect the fan from clogging with lint. When I opened my dryer duct - I had plenty of lint in the duct - which indicated that the lint screen in my dryer was passing a lot of lint - more on this later. So - onto eBay where I found a Fantech secondary dryer lint trap for a reasonable price.

Once the secondary lint trap and fan were received, I set to work. My dryer vent line ran through the basement under the first floor where the laundry room is. So - it was a simple matter to cut into the dryer line where it ran under the floor - and duct in the secondary lint trap and the booster fan.

The secondary lint trap has a clear plastic window which helps to show when the filter box needs cleaning. It's a neat looking installation - but would be much more convenient installed directly behind the dryer.
Installing the Fantech Secondary Dryer Lint Trap - Note the Laser Line - Simplifies Lining up the Ductwork
The filter box ending up screwing directly into some wood cross members under the floor - straight through the base of the filter box. Very simple.
Fantech Secondary Dryer Lint Trap - Installing the Filter Box with the Cover Removed - Note the Laser Line
When installing the secondary lint trap and lining up the booster fan - I used a laser level with vertical laser line to line the filter box, fan and ductwork nice and straight - to have a professional looking installation. The laser really facilitates the installation.
Installing a wood block to install the Dryer Duct Booster Fan - Four Tapcon Screws into the Elevated Concrete Slab

Secondary Dryer Lint Filter Upsteam of Dryer Booster Fan

Secondary Lint Filter and Dryer Booster Fan Installed
Very important installation point on the booster fan - the booster fan uses a pneumatic diaphragm switch - the copped colored cylinder in the photo below. The diaphragm needs to be oriented vertically so that gravity does not act on the diaphragm - which would work either for or against the pneumatic pressure and upset the operation of the switch - your switch would either be on all the time, or not activate reliably on duct pressure. It's very simple to rotate the fan on the installation bracket so that the diaphragm is vertical. When installing the bracket - take care not to install the self tapping screws to close to the center of the fan enclosure - you could screw into the fan impellor and block the impellor from turning. It's not as complicated as it sounds - you just need to take care with these points on installation.
Fantech Dryer Booster Fan - Note the Orientation of the Copper Colored Pneumatic Switch - This needs to be oriented vertically for it to work properly.

Conclusion

So - how does it work? Perfectly. It switches on and off automatically as described above. I haven't had any issues with the booster fan turning on when not required, and it recycles automatically in the ten minute intervals without any issue.  The secondary lint filter needs to be cleaned once every two dryer loads on average - which is more frequently than what I hoped. It would have been much more convenient to have the secondary filter installed in the laundry room - for easier cleaning - but this wasn't practical in my installation without adding a lot more ductwork. Something for me to consider in the future.

The dryer cycles have been reduced by almost one half, 2 hour dryer loads now dry in about an hour - and the automatic dry cycles now work reasonably well - before - the automatic dry cycles never got the laundry dry.

4 Year Update

Still working 100% reliably after 4 years - at least 6 laundry loads a week. The secondary lint filter is a MUST - it is amazing how much lint misses the dryer lint trap. Super impressed with the performance and durability of this fan - no problems at all. 

Sources and Links

I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to Amazon.com in the United States.

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Central Air Conditioning Condensation Drain, Trap and Cleanout


Last summer I began having humidity problems in my house, even with the air conditioning running. A quick inspection of the fan coil unit showed that the evaporator condensate pan was not draining properly, leaving the pan full with water. As the fan circulated ventilation air when the air conditioner was not running, it would simply evaporate the water in the condensate pan, and bring it back into the house.

My condensate drain was constructed of 3/4" CPVC pipe, and the installer put in a simple P trap made of 90 degree elbows, as shown below. I tried flushing out the P-trap by putting a hose nozzle inside the fan coil unit - very awkward, and not very effective. I had to find a better way of cleaning out the trap.

Condensate drain made from 3/4" CPVC pipe and 90 degree elbows
A second issue with this drain was that there was no slope added to the pipe when it hit the floor and ran for about 20 feet.

Drain runs about 20 feed along the floor slab to a floor drain
To be able to get in and clean out the P trap, I cut the trap out of the system, and reinstalled it with two CPVC union fittings. I started by installing the top union, to be able to measure the down pipe on the other side to get the right height for the second union. When I got the P-trap removed, it was completely gunked up with scale, rust from the condensate pan, and spider webs. It was easy to clean out once removed.
Installing CPVC union fitting on the trap

Here's the finished trap with two unions installed. 
I also corrected the slope of the pipe running along the slab, to avoid water pooling in the flat runs, evaporating, and leaving scale. 

Shimming the drain pipe to get the correct slope 
Adding shims under the pipe straps to correct the drain slope.
All told, this project took a couple of hours, but it should reduce the amount of maintenance required to keep the pipe flowing, and greatly simplify cleaning out the trap. If you're putting in a new drain, consider putting in the union fittings right from the start. They're not expensive, about $4 or $5 for a 3/4" union.

Water fllowing through the drain line again.

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My Indoor Air Quality Project

I've recently started tackling my indoor air quality project - I have a number of issues that I've been working on solving since moving into and renovating a 2500 square foot home with finished basement and two levels, and I'll post about the various solutions as I work through them.

Honeywell Prestige Thermostat
What are my issues?
  • Very dry air in the winter (dropping to the 20 to 24% range in the middle of winter on cold days;
  • Very humid air in the summer - getting up over 60% relative humidity
  • A musty odour on some days in the summer time, which tends to correspond with high humidity; 
  • Optmizing the HVAC performance, especially since one of the household members has Asthma, and seasonal allergies. For this reason, we rarely open the windows to the house, and rely on a Venmar ERV (energy recovery ventilator) for fresh air exchange.
The solution selected for the dry air in the winter was to install a whole house humidifier. I've been tracking humidity levels for the past two heating seasons, and I've been getting down to 24 or 25% relative humidity, and all the problems that go with humidity this low. Cracks opening up in hardwood floor, nosebleeds and dry throats, dry coughs, and the like. The installation of a Honeywell TrueEase central humidifier has solved the problem nicely. 

I suspect that my problem with high humidity levels in the summertime have been caused by two separate issues i) a blocked condensate pan drain, which keeps condensate water removed from the indoor air from the air conditioning evaporator recirculating in the indoor air stream, and ii) my Venmar ERV furnace fan interlock - which keeps the furnace fan running even when the air conditioner cycles end, not allowing the evaporator coil condensation enough time to drip down into the condensate pan and into the floor drain. Consequently, this condensate water just gets re-evaporated into the fan coil airstream, and back into the indoor air. Net result - buildup of humidity inside the house. The solution here was to correct the drain slopes, and to add unions to the condensate drain trap, to allow for easy removal and cleaning of the trap. I needed a way to independently control the ventilation ERV, the furnace fan, and timed with the air conditioning cycles, and the only thermostat that I found that would do that, and also independantly control humidifying, is the Honeywell Prestige 2.0 IAQ thermostat.

I also require central control of the humidifier in the winter time. This lead me to look at the latest generation of smart thermostats - in an attempt to get better control over the HVAC in my home, and address my air quality issues. I found that the Nest thermostat doesn't have the capability to intelligently control ventilation, has a single output to control humidification, and has the ability to control the air conditioning to control de-humidification. Similar situation with the Ecobee 3 thermostat. Finally, I found the Honeywell Prestige 2.0 IAQ thermostat - with the equipment interface module, it has three user outputs that can control ventilation (ERV/HRV), humidificationa and dehumidification. So - part of this plan included upgrading my thermostat and ERV control to the Honeywell Prestige IAQ thermostat.

I'll update this post as I work my way through this project.

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I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to Amazon.com in the United States.


 
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Installing the Honeywell Prestige 2.0 Indoor Air Quality (IAQ) Thermostat and Equipment Interface Module (EIM)

I suspect that my problem with high humidity levels in the summertime have been caused by two separate issues i) a blocked condensate pan drain, which keeps condensate water removed from the indoor air from the air conditioning evaporator recirculating in the indoor air stream, and ii) my Venmar ERV furnace fan interlock - which keeps the furnace fan running even when the air conditioner cycles end, not allowing the evaporator coil condensation enough time to drip down into the condensate pan and into the floor drain. Consequently, this condensate water just gets re-evaporated into the fan coil airstream, and back into the indoor air. Net result - buildup of humidity inside the house. I needed a way to independently control the ventilation ERV, the furnace fan, and timed with the air conditioning cycles, and the only thermostat that I found that would do that, and also independantly control humidifying, is the Honeywell Prestige 2.0 IAQ thermostat.

Honeywell Prestige 2.0 IAQ Kit with EIM, Outdoor Wireless Temperature and Humidity Sensor, and Duct Temperature Sensors

Honeywell Redlink Internet Gateway

I also require central control of the humidifier in the winter time. This lead me to look at the latest generation of smart thermostats - in an attempt to get better control over the HVAC in my home, and address my air quality issues. I found that the Nest thermostat doesn't have the capability to intelligently control ventilation, it only has a single output to control humidification, but has the ability to control the air conditioning to control de-humidification. Similar situation with the Ecobee 3 thermostat. Finally, I found the Honeywell Prestige 2.0 IAQ thermostat - with the equipment interface module, it has three customizable user outputs that can control ventilation (ERV/HRV), humidification, whole house dehumidification, and a fresh air intake damper. So - following my research, I ordered Honeywell Prestige IAQ thermostat kit with return and supply duct temperature guages, outdoor wireless temperture and humidity sensor, and the equipment interface module. In addition, I picked up the Redlink internet gateway, which allows me to control the whole system from my smartphone or tablet, even when away from home.

Installing the system may seem a bit complicated, but in practice, it's not much harder than installing a standard thermostat. The Prestige 2.0 thermostat that installed in your living space on the wall - is actually just a wireless controller for the system - like a small tablet computer. There are no relays inside this thermostat, just a small backup battery to retain settings during power failures, and two contacts for 24VAC power. The Equipment Interface Module, which installs close to your furnace / HVAC sysem, has all the relays and switching, connects to all the HVAC equipment using standard 24VAC hard wired controls, and connects wirelessly to the wall mounted thermostat in your living space. The nice thing about this architecture is that it is very easy to wire up additional elements to the Prestige thermostat system - temperature sensors, furnace / fan coil unit, ventilation system (HRV or ERV), whole house humidifier, whole house dehumidifier, an optional duct zone control system, etc) and the multitude of wired connections are all made close to the equipment, and don't all have to be run through your walls to your wall mounted thermostat. Very easy to wire up, very easy to add additional system components, and very easy to integrate the operation of everything using the smart thermostat.

The back of the Honeywell Prestige IAQ Thermostat. Note the button type backup battery in the top right corner, and the power connection posts in the center. 
This thermostat is small - slightly smaller than a dual electrical switch wallplate. Whatever you are replacing with this was probably larger, and you'll probably have some drywall patching and painting to do to make it look right. If you don't want to get into paint - there is an accessory backplate that covers the old thermostat hole. I went for the cleanest install possible, and did my patching and painting.

Thermostat powered up, while still sanding and patching the old thermostat space. 
Since the thermostat communicates with the EIM wirelessly, all the thermostat needs for connections is red and black - 24VAC and Common.

Wallplate is nice and small, terminals are a bit fussy.
Installing the Equipment Interface Module (EIM) is fairly straightforward. Find a suitable mounting place close to your furnace or fan coil, and mount it vertically. I found a good spot on the return ductwork just above my fan coil.

Cable tie holes make wire management fairly simple.
The connections you make here are your typical HVAC control connections - up to 4 stages of heating / 2 stages of cooling for heat pump systems, or 3 stages of heating / 2 stages of cooling for conventional system. It has power connections for running to the wall mounted Prestige Thermostat, 4 wired sensor inputs, for temperature sensors or switches, 3 control outputs for user defined applications - such as whole house humidification, dehumidification, fresh air damper and / or ventilation HRV / ERV.

Once installed - lots of wires running to the EIM - 2 temperature sensors wires, humidifier control and humidifier damper, ventilation ERV control, power to thermostat, control to fan coil unit. 
I found this system to be really well thought out, well architected, and logical. The EIM installs close to your equipment - and is designed to interface with all the control wires required even for a complex, multi-zone system. All the wiring is close to the equipment, so control wire runs are short and simple. You're only sending power to the thermostat, and all the switching is done close to the equipment. The thermostat communicates over a wireless protocol called Redlink - designed by Honeywell for low power consumption and reliability. The system also communicates with an outdoor temperature and humidity sensor which gives lots of control flexibility for things like ventilation, heat pump balancing and lockout control, fresh air intake damper options, and controling ventilation considering the outdoor humidity levels. You'll have to get a copy of the manual and installers guide to get a real good idea of everything that this thermostat can do - it is quite impressive. I should say here that this hasn't been designed for homeowner installation - it should probably be installed by a HVAC technician, especially if you are not familiar with HVAC controls and systems.

Controlling your ventilation HRV / ERV. I had a Venmar ERV installed when we renovated and moved into our home three years ago. Since our home has central ventilation, three zones of ductwork, our Venmar was installed to draw air from three separate places on each level of the house (three bathrooms), but the fresh air distribution runs into the fan coil return ductwork, and must be circulated by the furnace. So - the Venmar was set up (properly) with a furnace fan interlock, to force the furnace fan to run when the ventilation is running. We were running the ventilation constantly, and therfore, that forced the furnace fan to run constantly. A 3/4 HP blower fan running 24/7, 365 days a year draws a lot of power.  At $0.094 / kW-hr, this blower fan was consuming almost $1,100 a year of electricity. This lead me to my first major system upgrade,  the retrofit of an Evergreen IM electronically commutated motor. However, this furnace fan interlock would force the furnace blower to run - right through the end of air conditioning cycles - which has the effect of preventing condensed humidity on the evaporator coils from draining to the floor drain (and humidifying your air in the summer). So - I was getting high humidity levels in my home in the summer. You can set up the Prestige IAQ thermostat to force the blower fan off at the end of an air conditioning cycle - even if there is other demands to have the fan continue - giving time for this condensed humidity to drain away. However, for this to work, the ERV has to be controlled by the EIM / Prestige Thermostat. If you keep the furnace interlock connected directly to your green fan wire - it will still override the EIM / Prestige system. It is very simple to have the EIM control the Venmar - two wire dry contact from the EIM to the override terminal in the Venmar connection box, and now the EIM / Prestige thermostat is controlling the Venmar. I took my Venmar controller down from the wall above my old thermostat, and mounted it on the duct next to the EIM just in case I ever decide to control the Venmar independantly for any reason. I could have just left it uninstalled. I have three Venmar boost switches installed in each of my bathrooms - they will still force the Venmar to run, but I removed the furnace fan blower interlock, so when the boost switch in a bathroom calls the Venmar to run, it doesn't force the blower fan to run. It will still evacuate bathroom smell / humidity out of the house, the return air will just be pushed into the return ductwork by the Venmar fan.

On the Venmar AVS Duo 1.9 - shorting the OC and OL terminals forces the Venmar to run at high speed. This does not affect normal operation of any pushbutton switches you have installed on the same terminals. 
The kit comes with two temperature sensors designed to be installed in your supply and return ductwork to perform routine temperature rise logging and system performance evaluation. The system is called Delta T Alerts and Diagnostics. The installation manual provides clear instructions where to place the sensors in your ductwork in relation to any bypass ducts, humidifiers, zone splits, etc. Once installed in your ducts, they are wired to any 2 of the 4 sensor inputs - S1, S2, S3 and S4. Once added, you need to configure them in the system through the installer setup menu on the Prestige thermostat. Take note on the packaging whether they are 10kohm or 20kohm sensors - you'll need to specify this in the setup. Once installed, you can run temperature differential tests, and you can also download historical performance logs detailing the delta t of the system, with the indoor and outdoor temperature and humidity data. This is great for analyzing the performance of a heat pump, and setting lockout temperatures. You can also set alert ranges - for example, if delta T on air conditioning or heat pumping drops below a certain threshold, that could indicate loss of refrigerant or a dirty indoor or outdoor coil, and put an alert on the thermostat advising the owner to take action. Very nice feature. 

Testing equipment to determine baseline temperature rise. With this information, you can set alerts. 

Testing temparature rise on emergency backup heat.

Checking performance logs - note min and max delta T recorded for the specified interval. 

You can also download all the historical performance logs onto a USB key - for analysis in a spreadsheet on your computer. 
The completed installation, the EIM is on the top right corner mounted on the return duct:


I really like this instalation - I really appreciate the information provided on the thermostat screen. I like being able to see at a glance the indoor and outdoor temperature and humidity. The Nest thermostat has a nice industrial design, but for my needs, I appreciate the compact but useful screen display. 

Nice density of information - and you can set the screen colour and backlighting to about a dozen different colors, or any intensity level you wish. 
The smartphone application is also quite useful, but I think I'll make that the subject of another post. Ask any questions you would like and I'll try to answer.




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