What Sensors and Data Collection Do for HVAC

Back in 1990 we were at a major change in the way the world would work.  We went from making great products to generating data and collecting it.  By 2000 we had made computers distributed such that we could set up a data collection that was all over.  Many technologies were invented to make this work.   Today, we generate massive data that 80% did not exist 2 years ago.  Many major things will change now as we make use of this data.  A few companies can take this data and analyze it, process it so it is useful.  Data refining is the next major key to all that we care about.

Your furnace, AC, and thermostat has many computers, sensors, and devices to keep you safe and comfortable in your home.   About 5 years ago, we were behind on safety, heating and cooling and air flow.  Now we are in much better shape.  As we add sensors to what we have now, we will move far far ahead of where we are today.  We just have to make sense of what the data we are collecting is telling us.

Many or most sensors in the furnace are for safety.  They turn it off if it gets too hot; they make sure the flame is on if the gas is on.  There are no more pilot lighter units now, the flame is started with a spark or an igniter that gets very hot quickly.  This saves gas and also is safer for the customer.    The AC unit also has sensors that turn it off if all is not right.

As we go further now, more sensors will be put in to tune the units for heating and cooling the areas that are to be done.  Flow sensors, temp sensors, humidity sensors will help do all this by taking data and sending it to the micros that control the unit.  The data processing is a big part of this now.  This is true for all applications.  Humidity is a major issue for cooling and heating in many areas of the USA.  The gulf coast is very humid.  The AC unit can control this if the sensors are there and the system can control the fan speed.   Cooling is similar to this.  Heating does not require fast air but it does require good airflow.  Most areas, especially in Utah do not have good airflow. They do not have good return air ducts.  They do not have a constant torque variable fan system as well.  This is a major problem for cooling and a problem for heating.

What are the key issues to a great Furnace and AC System

Most customers believe that the brand of the equipment is the main issue for quality.  I agree that it makes some difference, but the number one reason that a system works or does not work well is the install in the home.  If that is done right, there are several brands that will do a great job for the customer.  I would say it is even 70%+ of the total cause of success or failure.

The top units that several companies make are about the same quality and have similar features and most of the time use the same parts in them.  For example, for a furnace the fan system is either number one or number 2 most important to success or failure for the unit to work on heating and cooling the best way.  It is what creates airflow.  What powers this is the fan motor which is a variable speed dc motor that is very efficient and powerful.   These are made by one company so many companies use the same motor for this.

AC units use a compressor made by one company, that is all there is.  For this reason the design and install for your needs is much more important than the brand of the equipment for quality,  and for performance.

Duct Work effects Air Flow in Homes

I purchased my house here in Utah about 12 years ago in 2007.  It was built in the very early 70’s;  many things have had to be updated over the last few years.   In prior years, I replaced all but 2 windows with double pane vinyl windows, and also replaced the doors.  This alone cut down the air leakage from outside and the dust in the house.     I  replaced all of the plumbing that was from the 70’s with PVC, copper and PEX.  In 2010, I updated the wiring in the kitchen and bathrooms and added GFCI receptacles.  I replaced the appliances, added a dishwasher, and painted all of the cabinets.   We tiled the kitchen and dining room, plus bathrooms and added heated floors there a few years back as well.  Two years ago I replaced the old carpet with hardwood in much of the house.  Two years ago I put a new furnace in and AC that is very efficient.    This year I replaced the breaker box and rewired several areas that were old aluminum wire ending in the wrong type of connections or just old wire.

When we moved in the house was set up for a furnace that was over sized to handle the windows and door leaks.   A small AC was added sometime to this house and the evaporative cooler was still on the roof not working.   The original duct work was set up for a small furnace that heated about 800 sq ft.  Very little return air and barely working.

This home made duct work was minimal in this house so I have replaced and added to bring it up to what I expect it to be.  I also have had very little air in about half of the house.   As I said, the furnace is 2 years old and I replaced the PSC motor for the fan with a constant torque motor that is set to put out about 1600 cubic feet per minute total air.  It is split between the kitchen, dining room, living room and large master down in the basement on one side and the other 3 bedrooms and bath rooms on the other side.  The bedrooms have had very little air coming through.

The ducts are in the basement which is finished.  I tore out sheet rock to find that three bedrooms were all fed from one 6″ duct that ran about 15 ft and then split three ways.  Now I know why no air on that side.

I took all the old 6″ duct that  began at the furnace on the bedroom side out and replaced it with two 8″ x 10″ ducts mounted side by side feeding a large 10″ x 20″ 10 ft duct across the same area.

         Looking up in the left picture you will see two ducts both 8″ x 10″ as this area has very limited room so one is 10 in wide the other is 10 in tall and 8 in wide.  The right picture is two 10 x 20 in ducts 5 ft long each.   Airflow went from two 8 x 10 ducts mounted side by side connected directly to the furnace output plenum and then combined into a 10 x 20 in duct to travel to the area where the bedrooms can be split off.

In the last 5 ft of duct, I distributed the air as follows: For the upstairs master, I put two 7″ round ducts up to 4 x 12 registers from a 7 in Elle on top;  I had already added a large return in that room and two others that needed it last year.  I then installed another 7″ duct from a Elle  for the down stairs bunk room which already had a good return.  I then added another 7″ duct to a smaller bedroom above that.   You can see the second 7″ duct for the master going through the variable ducting.

The airflow on this side has gone from hard to feel at 3 in away to very strong 3 ft away from each register.  With the 3 phase constant torque fan motor that provides good air and the changes to the duct system in the bedroom side,  it all works much better for this half of the house.  The other half was done last year and works very well also.

Now I will replace the sheet rock and texture it and get ready to paint all this.  This type of job takes two of us about 1.5 days to do if the area is open.  It took me about 3 days part time to do this as I took the sheet rock off and added good ducting here.   The cost to do this is about $2000 to $2500 depending on what we have to do.   I had already worked on the return system that helped the air flow as well.

Airflow in a home is as important or even more important than the Size of the AC unit for cooling a home

Summer arrived in Utah last week during a cool spell.  We have had some fairly hot days 85 deg + but Friday and the weekend was not.  Now Monday is back to 85 deg and tomorrow will be 90 or so and gaining from there.  We are back to cooling weather for the next 2 to 3 months here.

Here in Utah, we often run into customers who are adding an AC to there home to replace a evaporator cooler or a older, much less efficient AC unit.  Most of the time we can not get the best performance from our AC no matter how good it is.  Without good or very good airflow in the house the AC can not cool the house well.  Since about 2017 manufactures have gone to constant torque, variable speed fan systems.  This provides much more air in the home.  If we also do the measurements and help the duct systems both outgoing and return, we get very good results.

Often a customer will ask what we recommend to solve there problem or get the best performance.   If we are dealing with furnaces older than 3 years and many older than 2 years that are not the top units, we have a major airflow problem.  the best solution is to replace the furnace with a 96%-97% multiple stage unit with constant torque, variable fan system.    We can often replace what they have for less than $4000 and they get the best heating, cooling and air flow.  The value of their home just went up about $8000+ doing this.  In the winters this year and next they have little or no cost to heat their home.

On the AC side with good air flow we can design a system that will run about 20% of the time and the cost to cool the home perfectly is 1/3 of what it was before.  We put in many 3 ton units, 3.5 Ton units, 4 Ton units as well.  We pick very efficient Evaporator coils and line sets to get very close to 20 SEER on the performance.   We can do this for just under $4000 and the value of the house just went up another $8000++

If the customer can not replace the current furnace, we can replace the fan motor for $500 or less, but it is not a variable speed unit (they cost more than $900 each and need a controller to get good performance).  Total cost is often well over $1500.   You still have a old furnace when done.   In contrast, you can get the best performance from the fan system and best performance from the furnace for less than $4000.   A replacement fan will get more air and better performance,  but not close to what we get with a new high efficient furnace system.

Some people here do not believe what we say, even though we have years of experience and many years of formal training.  If they just do not like the truth, or how we measure the results, there is little that we can do except go to the next customer.  We get a lot of referrals here and all over where we work.  Tells me we are generally on the right track on what we say and do.

We make measurements on  system airflow, on cooling capacity, on heating capacity, on BTU gain, and on how a gas furnace is tuned.  We not only know how to do all this, we have the best equipment, understand how it works, and how to apply it.  Some people ask me if replacing their old windows will help with heating and cooling their homes.  The obvious answer is yes, it will help more than most things that can be done.  We can measure the difference before and after on this as well.

Many other things matter here.  Return air is a major issue here in Utah.  It takes about 1.8 times more return air than feed air to not cut the airflow going out.   We use 2X because it is easier and not exact thing.

Two good examples here from 2019:

#1    A couple here in Utah wanted a good AC unit that would keep there home cold.  I went and accessed the furnace, the size of the home, windows, doors, air leaks, etc and gave them a bid.  A 3 ton unit was perfect for this home.  They had an old furnace that had an old fan system; and I urged them to replace the 80% builder grade unit with a 96% two stage furnace with a constant torque,  variable speed fan system.  This included a computer driven smart thermostat that operated the furnace properly and could be done from there phone.   They insisted they did not want to do this.  I then explained that I could replace the motor in the old furnace but it would not be near as good as a new furnace and fan system would perform.  They decided to not go with a new furnace and go with a fan motor on this and a high efficient AC.   It turned out the old 80% furnace would not support any AC at all.   Before I replaced the board and relay at my cost, I  urged them to go with a new furnace again in place of putting now $700 in that old unit.  They said they did not want a new furnace.  I replace the board in the furnace and a relay to drive the ac and fan system.   The new AC worked very well and the fan system was much better than I started with.  That system worked OK but not as good as with a new furnace and thermostat.   They were unhappy later and wanted $500 back for all this.   They were told in advance about the risks and performance.   They have cold air.   Total cost just under $4000 The value of there home went up the $7000 from the AC but is down by $5000 due to the old furnace that needs replacing.   So all taken into account, about $2000 more is all.

#2  And older couple needed a AC to replace there evaporator system that no longer worked well here.   I went over to their home and told them they need both an AC and furnace along with updates in the main plenum duct system to support the extra ducts they wanted.    They listened and we put in a good 3 ton AC and 84,000 BTU furnace with variable speed fan system.   We doubled the flow in the plenum to support the air flow in much of the house.    The system works great and provides very good flow and cooling all over the house.  Their home is now worth about $18,000 more due to this.  The cost to run the AC will not be much more than they were paying for the evaporator system.  They are very happy  Total cost just under $8000