My heat pump installation
Our former vacation home, and now primary residence, needed some improvements in the heating, ventilation, and air conditioning system ( HVAC ). I decided to retrofit a heat pump. Our heating consisted of baseboard electric and our wood stove. Our air conditioning was a 12000 BTU unit in the kitchen which we tried to use for the whole 1500 square foot home. The baseboard heat does not actually any ventilation and it is the most expensive heat you can buy; it is well zoned though. We also wanted to heat our basement efficiently. (Please see my article on heating our basement.) Central air would be very desirable in that we spend quite a bit of time in all the rooms in our home, including quite a bit of time in the basement. No air is needed for the basement, but it definitely needs heat, and a lot of it, in the winter. I also have Spring and Summer allergies, so I hope a central filtered air system will help with these allergies. We have gotten rid of most of our carpets and replaced them with 3/4" solid hickory wood floors. The floors are beautiful and the dust reduction is tremendous. Carpeting is a tremendous source of dust and dust mites, I am glad we are rid of it. This really is too big a job to do yourself in a reasonable period of time. But even if you hire a contractor, a lot, and I mean a lot of oversight is required if you want the job to turn out well and end up with the system you truly desire. Please also note, if you are installing central air, spend a little more and install a heat pump. It can save you money even if you have gas heat now!
Heat pumps can be 400% efficient
We did not end up with the most efficient unit, BUT, we did end up with probably the most durable and simple heat pump unit in the industry. It is still efficient. For example it has an intelligent defrost cycle. The heat pump compressor measures the temperature differential across the heat exchanger coils to determine when and how long to defrost. This used to just be a timed event. The most efficient units have dual compressors, this is just too complicated for me, (and frankly for the installers). Please read the many reviews of the various manufacturers equipment. This purchase is certainly a BIG one!
Please remember a heat pump removes heat from the outside air (or ground). The heat pump compressor may consume 1 kilowatt of electricity but generate 4 kilowatts of heat! 400% efficient, wow! Baseboard heat is (only) 100% efficient, you can see why a heat pump can be cheaper, way more expensive up front though. Baseboard is the ultimate in simple however. Please see my article on installing baseboard setback thermostats, they are great!
Heat pump misconceptions
30 degree balance point, ridiculous!
Our Trane XL14i "Climatuff" heat pump will maintain our home's temperature down to 6 degrees F on a windy day with no auxiliary heat. That is with a 73 degree setpoint. The average low temperature in our area is 20 F. It can get to 15 below, but that is pretty rare. Our home could still have much better insulation; it is about R15 in the attic. The house does have 6 inch studs, due to baseboard heat. This helps reduce heat loss. So much information you see on the web says a heat pump is inefficient in climates that go below 30 F in the winter, that is ridiculous! Here is an excellent article about heat pump balance points, the problem is again this article chooses a balance point of 32 degrees F! It is just not the case any more unless you have a very old or very poorly insulated home!
Choosing the contractor for a heat pump installation
In our area this is a difficult task. At first I was interested in a ground sourced heat pump. They typically can produce more comfort and heat your hot water too! I had called two contractors claiming to be in that industry. One never returned my calls, and another never showed up for an appointment at my home. The third contractor I talked to on the phone tried to talk me into an air sourced heat pump. Our previous home was heated with an air sourced heat pump and this contractor had some very good arguments regarding why we should choose air sourced. So for the first time we had a contractor make it to our home. He proposed an air sourced Trane XL-14i 3.5 ton heat pump. The claim was this unit will produce heat down to 10 degrees F, sufficient heat to maintain the house temperature.
We had to choose between R22 and R410A refrigerant. R410A is more expensive. Our contractor insisted that R410A will give us a lower heat balance point and it is the "future" refrigerant. R22 will be phased out in the near future. Also we had to decide whether we wanted humidification and high efficiency dust removal; we wanted both. The other thing to remember, this is a full retrofit requiring complete installation of ductwork and returns. We had vague hopes the ventilation unit could be put in our attic. But our house has vaulted ceilings and there is just not room and I am glad the ventilation unit ended up in our basement, because it was the primary point of access for all the service issues. So another decision is equipment location for the outdoor compressor unit (which is huge) and the indoor ventilation unit.
Major Decision Problem
We almost cancelled the job which we had already agreed to. The "returns". First according to our contractor there should be a "high" and "low" return for the system. These are single, very large returns. When we accepted the quote, the returns were going to go in a particular central wall, no problem! I was doubtful of this at the time. What happens is the guy doing the quote is not the guy doing the installation. The guy doing the installation could not put the returns where the guy doing the quotes had specified. The returns are also 400 square inches, 20" x 20" inches, wider than your typical stud spacing. So after a lot of somewhat heated discussion we decided the return ductwork could be put in the bathroom with the returns themselves in a central hallway (This could have been done better). The returns cannot be in the bathroom, if they were the door would be blown off if you closed it with system running. This "change" required my wife and I to get rid of the existing sink and counter top, losing considerable space and storage, and put in a new smaller sink and mirror in the bathroom. So my wife and I redid some electrical, drywall, plumbing, a new fancy sink and base ($500), and fortunately we had left over matching wall paper. But the bathroom looks pretty good today.
Heat Pump installation
There were two people, sometimes three, in our basement for a total of six working days. They started out a little slow, worked more as time passed, and the last two days they were rushed, even though they left early the last day.
Admittedly our basement was a mess. So work was a little tough for the installers. You can see in the photo at the top of the page I ended up storing a bunch of stuff including furniture under a tarp below our deck. We just had to make some space. Initially there was a lot of stuff to store in our basement for the installation. It did rain so everything had to come inside. The duct work takes up a lot of space, along with boxes of flex vent XP, dampers, grills, and other miscellaneous ductwork..
Positive aspects of our heat pump system
The ductwork, and workmanship, were of high quality. The ducts are well insulated, both inside and out. This is important to avoid any condensation during air conditioning season. This will also quiet the system.
I think the selection of equipment is very good, Trane is well respected. Available documentation is a little limited.
Because we were buying both the heat pump and air ventilation unit at the the same time the system warranty is extended to 10 years.
The installer met all the the manufacturers installation requirements.
Problems I have found and repaired
Our thermostat is "armchair" programmable, but the first time I went to unplug it from the wall the mounting plate came completely out. The installer had used plastic wall anchors to mount the thermostat. This unit takes a firm pull to remove it from the base. I ended up using four metal hollow wall anchors into the drywall so now the base is firmly mounted, ah, now, I can finally program my thermostat in my armchair.
The thermostat itself is branded with the Trane name, but I am pretty sure it is a Honeywell unit. While this is a good unit, and has many desirable features, it may be a little dated and not quite appropriate for an R410A heat pump that can operate with some efficiency down to 6 degrees F. The quirk in this thermostat is having a programmable heat pump cutoff temperature that only goes down to 30 degrees F. It is programmed this way by default! As it got cold the first winter I noticed the heat pump was cutting out too soon and electric backup was kicking in. The electric backup probably should not kick in for this system until it is 10 F outside, not 30F! Fortunately there is a configuration where the heat pump runs no matter what the outdoor temperature and the electric backup still kicks in to provide the additional heat the outdoor compressor cannot provide. Since our system is electric backup, this setup is acceptable, it could be better though.
Condensate pump noisy
The system is in the basement and in the summer air conditioning season condensate is produced and in the winter the humidifier has waste water it produces, therefore a condensate pump is required for the system. The pump receives condensate from the air handler's evaporator coil in the summer and waste water from the humidifier in the winter. There is no place downhill for the water to go. A pump is required and a long hose was run to outdoors where the water can run into one of our outdoor drains. The problem with the setup as installed was the outlet of the hose was actually below the level of the pump causing a siphoning action to occur. This siphoning would continue for a couple of minutes after the pump cut off, making all sorts of annoying noises in the basement.
Also with the installed setup, on extremely cold days the outdoor portion of the hose would just freeze up. This still has to work in the winter to support the humidifier. So I cut the hose off just after it exits the house, and provided and open PVC pipe to guide the waste water to the downspout drain. This change eliminated the siphoning noise and the freeze up.
Condensate pump cord runs across floor.
The condensate pump provided by the contractor was a 120 Volt unit. They just ran the cord across the floor with an extension cord. This was very inconvenient. They offered to install an outlet mounted on the air handler unit, but the way they had wired the 220 Volt air handler, they could not provide a 120 volt outlet and still meet electrical code. I had to explain this to them or they would have gone ahead and made an unsafe installation. To install a 120 volt outlet as they proposed would require a Neutral wire to the air handler and the cable they used did not have one. They would have used the electrical ground wire which defeats safety's in the electrical system. I let this go at the time. Astonishingly, due to another project I had in the house, (my Hot Water Heat Pump), I had a 220 Volt condensate pump and even an appropriate fuse panel for a 220 outlet that could be installed on the air handler so that my condensate pump could just be plugged into the air handler.
Humidifier water flow was continuous with fan off
The humidifier provided was a 24 volt unit. To power the unit the installers had wired a 120 to 24 volt transformer inside the air handler and they had connected the transformer to one side of the power switched to the air handler blower motor. This does not meet safety codes and also does not function correctly. As installed, and wired, the water flowed through the solenoid valve to the humidifier even when the air handler blower motor was off! You never want water flowing to a humidifier when the fan is off! But that is what was happening. This was a 220 volt blower motor, to turn it on and off the control unit had only one contact breaking the 220 volt circuit. An AC motor is like a short circuit when it is not running, so current flowed through the motor to the transformer keeping it powered all the time, even though the motor was not running! Anyway I am an electrical engineer and informed the boss the only safe way to correct the installation was to buy a 220 volt to 24 volt transformer and wire it across the motor not to just one side of the motor's connections. The installers comments were, this was the first time they had installed a air handler unit that had a 220 blower motor. These guys do industrial and commercial installations, I think they have made these electrical mistakes before.
Automatic humidifier control set to manual
As installed it is required of the operator (me), in the winter, to adjust the setting of the "automatic" humidifier control. This control does cycle the humidifier based on internal humidity in the house, but it also needs a $6 outdoor sensor installed for full automatic control. The reason for this is avoiding over humidification on very cold days, excess humidification that can damage your home, lead to mold buildup, and other harms. All that is required is to install an outdoor temperature sensor in a shaded location. Why the installers did not do this I do not know. I did not discover this immediately, or know of its requirement.
Several balancing dampers do not function
The system did have a complete suite of balancing dampers. But even after the system was "balanced" I found a balancing damper that was completely closed, no wonder that room was a little chilly! There is one major balancing damper that cannot be reached because it was probably installed on the wrong side of the duct. At least two more damper's blades were trapped by the flex duct installation, necessitating removal and careful replacement of the flex duct.
Supporting flex duct KP properly. Requires supports 1 1/2" wide minimum.
The flex duct runs are supported by 1/4" strips of aluminum. The manufacturer specifications call out a minimum width support of one and one half inches. Also there were areas of excessive droop of the flex duct.
Flex Tie support specifications, 1 1/2" minimum width, maximum sag is 1/2" per foot!
A primary insulated metal duct had insufficient support
The end of one of the ducts only has one strap supporting one side of the duct. The duct is visibly twisted! Another support hanger is required.
Problems I have found
After startup a significant refrigerant leak. The air handler unit evaporator coil was freezing up repeatedly. The installer found the evaporator coil was leak refrigerant and was defective. This is odd though because I believe Trane ships these cores pre-charged, therefore the installer would have had to notice a lack of charge when the unit was prepared for final installation in the air handler. The leak could have occurred, during startup or charging, fortunately for me, it was all repaired for free, but I have one concern; The compressor operated for a day and a half before I figured out what was going on, was it stressed? I guess I will find out, hmm. Even though there is a ten year warranty there is no reason with good maintenance this system shouldn't last 20 years, but, now it has been stressed.
Unbalanced auxiliary or backup heat.
Because of the design of a ductwork splitter almost all the heat from the auxiliary heating ( electric resistance coils ) goes up one side of the system heating the North side of the house, but returning ambient temperature air to the South side of the house. This was quite a surprise and had fooled me into thinking I had no auxiliary heat at all. Also, I think this quirk is confusing the thermostat. When it calls for auxiliary heat it first sees cool air then warm air. The aux. heat will cycle off prematurely, in my opinion, as if the thermostat thinks aux. heat has failed.
The installation work was rather rushed on the final days. The heat / ventilation system balancing consisted of waving hands in front of each vent and making sure air was coming out. It turned out I found one vent whose balancing damper was pretty much turned off. I have since found that several heat balancing dampers do not work.
The south west quadrant of the house was overheating.
The basement is to cold, not nearly enough air moving.
Problems after heat pump installation
No auxiliary heat.
Loud heat pump compressor noise after defrost cycle.
Heat pump cuts off at 30 degrees.
Heat pump installation suggestions
I would recommend suggesting to your contractor that as part of your agreement there be a thorough walkthrough and review of your system once it is installed. The walk through would demonstrate the full functionality of every component in the system, especially all balancing dampers should work. All floor vents should open and close properly. There should be a balanced airflow throughout the house. If you requested your basement be heated, it should be, and there should not be a hurricane of air flowing in and out of your basement door!
I hope this helps you with heat pump reviews and your choice, and making sure you choose a good heat pump contractor.
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