Programmable Thermostats

Reviews of digital programmable thermostats

Heat Pumps

There are two main types of heat pump: compression  heat pumps and absorption heat pumps. Compression heat pumps rely on mechanical (electrical energy); whereas absorption heat pumps also run on heat energy (from electricity or burnable fuels). Thus compression heat pumps run on electricity whereas absorption heat pumps can run on either electricity or natural gas. Deciding which type of heat pump is best for your home depends on the cost of electricity vs. the cost of natural gas; and, also the climate – absorption heat pumps work better in cold climates due to a lower minimum operating temperature.

In effect a heat pump is like a 2 way air-conditioner. It can take heat from outside and heat up a house or it can take heat from inside a house and disperse it outside. Heat is moved from a ‘source’ at a lower temperature to a ‘sink’ at a higher temperature. On a heat pump there are 2 coils depending on whether heat is being pumped into or out of a house one coil is an evaporator and one coil is a compressor. The direction of heat is changed using a reversing valve. This is how a heat pump is different to an A/C unit – air-conditioning doesn’t have a reversing valve.

Typically, heat pumps draw heat from the air or the ground. If a heat pump is used to cool a room it is basically the same as an A/C unit. A fluid or refrigerant is used to absorb the heat in a room as it vaporizes  and release it outside when it condenses. An evaporator is inside to absorb the heat and a condenser is outside. It is the reversing valve that allows for the refrigerant to change direction and for the evaporator and condensers to change roles.

The performance of heat pumps is measured in terms of the coefficient of performance or COP. This is the amount of heat moved per unit of input work required; or, in other words the amount of electricity or gas needed to heat or cool. Due to the laws of thermodynamics the coefficient of performance decreases with increasing temperature difference between inside and outside. Thus, one way to improve the coefficient of performance is to improve insulation in a home that way the energy used to maintain a cooled space is decreased. It is normal for heat pumps to have a back-up system when the difference in temperature between inside and outside is so great that the coefficient of performance drops low. This back-up is normally a standard oil, gas or electric heating/cooling system.

The most eco-friendly version of the heat pump is the geothermal heat pump. This type of heat pump uses water as a medium rather than a refrigerant. The ground is used as both a heat source and a sink. Geothermal heat pumps are much cheaper to operate than standard heat pumps. They can be made  more efficient if summer heat is stored in the ground for use in the winter and if winter coldness is stored in the ground for cooling in the summer.

Efficiency compared to other types of heating and cooling

As mentioned the COP is dependent on the temperature difference between inside and outside a house. The greater the difference the lower the COP. On a mild day at say 10 degrees Celsius a typical air source heat pump has a COP of 3 or 4. A typical space heater has a COP of just 1. Thus during a mild winter a heat pump is 3 or 4 times more economical than conventional forms of heating. At an outside temperature of about -18 degrees Celsius the COP of a heat pump reaches 1.

The advantage of a geothermal heat pump is that it takes its heat from the ground. The ground temperature 1.5 meters below the ground remains warmer than on the surface in  the winter. The average COP of a geothermal heat pump is between 4 and 5.

Another important variable in determining the COP of a heat pump is the size of the heat exchanger: the larger the heat exchanger the more efficient the heat pump is and the higher the COP. This is worth bearing in mind when buying a heat pump because heat exchangers are expensive and the cheaper heat pumps generally have small heat exchangers.

Units of measurement

To describe the performance of a heat pump in cooling mode a measurement of energy efficient ratio (EER) or seasonal energy efficient ratio (SEER) is given in BTU/(h•W). The higher the EER the better the heat pump performs as a cooler.

Costs

If you live in a mild climate where the temperature differential between inside and outside does not reach extremes, the best option is an air source heat pump. They maintain a COP that makes them more economical than electric resistance heaters. Air source heat pumps are easy to install and will save you money.

More expensive to install are ground source or geothermal heat pump because installation involves digging trenches. However, for homes located in more extreme climatic conditions the expense is worth it. Ground temperature is more constant  and geothermal heat pumps thus maintain a better COP all year round.

Thermostats

The key point about digital thermostats that are used to regulate heat pumps is that they only switch to auxiliary or back up heat when it is absolutely necessary. That is when the temperature difference is so great that the COP drops to 1. The only way to effectively know when this point has been reached is to have a thermostat that can read the temperature both inside and outside a home. The Honeywell Prestige HD has an Outdoor Sensor that allows the thermostat to determine accurately when auxiliary heat is necessary. The Honeywell Prestige HD is a state of the art device that can manage 2 stages of cooling and 3 stages of heating.

The Lux Products HP2110 Heat Pump Thermostat doesn’t have an outdoor sensor but reviews of the device are generally indicative that the thermostat does a good job with heat pumps. The Lux Products HP2110 can manage heat pumps with 2 stages of heating and 1 of cooling.

Sun, March 20 2011 » Heat pumps » No Comments

Honeywell THX9321R5000 Prestige HD Thermostat

Honeywell Prestige HD and Outdoor Sensor and Comfort Station

Click Here to Find the Best Price for the Honeywell Prestige HD

Click Here to Find the Best Price for Honeywell Prestige HD with Outdoor Sensor & Comfort Station

List of Specifications:

  • RedLINK™ Wi-fi
  • Can display outdoor temperature and humidity via an Outdoor Sensor
  • Can wirelessly connect with portable Comfort Station to give the ultimate ‘armchair programming  experience’
  • High Definition digital touchscreen display with adjustable backlight
  • Can control dehumidifiers and humidifiers for total indoor climate control
  • 7 Day Programming with 4 periods of heating/cooling per day
  • Smart Response technology
  • Auto Change-over
  • Accurate to +/- 1 degree Fahrenheit
  • Easiest programming of any thermostat
  • Choice of 3 languages: English, French and Spanish
  • Programming wizard
  • USB port
  • 3 fan settings
  • Multiple holds and vacation mode
  • Multiple warnings for filters and humidity pads and light
  • Keyboard lockout
  • Energy Star approved
  • Automatic daylight saving adjustments and settings kept after power outage
  • Powered by battery or HVAC power
  • 5 year warranty
  • Price for just Honeywell Prestige HD is $228. For the Prestige HD and outdoor sensor $283, and for Honeywell Prestige HD with Outdoor Sensor and Comfort Station $393  (click the links above to check  the price on Amazon.com)

Compatibility:

  • 2 stage heating / 2 stage cooling; and heat pumps with 2 stage cooling and 3 stage heating

Review

Honeywell is one of the most trusted brands for programmable thermostats. They have been making control technology for the home and the aviation industry for more than 100 years. Honeywell makes a number of thermostats that range in price from just $22 to over $500. This post will look at the Honeywell Prestige HD – one of their top of the range devices.

A lot of attention has obviously been paid to designing this digital programmable thermostat. The goal was obviously to make a powerful device that can control every aspect of indoor climate control while at the same time being user friendly. This is a difficult balance to strike as often the more sophisticated a device becomes the harder it is to control.

The Honeywell Prestige HD can be bought as a stand-alone thermostat or in a comfort kit that includes a wireless Outdoor Sensor and a Comfort Station. Buying the Deluxe Comfort System Kit that includes all three is not much more expensive than just buying the Honeywell Prestige HD.

This thermostat has redLINK enabled wi-fi capability. It uses this wireless technology to connect with the Outdoor Sensor to find out the temperature and humidity outdoors. It uses this information to suggest the best settings for temperature and humidity indoors.

Furthermore, the wi-fi connection is used by the portable touchscreen device called the Comfort Station. It allows the user to change the settings of up to 16 Honeywell Prestige HD thermostats around the house. This brings tremendous power to the armchair. You can turn down the temperature in parts of the house that are unoccupied and start warming/cooling parts of the house soon to be occupied.

The other great function on the Honeywell Prestige HD is that it can control humidity devices that are either hardwired to the HVAC or that have redLINK wi-fi. This thermostat  controls not only the temperature in a home but also the humidity. This adds greatly to the comfort of a home and helps to protect hardwood furniture and flooring.

With all this sophistication, Honeywell have worked hard to make the Honeywell Prestige HD easy to use. According to consumer testing the device scored 9.5 out of 10 for ease of use.

This is partly because the touchscreen features a programming wizard that asks questions to the user with simple, easy to understand options. From the answers the device sets up the 7 daily programs. Another great feature is a USB port that makes it easy to download/upload program settings from one Honeywell Prestige HD to another. It also allows dealers to store their contact details on the thermostat after installation so you can quickly contact someone if something goes wrong.

The display itself uses high definition color graphics that makes the thermostat stand apart from other thermostats. The display is sharper and the adjustable backlight makes it very easy to read in any light conditions. Moreover, the user can choose from 3 languages: English, French or Spanish.

There are 3 fan settings and quiet unusually for a Honeywell thermostat, a keyboard lockout function.

And of course there is smart response, auto change-over and a range of warnings including warning about when to change the pads on humidity control devices. There is also a range of holds that cover just about any contingency.

There really is very little that is missing from this thermostat, other than swing control. As discussed in other posts, Honeywell favors a system of limiting cycles per hour rather than setting up a range around the set point. This works fine for houses with good insulation and for places where the extremes  of hot and cold are not experienced.

Drawbacks

Other than swing control, it is hard to see how this thermostat can be improved. It has nearly every imaginable function. The only thing that could be added is an internet connection so you could program it from your laptop or telephone.

The only real drawback is the price. Although, using the Honeywell Prestige HD will save you money, many people will be put off by the price tag of $350 for the Honeywell YTHX9321R5003 Comfort System Kit.

Another possible disadvantage of the Honeywell Prestige HD is that Honeywell advises that you get a HVAC specialist to install it. This obviously greatly increases the overall cost. However, there are many people who manage self-installation. YouTube has a number of how-to videos on this subject. Programmable Thermostat Reviews is not condoning ignoring manufacture recommendations.

Amazon Reviews

The most purchased Honeywell thermostat on Amazon is it cheapest device, the Honeywell RTH221B. This device, one of its most expensive, obviously has had comparatively few sales. Only 6 people have reviewed the Comfort System Kit. None have reviewed just the Honeywell Prestige HD (Honeywell THX9321R5000). Regarding the 6 reviews, 4 are five star, 1 four star and 1 three star. Thus, reviews are all favorable.

Comments made include how well the set point temperature is kept with short bursts of heating/cooling and how handy the Outdoor Sensor and Comfort Station are.

One reviewer goes into details about how to do your own installation. Another warns that the Outdoor Sensor must be protected from the wet or it will malfunction. The same reviewer made this very astute observation:

“1st and foremost this t-stat has to work off the transformer on the board in the system; you cannot use this t-stat with a battery… That means running new t-stat wire that has 5 or more colored wires in the actual wire.”

It is not, therefore, a surprise that Honeywell recommends against self-installation.

Keynote Quote:

“The Honeywell Prestige HD is a wonderfully-designed thermostat. The thermostat is wonderful and extremely easy to program. The touch screen is bright, responsive, and extremely user-friendly.”

Aok3210, Colorado Springs

Wed, March 9 2011 » from $200, Honeywell » No Comments

Hunter 44860

Click Here to find the Best Price on Amazon for the Hunter 44860

List of Specifications:

  • 7 Day Programming with 0, 2 or 4 periods of heating/cooling per day
  • Auto Change-over
  • Auto Recovery (AKA smart response or adaptive intelligent recovery
  • 3 fan settings
  • Temporary hold
  • ‘Home Today’ hold
  • Vacation mode
  • Digital display with backlight
  • Trilingual display: English, Spanish or French
  • Filter Change indicator
  • Fahrenheit and Celsius readout
  • Energy Monitor
  • Default Energy Star settings
  • Energy Star approved
  • Permanent memory for clock, programs and daylight savings
  • Powered by battery or HVAC power
  • 1 year warranty
  • Price about $69 from Amazon (click the link above to check the price on Amazon.com)

Compatibility:

  • Up to 2 Stage Heat/2 Stage Cool, Heat Only or Cool Only Systems, Single and Multi-Stage Heat Pumps, Gas, Electric or Oil Systems, Millivolt Systems,2-Wire Hydronic Systems

Review

The Hunter 44860 7-Day Programmable Touchscreen Thermostat costs $70 if you buy it from Amazon and over $100 if you buy it from the official Hunter website. This is a sophisticated 7 day thermostat with many useful functions. The thermostat has the all important Energy Star approval rating which is a guarantee that if used correctly the thermostat will save you money on your heating and cooling bills.

The Hunter 44860 has a good range of compatibility. It can be affixed to cooling only, heating only, millivolt systems, gas, electric oil, 2 wire hydronics and up to 2 stages of heating and 2 stages of cooling. It can also manage single and multi stage heat pumps. There is also the option to power the unit from the HVAC power supply or from batteries.

Installation of the Hunter 44860 is similar to other programmable thermostats but care must be taken. Reviews of the Hunter 44860 make numerous references to the poor instruction manual that does not help the user overcome a number of tricky issues including installation.

The Hunter 44860 is a 7 day thermostat. In other words, it gives you a program slot for each day of the week. One useful feature is that you can choose between 0, 2 and 4 custom temperature settings per day. This is different to most Lux Products and Honeywell programmable thermostats that have a fixed 4 periods a day to set up. You can also copy programs from one day to the next to speed up programming.

There is an Energy Star button that automatically switches the settings to Energy Star recommended set point temperatures.

Programming is via a large backlit display that is mercury free. The programming style is not as intuitive as with Honeywell touchscreen thermostats such as the RTH8500D or RTH7600D.

One of the reasons for this is because the auto change-over function places a fixed span between heating and cooling. This can be changed to 5 degrees or 3 degrees. An auto change-over function is designed to allow the thermostat to detect changes in the weather and automatically switch between heating and cooling. In the case of this thermostat it creates some confusion that is not immediately clarified by the instruction manual. The main fault of this thermostat is that the auto change-over cannot be disabled so you always have to be aware of the span buffer between heating and cooling.

One of the best things about the Hunter 44860 is the fan settings. You can set it to on, auto (which turns on only when the compressor is running) and refresh which is the same as auto but also turns the fan on if the system is idle for more than an hour to keep the air fresh. This really helps energy efficiency because the hot/cool air is better circulated around the house.  Also the refresh mode improves circulation and keeps the air fresh in the house.

There is also auto-recovery on this Hunter programmable thermostat. It is not as sophisticated as the Honeywell smart response technology and generally just starts the heating or cooling 30 minutes before the start of a programmed period.

The Hunter 44860 has a good range of holds. There is a temporary hold, a vacation mode and a ‘home today’ hold. Once these various hold buttons are mastered they allow you to quickly make changes to the set point temperature without re-programming the daily settings.

Two other capabilities of the Hunter 44860 that help the user are a language option (English, Spanish or French) and an Energy Monitor. The Energy Monitor allows the user to check on run times and thus gauge future utility bills.

Reviews of the Hunter 44860 7-Day Programmable Touchscreen Thermostat on Amazon

This thermostat has provoked quite a few reviews from Amazon customers. Of the 57 reviews, 18 people give the thermostat 5 stars, 12 give it 4 stars and 14 people give it 1 star. Of all the thermostats reviewed in programmable thermostats review this unit has the most 1 stars (you cannot give a zero star review on Amazon). This is food for thought.

The main complaints about the Hunter 444860 are as follows:

1)    The instruction manual is poorly written in parts.
2)    The back light activation requires starting a program change that means cycling through a menu to get to the ‘home’ where you can check the temperature.
3)    The auto span setting on the auto change-over function cannot be disabled and this causes complications with trying to set up heating and cooling set points. One Hunter employee suggested to a disgruntled customer that the only solution is to re-program the settings each season.

To balance the negatives, customers liked:

1)    The 3 fan settings that do a great job of keeping the air fresh and evenly distributing the warm/cool air.
2)    The 3 different types of override gain plaudits.
3)    The thermostat holds the indoor temperature well.

Keynote Quote:

“The killer for me is that the implementation of the auto-changeover is poor, and there’s not even a way to turn it off.”

Elezar, Louisville, KY

Sat, March 5 2011 » Hunter, Under $100 » No Comments

Swing Control Explained

Swing control is a very important function for a programmable thermostat. Swing control is adjustable on all good programmable thermostats. Usually you can alter swing control in 0.25 degree Fahrenheit increments.

The purpose of swing control is to set up a range around the set point temperature and within this range the thermostat DOES NOT activate the heating or cooling. So for example, if the set point temperature is 78 degrees and the swing control is set to 1 degree then the thermostat won’t cycle the cooling until the room temperature rises past 79 degrees and it won’t cycle the heating until the temperature in the room falls below 77 degrees. Of course, in most cases you will only use either heating or cooling not both. So for the example above if the temperature reaches 79 degrees it is more likely that the HVAC won’t cycle and instead the cold weather outside will naturally cause the temperature to drop to the desired 78 degrees.

On  first consideration swing control might not seem important. After all, you want a house that stays at a constant temperature not one with a fluctuating temperature. However, in reality it is bad for your HVAC equipment to try and keep an exact temperature because it means a lot of short cycling. Short cycling is when the heating or cooling comes on for a few minutes. If a heater or cooler goes on and off many times in an hour the equipment can wear out quickly and lead to expensive parts replacements. This is particularly true of furnaces.

Another factor is noise. It can be very irritating to hear the HVAC constantly clicking on and off. It is much more energy efficient to let the temperature rise and fall a degree or two and then run the heating/cooling for a longer time. This is what swing control does.

All Lux Products thermostats come with swing control as does the Hunter 44550 Auto Save. What is a mystery to those looking at thermostats is why there is no swing control on Honeywell thermostats. It is not a simple oversight on Honeywell’s part. Honeywell is one of the earliest makers of control technology for the home and they have deliberately done away with the idea of swing control.

Honeywell’s Alternative to Swing Control

Honeywell instead of letting you input a number to represent the parameters of the swing control give you the option on their thermostats of letting you set the number of cycles per hour for your HVAC equipment. In the Honeywell instruction manuals you will find the relevant information in the part entitled “Configuration Menu”.

How does this different system work?

When the heater is bringing up the room temperature to your programmed set point temperature the heating cycles per hour function is alerted when the set point is nearly reached. Say it you set the temperature at 70° an anticipator circuit cuts off the heat at a predetermined point say 69° to stop the heating overshooting the mark. The idea is that the residual heat will raise the room temperature to the desired 70°.

The problem comes if your room is poorly insulated or a window is open or your furnace is too small. It might be for one of these reasons that the residual heat in the room doesn’t nudge the room temperature up to 70°.

What happens now? This is where Honeywell’s alternative to swing control comes into play. If you have set your cycles per hour for the heater to 3 then the heater cycles 3 times in an hour. Each cycle is 10 minutes long or until the room reaches 69° and again the anticipator will cut the heat. If after 10 minutes the temperature is still not 70° the heater will start up again.

This system works fine if your house is well insulated or the outdoor temperature is mild. The problem is if the weather is really hot or cold or your house fails to adequately keep its warmth or protect you from the heat. It can be that at 69° the heating keeps cutting out and that 70° is never reached leading to many cycles per hour of the heater.

This issue of Honeywell thermostats and their absence of swing control is sometimes mentioned in reviews by people who have bought a Honeywell thermostat. Some reviews report very poor performance and complain of constant short cycling and others report that their Honeywell programmable thermostat manages to keep the room temperature at the same point with only a couple of cycles per hour.

One thing to remember about setting the cycles per hour program on your Honeywell thermostat is that different types of heating and cooling require different cycle rates to be effective. Hot water that sends hot water to radiators requires longer cycles because it takes time for the heat from radiators to raise the room temperature. It is very energy inefficient to have hot water only cycle for a short time. The best setting for hot water is 3 cycles per hour.

In contrast a wall heater is much faster in raising room temperature. They only need a short burn to reach our hypothetical 69° at which point there should be enough residual heat to make 70°.  The best setting for electric heat is 9 (9 cycles of 6.7 minutes per hour).

Summary

To sum up: Honeywell thermostats don’t allow you to set up a swing control range around your set point temperature. Instead you have to input a number to indicate how many and how long the heater or cooler should cycle to maintain the set point temperature. This number depends on the type of HVAC system you use. Hot water needs less cycles per hour (3) and electric heaters need more cycles per hour (9). This system seems to work best in houses  that have good insulation and in areas where the weather is temperate. It is not advisable to use a Honeywell thermostat in the tropics or in Alaska.

Sat, February 26 2011 » Functions, Honeywell, Hunter, Lux Products » Comments Off on Swing Control Explained

Lux Products BBHP2110-008 Smart Temp Programmable Heat Pump Thermostat

Lux Products HP2110 Smart Temp for Heat Pumps

Click Here to find the Best Price on Amazon for the Lux Products BBHP2110 Smart Temp for Heat Pumps

List of Specifications:

  • 5-1-1 Programming with 4 periods per program slot
  • Swing Control
  • Temporary hold
  • Vacation mode
  • Program lock
  • Digital display with backlight
  • Lux Products patented speed dial
  • Default Energy Star settings
  • 1 year warranty
  • Price about $57 from Amazon (click the link above to check the price on Amazon.com)

Compatibility:

  • Heat Pumps only – up to 2 stages of heating and 1 stage of cooling

Review

The Lux Products BBHP2110-008 Smart Temp Programmable Heat Pump Thermostat is device designed for controlling heat pumps made by the reputable brand, Lux Products. It costs about $56. If you rely on a heat pump for your heating and cooling then this is a thermostat you should look at more closely.

The Lux Products BBHP2110 Smart Temp is compatible with up to 2 stages of heating and 1 stage of cooling. It cannot be hardwired to run off the heat pump power, but the unit has a long battery life so this is not a great inconvenience.

The advantage of having a thermostat that is designed for heat pumps only is that it allows you to make the most of your 2 stages of heating so you are running the heat pump at its most energy efficient.

Reviews by people who bought this thermostat testify that it is easy to install. It also has the Lux Products patented speed dial for quick programming. There is a large backlit display so you can clearly see what you are doing.

The Lux Products BBHP2110 is a 5-1-1 thermostat. This means it has a program slot for weekdays, Saturday and Sunday. If you have a regular weekday schedule but like to do different things at the weekend then a 5-1-1 device is probably suitable for you.

For each of the 3 program slots there are 4 different periods of heating/cooling to set up. This is standard for all good programmable thermostats as it makes sure you can fit the indoor climate control with your schedule so as to prevent heating/cooling an empty house and wasting money.

To further help you the Lux Products BBHP2110 comes pre-set with Energy Star recommended settings that you can use as a basis for your own programming. This makes finding a compromise between comfort and energy saving easier.

The heat pump thermostat also has a number of useful functions. It has swing control to stop you damaging your heat pump with frequent short cycling. There is also a handy temporary override and vacation mode.

The display includes a filter usage monitor and battery level warning to make sure you are neither late changing the filters nor caught short by drained batteries. The display can also be adjusted to show the temperature in either Celsius or Fahrenheit and the time in either 12 or 24 hour styles.

Drawbacks

This thermostat is designed specifically for controlling heat pumps so the fact it cannot manage central air, hot water etc. seems irrelevant.

In terms of functions the Lux Products BBHP2110 has nearly everything that is needed. Perhaps the only notable function missing is auto change-over. This is a ‘perhaps’ because there is a school of thought that considers this function as mostly unnecessary since the temperature difference between inside and out naturally decreases/increases the indoor temperature if the HVAC ‘overshoots the mark’. For example, if it cold outside and you have the set point to 78 degrees inside and the heating pushes the indoor temperature up to 80 degrees inside then by turning off the heating the cold outside will soon cause the indoor temperature to fall by 2 degrees to the set point temperature.

Finally, there is the disadvantage of having to rely on battery power. This disadvantage is somewhat mitigated by reviews that state it is not a thermostat that quickly drains the power from batteries.

Amazon Reviews

There have been 18 customers who bought the Lux BBHP2110 from Amazon.com and wrote reviews. Of these 18, 12 gave the heat pump thermostat 5 stars and only 1 person gave the device a single star.

Most reviews mention that the Lux BBHP2110 Smart Temp was easy to install and that it does a good job of controlling heat pumps.

One reviewer mentioned how useful it was that the swing control could be adjusted. Another noted that you must have new batteries to hand as you only have 1 minute after taking out the old batteries to replace them with new ones before your program settings are lost.

Several people write about how well the thermostat holds the right temperature and how useful the default settings are to help you program the device so you maximize your energy efficiency and savings on your heating and cooling bills.

The most dissatisfied customer spoke of how his unit was faulty and the tardiness of the Lux Products support to help. In the end he appealed to Amazon.com who immediately shipped out a new unit and the problem was solved.

Keynote Quote:

“Very good product at a good price. The installation was quick and quite simple. I did not know if this thermostat would work with my brand new two stage heat pump but it functions perfectly. The programming steps are straightforward and very user friendly. I highly recommend this product for those that want to upgrade their heat pump thermostat.”

– Daryl L. Anderson

Fri, February 11 2011 » Lux Products, Under $60 » No Comments