Bests & Worsts Reviews from Amazon

In searching for an energy efficient hot water heater, I was quickly drawn to this GE hybrid tank because it is quiet, efficient, receives high ratings and readily available at the Lowe’s store near my house. 2016 State and Federal incentives total to $1050 in Massachusetts, making it virtually free. GE offers 10/1 year warranty on parts/labor. Lowe’s offers extra 5 years of labor coverage at minimal cost. Why would anyone not want to buy one to replace their old electric tank? Upon checking the detailed user reviews, I was surprised that they are highly polarized with many extremely negative comments. It took some more investigation before I decided to not worry about them. I share my reasoning below because many other shoppers would have the same worries. First, I checked user reviews of other hybrid tanks and found that they all have some very negative reviews. So there are no “safe bets”. In addition, the technology used in the hybrid tank is not new. It’s like a little air-conditioner put on top of a conventional tank, and these are rather reliable devices. Some users speculated that tanks made in China are less reliable than the ones made in the US. This is perhaps more national pride than anything else. Lots of US products are less reliable than their foreign counterparts. Besides, it’s a moot point because GE is selling its appliances business to Haier. This led me to wonder if the poor experience may have more to do with DIY owners who made some mistakes that professionals would not. Even some plumbers could make mistakes because most people would place the hybrid tank in the same spot occupied by the old electric tank. That would often result in poor performance and no significant savings. Many reviews complained about water leaks. That could be caused by owners who didn’t realize the heat pump is just like an AC or a dehumidifier which naturally condenses moisture in the air. They have to drain the condensation properly, e.g., by installing a small pump like they would for dehumidifiers. Some reviews show that the unhappy owners did not install expansion tank or vacuum relief valve for the tank. When water expands or contracts with temperature change, or when the supply line pressure changes, some seals would leak. Of course, experienced DIYers and professionals would not make these mistakes. When mistakes are made, the system displays error codes that help people to figure out how to correct them. For example, if the filter is dirty or clogged, there would not be enough air circulation and frost would develop. The heat pump would be shut down to prevent damage and display codes FC (to indicate frost) or FD (to indicate slow heating). Even if the filter is cleaned regularly, dirt could build up on the heat fins and make the heat exchange less efficient, result in lower performance. This behavior is the same as any AC. Some people take error codes to mean there's something wrong with the heater while in fact they could mean owner mistakes. Even when no obvious mistakes were made, many were disappointed with the performance of hybrid tanks. Some reported that they had trouble getting 2 hot showers, but others had no trouble getting 3. This could be caused by differences in the flow rates of different shower heads and how people shower. It’s also possible that some did not understand how to choose among the various settings of the tank to suit their needs. It is important to understand the basic science behind the hybrid tank and know why, when set up properly, it should always outperform a conventional tank. Below is an explanation that goes beyond the guidance owner’s manual. A conventional 50 gallon tank heats water by a 4.5kW element. This electric power is converted to 4.5kW of heating power. The COP (coefficient of performance) is 4.5/4.5=1. The hybrid tank uses the same 4.5kW element as a “safety back up” option to ensure that it could do no worse than a conventional tank. The energy saving comes from a 600 W “heat pump” that has a COP around 3, i.e., it generates 1800W of heat (1800/600 =3). This cuts down the energy usage by sacrificing the speed of heating. This is fine because hot water uses in a household are usually separated by long idle periods. However, when there is a continuous draw like a shower, cold water flows into the tank and lowers the temperature. The electronics senses the temperature drop and turns on a supplemental 4kW heating element. The combined electric power is 4.6kW and the heating power is then 5.8kW, more than the back-up 4.5 kW heater. This means the hybrid tank heats faster. At the same time, the COP is never less than 5.8/4.6 = 1.26, which means that it always saves energy. The savings is at least 21%, because 1/1.26=0.79. If the average COP is 2, the savings is 50%, because 1/2 = 0.5. If the tank operates in the “heat-pump only” mode, COP = 3 would result in 67% savings, because 1/3 = 0.33. Marketing brochures usually quote the highest number with the caveat “up to”. In reality, the heat pump performance varies strongly with the ambient air temperature. Simple calculations would make things clearer. Assuming that water is heated from 20C (68F) to 50C (122F), it takes about 6.7 kWh of energy to heat a 50 gallon tank of water. A conventional tank with a 4.5kW heater would take about 80 minutes. The hybrid tank using heat pump only would take about 220 minutes, but it shortens to about 69 minutes when the 4kW heater is on. The energy used by the hybrid tank is at best 2.2 kWh (heat pump alone) and at worst 5.3 kWh (heat pump plus 4kW heater). Should the heat pump fails, the hybrid tank falls back to work like a conventional tank with a 4.5kW heater, consumes the full 6.7kWh. In other words, the tank would save at least 1.4 kWh (6.7-5.3=1.4), or as much as 4.5kWh (6.7-2.2=4.5). Heat pump efficiency is always lower for a larger temperature difference. The rated COP is a statistical sampling average for a wide range of operating conditions. The same is true for the EER rating of air conditioners. The two numbers related by EER = 3.14 x COP. So EER=10 means COP = 10/3.14=3.18. The AC takes heat from the house and dumps it outside, whereas the hybrid tank puts the heat in the water for good use. Some people wonder if they could circulate hot water from the tank to heat the home. The answer is obviously not because the heat pump is taking heat from the house to heat the water, i.e., cooling the house. So to put that heat back into the house would just be a waste of electricity. On the other hand, the hybrid tank does serve as an air-conditioner that cools and dehumidifies the air. If it's installed in the basement, circulating the in the basement air up to the main floor would be a bonus. Theoretically speaking (at the level of freshmen physics of “ideal” heat pump), the COP is inversely proportional to the temperature difference. For example, if the COP is 3 for surrounding air at 20C (68F) and the hot water is at 50C (122F), the heat pump works against a difference of 30C. If the ambient temperature is only 5C (41F), the heat pump has to work against a difference of 45C and its COP would drop to 2, because the ratio 45/30 = 3/2. Conversely, if the ambient temperature is 30C, the heat pump only works against a temperature difference of 20C, and the COP would increase to 4.5 ( 30/20 = 4.5/3). The same 600W heat pump would have 1200W of heating when COP = 2, it rises to 2600W of heating when COP = 4.5. Of course, the inlet “cold water” temperature also changes with ambient air, requiring more heating when the air is cold, i.e., when the heat pump is less efficient. This double jeopardy means one has to choose the location of the hybrid tank wisely. An unheated garage would have seasonal temperature cycles as well as day/night swings. Taking showers at 6AM or 6PM can make a noticeable difference. Conventional tanks have no such difference because COP=1 all the time. This may be why there are many bitterly disappointed owners across all brands of hybrid tanks: they pay more for the tank, do not realize the advertised savings, and have more failures. This could be avoided if the manufacturers educate the consumers better and not hype up the expectation to promote sales so much. The best location for installing the hybrid tank is in the basement where the ambient temperature is usually stable and not far from 20C. In addition to having higher COP for the heat pump, there are unadvertised benefits. Since the heat pump keeps the basement cooler and dryer, it reduces the need for a dehumidifier in the summer months. Freezer and wine chiller in the basement would also run more efficiently. The power saved from these devices may offset a good portion what the heater uses. For example, my basement has a 550W dehumidifier that runs 24/7 in the summer, consuming more than 10 kWh in a day. With the hybrid heater, the dehumidifier will run less because some moisture is condensed by the heater. The heat generated by the dehumidifier usually warms the basement, but the heat pump puts the heat in the air back into the water to keep the basement cooler. It's often 10F cooler in the basement than the main floor. With a 4" inline fan and flexible exhaust duct, it's not difficult to circulate the cooler air up to the main floor as an inexpensive AC in the summer. I actually bought the hybrid tank to add to (not replace) an existing tank heated by an oil burner. The two tanks together make a 2-stage system that will improve the hot water supply and save energy. In the warm seasons, the oil burner can be turn off entirely with the hybrid tank alone supplying the hot water. In the cold months, the oil burner is on to heat the house and it’ll be the primary water heater, but it’s outlet will feed into the hybrid tank for storage. This makes the hot water temperature more stable and adds an extra 50 gallon supply. Oil heat is more efficient and less costly than electric heat, but not if the furnace has to stay hot full time for occasional use of hot water. Having 2 tanks that can heat water separately also means if one fails the other can take over and there would not be an emergency that requires paying double overtime for service calls. The drawing below shows the simple pipe and valve configuration that allows the two tanks to work together or alone. Altogether the hybrid tank is a 5-in-1 energy saver in my house: heats water with less energy, saves power used by the dehumidifier, makes other appliances in the basement run more efficiently (freezer, wine chiller), saves oil during the warmer months, and boosts hot water storage capacity by 50 gallons in the winter while keeping water temperature more stable at minimal extra cost. These benefits apply to any brand, not just GE. The last issue to address is that many owners reported poor experience dealing with GE’s customer service about warranty claims. This problem could be avoided if one buys Lowe’s extended warranty and have the tank installed professionally. If something goes wrong, one would call Lowe’s hot line and not GE’s during the first 6 years of service. By then one would know if the tank is reliable and worth spending money to repair. If it is, GE covers the parts for 4 more years. If not, the cost is surely recovered after 6 years and buying a new one should not be a painful decision. It is useful to keep in mind that heat pumps do not fail easily, much like air-conditioners, dehumidifiers, and refrigerators. They all use a motor to run a compressor to transfer heat, with a fan that circulates the air. They are just optimized for different applications. The only thing different in the hybrid tank is the electronic brain (microprocessor) that decides when to engage the heat pump and the two conventional heaters. If the system is kept in a clean and stable environment, it could last well beyond 10 years. Conversely, extreme temperature, humidity, dusty or corrosive air could cause anything to fail. Any device with more parts will always have more ways to fail. In that sense, the hybrid tank is always less reliable than a basic electric tank without the heat pump. The question is whether the extra $500 dollars of the hybrid tank is worth spending. My answer is YES, because the expense will be more than repaid and everyone will cut down the energy use. The power plants will burn less fuel and the world will be a little greener. This is why in a state like Massachusetts, which produces no fossil fuels, the there is a whopping $750 rebate to encourage people to switch over to the hybrid tank. Even if the old electric tank is still working, people could use it in a 2-stage set up so that water is first heated with the hybrid tank and then stored in the old tank. They'll increase the hot water capacity and reduce energy cost at the same time. Update (7/6/2016): With a few feet of 4" duct and a 4" exhaust fan, the cool air in the basement is drawn up to the hallway on the main floor. The vent directs the air upward to blow straight up to the second floor, keeping it below 80F on the hot summer days when it's over 90F outside and over 120F in the attic. The energy used by this heat pump is almost surely less than what it saves. Not every home can implement all the possible ways to save energy, but I hope this example here will give people some ideas to try out. One thing I forgot to point out is that this type of water heaters require extra care in transportation, because the weight of the heat pump is at the top of a tall and empty tank. Internal damage could result from incorrect positioning in the truck or excessive bouncing on rough roads. Update 8/5/2015: For installing this heater in a closet, a reader reported today in the Comment section that GE has a customer part to couple to 8" ducts for the inlet and outlet airs. General Electric GVK8HS Ducting Kit, White