Today is a really hot topic: water heaters. No, it’s not sexy, but water heater technology is kind of ingenious with its simplicity. A typical electric water heater has two heating elements; one near the bottom and one near the top, all housed in a very well insulated cylinder. As cold water is fed in near the bottom of the tank, the hot water is pushed out near the top. It’s also pretty simple efficiency-wise. For each unit of electricity that’s used, you get one unit of heat energy added to the water.
However, my water heater is wearing one additional piece of technology on top … like a hat. It’s a heat pump. That means for every unit of electricity I’m spending I’m getting 3 to 4 units of heat added to the water. It’s way more efficient than any electric or natural gas water heater you can get, but hybrid heat pump water heaters have some quirks and challenges. Also, my setup is a little unique … like … what’s that strange mini-me version of a water heater sitting next to it?
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Best Educational Video AwardI keep saying, “heat pump all the things” and I’m not kidding. When it comes to energy efficiency you can’t beat a technology that seems to break the laws of physics. Generating more heat energy than the amount of energy you put into it seems like a magic trick, but it’s not. I’ve got a 50 gallon Rheem Proterra hybrid water heater here. I’ll be sharing my thoughts on this specific model as we go, but this is more about just using a heat pump water heater in general. Brand doesn’t matter, but I’ll be getting to the quicks and downsides in a bit.
The biggest reason you’d want a heat pump version is for exactly the reason I mentioned already. It’s mostly about the Coefficient of Performance (COP). That’s the ratio of energy in vs. energy out … or more simply how much heat energy you get for every kW of electricity or natural gas therms you put in. Just for clarity, because I’ll be getting into comparing my old natural gas water heater to this new one, one therm is the energy content of about 100 cubic feet (2.83 cubic meters) of natural gas.
The massive boost in COP is the big selling point of heat pumps in general. You’ll be spending far less energy and money, in theory, to create hot water for your home. It’s a very appealing sales pitch. However, this is where some of the downsides start to creep in, or at least the perception issues start to creep in.
The first potential pitfall is the cost. Heat pump hybrid models are just more expensive than straight electric or natural gas models. In my old house, we had a 40 gallon natural gas model that cost about $800, not including installation. The Rheem I have now retails for around $1,500 plus installation, so there’s a sizable jump in cost. However, there are rebates and incentives available in most places to help knock that cost down. Sometimes those rebates come from the state or your local utility company, so it’s best to do your due diligence before you make a purchase. In my case, here in Massachusetts, there’s the MassSave program which will cover $750 of that cost. The best part about that one is that it’s usually available as an instant rebate when you buy the water heater. So, suddenly that $1,500 is now $750. There’s also a federal tax credit of up to 30% (which is capped at $2,000) off the full installation (after local rebates have been applied). So if the total including installation was $2,500, here in Massachusetts you’d end up paying about $1,225 (eg. original cost: $2,500 – $750 in state rebates – $525 in Federal incentives). Bottom line: in some cases it can be equal to or cheaper than a standard water heater depending on what rebates are available in your area.
The other couple of common elements that I see brought up a lot are: noise and recovery time. When it comes to the noise issue, your mileage will vary wildly by brand, model, and sometimes the luck of the draw. In my case, I haven’t noticed any significant noise issues at all. I have an insulated mechanical room that’s not too far from the main living room area and I never hear the water heater running. However, I do hear my HVAC system ramping up and down. I have heard from others that they’ve had some noise issues with this exact model of water heater, so be aware. A friend of the channel, Paul Braren, has some great articles on his website about this.
As for recovery time, which is a measure of how quickly it can heat cold water back up, it’s also been a non-issue for me. In fact, I’d argue that this is largely a myth that heat pump water heaters have a slow recovery time. It’s going to depend on how much hot water you use and what settings you have on your water heater. For this Rheem, there are a few different modes you can put it in: Energy Saver, Heat Pump, and High Demand. Energy Saver is the default and what I’ve been using. On this setting, it fully utilizes the heat pump compressor for the best COP possible, but also incorporates the electric heating elements for high demand and recovery needs. It’s a balanced approach. The other two modes are what you’d expect. “Heat Pump” is full on heat pump only, which can affect the recovery time and can even increase energy consumption, according to Rheem. “High Demand” mode puts more emphasis on the electric elements and also increases energy consumption. I’ll get into what I’m actually seeing in just a minute.
The final potential pitfall of a heat pump water heater is space … and I mean physical space. Because they have an air source heat pump strapped to the top, like a hat, they need a certain air volume in the room they occupy. The way the heat pump works is that it passes the room’s air through a heat exchanger to extract the heat into a working fluid. That fluid is then sent through a compressor and turned into vapor, which circulates through pipes snaking around the water heater, making hot water. As the heat is extracted back out of the working fluid it cools off, turning back into a liquid, and ready to repeat the cycle. The side effect is that the air that’s getting ejected from the heat exchanger is cool and dry. If the room’s volume is too small, the heat pump will lose efficiency as all the usable heat is extracted from the room’s air.
This is VERY noticeable in my setup. My mechanical room is technically too small. You need about 700 cubic feet, but my mechanical room is only about 600 cubic feet … and that doesn’t account for all the equipment inside it taking up space. It’s probably closer to 450-500 cubic feet. When we first moved into the house, the mechanical room felt like a meat locker when you opened the door: in other words, very cold. There are ways you can vent the water heater to alleviate this issue, but we opted to not do that … at least not yet.
The reason? That little mini-me tank sitting next to the Rheem is why. I have my water heater tied into my geothermal HVAC system that’s heating and cooling my entire house. The excess heat from that system’s compressor is captured into water that sits in that tank waiting to be used by the Rheem water heater. That means our Rheem isn’t refilling itself with cold water straight from the outside — it’s refilling with water that is probably already over 110F. I really want to wire a sensor into the holding tank to track the water temp, but haven’t gotten around to it yet. Anyway, the end result is that my water heater doesn’t have to work as hard to get my water up to temp.
We didn’t get the geothermal desuperheater hooked up and working until we’d been living here for almost two months. After we did, I noticed that the mechanical room isn’t meat-locker cold anymore, but it’s still cool … which is cool.
That leads me right into the performance I’ve been seeing. So strap on your nerd hardhat, because I’m about to drop some numbers and charts right on your head. At this point I still don’t have a ton of data, but enough to start getting a sense of where this is going. Since we didn’t move in until August, I’m only looking at September through January and comparing this to the same months last year with our old natural gas water heater. If you’re curious, I had an Aquanta smart device installed on my water heater that tracked exactly how much gas we were using.
For this first chart it’s the amount of gas vs. amount of electricity. You’ll notice that there’s a noticeable jump in October for both gas and electric because that’s when the cold weather really kicks in. December through February tend to be the highest use case months, so there’s another uptick noticeable for gas in December. What’s interesting though is that you can see our electricity didn’t jump in December. In fact, it’s slowly been declining each month since October. My hunch right now is that it’s because of the geothermal holding tank, which started up in October. It counteracted the typical increase.
Operational costs are another story though.
If you look at this chart, you’ll notice that gas and electricity are basically a wash in September and December, but electricity is dramatically higher in October and November. The reason? Gas and electricity prices in my area. Electricity in Massachusetts is very high. In fact, we boast some of the highest in the country. We’re paying around $0.30/kWh vs. gas which was coming in around $2.18/therm (at the time we were using it). The cost benefit is kind of a mixed bag in my area. Massachusetts electricity and gas prices mean this costs me about 22% more for hybrid heat pump hot water based on the limited data I have. I have a hunch that will change over the coming months because we’re still experimenting to find the best settings for us. We may still try venting the water heater, so it has more air to draw from. However, if you look at the national average cost of electricity ($0.17/kWh) and gas ($1.66/therm) and apply it to my usage, it’s a different story.
Electricity wins hands down across the board. Nationally it would cost almost 21% less to go with an electric heat pump water heater. Again … based on only a few months of my personal data.
I also have solar on my house, which is currently trending towards my goal of net zero energy from the grid over the course of a year. If that plays out, the actual cost of electricity to generate my hot water will be zero, which isn’t possible with natural gas.
Is it worth it to go with a heat pump water heater? Yes, in the vast majority of cases, it’s absolutely the best option out there. However, as you can see in my current data, it’s not completely cut and dry depending on what your electricity and natural gas prices are. If you’re already using a standard electric water heater, it’s a no-brainer to go heat pump. Again, upfront costs really aren’t that different right now with all the rebates available from utilities, state and federal rebates. In some cases, it can be cheaper to install a heat pump water heater … and then the long term benefits after that.
Choosing the right hot water system for your home is imperative. You’ll have to choose the right heating method, choose between storage or continuous flow systems, and weigh up the size, cost and energy efficiency of each. If you’re thinking of buying a hot water heat pump system, this article offers a few important factors to consider.
Heat pumps work by providing a heat exchange from one point to another, using a compressor and a liquid or gas refrigerant in a circular structure, extracting heat from the exterior to the indoors. They have many advantages, such as low energy use. Heat pumps are increasing in popularity across the world, as an efficient way to lower the cost of running the home. Many different brands, including Rheem, Dux, Rinnai and Stiebel Eltron have started stocking heat pumps and related products as part of their range in response to this high demand.
If it’s time for a new hot water system, read on to discover whether a heat pump system is right for you.
The easiest way to understand heat pumps is that they are a refrigerator in reverse, extracting heat from the environment and releasing it into the system to heat the property. Essentially, a heat pump will transfer heat from a lower temperature to a higher one, pumping heat from one place to another. Many heat pumps have the capacity to cool the building by removing heat from space and transferring it outside.
In heating mode, the outside temperature is compressed, causing the refrigerant in the heat pump to become hot. This thermal energy can be transferred into the indoor unit, before being moved outdoors again for decompression. Heat pumps have a low carbon footprint, and their efficiency can be expressed as a coefficient of performance or COP. The number becomes higher with less energy consumed.
A heat pump has four major components: evaporator, compressor, expansion valve and condenser, and works through a four-step process:
At the evaporator, the heat will be transferred from the outside environment to the refrigerant flowing through the system.
As the refrigerant heats up, it will expand and turn into gas.Before making any major purchase, it’s important to understand the perks and downfalls so you can make an informed decision.
The more energy efficient a system is, the more potential savings exist for monthly energy bills. Pumping the heat through a heat pump uses less electricity, and when paired with solar panels, a heat pump can attain more than 300% efficiency.
Generally, the elements of a heat pump can be checked by the owner of the system. Overall, they require less maintenance than other systems, with a professional maintenance check only required every 3-4 years.
A heat pump moves heat rather than generating it, consuming much less energy and producing fewer greenhouse gases than any other system on the market.
Heat pumps are safer than some other heating systems that rely on combustion technology. They do not require fuel to produce energy and come with fewer safety risks than some other water heaters.
Air source heat pumps don’t require a high amount of power consumption to run, as their power comes from the air at the external temperature, with electricity only required to power the heat pump’s internal operations. This can reduce electricity use and your carbon footprint dramatically.
If you live in an area with extremes of both temperatures, heat pumps will serve you well year-round, with the ability to reverse the process and act as an air conditioning unit.
Not every DIY’er can install heat pumps. Plenty of research is required to understand the heating and cooling needs of your household. You will also need to understand the best position for your heat pump and the way the heat moves in your area. It’s best to hire a professional hot water installation expert for this.
Heat pump water heaters are well-built and long-lasting machines, resulting in their initial costs often being higher than some other water heater types. However, their lower energy use will quickly provide cost savings.
Some heat pumps can struggle in cold weather, not reaching their full efficiency and damaging the internal components. However, instead of avoiding them altogether, chat to our team about upgrades to help during winter.
Some heat pump water systems can be noisy during operation, which can be remedied by strategic placement away from the house.
Many households benefit immediately from heat pump system installation. Particularly ideal for those without room to install a storage tank, consumers can enjoy reliable, affordable hot water with the peace of mind that they’re lowering their greenhouse gas emissions overall. Heat pumps are quickly becoming the finest, most recommended heating solutions available owing to their impressive level of efficiency, affordability, long lifespan, low maintenance requirements and reliable functionality. With every con having a remedy, there is little question that a heat pump will provide the hot water solution you’ve been looking for.
There is only one name to remember when considering your hot water system needs – Same Day Hot Water. With supply Australia-wide and installation in every state and major city, we can help your home experience the advantage of reliable and efficient hot water at the click of a button. Shop our range of hot water systems online, or get in touch to discuss your repair and maintenance needs.