Unrelated but honorable mention for indirect fired water heater tanks… For anyone who lives with a boiler for heat. It turns out not having a flame under your tank works wonders for longevity. I also really appreciate the built-in early warning throughout the warmer months if there might be a boiler problem before it gets cold.
You can set up a solar panel or small wind turbine to pump electric into an element thats installed in a home radiator. On winter days where there is more sun light than sun heat it produces heat through the resistance of the element and warms the water within. A few people on youtube have made videos on this.
As opposed to resistive electric heaters? Well, that’s hardly a surprise. It’s not going to come close to being as cheap as NG though, and an NG heater is 1/4 of the price.
Heat pumps are nearly as cheap in Ohio as NG and save you money over the life of your house. Despite being run by MAGA, Ohio has some pretty sweet green energy subsidies and tax write-offs.
I’m in the market for a water heater in Ohio. The cheapest heat pump water heater I could find is more than twice the price of a typical NG heater. Where are you finding them for anything remotely close to the same price?
One important thing to note: heat pump water heaters take heat from the house and put it into the water. In an Ohio winter, that might not be desirable: you’re paying for the heat from the furnace, then paying for the same heat again into the tank.
Wow that’s wild, man, maybe it’s because I had to do a whole rip job on my heater? I sunk $20k into my heating and cooling system this year. Was a fuckin nightmare. Maybe if you’re going whole cloth the savings show up more?
You’re talking about HVAC while everyone else is talking about water heaters. I think it’s pretty well demonstrated that heat pumps for HVAC are the way to go but not for heating water.
There’s a federal tax credit worth 2k for HPWH. I’m not aware of any Ohio specific subsidies, although there are programs coming through the IRA that are run through the states and will offer more incentives.
The tax credit is 30% of the total project price, up to $2k. If the HPWH is over double the cost of NG, you’re still paying quite a bit more even with the tax credit.
It’s also more energy efficient and therefore less environmentally burdensome in a lot of cases to use natural gas to generate electricity and transmit that electricity to your house to power a heat pump, than it is to directly pipe gas into your house and burn it even in a high efficiency appliance. This is because a heat pump literally gathers ambient energy from the environment and can typically concentrate 4x as much heat per unit electricity input than the electricity itself can provide if directly converted into heat.
Basically, they’re the closest thing we have to one of those fake overunity machines where a motor turns a generator that’s powering the motor.
That’s another important point: if you are using a heat pump water heater, the source for your heat is the air in your house. If you have a gas furnace and a heat pump water heater, all winter long you are heating your water with gas, and using extra electricity to do it.
Heat pump water heaters make perfect sense in the summer, though. And they’d make even more sense on the top floor of your house than in a cool basement.
I haven’t seen those offered in my area, but In that case, I’ll have similar criticism in about 6 months, when I have to run a separate AC unit to pull heat out of the house. It’s almost like the water heater should be able to use either internal or external air as a source.
This is example highlights the benefits of heat pumps as the heat from the gas furnace is waste heat from something functioning on an entirely separate purpose that will occur independently from the water heater. In turn this situation benefits the heat pump as it is actually more efficient to scavenge the wasted heat from the gas furnace. It is super odd that your post is suggesting that it is not efficient because it is using “extra electricity” when the efficiency is from reduced running costs(money) and not hype fixating on just electrical usage. On the flipside, a gas water heater will use extra gas to heat the water, too! This is just silly
A furnace puts BTUs into the house. A heat pump furnace pulls BTUs from the atmosphere and pushes them into the house; a gas furnace extracts BTUs from fuel and puts them into the house. An electric furnace extracts BTUs from electrical energy, and puts them into the house.
The heat pump water heater pulls BTUs from the house and pushes them into the water. They use internal air as their heat source. They do not draw heat from the outside atmosphere; they draw heat from the furnace-heated air inside the house.
The two systems are not “separate” or “independent”. The heat pump water heater is daisy chained to the furnace. Both use the same, household air for opposite purposes: one sinks heat into the house, the other sources heat from the house.
And how is it a bad thing that it is making good use of the heat around the furnace to heat up water? You do realize that the electricity in the heat pump also is making some heat on its own.
All that energy can be harvested for a hot shower or bath instead of having a heat pump outside in the colder temps running at a lower efficiency. On top of that, the furnace will not always be running throughout the year, and the warmer months will be more beneficial to have the heat pump than a gas water heater.
I am assuming that the heat pump water tank and gas furnace are in the basement, or garage. not inside the well insulated house…
On top of that, the hot air is directed out of the gas furnace to the house, while the air surrounding the gas furnace is lost heat that can be scavenged by the heat pump. They are independent and work for separate reasons.
I am assuming that the heat pump water tank and gas furnace are in the basement, or garage. not inside the well insulated house…
Ah. That’s the issue. Your assumption is faulty.
Water heaters have water lines leading to them. Anywhere the temperature regularly falls below freezing, the water heater must be located inside the heated structure, not exposed to the elements. Otherwise, the plumbing could freeze. The basement may be colder than the rest of the house, but it is still part of the heated structure.
If your basement, garage, or whatever room contains your water heater is not within the heated structure, you are living well south of Ohio.
The Washington State Building Code Council voted to update the state energy code to require all-electric water heating in new multifamily and commercial buildings.
Until recently, all of my installations had been in basements here in upstate New York. There are several obvious advantages to locating a heat pump water heater in a basement.
It’s definitely not something the south states are alone in installing water heated tanks in basements or the garage.
Where sub-zero temperatures are regularly experienced, you cannot install a water heater or other plumbing in an unheated space. The cold water supply lines will freeze and burst.
It’s rare for northern homes to have water heaters in garages. In the few cases where they are, the tank is installed in a heated alcove or closet within that garage.
-20F winter nights and exposed plumbing do not mix.
Washington basements are heated. New York basements are heated. Ohio basements are heated.
Do you understand this now? Do you understand that northern water heaters need to be installed in heated spaces? Do you understand that northern basements are heated spaces?
Did you read the articles where they are talking about heat pump water heaters? There is even a mention of placing the tank on the roof. This is a dead end conversation. I am not going to argue about this as it does not help or will convince people up north how to install their water heaters. Its a moot topic and this should just die. I said my piece and you said yours. I am still convinced that having the gas furnace and heat pump combo is a good way of going about the whole setup.
With a gas furnace and a heat pump water heater, the furnace is providing the heat for the water, and all of the electricity used by the water heater during winter is wasted, relative to using a gas water heater. Gains are only made in the summer, while the water heater is helping to cool and dehumidify the home.
Your second article discussed using heat from the dryer in a second floor laundry space. The “waste” heat from the dryer would have normally gone into heating the house, reducing demand on the furnace. The author saw “waste heat” from the dryer, but didn’t think about where that “waste” heat was going, and didn’t properly account for it in his calculations.
You cannot treat a heat pump water heater as “independent” and “separate” from the home’s HVAC system unless it is actually drawing heat from outside the home.
I am not going to argue about this as it does not help or will convince people up north how to install their water heaters.
The question isn’t where they should install them. The question is whether they should switch to heat pump water heaters at all. If using gas heat, that answer is “no”, because these just shift which appliance will be burning that gas, and use additional electricity on top of that.
The same is true for an old house with resistive or radiant heat: the heat source for a heat pump water heater in a resistively-heated house is the resistive heating. The heat pump doesn’t make the household’s radiant heating any more efficient, it just adds additional load on that system.
Heat pump water heaters only make sense where with a hypothetical “split” system that draws heat from outside the home in winter, or if the household heat source is considerably more efficient than either a gas water heater or resistive electric water heater.
Common heat sources more efficient than gas or resistive electric water heaters are heat pumps, solar, geothermal, or a climate that doesn’t require much supplemental heat. If you have any of these, a heat pump water heater will make sense.
If you don’t have any of those, you have to compare the summertime gains against the wintertime losses to find the net efficiency.
The article I linked about Washington state says that new built homes have to install heat pump water heaters. This means its not a question on which to choose but how to make the heat pump water heated tanks more effeciently sound. This topic is a moot point, and should be let go.
First, That’s Washington. Not Ohio, New York State, or the overwhelming majority of the US.
Second, the Washington rule only applies to commercial buildings and large, multi-family residences: apartment buildings. It does not apply to single-family homes. I can’t find the specific criteria, but I doubt it applies to duplexes or triplexes.
Third, the rule only applies to new construction, and not renovation. You can still replace existing gas water heaters with new gas water heaters, you just can’t install a gas water heater in a new, large building.
Fourth, that same rule in Washington requires heat pumps for HVAC, and prohibits gas furnaces. The situation you envision of gas furnaces and heat pump hot water is prohibited in the circumstances envisioned in that rule. The only situation where we can consider gas heat and heat pump hot water is in renovating existing buildings, where the Washington rule does not apply.
Your “Washington” rule is therefore irrelevant to your argument, and my point is perfectly relevant. The conclusion is simple: you must replace a gas furnace or resistive/radiant electric heat with an HVAC heat pump before you will save energy from a heat pump water heater during winter. During winter, whatever your heat source your furnace uses will be the heat source for your hot water. If that is gas or resistive heating, your total efficiency will drop, and every watt hour consumed by your water heater will be wasted compared to a water heater that uses the same type of heating as your furnace.
Clearly washington knows that the long-term solution to replacing gas appliances is with heat pump. Its a state that is north and was used as an example for a place that is much colder than southern states that you claimed would only make sense for heat pump water heaters to be sensible in.
The conclusion is simple: you must replace a gas furnace or resistive/radiant electric heat with an HVAC heat pump before you will save energy from a heat pump water heater during winter.
Then for anyone making the switch, they should get the heat pump powered equipment when they can, be it if the water heater is replaced before the hvac unit or vice versa. Logically speaking there is not downside to having a heat pump water heater next to the gas furnace. It does not need to heat up a large volume the size of the house, only a tank of water. It is still efficient and the losses you claim are negligible or measurably not there.
Its a state that is north and was used as an example for a place that is much colder than southern states that you claimed would only make sense for heat pump water heaters to be sensible in.
Where did I supposedly make that claim?
I’ll give you a hint: I didn’t. All my references to northern climates were only to demonstrate that water heaters in northern climates are indoors, within the heated space of the northern home.
I never claimed that heat pump water heaters were not sensible for northern climates. My claim was that they were not sensible for winter use in gas-heated homes.
Logically speaking there is not downside to having a heat pump water heater next to the gas furnace.
Yes, there absolutely is. The heat inside a gas-heated space is produced from burning gas. Pump heat out of that space and into water, and the temperature of the space drops. To get the temperature back up, you need to put more heat into the space. Again, the source for that heat is gas.
You’re burning gas to produce heat, then pumping that heat into the water. You can make this process more efficient by moving the flames closer to the water. Get them close enough, and the flames can heat the water directly, without needing the pump.
Look, a heat pump water heater does not generate its own heat. It takes heat from a space, and puts it into water. Where the heat got into that space by gas, the water is heated with gas. Where that heat got into that space by solar, the water is heated by solar. Where the heat got into that space by robot ninjas, the water is heated by robot ninjas. The heat pump merely takes the gas-heat, wood-heat, or ninja-heat, out of the living space, and into the water. To maintain the temperature of the living space, you need to add heat: gas heat, wood heat, ninja-heat, whatever.
If the source of the heat around the water heater is provided by gas, you would be better off burning the gas inside the water heater, where it doesn’t need a “pump” to push it into the water.
Another way to look at it: Furnaces located inside insulated structures, like northern furnaces located in basements, do not produce “waste” heat. The heat that doesn’t come from the ducts still goes into the house.
Yet another way to look at it: would it make sense to install a traditional heat pump to draw heat out of the insulated, gas-heated, northern basement and push it into the living room?
Then for anyone making the switch, they should get the heat pump powered equipment when they can, be it if the water heater is replaced before the hvac unit or vice versa
False. To see any winter gains, the HVAC system must be switched first. All of the gains of the heat pump come from the “free” heat drawn in from the atmosphere. Until the heat pump HVAC system is installed, your heat pump water heater is a particularly inefficient gas water heater all winter long, more than erasing any gains you will achieve during the summer.
Replace your furnace with a heat pump long before you even think about upgrading your water heater.
Think of a HPWH as an air conditioner, that dumps heat into water instead of the outside air. Do you want your furnace and your air conditioner running in your home simultaneously? All winter long, that is what a HPWH will be doing. Because your furnace heats your house, and the HPWH gets it heat from your house, your furnace will be providing the heat for your water as well.
In summer, HPWHs make perfect sense. The HPWH will be working with your AC instead of against your furnace.
If you have a heat pump HVAC system, a HPWH is just a second stage heat pump. Your HVAC is still going to be providing the heat for your water as well as the house, but the heat pump HVAC can provide heat more efficiently than a gas water heater or resistive electric water heater. Since the HVAC heat pump is more efficient than a traditional water heater, it is reasonable to shift that water heating load onto your HVAC with a HPWH.
Make sure your HVAC heat pump installer knows you want to install a HPWH in the future. You’ll want to make sure your HVAC heat pump is sized a little larger than normal.
Right now, and that’s not even the case everywhere in the world. In many parts of Europe, the operational costs of heat pumps are already lower than those of gas furnaces.
Gas is cheaper to run as well, although that is more subject to the wonders of international incidents.
I like the idea of a renewable energy way to heat the home, as trickling the heat in would work there, run the electricity when it’s cheaper and that, but for hot water, gas is just so convenient. A heat pump is never going to produce enough concentrated energy to run a bath or have a shower more powerful than a piss.
Hated having a water tank when I had a rubbish old gas boiler, and I’m not going back to one if I can avoid it.
There are electric water heaters that can take the preheated water from the general system and give it the last boost to exactly the temperature you desire. Ideally those would be installed relatively close to wherever you need the water. They are less efficient, but on the plus side, they only heat whenever and exactly how much you need
I’ve contemplated a heat exchanger on the tub drain line to capture the heat from my shower to preheat water into the tank.
A small, non-functional gas water heater, located in a hot, summer attic, and with a small fan blowing air down the exhaust stack, makes an excellent pre-heater.
Stick a small window air conditioner in there, and it becomes a redneck heat pump water heater.
If I’m getting a new water heater, I’d rather get a tankless honestly. I figure by the time I’m ready for a new water heater, the tankless technology will be even better and will be perfectly ready for me to use it.
Tankless still uses gas and it won’t make the water coming out of your faucet instantly hot. If that’s what you are looking for you want a recirculating pump or two.
If methane gas is cheap because you’re in the US, don’t count on it staying that way; there are a ton of export terminals under construction, and when completed, they’ll raise domestic prices in the US to match those on the world market, which are 2-3x higher.
I’m not in the US, and tbh I don’t really use a ton of hot water. I think a tankless would still be a good investment for me. I’ll also end up getting an air-to-air heat pump probably with a gas furnace as a backup for the really really cold winter days.
You can, but not as a heat pump so you wouldn’t get all the efficiency gains and it will very often end up being more expensive to run than gas tankless in the near term.
The more and more hot water spouts you have the more expensive the tankless design is, especially for running costs and short life span. The recirculating with a water tank will last longer, cheaper running costs, and can be fitted in already existing infrastructure of water tank designed homes. In building a new home, it is possible to have tankless water heaters be better than water tanks. especially if you can use Solar Panels to make the running costs near 0.
My coworker bought one and had to buy a new electrical panel because it required 45A of electricity to run it meaning 3 dedicated circuits at 120V (5400 watts!). IMO an electric tankless is the worst of both worlds.
Depends on the size of the house and the water needs.
I installed a totally electric tankless water heater made by a reputable manufacturer in my home on my own 11 years ago and just wired in a new 40 amp 220V breaker into the panel to support it.
It was actually very easy and plenty adequate for the water usage in a 2 bed / 1 bath home (including kitchen usage) for a 2 adult and 2 child household.
For more bathrooms or occupants it might be more difficult, expensive, or rare but in my case I did the whole job myself for under $350 including everything… But again, it was 11 years ago so I’d expect prices to be a bit higher
That’s not constant throughput though. That’s absolute peak possibilities.
Editing to add:. FWIW, it also didn’t increase the monthly average electrical usage at all… In fact, I believe I had a small reduction in the average… It was replacing a significantly older traditional 30 gallon electric water heater.
Thankless really never appealed to me, unless you have massive space restrictions. Water tanks are amazingly insulated so the loss is basically nothing and you’ll almost never run out of hot water. Thankless always claim infinite hot water but it almost never works and it’s way more complicated for what it’s doing. Anyway just my 2c.
Tankless only shines if you have a large household where you need an endless supply of hot water. For everything else, they’re going to operate the same or worse than a tank heater and also come with more maintenance.
I figure by the time I get tankless in probably another 10 years the tech will likely be more stable so it won’t have nearly as many problems as they do now which is already less than they had before.
It’S a WiNnEr On YoUr WaLlEt! But yet they cost $1699. This stupid article thinks we’re high class people instead of poverty class, because there is no way I could ever be able to afford something that expensive
Expect install cost to be $500-1000 on top of that. Water heaters tend to last around 10 years (though this can extend out a lot with proper maintenance), so homeowners are going to have to have an expense like that at some point.
You could diy the install. If the old one is gas, you probably shouldn’t, though. Cities often don’t care about people doing diy plumbing and electrical, because if you fuck up, it tends to fuck over only yourself. If you fuck up gas work, it can fuck over your neighbors.
Idk, I DIY swapped out old gas water heater for an electric heat pump water heater heater and it was super straight forward. If you have the plumbing and electrical skills to add a circuit and move your hookups (since on most gas water heaters they are on top and most heat pump water heaters they are on the sides top and bottom), you probably have the skills to safely disconnect and cap off the old gas line. Just be sure to use pipe dope that is rated for gas, and check with soapy water once you pressurize the line again for leaks.
Just installed one recently. Got $500 back in a rebate from the electric company and will get 30% back in taxes at the end of the year. These incentives alone bring the cost down to an equivalently sized traditional electric water heater. I haven’t had it running long enough to see what the average electric bill reduction will be; however my last bill (and first full one with the new heater) was my cheapest in the 5 years I’ve been here ($125 vs $150 from the same month last year). I don’t expect it will take long to fully pay for itself compared to the highly inefficient 20-year old model it replaced.
For me it means I don’t need any propane deliveries in the summer, and it helps dehumidify a damp corner of the basement. I’m not sure if it actually saves me any money though.
YMMV of course, and will highly depend on how many people are in your house and how you use hot water, but a 50 gallon heat pump water heater easily supplies a dishwasher and two long showers with 1/3 of a tank of available water left in our house (and I take pretty hot showers that are not always as short as they should be). Sure, it takes an hour or two to fully recover but we aren’t ever looking to use much more hot water at one time. If you have a household of four, it may be a bit more of a problem, but then you can easily schedule other hot water uses to happen “off peak” like a dishwasher.
The recovery time, aka first hour rating, should be in the specs for the models to find one that suits your needs. There’s more detailed research on them available as well if you’re so inclined.
Sure, I know the info will be there. But someone generically selling the idea needs to address or at least mention the impediment. I’m not to the point of wasting my time trying to find the details so the pitch is a failure
In Midwest USA gas is so ridiculously cheap that it still beats total cost of ownership. Plus the new electric to install. Even central heat pump is hard to justify (on price alone I mean).
This is true in central Canada too. Heat pumps get pushed saying they put out 3 times as much heat as the energy they use, but electricity is 7x the cost of natural gas.
Right, they make absolute sense if you don’t have access to cheap natural gas. I’m worried for the day NG prices rise though. It’ll be a double whammy for those of us in SK with the vast majority of the heating in the populated south provided by NG and a grid that has a significant portion produced by NG. You’ll see the increase even if you aren’t heating with gas.
Well, they have took off in Europe due to the cost of natural gas and … the source being a evil dictator who uses his control over natural gas to control other countries foreign policy.
Governments need to punish carbon emitting fuel sources more. People are going to use the cheaper option, not the one that will benefit the planet. It needs to be cheaper to use renewable energy, or at the very least energy efficient options need incentives.
No, they most definitely should not! Implementing such a measure unnecessarily increases the difficulty for low-income families. Instead, there should be support for the installation or a tax reduction for those who have one. Let’s focus on making it easier for people to adopt environmentally friendly practices without making things more expensive.
This is still blind to the fact that those families could be in much much worse condition in 50 years if we don’t drastically change our carbon emissions. The increasingly frequent and more dangerous natural disasters could very easily leave them without a home at all. Low income families will also be the ones to suffer the most when it comes to the worsening climate disaster
I don’t deny that. However, forcing people to change by making things more expensive only harms these families. Of course, the ongoing climate situation is concerning, but in the short term, we also need to take care of those who are financially vulnerable. We can’t just let them go under.
A better option would be a discount on the electrical bill for having green tech installed. If you want to help poor families, help their month to month costs.
Maybe my gas is more expensive than other parts of the Midwest. But my old gas water heater just died about 6 weeks ago. I swapped in a 55 gallon hybrid / electric heat pump model. I did the re-wire and install myself (which I acknowledge not everyone is comfortable doing).
My most recent gas and electric bills were compelling. I’ve been using my gas furnace already, and my gas bill is the lowest it’s ever been since I bought this house 5 years ago (including summer, non-heating months). And my electric bill increase was negligible.
Sure, my old unit was not running as efficiently as it could bave. And newer gas models probably have improved efficiency. But I can’t deny the savings in my bills. Between the tax rebate and the savings, I’ll make back my extra investment and then some before this thing dies.
As soon as I can afford it, I’m getting one. I just don’t have the 4 figures laying around to pay for it and I won’t do it on credit if it’s not an emergency.
Do the math for how long it will take to pay off itself. Between my old inefficient water heater and the tax credit if I keep this thing for longer than a year I’ll be saving money.
It would be about $400/year cheaper to operate, but cost between 1200-1500 up front to buy and get installed (no idea how much installation actually is because no one wants to spill I guess).
So I’m guessing between 2-3 years to recoup the cost.
Bigger problem is that I’m not liquid enough to afford the up front cost right now.
Got it. They go on sale regularly. I bought my 50 gallon for $850 out the door back in May 2020. Swapping it out was easy if you’re at all comfortable with electrical and plumbing.
I’m not so worried with the electrical or plumbing (I imagine it’s not far off from the dishwasher I just installed), it’s more the installing it to code that I’m worried about. I don’t know all the tools I need and I’m not keen on screwing up and it turning into a multi day job.
Water heater and breaker box work are two things I contract out.
I have a Sanco2 heat pump water heater. The heat pump is located outside the house, with the tank in the basement (so no noise!). It is so absurdly efficient that I thought I was measuring the power draw wrong. Its expensive up front, but a big fat govt tax credit sure helped and the monthly power cost is about the same as my coffee maker.
The tank inside is 83 gallons. I can run the dishwasher, two showers, and anything else I can imagine and it handles it like a champ. The heat pump heats the water so fast that it refills it in minutes, not hours.
And since there’s no element or anything in the tank, there’s virtually nothing to break or fix in it. Nothing to rust, no joints to go bad. The tank is constructed solely for water in and out via pump and that’s it. It looks like a military designed tank because there’s no reason not to fortify it to last forever. So they did.
Between that and my induction range and heat pump AC/furnance, we turned off our natural gas connection. I love love love all of them.
Oh yeah, I’m with you that dishwashers conserve water. I was making a playful remark that in Europe, the dishwasher takes cold water and heats it up itself, not arguing for or against dishwashers as a concept.
I believe it’s mostly due to not having always hot water hookups available where laundry would be or not consistently having hot water always available. (as in on demand, from a large boiler that wouldn’t impact the remain of the hot water uses)
I’m intrigued- does that mean the UK uses “tankless” water heaters, at least in smaller residences? Are they underspecced that they can’t handle a shower at the same time as a (typically) 3.5 gallon dishwasher?
In the UK your dishwasher is typically connected only to the cold water intake, so that’s not a problem unless you have multiple showers in your house… that said, water heaters are often limited to either heating or hot water (not both at the same time), but that’s not an issue in practice since you’re not going to be using the hot water for long periods of time.
Speaking for The Netherlands here, but I believe our situation is very similar to the UK in this regard. A lot of houses are equipped with a gas-powered tankless heater which supplies both central heating and hot water. These come in various sizes and output capacities, so you can install one which comfortably suits your needs. Using hot water for multiple things at once shouldn’t be an issue if you have the right heater installed.
Same in the U.K. Although my experience is that you’ll have to have a gas boiler with some buffer (40L say) to not experience a pressure drop of hot water when somebody else washes their hands. It doesn’t matter how often I’ve heard a plumber say “you won’t feel the pressure drop with this bad boy installed”; you always feel it.
It depends. Spraying your dishes with water that is prone to legionella doesn’t seem super safe to me. But even assuming that, I have dishwasher programs than run at 70C, which is above what my hot water tank produces.
Besides, isn’t there a heating element in a US dishwasher regardless? Otherwise, it feels like it has got to continually add more hot water to keep the temperature up…
It depends. Spraying your dishes with water that is prone to legionella doesn’t seem super safe to me.
That is the real reason why UK / EU dishwashers use the cold water supply. They don’t consider a building’s hot water supply to be potable water. Their hot water was once held in atmospheric pressure, gravity-fed tanks, exposed to environmental contamination. Brits treated central hot water as unclean. This is also why they often used separate taps for hot and cold water. If they need clean, hot water, they heat cold water at the point of use.
The US never allowed atmospheric pressure hot water tanks. Our hot water is not exposed to environmental contaminants, and is presumed potable.
As a Dane living in the U.K., I agree. I’d never seen an atmospheric pressure water system growing up but coming here, that seemed the norm. Now, 20 years after, the norm in U.K. new installation is high pressure water systems (so called “system boilers”) so it is changing slowly. But in the U.K. they have an almost mortal fear for high pressure systems, thinking they’ll explode at any moment.
I’m confused, our as in European dishwashers are more efficient and environmentally friendly?
But wouldn’t it be even more so if the hot water that was stored and not being used was the feed instead of cold water? That was the temperature increase is minimal and a lot more efficient.
The majority of our hot water is on-demand so no. Also, is it more efficient to heat the water, pump it through a potentially cold pipe, only to have to reheat it again? Nope,just heat it where you need it, and with a lower wattage heater
everyone, ever. unless you are running some industrial operations that require constant hot water, there is no reason for even a large family to be using water continuously, and hot at that
Heating a volume of water a given number of degrees takes the same amount of energy regardless. Using a lower wattage heater is just going to make it take longer, not save any power.
Your system - Add cold water to water heater and heat (using energy). Keep at required heat until needed, could be a whole day or more (using energy). Pump hot water through cold pipes to dishwasher, losing energy. Reheat (using energy)
Our system - add cold water to device directly. Heat (using energy)
No idea how Americans can’t understand that most of the developed world is decades ahead of them environmentally 😂
Using gas to heat water is considerably cheaper than using resistive electric. Especially when the electric was historically provided by coal or gas anyway.
Burning gas to heat water into steam to turn a turbine to turn a generator to pump electricity to a resistive element inside a dishwasher is not nearly as efficient as just burning the gas inside a water heater and sending it to the dishwasher. The heat losses incurred while passing the water from a gas heater to the dishwasher are a tiny fraction of the losses incurred in the convoluted processes involved in traditional electrical generation.
It has nothing to do with energy efficiency, and everything to do with UK plumbing. A building’s hot water system is presumed to be subject to environmental contamination, and not considered potable. Only the cold water supply is considered potable.
It’s the same reason why they have separate taps for hot and cold water, while the US uses mixing taps almost everywhere.
Why would that save energy? It’s going to be resistive heat, which at best matches the water heater. Some models in the US include a heating element, but it’s more of a convenience. The vast majority are simply connected to the hot water line, since that’s why it’s there.
Also, let’s talk numbers. From what I could Google, EU dishwashers use 1-1.5KWh/load, while US dishwashers use an average of 1.15KWh/load. Certainly there are more efficient models, but this shows that there isn’t a significant difference in energy usage between them.
Your system - Add cold water to water heater and heat (using energy). Keep at required heat until needed, could be a whole day or more (using energy). Pump hot water through cold pipes to dishwasher, losing energy. Reheat (using energy)
Our system - add cold water to device directly. Heat (using energy)
I couldn’t explain it any clearer so I’ll fuck off now
I’m so confused. Whose dishwashers are you talking about? I’m in the US, you’re describing every dishwasher I’ve ever had, except that we always hook it up to the hot water line. Our unit takes very little water, it takes hours to run a load due to efficiency features. It has a heating element inside to take whatever water it gets and keep it hot for the cycle.
I don’t really see why it’s any less efficient to use the hot water we are already heating with our water heater (which heats much more efficiently than a small electric heater would). The water originally arrives to my house cold, it has to be heated one way or another. My dishwasher is less than 10 feet away from my water heater, water is not losing appreciable heat on the way to the dishwasher.
The reason your dishwashers use cold water is because your hot water supply is not presumed to be potable water.
EU regulations allows for gravity-fed hot water tanks in certain jurisdictions, open to atmospheric pressure, and thus possible contamination. They did this to prevent the possibility of exploding boilers.
Since the building’s hot water supply is presumed unsafe, dishwashers are required to use the safe, cold water supply to generate their own safe, hot water.
US regulations do not allow hot water to be held at atmospheric pressure. We use T&P valves to limit boiler pressures and prevent explosions. Our hot water is not exposed to environmental contaminants, and is presumed potable.
That wouldn’t work with every dishwasher I’ve ever had. They all start the cycle by draining any liquid in the dishwasher before they fill to run the first pre-wash cycle.
This is crazy to me. How do the dishwashers in US heat the water up hot enough to clean effectively? Our dishwashers heat the water up past scolding, really helps cleaning.
Every dishwasher I’ve used in the United States has a built-in heating element. Mine has a steam sanitize function and gets quite hot.
However, it is conventional here to plumb the dishwasher to the hot water line, and it is my understanding that the dishwasher is designed to assume the water is hot and doesn’t try to heat it from cold during the first rinse.
I’ve found that running some water from my kitchen sink to prime the hot line with hot water makes the dishwasher more effective. I use that water for plants, or I keep it in a jug and pour it into a load of laundry in the winter.
Awesome. I so wanted the Sanco2 but the price put it out of reach, and we don’t use enough hot water toake the payback remotely reasonable. For anyone else reading, it’s an R744 (CO2) refrigerant system that’s massively better for the environment than HFCs (and HFOs) as well.
Most models are 220V 30A. If you have an electrical already, you likely have everything you need here. If you have gas, you will need to run 10 AWG or 8 AWG wiring and install a new breaker. Depending on where you live, you'll likely need a permit and have your handy work inspected before putting the water heater to service. If you aren't sure when you'll need 10 AWG over 8 AWG, hire a professional.
The 120V 15A models are slower at heating water and do so for a smaller volume. These models you can plug right into the wall, but they are usually a bit slower at coming to temperature for the water and for smaller volume. There's a Rheem version that's plug-in and has something like a 80 gallon store. However, it is highly recommended for use only in warm climates and installed outside in a small enclosure. Basically if you don't live in Southern California, Texas, Florida and all the states that touch those states in between them, you shouldn't try using this.
Like all heat pumps, there is an air filter that you need to replace. Usually these devices have apps that will notify you when a filter is needing to be cleaned or replaced.
Also like all heat pumps, there's a fan motor that will make sound. Luckily, most heat pump water heaters attempt to minimize the sound. That said, it's not zero sound and nobody should be recommending that one of these things be installed in a room adjacent to a bedroom. I mean, this is one of those things that really depends on "how well do you tolerate noise?" But these things will produce a pretty consistent hum.
The act of cooling the air from these reduces the humidity in the air. So you must drain that water that is produced. I think this is one thing that catches most people off-guard about these. Most water heaters don't have a method for draining water because water around a water heater is usually a bad sign. So you do need to drain off the condensate. You can take a big bucket and collect the water to bail later, but how much water it'll produce is dependent on what the humidity is in your area. If you're in like Florida except something like a hint over a gallon of water per day. But most professional installations will install a drain line for you that leads to the outside, unless you're putting this thing like smack dab in the dead middle of your house and you're on a slab. That would obviously present a slightly higher challenge for that drain line installation.
But all that said, these things are super neato. It's just really important for people to have realistic expectations before installing one.
What crazy ass compressor needs 220V 30A? Here in Netherlands heat pump is standard as new gas connections are banned for environmental reason, and most homes heat water and the whole house on 7 kW heat, 1.5 kW electric, or about 7A on 240V.
The backup element which only runs at extreme cold outside is a few kW yes but for hot water we just let it run dry and the tap gets colder, no big deal.
Dedicated hot water only boilers have a 300-700W compressor and sometimes a 1.5 kW backup coil. If electrical connection is an issue, just look for a pure compressor driven boiler.
They almost always have two high wattage resistive elements installed like a traditional electric water heater which require the 220v/30a circuit. The compressor runs on 220v but sips almost no real current while running.
We have two main models here, one with a sizable compressor enough to heat a whole home (7-20 kW heat) and a water tank on the side which doesn’t need resistive backup, or smaller, hybrid models that have a few hundred W compressor and maybe 1-3 kW heat output. The latter are almost all backed up by a gas boiler in a hybrid setup, usually uses zero gas until you run it dry - then the 25ish kW gas powered furnace can provide enough power to quickly fill a bath or send tons of hot water to a rain shower.
Thanks for this, I live in Florida and have a conventional resistance electric heater in my garage so I’m looking pretty hard at this. Why can’t the condensate be drained into the water tank to be used in the house? Is it unsafe?
A lot of these depend on the model and where it’s installed (geographically and within the house). In many areas of the US, there is a drain in the floor near all water heaters as a matter of code, you can drain condensate directly to that (and unlike gas appliances, the condensate is clean and does not need treated to go in household drains). I honestly think the noise concern is hugely overblown and used as an excuse for people that don’t like change. Sure it exists, but if your water heater is in the basement or garage like the majority are at least in my areas of the US, you’ll never notice it. I also look at the cooling air as a benefit for at least half the year, I can close all the vents in our basement for the whole spring/summer and it’s super comfortable. In the winter it’s a tad chilly, but not uncomfortable. Drying the air is also great for our basement, it’s literally a dehumidifier in what’s usually a pretty damp location for many people. Ours (a rheem unit) has a flimsy plastic air filter you vaccuum off once a year as well so not really a huge deal. I think most are like this.
I agree that folks should do their homework and understand what they are getting. Heat pump water heaters are great, but are overpriced at the moment. Even with electric company rebates and a tax credit it cost more than a decent gas replacement would for us. It’s likely to only pay off because we have solar and so don’t really pay for electricity for a large chunk of the year. But I expect costs to come down over the next 5-10 years as these become the go to for most electric installs (and with fewer new gas hookups in new and renovated buildings that’s like to be most installs). Once these hit that $700-$1000 price point there’s really no good reason most people shouldn’t default to installing one.
We’re doing a major bathroom remodel at the moment and as part of the project are planning to replace the 15 year old electric water heater that came with the house when we bought it. Heat pumps work by exchanging heat from the air around to the water in the tank, which means that in addition to reducing humidity they also put out cool air. Usually they are installed in a garage or basement where that doesn’t matter as much, but we don’t have a basement and putting it in the garage would require a lot more work in terms of plumbing and electrical work, so we’re going to keep it where it is in the house but install vents that exchange air from the attic in the winter, then in the summer we can flip open the vents and cool/dehumidify our house.
They’re expensive up front but there are federal tax credits through 2032 (I think) of up to 30% of the project cost ($2000 max) and on top of that our local electric company is offering rebates of $800 to replace an electric or gas heater with an air pump. So that will reduce the upfront cost by a pretty good amount.
The only thing I’m at all concerned about is the noise of the motor, but the heater won’t be adjacent to any bedrooms so I don’t think it’ll be a big problem in any case.
We had a GE that had the heat pump die after a couple years. Now our AO Smith will randomly not have hot water some mornings with no error codes. I am all for heat pumps, I am just not enjoying being a beta tester. I’d like to replace my gas furnace with a heat pump but my previous experiences make me nervous. Hopefully in a few years they will be rock solid reliable.
We had our electric bill go down by 1/4 after installing our AO Smith Signature 900. Then the heat pump broke 13 months into a 12 month labor warranty (it no longer blew cold air, so it wasn’t working). We found out nobody even fixes the heat pump part. AO Smith agreed to take it back and refunded us but we had to hire a plumber to put in another one, this time a less expensive one.
Heat pump water heaters are relatively new, but heat pumps for interior heating and cooling have been around for decades. I have a 14 year old system that works well.
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