this post was submitted on 22 Nov 2023
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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.
There are multiple kinds of heat pump water heaters.
For the one I have, only the tank is inside. The full heat pump is outside, and water is piped between it and the tank.
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.
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.
https://www.coffman.com/news/water-heating-washington-standard/
https://www.greenbuildingadvisor.com/article/where-does-the-heat-pump-water-heater-go
It's definitely not something the south states are alone in installing water heated tanks in basements or the garage.
You're still not comprehending.
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.
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.
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.
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.
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?
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.
So much anger. Have a good day, I cannot read your post intellectually anymore and will not participate