I am currently looking for new faucets, starting with the bathroom. Right now, there is a common single-lever mixer, but in our case, the water is either hot/warm or cold and should not be mixed—or it would be pointless.
Is there another solution besides having two cold water taps connected separately to the respective pipes, since washbasins usually only have one hole?
Basically something like the old-style taps with turn knobs on the left and right, but without the turning handles. Maybe with push buttons?
It should be a bit modern. Also, you don’t want to have to turn the taps for ages until the strongest flow finally comes out.
I have also thought about sensor faucets, but I’m bothered by the batteries.
Somehow, I am missing the right term to search for (searching for “two-temperature faucet” or “faucet without mixer” returns no results).
Is there another solution besides having two cold water taps connected separately to the respective pipes, since washbasins usually only have one hole?
Basically something like the old-style taps with turn knobs on the left and right, but without the turning handles. Maybe with push buttons?
It should be a bit modern. Also, you don’t want to have to turn the taps for ages until the strongest flow finally comes out.
I have also thought about sensor faucets, but I’m bothered by the batteries.
Somehow, I am missing the right term to search for (searching for “two-temperature faucet” or “faucet without mixer” returns no results).
Steffi33 schrieb:
Hello Saruss, thank you very much for the detailed explanation. This kind of information is really interesting. What I didn’t quite understand is the meaning of the 20 days in your calculation. Is that the time the tankless water heater could operate to compensate for the heat loss from the storage tank (in terms of cost)? Best regards, Steffi.The 20 days represent the amount of time you can keep the water warm in the storage tank without it being more expensive than using the tankless water heater. In other words, if you need more hot water in a 20-day period than the storage tank can hold (which is usually the case), the hot water from the tank is cheaper than using the electric tankless water heater. How much cheaper depends on details like your electricity rates and your hot water consumption.
When you look at it this way, it becomes clear that, considering only the heat loss costs, you could never afford to pay for hot water using the tankless water heater. The only meaningful calculation is to determine whether the investment in the storage tank and boiler pays off within about 10 years, and for that you need to calculate based on your actual consumption.
Sent while traveling
I think it largely depends on how much water the storage tank holds and how much hot water is used daily. You definitely can’t generalize with a fixed period of 20 days.
It makes sense that an instantaneous water heater (tankless water heater) becomes more worthwhile the less hot water is needed. For us, with 2 people and only showers, plus a total water consumption of 33 cubic meters (about 8,700 gallons) per year including hot and cold water, the tankless water heater is definitely worth it. Calculated per day, we use 90 liters (about 24 gallons) of water per day for 2 people, including cold water.
Compared to our rented apartment, we probably use about the same amount, although there we were also paying for the neighbors’ hot water. Operating costs are therefore similar, so it’s really just a question of whether a new installation makes sense. The hot water heat pump would cost around 700 euros, which is hard to recoup. The only advantage would be that it could charge during the day using photovoltaic energy, making the kWh cost only about 10 cents. Here, showers are mainly taken late at night and around midday, with plenty of time between, so I don’t expect any problems with the storage capacity.
Initially, we also thought we would definitely need the heat pump instead of the instantaneous water heater to meet the KFW 100 standard, but that was not the case since the renewable energy share was already easily exceeded by the pellet boiler alone.
It makes sense that an instantaneous water heater (tankless water heater) becomes more worthwhile the less hot water is needed. For us, with 2 people and only showers, plus a total water consumption of 33 cubic meters (about 8,700 gallons) per year including hot and cold water, the tankless water heater is definitely worth it. Calculated per day, we use 90 liters (about 24 gallons) of water per day for 2 people, including cold water.
Compared to our rented apartment, we probably use about the same amount, although there we were also paying for the neighbors’ hot water. Operating costs are therefore similar, so it’s really just a question of whether a new installation makes sense. The hot water heat pump would cost around 700 euros, which is hard to recoup. The only advantage would be that it could charge during the day using photovoltaic energy, making the kWh cost only about 10 cents. Here, showers are mainly taken late at night and around midday, with plenty of time between, so I don’t expect any problems with the storage capacity.
Initially, we also thought we would definitely need the heat pump instead of the instantaneous water heater to meet the KFW 100 standard, but that was not the case since the renewable energy share was already easily exceeded by the pellet boiler alone.
The 20 days refer to the values from my storage tank. If the hot water is used within a few days from the tank, the energy costs are about one third compared to an instantaneous water heater. This was asked, so I calculated how minimal the storage losses actually are. The operating costs with a storage tank are therefore lower; whether it’s worthwhile, as you say, depends on the annual amount. For us, the difference (compared to a heat pump with storage versus a hypothetical instantaneous water heater) would be about 350 euros in favor of the storage tank. With gas, the difference should be similar because the kWh (kilowatt-hour) price for gas is cheaper than for electricity. If you can get a small storage tank and a boiler cheap enough, it might be worth it. When the children are a bit older, it might even be more beneficial. At the mentioned price of 700 euros for the heat pump plus some extra for the storage tank, it would be worth it for me.
Sent while on the move
Sent while on the move
Sir_Kermit24 Jul 2016 13:25Hello,
It will probably be similar for us. Since we are still undecided between a gas condensing boiler with solar thermal and an air-to-water heat pump for our small project, the idea of a tankless water heater also came up. I wasn’t aware that these units can be precisely adjusted, but that’s a really good point. Thanks.
As an example, I found the Junkers ELAFLUX ED 18/21-3 ES, where the temperature can be set directly on the unit. Or do you have a separate remote control for the device?
Maybe this way we can still postpone the decision.
Kermit
P.S.: Spiegel Online has a somewhat older article on this topic titled “Technical annoyance single-lever mixer: Mixing impossible.”
Elina schrieb:
For us, with 2 people and only a shower, and 33 cubic meters of water consumption (hot and cold) per year, the tankless water heater definitely makes sense.
It will probably be similar for us. Since we are still undecided between a gas condensing boiler with solar thermal and an air-to-water heat pump for our small project, the idea of a tankless water heater also came up. I wasn’t aware that these units can be precisely adjusted, but that’s a really good point. Thanks.
As an example, I found the Junkers ELAFLUX ED 18/21-3 ES, where the temperature can be set directly on the unit. Or do you have a separate remote control for the device?
Maybe this way we can still postpone the decision.
Kermit
P.S.: Spiegel Online has a somewhat older article on this topic titled “Technical annoyance single-lever mixer: Mixing impossible.”
Saruss, okay, I must have overlooked that the calculation specifically applied to your case, but it’s interesting to have solid facts and figures as a reference.
Kermit, I believe most of the newer tankless water heaters can be adjusted to half a degree accurately. My older one still has a rotary dial without a display, with a scale similar to a stove, so it’s not as precise. The newer one is a Stiebel Eltron DHE 18 kW, although it’s probably already about 10 years old. Some of the latest tankless water heaters can even be controlled remotely with a remote control.
Mixing is impossible, haha. Yes, I already suspected that. Everything we have bought for the house’s electrical appliances has broken down at least once (air conditioner after 6 months, refrigerator twice in 3 months, inverter after 1 year, front door lock after 1 year…). Whatever can break will probably break, unless it’s already 10 years old, then it lasts forever.
Kermit, I believe most of the newer tankless water heaters can be adjusted to half a degree accurately. My older one still has a rotary dial without a display, with a scale similar to a stove, so it’s not as precise. The newer one is a Stiebel Eltron DHE 18 kW, although it’s probably already about 10 years old. Some of the latest tankless water heaters can even be controlled remotely with a remote control.
Mixing is impossible, haha. Yes, I already suspected that. Everything we have bought for the house’s electrical appliances has broken down at least once (air conditioner after 6 months, refrigerator twice in 3 months, inverter after 1 year, front door lock after 1 year…). Whatever can break will probably break, unless it’s already 10 years old, then it lasts forever.
D
daniels8724 Jul 2016 15:17Elina schrieb:
The hot water temperature is set directly at the heat source, so it would make no sense to then mix the costly heated water back down with cold water. You can of course adjust the temperature with a single-lever mixer, which we currently do, but you can also set intermediate positions there, and since we don’t need that, it would just be unnecessary. The same goes for the shower, actually—we would only need an on/off button since the water temperature is set precisely at the heat source. By the way, I find this very practical. In rental apartments before, you had to turn the controls endlessly until you finally got the right temperature, and it never stayed constant, so you always had to readjust, including those sudden shifts from freezing cold to scalding hot.
For us, hot water now always comes at 42°C (108°F), which is fine for all purposes, and if it needs to be hotter, I can briefly set it to 60°C (140°F) — and the 60°C (140°F) is immediately available. In summer, I can set it to 37°C (99°F) as well. This saves energy quite well, and the lack of constant readjusting saves water.
@ Kermit
I’ll look into a two-handle faucet! This Retro Almendro is exactly what I don’t want—twist knobs. You have to keep turning and turning... But the general idea is about right. The only thing missing would be buttons that provide a full flow at the push of a button.This is not entirely correct. When heated water is mixed with cold, there is less flow through the hot water pipe. For example, if the faucet is fully opened and 5 liters per minute (1.3 gallons per minute) flow through, and you set the mixer to 50/50 hot/cold, only 2.5 liters per minute (0.66 gallons per minute) come from the hot water pipe. This is more environmentally friendly than having a fully open hot water flow of 5 liters per minute (1.3 gallons per minute).
Our faucet is controlled via a rotating axis. The first few centimeters adjust the flow rate (0-100%), but only for cold water. If you turn further, the temperature changes from cold to warm, still at 100% flow.
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