Instant water heater: be careful!

[LOGIC12]

hello: Instantaneous water heaters are only valid for small consumption, such as hand washing for example. Do not take this to fill a bathtub for example.

In addition we note that the smallest power is around 3,7 kw, so we do not plug it into the first outlet. You must bring a line accordingly from the counter. For a power comparison: a m. at l. the linen when it heats has a power of 2,4 kw, ditto the dishwasher.

So these small heaters already occupy a lot of the meter when you have a 30 amps, or 6,8 kw available. As the water heats up as it passes, you need what you need.

In a holiday home, we have a small 30 liter water heater which is only 9 kw and which is doing very well. It is continuously supplied with electric current, which does not mean that it heats continuously, because the thermostat. We are careful, we have reduced the flow rate at the inlet of the water heater for those who are used to opening the taps fully and we are very satisfied. We don't ruin ourselves.
And even if the hot water were to break down a bit, we wait a bit and we have hot water quickly. We avoid consecutive showers, we space a little.

But we still see a lot of people who want unlimited hot water, and at the same time complain about energy bills.
I think that it will be necessary to put a counter above each tap, because as they do not see the counter, they do not realize.

[dirk pitt]

even if the instantaneous power of these water heaters is high, the energy spent in the end (and therefore the corresponding bill) is identical to the energy spent to heat the water in a cumulus. the energy will even be slightly lower because the losses are almost nonexistent with the snapshot.
the difference in the invoice level will be small and due to the difference in price of the subscription.
the reduction of the flow (which is a very good idea) can be done as well on the exit of the cumulus as on the entire water network of the house.
when to heat the water of a bath, neither, no difference between the snapshot and the water heated by a cumulus.

last precision: all classic sockets are capable of delivering 16A or 3,6kw. you must therefore limit yourself to this power or draw a specific 20A line to the water heater

[Did67]

even if the instantaneous power of these water heaters is high, the energy spent in the end (and therefore the corresponding bill) is identical to the energy spent to heat the water in a cumulus.

Indeed, the amount of energy is the same. But the price may not be the same, if you have a subscription (which is more expensive!), With a reduced rate. In this case, we “fill up” with hot water at low cost for the day. What we cannot do with a snapshot.


We must therefore do a calculation. From a "certain" consumption, from a financial point of view, it becomes profitable to switch to double tariff - with, if necessary, also the dishwasher (with delayed start) and the washing machine (with delayed start ).

[dirk pitt]

I'm doing a little digging up of the subject because I'm considering a mixed solution in a very specific case.
in a studio made for two people, I have no place to install a conventional storage water heater or a very small one (50Lmaxi).
however, information taken, for an acceptable flow for a shower, it is necessary at least 5 or even 6kW in instantaneous water heater. so a little too close to the limit of the counter.
so I said to myself the following thing: why not a hybrid:
a small power snapshot of the 3kW style which can only heat the water from 15 to 35 ° which I mount upstream of the small cumulus of 50L
in this way, the water entering the cumulus is already at 35 ° instead of 15 ° and allows mixing with the 50L at 60 ° to make "virtually" the equivalent of a larger capacity water heater (I haven't calculated by how much)
and hop, that solves my space problem.

qu'en pensez-vous?

[oiseautempete]

I'm doing a little digging up of the subject because I'm considering a mixed solution in a very specific case.
in a studio made for two people, I have no place to install a conventional storage water heater or a very small one (50Lmaxi).
however, information taken, for an acceptable flow for a shower, it is necessary at least 5 or even 6kW in instantaneous water heater. so a little too close to the limit of the counter.

and hop, that solves my space problem.

qu'en pensez-vous?

My brother has an instantaneous water heater with a 30 liter buffer tank under his sink: that is more than enough to take 2 consecutive showers, knowing that a normal shower is ~ 20 liters of water so 10L of hot water to 60 ° ... I checked my personal consumption several times by taking a shower: it's always between 15 and 20L of water ... by cutting off the water during the soaping phases of course ... Taking a bath however it is a huge waste of water and energy ...

[Christophe]

and hop, that solves my space problem.

qu'en pensez-vous?

Uh I think that I do not understand well because that will not solve your problem of maximum power: instantaneous and cumulus could very well start at the same time ... then having a snapshot of this power ...

[dirk pitt]

the cumulus of 50L has a low power because it works over time. it's 1200W

[Christophe]

Yes but you will still be (when a large amount of water is required) at more than 3 + 1.2 = more than 4kW on the 5kW that you did not want to reach ...

So I'm not sure if it's worth getting into trouble compared to an instant of the same power ...

[bamboo]

Hello,

Wouldn't it be more logical to mount the instantaneous water heater downstream of the cumulus?

In this way:
- The cumulus takes cold water and heats it during off-peak hours (at night).
- The instantaneous water heater only heats cold water if the cumulus does not have enough hot water. Thus, the instantaneous water heater (which only works during the day, a priori, and therefore at full hour) will only start up in the event that the cumulus cloud is in "harbor".

Note, Christophe, that the 2 should not start at the same time. One is more intended to operate during the day, and the other at night.

Did I miss a hiccup?

A+

[chatelot16]

to make the compromise between snapshot of too high power, and cumulus of 200l taking up too much space, it is possible to mount in a 50litre a more powerful resistance than of origin ... thus even if one consumes the 50l of water already hot it will heat up quickly