Using the Grohe Smart control causes the hot water to run out quickly?

[YudNun]

My plumber have installed the Grohe Grohtherm Smart Control system in my shower (actually, 2 systems in 2 showers).
After ruling out other possibilities, I came to the conclusion that using this system causes the hot water in the water tank to run out too quickly (the hot water runs out after 1-2 showers, instead of 4-5). Very wiered.

Has anyone encountered this phenomenon? What could be the cause of it?

 

[Gasmk1]

I would say you are probably using it more and not setting it right if it was ok before. Also your shower heads are possibly bigger than before, I would say read the instructions fully and test it out

 

[YudNun]

No. I did my checks right.

 

[Ben-gee]

You need to tell us what hot water system you’ve got and what other outlets.

When you say ‘after ruling out other possibilities’ - what do you mean and how have you ruled them out?

Bit more info and we’ll be able to help.

 

[YudNun]

Ok.
I have a 150 liter water tank, which is heated solar (And when there is no sun, by an electronic heater). This is a common solar system in the building. The solar panels are on the roof, and the water tank is 5 feet from my shower.
But I do not think the source of the problem is related to this solar system, because the problem also occurs when using water heated by the electric heater.
But I do not think the source of the problem is related to this solar system, because the problem also occurs when using water heated by the electric heater.
I started the elimination, by filling buckets of hot water with other faucet in the house. I counted 110 liters of hot water suitable for a hot shower (for men, not women ...). This means that there is no problem with the water heating system and the transmission of the water in the pipes to the faucet.
Another day (when I know there is a hot-water tank like last time), I started filling buckets with the water faucet coming out of the SmarControl system. Here too I took out about 110 liters of hot water.
I thought, maybe the problem is that the water runs out for the second (or third) person taking a shower, related to the fact that there is a time gap between the two showers. So I did a test another day: I took out from the SmarControl in the shower 40 liters of hot water, and took a break. I waited 15 minutes and then continued to take out hot water. But I find no problem because I took out another 70 liters of hot water.
It is important to note that when we shower while there is still sun in the sky (i.e. there is circulation of the water coming from the solar panels), the hot water lasts longer.

So I can't understand what can be the cause to the problem, that when I or anybody else take shower, the hot water is running out after one or two showers.

Also, my plumber installed two similar Groa SmartControl systems, in my two showers, so it is unlikely that this is a problem in the system itself.

 

[YudNun]

You need to tell us what hot water system you’ve got and what other outlets.

When you say ‘after ruling out other possibilities’ - what do you mean and how have you ruled them out?

Bit more info and we’ll be able to help.

BTW, my plumber has uploaded a video showing the entire installation process of the Grohe SmartControl system.

 

[Ben-gee]

There you go, you need a bigger hot water cylinder.
I can’t find the specifications but that type of system easily delivers say 18 litres per minute on the overhead if you have decent pressure. Assuming hot is stored at 60 deg centigrade , a 5 minute shower will use approx 50 litres of hot - hence your hot water runs out after two showers.

We have four people to shower each morning and a 210 litre unvented cylinder at 60 degrees does this.

You need at least 250 litres for heat you require. I would suggest a 300litre cylinder, depending on reheat times with your system.

Or encourage everyone to have quicker showers.

 

[YudNun]

There you go, you need a bigger hot water cylinder.
I can’t find the specifications but that type of system easily delivers say 18 litres per minute on the overhead if you have decent pressure. Assuming hot is stored at 60 deg centigrade , a 5 minute shower will use approx 50 litres of hot - hence your hot water runs out after two showers.

We have four people to shower each morning and a 210 litre unvented cylinder at 60 degrees does this.

You need at least 250 litres for heat you require. I would suggest a 300litre cylinder, depending on reheat times with your system.

Or encourage everyone to have quicker showers.

Thank you for your reply.
You may be right. I've just got the answer from Grohe, saying "With both the rain shower and a shower head running at the same time you will be using 5 gallons of water per minute".
So it is about 20 liters per minute.
I didn't notice that this system uses double amount of water.

 

[YudNun]

I did the test. Using both streams in the head, flow 10 liters in 37 seconds. That means a little over 16 liters per minute.

 

[ShaunCorbs]

In around 8 -10 mins you’ve run out of hot water