ᐅ Heat pump is not compatible with a hydronic (water-heated) fireplace.
Created on: 20 Oct 2023 18:54
J
Jessica388
Hello everyone,
I hope someone here can help us because our heating engineer doesn’t seem to be able to…
Key data
New build 2022 with 250 m² (2,691 ft²)
Heat pump Viessmann Vitocal 200-A
Multifunction storage tank MFS1000S
Water-heated stove with heating capacity on the water side of 8 kW
Photovoltaic system
Electric heating element
I am attaching the schematic of the storage tank layout.
The stove was initially connected under “old” and now it has been modified.
Everything works fine as long as the underfloor heating is off.
When the underfloor heating is on, our hot water temperature doesn’t exceed about 55°C (131°F).
When the underfloor heating is off, the temperature ranges between 65–75°C (149–167°F), either via the electric heating element during sunshine or by stoking the stove.
Now, however, this energy seems to be wasted. It can’t be that the underfloor heating requires 70°C (158°F) supply temperature to achieve a flow temperature of 35°C (95°F), right? The return water is only slightly cooler. So the water should only need to be heated by a maximum of 5°C (9°F).
We assume either a) something is still connected incorrectly, or b) the cold water from the underfloor heating causes such circulation that the hot water cools down within minutes.
What can be done about this?
Has anyone experienced similar problems?
Normally, we should almost run without electric power, but currently the heat pump switches on almost every hour to heat hot water…
I hope someone here can help us because our heating engineer doesn’t seem to be able to…
Key data
New build 2022 with 250 m² (2,691 ft²)
Heat pump Viessmann Vitocal 200-A
Multifunction storage tank MFS1000S
Water-heated stove with heating capacity on the water side of 8 kW
Photovoltaic system
Electric heating element
I am attaching the schematic of the storage tank layout.
The stove was initially connected under “old” and now it has been modified.
Everything works fine as long as the underfloor heating is off.
When the underfloor heating is on, our hot water temperature doesn’t exceed about 55°C (131°F).
When the underfloor heating is off, the temperature ranges between 65–75°C (149–167°F), either via the electric heating element during sunshine or by stoking the stove.
Now, however, this energy seems to be wasted. It can’t be that the underfloor heating requires 70°C (158°F) supply temperature to achieve a flow temperature of 35°C (95°F), right? The return water is only slightly cooler. So the water should only need to be heated by a maximum of 5°C (9°F).
We assume either a) something is still connected incorrectly, or b) the cold water from the underfloor heating causes such circulation that the hot water cools down within minutes.
What can be done about this?
Has anyone experienced similar problems?
Normally, we should almost run without electric power, but currently the heat pump switches on almost every hour to heat hot water…
Jessica388 schrieb:
So in summer, it heats the water up to 75°C (167°F) and we don’t need any electricity.But do you really need the water at 75°C (167°F)? I’d rather take the 8 cents. 😀
K
KarstenausNRW21 Oct 2023 11:40Buchsbaum schrieb:
In plain terms, neither your heat pump nor your photovoltaic electric heating element can significantly heat your domestic hot water.No, but the optional electric heating element with up to 27kW (36 horsepower) does heat the buffer tank quite effectively. You could definitely call 27kW a significant amount... And therefore, the domestic hot water is indirectly heated as well, since it is warmed via the heat exchangers in the buffer tank.
What I find much more interesting is the question of how the hydraulic integration has actually been done. Something like this, for example?
R
RotorMotor21 Oct 2023 12:02Buchsbaum schrieb:
Again. Please read my post from page 1 and review the technical data of your buffer tank. It should then be self-explanatory. So self-explanatory, yet once again you didn’t understand anything.
Buchsbaum schrieb:
It’s in there. Domestic hot water heating is done using the instantaneous water heater principle. You barely have any hot water storage inside your buffer tank. Have you ever heard of a fresh water station/storage system?
A great solution—if you understand it.
Buchsbaum schrieb:
In plain terms, this means neither your heat pump nor your photovoltaic heating element can significantly heat your domestic hot water. At this point, the misinformation is so wrong it’s painful.
Can’t you find a forum where topics are discussed that you at least somewhat understand?
With subjects like: What are the favorite topics of a parking meter? Or should I react to a sack of rice falling in China?
J
Jessica38821 Oct 2023 12:26KarstenausNRW schrieb:
No, but the optional heating element with up to 27kW (36 hp) does heat the buffer tank quite well. The 27kW (36 hp) can definitely be considered significant...
And indirectly, the domestic hot water is heated as well, since it is warmed by the heat exchangers inside the buffer tank.
I find the question more interesting how the hydraulic integration was actually done. For example like this? 
Take a look. This is what we received and I have now added to it. The stove currently has 4 connections, so we can choose. At the moment, it is set to "new."
J
Jessica38821 Oct 2023 12:29kati1337 schrieb:
But you need the water at 75 degrees Celsius (167°F)?
I’d rather go with the 8 cents. 😀That’s enough to last through the whole night until morning, then new energy arrives.J
Jessica38821 Oct 2023 12:30RotorMotor schrieb:
That’s just the household electricity consumption.
Or where do you see what the heat pump is using here?
The heat pump keeps having peaks, which is also called short cycling.
It can’t get rid of the heat because you have 90% of the rooms basically with the handbrake on.
Turn the heating curve down to 0.4 and open the room thermostats, then let’s check again in a month. ;-) I’ve done that now, according to your instructions. I’m curious.
Thanks in advance!!!
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