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…
J
Jessica38821 Oct 2023 10:56RotorMotor schrieb:
Ah, yes, one more thing: is there a domestic hot water circulation system installed and running?I don’t know. How can I find out?W
WilderSueden21 Oct 2023 11:03Jessica388 schrieb:
No, it is set to 54 degrees Celsius (129°F). The high value comes from the heating element on sunny days, and from the stove on cloudy days. Why do you need the heating element if you have a heat pump? The heating element is used in extremely cold temperatures or if the heat pump is not working properly. Otherwise, it can be disabled.
J
Jessica38821 Oct 2023 11:16WilderSueden schrieb:
Why do you need the heating element if you have a heat pump? The heating element is used in extremely cold temperatures, like in Siberia, or if the heat pump itself is experiencing issues. Otherwise, it can be turned off.We only had the heating element installed three weeks ago. It converts the excess energy from the photovoltaic system into hot water…R
RotorMotor21 Oct 2023 11:23Circulation: Does hot water reach your faucet or shower quickly, or do you have to wait a bit? If it’s the latter, check your contract or ask your heating technician! Circulation means that hot water is continuously circulated through the system, but it naturally cools down and then needs to be reheated accordingly.
Heating element:
Your heat pump has one integrated, so you wouldn’t have needed to buy one separately. Moreover, even on sunny days, it’s more efficient to produce hot water with the heat pump than with a heating element. Was this the same heating technician who gave you questionable advice about the rest?
If you say the heating element is off, are you only referring to the newly installed one?
It’s essential to check whether it is only activated in the heat pump during severe freezing temperatures!
Heating element:
Your heat pump has one integrated, so you wouldn’t have needed to buy one separately. Moreover, even on sunny days, it’s more efficient to produce hot water with the heat pump than with a heating element. Was this the same heating technician who gave you questionable advice about the rest?
If you say the heating element is off, are you only referring to the newly installed one?
It’s essential to check whether it is only activated in the heat pump during severe freezing temperatures!
J
Jessica38821 Oct 2023 11:28RotorMotor schrieb:
Circulation: Does hot water come quickly at the tap/shower, or do you have to wait a bit? Otherwise, check the offer or ask the plumber!
Circulation means that the hot water is constantly pumped in a loop and naturally cools down, so it has to be reheated accordingly.
Heating element:
Your heat pump has one integrated. So you wouldn’t have needed to buy one separately.
And it’s also more efficient to produce hot water with the heat pump even when the sun is shining than using a heating element.
Did the same plumber who messed up the rest talk you into this?
When you say the heating element is off, do you always mean the newly installed one?
You should urgently check whether the one in the heat pump only activates at very low temperatures below freezing! Hot water comes almost immediately, so yes, we do have circulation; I think it’s just switched off at night, as far as I remember.
The integrated heating element was switched off last winter, so it only turns on during severe subzero conditions.
The new heating element was sold to us by the electricians, claiming the built-in one wouldn’t work together with the photovoltaic system.
It only switches on if there is surplus electricity that would otherwise be sold. And selling electricity brings almost no benefit, while buying electricity is more expensive. That’s the idea behind it. This way, it heats the water up to 75°C (167°F) in summer, and we don’t need to buy electricity.
B
Buchsbaum21 Oct 2023 11:29Once again, please read my post from page 1 and review the technical specifications of your buffer tank. It should then be self-explanatory.
You will find that the domestic hot water is heated using an instantaneous heater system. Your buffer tank contains almost no storage for hot water.
In simple terms, this means that neither your heat pump nor your photovoltaic heating element can significantly heat your domestic hot water.
And water heated to only 40 or 45 degrees Celsius (104 or 113 degrees Fahrenheit) is definitely not recommended. It also doesn’t make sense.
You will find that the domestic hot water is heated using an instantaneous heater system. Your buffer tank contains almost no storage for hot water.
In simple terms, this means that neither your heat pump nor your photovoltaic heating element can significantly heat your domestic hot water.
And water heated to only 40 or 45 degrees Celsius (104 or 113 degrees Fahrenheit) is definitely not recommended. It also doesn’t make sense.
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