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…
Buchsbaum schrieb:
Well, I still expect to be able to set different temperatures in each room with any heating system. Who wants the same temperature in the bedroom as in the bathroom? This is only possible to a limited extent and within certain boundaries. Not efficient at all.
Basically, the underfloor heating circulates water at the same temperature in every room. You only control the flow rate in the manifold and the electronic radiator regulators (ERRs) determine when the heating circuit is closed. It’s not like you can have 24 degrees or 20 degrees to a tenth of a degree. If you want 24°C (75°F) in the house, water at about 37°C (99°F) is circulated under the floor everywhere. That water must be heated to 37°C (99°F), which takes a long time in winter when it’s 0°C (32°F) outside. The colder it is outside, the longer it takes. That’s why a low indoor temperature is more efficient, as the heat pump doesn’t have to work as long.
R
Radfahrer25 Oct 2023 12:39Buchsbaum schrieb:
The client who is building a new house often doesn’t even know the difference between convection and radiant heat. They come from an apartment with radiators and then have to realize how different underfloor heating feels. I think this is the real issue. People tend to rely on someone—usually the architect in this case—without informing themselves beforehand.
Buchsbaum schrieb:
But not everyone likes it. Personally, I don’t either. I always have warm feet, and I don’t like that constant heat from below. It is said that underfloor heating can promote the development of varicose veins and similar issues. So, from a health perspective, underfloor heating is not always an advantage. It’s good that people have different preferences. I like that I have the same temperature at 2 cm (1 inch) height as at 170 cm (67 inches) and even at 380 cm (150 inches). Does that mean I’ll get laughable varicose veins?
R
Radfahrer25 Oct 2023 12:43Zaba123 schrieb:
This only works to a limited extent and within certain boundaries. It’s definitely not efficient. Basically, the same tempered water circulates through the underfloor heating in every room. You only control the amount of flow in the heating circuit manifold and, with the electronic radiator regulators (ERRs), when the heating circuit is closed. It’s not like you can set precisely 24 degrees or 20 degrees to the decimal. If you want 24°C (75°F) in the house, then 37°C (99°F) water has to run through the floor everywhere. The water must be heated to 37°C (99°F), which takes longer in winter when it’s 0°C (32°F) outside. The colder it is outside, the longer it takes. Therefore, a low indoor temperature is more efficient because the heat pump doesn’t have to work as long. In that case, you should get a heat pump—that makes it possible.
Radfahrer schrieb:
Then you should get a heat pump, that will do the job. I have a heat pump 🙂 The target return temperature is 25.5°C (78°F), but the heat pump has to raise the water temperature to 33°C (91°F) until, with a temperature difference of 2°C (3.6°F) to the actual return temperature, the heat pump switches off and the screed maintains the room at 21.5°C (71°F).
The target return temperature is not the maximum water temperature, but rather the maximum temperature of the screed that keeps the room at 21.5°C (71°F).
R
Radfahrer25 Oct 2023 13:08Zaba123 schrieb:
I have a heat pump 🙂 The target return temperature is 25.5°C (78°F), but the heat pump has to heat the water to 33°C (91°F) until, with a temperature difference of 2°C (4°F), the heat pump switches off and the screed maintains the room at 21.5°C (71°F).OK, that’s just how it works when you first warm water with losses and then pump it through the screed. It also works without the water, and then the heat pump only heats the areas in the room where it’s needed.
K
KarstenausNRW25 Oct 2023 13:18Not everyone likes it. Personally, I don’t either. I always have warm feet, and I don’t like that constant heat from below.
It’s also said to promote the development of varicose veins and similar issues.
Yep. Supposedly it promotes varicose veins. I’ve also heard that the Earth is flat. Medically, that myth is just as debunked as the flat Earth theory has been settled. That’s just pub talk.
And the constant heat is nonsense too. At least in new buildings. Currently, the heat pump (with 6-8 degrees Celsius (43-46°F) at night and 13-14 degrees Celsius (55-57°F) during the day) runs at about 26-28 degrees Celsius (79-82°F) in the new building (with a 5K temperature difference). That should result in a floor temperature of around 22-23 degrees Celsius (72-73°F) at a room temperature of about 21-22 degrees Celsius (70-72°F).
I measured it myself. Depending on the room, the floor temperature is just 22-22.5 degrees Celsius (72-73°F). That doesn’t feel warm at all. It won’t be much different in the deep winter.
P.S. The relatively high flow temperature (!) is due to the fact that above my entire apartment (duplex house), there is an unheated floor. I obviously heat that indirectly from my apartment. Upstairs it’s only 17.5-18 degrees Celsius (63-64°F).
If that happens in winter, you either live high up in the mountains or a nail stylist planned your heating system ;.)
It’s also said to promote the development of varicose veins and similar issues.
Yep. Supposedly it promotes varicose veins. I’ve also heard that the Earth is flat. Medically, that myth is just as debunked as the flat Earth theory has been settled. That’s just pub talk.
And the constant heat is nonsense too. At least in new buildings. Currently, the heat pump (with 6-8 degrees Celsius (43-46°F) at night and 13-14 degrees Celsius (55-57°F) during the day) runs at about 26-28 degrees Celsius (79-82°F) in the new building (with a 5K temperature difference). That should result in a floor temperature of around 22-23 degrees Celsius (72-73°F) at a room temperature of about 21-22 degrees Celsius (70-72°F).
I measured it myself. Depending on the room, the floor temperature is just 22-22.5 degrees Celsius (72-73°F). That doesn’t feel warm at all. It won’t be much different in the deep winter.
P.S. The relatively high flow temperature (!) is due to the fact that above my entire apartment (duplex house), there is an unheated floor. I obviously heat that indirectly from my apartment. Upstairs it’s only 17.5-18 degrees Celsius (63-64°F).
Zaba123 schrieb:
If you want 24 degrees Celsius (75°F) in the house, there’s 37 degrees Celsius (99°F) warm water running through the floor everywhere.
If that happens in winter, you either live high up in the mountains or a nail stylist planned your heating system ;.)
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