ᐅ Question about Heat Demand Calculation and Supply Temperature
Created on: 16 May 2016 17:56
T
tecker2010
Hi,
We’re about to start building soon, and regarding the underfloor heating and flow temperature, I received a suggestion from an expert and wanted to get your opinions here.
Brief summary of the house: a 152 sqm (1,637 sq ft) city villa with underfloor heating, 30cm (12 inches) Ytong exterior walls, 3 solar collectors, and heating via a gas boiler.
The expert recommended installing the underfloor heating with closer pipe spacing throughout the entire house so it can operate at lower flow temperatures (35°C (95°F) instead of 40°C (104°F)). There are initially higher costs for the extra work and materials, but it saves money in the long run because the gas boiler doesn’t need to reach as high a temperature and therefore uses less energy. The investment is expected to pay off after a few years. Additionally, this approach keeps options open for switching later to an alternative heating system (heat pump, etc.) since these usually cannot deliver the 40°C (104°F) flow temperature required, and it’s uncertain which cost-effective alternatives to gas will be available in the future.
As a layperson, this sounded reasonable to me at first. What do you think?
Regards
We’re about to start building soon, and regarding the underfloor heating and flow temperature, I received a suggestion from an expert and wanted to get your opinions here.
Brief summary of the house: a 152 sqm (1,637 sq ft) city villa with underfloor heating, 30cm (12 inches) Ytong exterior walls, 3 solar collectors, and heating via a gas boiler.
The expert recommended installing the underfloor heating with closer pipe spacing throughout the entire house so it can operate at lower flow temperatures (35°C (95°F) instead of 40°C (104°F)). There are initially higher costs for the extra work and materials, but it saves money in the long run because the gas boiler doesn’t need to reach as high a temperature and therefore uses less energy. The investment is expected to pay off after a few years. Additionally, this approach keeps options open for switching later to an alternative heating system (heat pump, etc.) since these usually cannot deliver the 40°C (104°F) flow temperature required, and it’s uncertain which cost-effective alternatives to gas will be available in the future.
As a layperson, this sounded reasonable to me at first. What do you think?
Regards
P
Peanuts7420 Jun 2016 10:26Sebastian79 schrieb:
I find the pipe length quite high for such a small area – we spaced ours between 10-15cm (4-6 inches) depending on the room and installed just under 1300 meters (about 4265 feet) with 22 or 23 heating circuits for around 240m² (2583 sq ft) of heated floor area...Oh dear, then we probably overdid it quite a bit with around 10 meters (33 feet) of pipe per square meter of heated floor area on average. Overall, we have just under 160m² (1722 sq ft) of heated floor area and installed almost three 600m (1969 feet) rolls. In the bathroom, however, there are also 2 circuits laid with almost zero spacing; otherwise, about 7.5cm (3 inches) spacing.
With an outdoor temperature of 0°C (32°F), our supply temperature is about 28°C (82°F), and the living room maintains a comfortable 24°C (75°F)...
@krussi
That would roughly match the 10 meters (33 feet) per 1m² (11 sq ft) of living area.
S
Sebastian7920 Jun 2016 10:28I don’t find 24 degrees comfortable anymore, so 😉
I also think a 7.5cm (3 inch) laying gap is completely exaggerated. But if you like it, that’s fine 🙂.
I also think a 7.5cm (3 inch) laying gap is completely exaggerated. But if you like it, that’s fine 🙂.
P
Peanuts7420 Jun 2016 10:54Oh, the pipe was already there and paid for, so we installed it. Supposedly, it can’t have any negative effects as long as the loops don’t become too large.
In general, however, the heating coils should be installed close enough together so that the house can still be heated later with a different heating system. Designing the spacing based on needing a 40°C (104°F) supply temperature with the current gas system doesn’t seem very practical or forward-thinking to me...
In general, however, the heating coils should be installed close enough together so that the house can still be heated later with a different heating system. Designing the spacing based on needing a 40°C (104°F) supply temperature with the current gas system doesn’t seem very practical or forward-thinking to me...
S
Sebastian7920 Jun 2016 10:56No, not for me either – but for that, you don't need such small spacing. With a heat pump, we calculated 20cm (8 inches) spacing in most rooms.
However, we installed 15cm (6 inches) and less in the bathrooms.
However, we installed 15cm (6 inches) and less in the bathrooms.
E
ErikErdgas24 Jun 2016 10:46Hello krussi,
The installation spacing depends not only on the system parameters but also, for example, on the type of floor covering and the resulting heat transfer. It behaves differently if you have installed carpet or tiles.
As with any planning, it is important to ensure the overall consistency of the concept—that is, the coordination between the heat generator and the heat distribution. Just a quick note so you always keep this in mind when consulting with your designer.
Best regards, Erik from moderne.heizung
The installation spacing depends not only on the system parameters but also, for example, on the type of floor covering and the resulting heat transfer. It behaves differently if you have installed carpet or tiles.
As with any planning, it is important to ensure the overall consistency of the concept—that is, the coordination between the heat generator and the heat distribution. Just a quick note so you always keep this in mind when consulting with your designer.
Best regards, Erik from moderne.heizung
Thank you for your many contributions. My wife got in touch with the supplier of the heating system and the materials, who also handles the calculations, and had a very informative conversation where all questions were answered.
We are sticking to the installation spacing of 10-15 cm (4-6 inches), and only in the hallway will it be 15-20 cm (6-8 inches).
This was all finalized the day before yesterday, and today the screed is being poured. I’m quite curious to see how it turns out.
We are sticking to the installation spacing of 10-15 cm (4-6 inches), and only in the hallway will it be 15-20 cm (6-8 inches).
This was all finalized the day before yesterday, and today the screed is being poured. I’m quite curious to see how it turns out.
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