ᐅ Lowering the Supply Temperature in Underfloor Heating Systems More Complex Than Expected?
Created on: 9 Mar 2023 22:07
J
JohnnyEH
Hello everyone!
We are currently discussing the supply temperature for the underfloor heating system with our prefab house provider.
The house is a timber frame panel construction and meets the KFW40 standard.
According to the construction description, the provider sets the supply temperature of the underfloor heating to 35°C (95°F). We mentioned that we consider this outdated for a new build and would prefer a supply temperature of around 30°C (86°F). We were then told that with a supply temperature of 30°C (86°F), a larger heat pump and a completely different heating system design would be required, and the additional costs could quickly reach five figures. Such extra costs obviously would not make financial sense.
Until now, I thought the supply temperature was primarily determined by the pipe spacing and would be lower if the pipe spacing was reduced.
Why could a lower supply temperature lead to a larger heat pump? What am I missing?
I should add that the heating load calculation and the exact determination of the heat pump have yet to be done. In any case, a Vaillant Arotherm Plus will be used.
Additionally, a question about the floor covering.
We know that tiles are optimal for underfloor heating but vinyl is almost equivalent. We will also have an active underfloor cooling system installed (via the air-to-water heat pump). Does either floor covering—tiles or vinyl—have advantages for cooling? Or would laminate flooring actually be the best option for cooling?
We are currently discussing the supply temperature for the underfloor heating system with our prefab house provider.
The house is a timber frame panel construction and meets the KFW40 standard.
According to the construction description, the provider sets the supply temperature of the underfloor heating to 35°C (95°F). We mentioned that we consider this outdated for a new build and would prefer a supply temperature of around 30°C (86°F). We were then told that with a supply temperature of 30°C (86°F), a larger heat pump and a completely different heating system design would be required, and the additional costs could quickly reach five figures. Such extra costs obviously would not make financial sense.
Until now, I thought the supply temperature was primarily determined by the pipe spacing and would be lower if the pipe spacing was reduced.
Why could a lower supply temperature lead to a larger heat pump? What am I missing?
I should add that the heating load calculation and the exact determination of the heat pump have yet to be done. In any case, a Vaillant Arotherm Plus will be used.
Additionally, a question about the floor covering.
We know that tiles are optimal for underfloor heating but vinyl is almost equivalent. We will also have an active underfloor cooling system installed (via the air-to-water heat pump). Does either floor covering—tiles or vinyl—have advantages for cooling? Or would laminate flooring actually be the best option for cooling?
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RotorMotor13 Mar 2023 13:53neo-sciliar schrieb:
As far as I’m concerned... it’s not my money. I have an annual heating demand of 8500 kWh at a design outdoor temperature of -11°C (12°F).
@JohnnyEH I’ll repeat myself, I wouldn’t spend a single cent just because a data sheet shows a lower flow temperature. I also believe it’s very important that this doesn’t happen just on paper.
As long as some basic rules are followed, like avoiding heating circuits that are too long or too short, keeping pipe spacing below 10/15cm (4/6 inches), preferably 5cm (2 inches) in bathrooms, and ideally also installing pipes in walls.
Otherwise, the hydraulic design often becomes a real disaster.
neo-sciliar schrieb:
I would invest the money in getting cheap electricity. One thing has absolutely nothing to do with the other.
Hydraulics last a very, very long time, so I wouldn’t cut corners in the wrong place!
S
stjoob_at15 Mar 2023 15:22Definitely install a wall heating system in a bathroom with two exterior walls. The heat emission surface area takes priority over the pipe spacing.
Trying to maintain 24°C (75°F) in the bathroom and 20°C (68°F) in the other rooms will be difficult because rooms in a new building tend to equalize temperatures more due to the much lower U-value of the exterior components compared to the interior walls.
Avoid large differences in heating circuit lengths, and connect the heating manifold with a sufficiently large supply pipe (at least DN30). The larger supply pipe also reduces pressure loss.
If you can lower the supply temperature by 5 K (9°F), you can improve the heat pump’s efficiency by about 10%.
Trying to maintain 24°C (75°F) in the bathroom and 20°C (68°F) in the other rooms will be difficult because rooms in a new building tend to equalize temperatures more due to the much lower U-value of the exterior components compared to the interior walls.
Avoid large differences in heating circuit lengths, and connect the heating manifold with a sufficiently large supply pipe (at least DN30). The larger supply pipe also reduces pressure loss.
If you can lower the supply temperature by 5 K (9°F), you can improve the heat pump’s efficiency by about 10%.
B
Benutzer 100116 Mar 2023 07:02JohnnyEH schrieb:
Installing wall heating in the bathroom will be difficult – I’m afraid the general contractor might not agree, but I will definitely bring it up.
Once we have the detailed plans for the underfloor heating in our house, I will definitely get back to you again 🙂 If that’s not possible, although I wonder why it shouldn’t be, you could simply get a stylish fan heater to use sometimes when bathing the kids. For adults, 22°C (72°F) is sufficient.
That’s correct, I have just over 22 degrees Celsius (72°F); if you have a good and even flow, that is absolutely sufficient. The temperature rises naturally through showering, blow-drying, etc. Designing everything based on 24 degrees Celsius (75°F) room temperature in the bathroom is very costly.
Offtopic schrieb:
If it doesn’t work, although I wonder why it wouldn’t. Just get a stylish fan heater and use it sometimes when the kids are bathing. As an adult, 22°C (72°F) is enough.A fan heater (1800W) is included for us – though I’m not sure if it’s stylish yet 😉. An electric (towel) radiator doesn’t make sense from an energy perspective, does it?
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