ᐅ Underfloor heating on the ground floor and upper floor, radiators in the basement?
Created on: 19 Oct 2015 22:26
A
andimann
Hi everyone,
We are planning to build a single-family house next year with about 170 sqm (1,830 sq ft) and a full basement. The basement will be constructed as a waterproof concrete structure (“WU slab”) with 100 mm (4 inches) perimeter insulation. Heating will be provided by a gas boiler (Vaillant Vitodens 300-W). Underfloor heating will be installed on the ground floor and upper floor, but the question is about the basement.
In the basement there will be an office (just for normal private use and occasionally working from home, so not permanent use), a workshop room, and a large room (40 sqm (430 sq ft)) used for general storage. This might eventually be divided to create a multipurpose room for the kids. So, a pretty normal basement.
I think equipping the basement fully with underfloor heating is excessive given the additional costs charged by several general contractors, with the highest quote being more than 50 euros per sqm (about $50 per sq ft) extra!
My plan is to install regular radiators on the walls in the basement, just one or two sizes larger than normal, and run them at a flow temperature of 35°C (95°F). That’s it. Is there any reason not to do this? It doesn’t need to be exceptionally warm down there—I just want to be able to raise the temperature from about 15°C up to 20-21°C (59-70°F).
One of the contractors keeps trying to push electric heaters on me (because it’s less work for him), but I definitely do not want electric heating. We currently live in a house with a waterproof basement. As the first occupants, we had to keep the basement gently heated to keep it dry, and without continuous low-level heating, the basement would never have dried out. Heating 85 sqm (915 sq ft) electrically for three years straight is not a smart idea in my opinion.
Another contractor says, “No, flow temperatures that low won’t work; you need a completely different heating system with two heating circuits, etc.” My parents’ house was built in 1971, and for 20 years, we hardly ever set the flow temperature above 38°C (100°F)... it worked perfectly and drove the heating technician crazy!
So, has anyone here implemented something similar (underfloor heating on ground and upper floors, and regular radiators in the basement) and can share their experience? Or does anyone have other suggestions? Maybe wall or ceiling heating?
Thanks and best regards,
Andreas
We are planning to build a single-family house next year with about 170 sqm (1,830 sq ft) and a full basement. The basement will be constructed as a waterproof concrete structure (“WU slab”) with 100 mm (4 inches) perimeter insulation. Heating will be provided by a gas boiler (Vaillant Vitodens 300-W). Underfloor heating will be installed on the ground floor and upper floor, but the question is about the basement.
In the basement there will be an office (just for normal private use and occasionally working from home, so not permanent use), a workshop room, and a large room (40 sqm (430 sq ft)) used for general storage. This might eventually be divided to create a multipurpose room for the kids. So, a pretty normal basement.
I think equipping the basement fully with underfloor heating is excessive given the additional costs charged by several general contractors, with the highest quote being more than 50 euros per sqm (about $50 per sq ft) extra!
My plan is to install regular radiators on the walls in the basement, just one or two sizes larger than normal, and run them at a flow temperature of 35°C (95°F). That’s it. Is there any reason not to do this? It doesn’t need to be exceptionally warm down there—I just want to be able to raise the temperature from about 15°C up to 20-21°C (59-70°F).
One of the contractors keeps trying to push electric heaters on me (because it’s less work for him), but I definitely do not want electric heating. We currently live in a house with a waterproof basement. As the first occupants, we had to keep the basement gently heated to keep it dry, and without continuous low-level heating, the basement would never have dried out. Heating 85 sqm (915 sq ft) electrically for three years straight is not a smart idea in my opinion.
Another contractor says, “No, flow temperatures that low won’t work; you need a completely different heating system with two heating circuits, etc.” My parents’ house was built in 1971, and for 20 years, we hardly ever set the flow temperature above 38°C (100°F)... it worked perfectly and drove the heating technician crazy!
So, has anyone here implemented something similar (underfloor heating on ground and upper floors, and regular radiators in the basement) and can share their experience? Or does anyone have other suggestions? Maybe wall or ceiling heating?
Thanks and best regards,
Andreas
Hi everyone,
let’s avoid any arguments, please…
Bauexperte is probably right when recommending more insulation; it doesn’t hurt. The actual additional cost for 120 mm instead of 100 mm (4.7 inches instead of 3.9 inches) should be almost negligible when you look at the material prices. The labor is basically the same since you’re installing either 100 mm or 120 mm boards on the wall. However, tradespeople tend to charge quite heavily for such changes, and the extra effort usually doesn’t justify the higher costs they demand. In other words, they take advantage of the situation…
I also learned the hard way that my negotiating position is much weaker here than in my usual professional environment. Suppliers trying to play those games still get to finish their coffee with me, but then they’re politely shown the door. There’s always someone else ready to do the job. Of course, I’m dealing with significantly different sums of money in those cases.
@Bauexperte: If I understand correctly, you suggest running the heating system at a higher supply temperature (e.g., 50°C (122°F)) and then splitting the output—one part goes as 50°C (122°F) to the radiators in the basement, and the other part is mixed with the return flow down to around 35°C (95°F) for the underfloor heating on the ground and upper floors. Is this the three-way mixing valve you mean?
That would solve the problem quite elegantly and, above all, simply…
Best regards,
Andreas
let’s avoid any arguments, please…
Bauexperte is probably right when recommending more insulation; it doesn’t hurt. The actual additional cost for 120 mm instead of 100 mm (4.7 inches instead of 3.9 inches) should be almost negligible when you look at the material prices. The labor is basically the same since you’re installing either 100 mm or 120 mm boards on the wall. However, tradespeople tend to charge quite heavily for such changes, and the extra effort usually doesn’t justify the higher costs they demand. In other words, they take advantage of the situation…
I also learned the hard way that my negotiating position is much weaker here than in my usual professional environment. Suppliers trying to play those games still get to finish their coffee with me, but then they’re politely shown the door. There’s always someone else ready to do the job. Of course, I’m dealing with significantly different sums of money in those cases.
@Bauexperte: If I understand correctly, you suggest running the heating system at a higher supply temperature (e.g., 50°C (122°F)) and then splitting the output—one part goes as 50°C (122°F) to the radiators in the basement, and the other part is mixed with the return flow down to around 35°C (95°F) for the underfloor heating on the ground and upper floors. Is this the three-way mixing valve you mean?
That would solve the problem quite elegantly and, above all, simply…
Best regards,
Andreas
S
Sebastian7920 Oct 2015 13:04Don’t underestimate this – 20mm (about 0.8 inches) more would have cost us around 500 euros more (and that’s with self-installation, excluding materials from the contractor).
It may not sound like much, but you’d have to compensate for that by saving on heating costs through an extra 100mm (about 4 inches) of insulation – which you probably won’t see happen. For that reason, a critical assessment of some insulation is certainly justified.
It may not sound like much, but you’d have to compensate for that by saving on heating costs through an extra 100mm (about 4 inches) of insulation – which you probably won’t see happen. For that reason, a critical assessment of some insulation is certainly justified.
B
Bauexperte20 Oct 2015 13:40Hello Andreas,
Since I don’t know the correct term for the "mixer" (for me it just has to work), I quickly searched online (information is also available from the popular general suppliers here) and found the following on the topic:
**“Regardless of how the rotary slide of a heating mixing valve is adjusted, there are two types of mixers: the three-way mixing valve and the four-way mixing valve.
In the three-way mixing valve, cooler return water is mixed with the hot water from the boiler. This lowers the temperature in the heating supply line to the desired level. The three-way mixer does not directly affect the boiler return temperature.
In the four-way mixing valve, both the heating supply temperature is lowered, and the boiler return temperature is increased simultaneously. The latter is achieved by mixing hot water from the boiler supply according to the position of the rotary slide. The four-way mixer effectively creates two circuits in the system: the boiler circuit and the heating circuit. However, the fact that the four-way mixer raises the boiler return temperature is unfavorable in condensing boiler systems. Condensing boilers achieve their highest efficiency when the return temperature is below the dew point of the water vapor in the combustion gas (approximately 47°C (117°F) for oil heating, and about 57°C (135°F) for gas heating). This allows a large part of the water vapor in the combustion gas to condense, releasing latent heat that can be used as additional heating energy. When using a four-way mixing valve, the elevated return temperature (depending on the boiler’s load) can sometimes or permanently be above the dew point temperature of the combustion gas. This prevents the condensing effect. For this reason, a three-way mixing valve should be used when operating a condensing boiler."
Source: SBZ Monteur SHK Magazine
HTH
Regards, Bauexperte
andimann schrieb:I am an ambitious salesperson, not a heating specialist.
@Bauexperte: If I understand correctly, you suggest running the heating system with a higher supply temperature (e.g., 50°C (122°F)) and then splitting the output – part goes as 50°C (122°F) to the radiators in the basement, and the other part is mixed down with the return flow to, say, 35°C (95°F) for the underfloor heating on the ground and upper floors. Is this what you mean by the three-way mixing valve?
That would solve the problem quite elegantly and, above all, simply...
Since I don’t know the correct term for the "mixer" (for me it just has to work), I quickly searched online (information is also available from the popular general suppliers here) and found the following on the topic:
**“Regardless of how the rotary slide of a heating mixing valve is adjusted, there are two types of mixers: the three-way mixing valve and the four-way mixing valve.
In the three-way mixing valve, cooler return water is mixed with the hot water from the boiler. This lowers the temperature in the heating supply line to the desired level. The three-way mixer does not directly affect the boiler return temperature.
In the four-way mixing valve, both the heating supply temperature is lowered, and the boiler return temperature is increased simultaneously. The latter is achieved by mixing hot water from the boiler supply according to the position of the rotary slide. The four-way mixer effectively creates two circuits in the system: the boiler circuit and the heating circuit. However, the fact that the four-way mixer raises the boiler return temperature is unfavorable in condensing boiler systems. Condensing boilers achieve their highest efficiency when the return temperature is below the dew point of the water vapor in the combustion gas (approximately 47°C (117°F) for oil heating, and about 57°C (135°F) for gas heating). This allows a large part of the water vapor in the combustion gas to condense, releasing latent heat that can be used as additional heating energy. When using a four-way mixing valve, the elevated return temperature (depending on the boiler’s load) can sometimes or permanently be above the dew point temperature of the combustion gas. This prevents the condensing effect. For this reason, a three-way mixing valve should be used when operating a condensing boiler."
Source: SBZ Monteur SHK Magazine
HTH
Regards, Bauexperte
Wow, you’re right, increasing from 100 to 120 millimeters (4 to 5 inches) is indeed a significant jump—I hadn’t even noticed that before. Thanks for pointing it out! For over 100 square meters (1,076 square feet) of wall insulation, that adds up to about 400 euros. *Wow* The contractors will probably charge around 1,500 euros for it.
I think you really need to look at the building physics in detail—what wall thicknesses are used, which materials, where the dew points are located, temperature gradients, and so on—to decide what makes sense.
You probably won’t recoup the 400 euros financially. But, then again, cost-effectiveness isn’t really the main goal in house building...
Best regards,
Andreas
I think you really need to look at the building physics in detail—what wall thicknesses are used, which materials, where the dew points are located, temperature gradients, and so on—to decide what makes sense.
You probably won’t recoup the 400 euros financially. But, then again, cost-effectiveness isn’t really the main goal in house building...
Best regards,
Andreas
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