ᐅ Is the electricity consumption and procedure for screed drying typical?
Created on: 21 May 2025 11:59
M
medow1982
Hi everyone,
I’m building with solid construction, and according to the site manager, a construction dryer is needed for the screed drying. So, for the past week, a 15 kW (kilowatt) heater has been running continuously, heating about 270 sqm (2,900 sq ft) at a supply temperature of 35°C (95°F). According to the protocol, you should start at 25°C (77°F), but nobody seems to care.
There is dripping from the walls, and the windows are always wet, like in a sauna.
Will this get better? At some point, all the moisture has to come out, right?
I ventilate twice a day, sometimes even three times, and always remove visible drops.
At 35°C (95°F), the energy consumption is 200 kWh per day. I calculated that over the planned 3 weeks, this will be over 4,000 kWh.
Does this sound about right, or could there be something wrong with the heater?
Moisture is also coming down from above through the precast ceilings—is this normal?
Unfortunately, my site manager is not very proactive, so I’m looking for advice here.
Best regards,
Felix
I’m building with solid construction, and according to the site manager, a construction dryer is needed for the screed drying. So, for the past week, a 15 kW (kilowatt) heater has been running continuously, heating about 270 sqm (2,900 sq ft) at a supply temperature of 35°C (95°F). According to the protocol, you should start at 25°C (77°F), but nobody seems to care.
There is dripping from the walls, and the windows are always wet, like in a sauna.
Will this get better? At some point, all the moisture has to come out, right?
I ventilate twice a day, sometimes even three times, and always remove visible drops.
At 35°C (95°F), the energy consumption is 200 kWh per day. I calculated that over the planned 3 weeks, this will be over 4,000 kWh.
Does this sound about right, or could there be something wrong with the heater?
Moisture is also coming down from above through the precast ceilings—is this normal?
Unfortunately, my site manager is not very proactive, so I’m looking for advice here.
Best regards,
Felix
G
Gerddieter23 May 2025 10:33Tolentino schrieb:
Why is he using a heating device instead of the intended heating system? Is it not installed yet? Why? The heating technician explained it to me and gave me the choice:
Screed heating device = higher electricity consumption
Heat pump = brand-new pump is stressed near its limits over a period of 3-4 weeks using the screed drying program, and it is actually not designed for that. He believes this significantly shortens the lifespan of the pump.
Gerddieter
N
nordanney23 May 2025 10:41Gerddieter schrieb:
Heat pump = brand-new pump is stressed at the limit over a period of 3-4 weeks using a screed program and is actually not designed for this. He believes that this significantly shortens the pump’s lifespan. Yes and no. If you strictly follow the heating protocol and end up heating for a long time at 45-50 degrees Celsius (113-122°F), you definitely put considerable strain on the heat pump.
But these temperatures and protocols date back to when gas heating systems needed such flow temperatures during severe winter conditions. Since nowadays you supply maximum 30 degrees Celsius (86°F) to the underfloor heating, 35 degrees Celsius (95°F) is sufficient for functional heating. The aim is to test the screed to withstand the maximum possible flow temperature—which with a heat pump is no longer 45-50 degrees Celsius (113-122°F).
A
Aloha_Lars23 May 2025 11:08Tolentino schrieb:
With monoblock, it could be done differently. Not every heating system is as tricky as mine
Or the base for the interior is poured beforehand.That’s exactly how it was done for me. Right from the start, a base was poured, then the monoblock was installed on top, and that was used to heat the screed :-)
Normally, this is done using a special screed drying program and not kept permanently at 35°C (95°F). That’s probably better for the stresses in the screed, but I’m not an expert. However, it will definitely dry that way. Just watch out for any cracks and report them immediately.
Having a sauna-like environment for several weeks is quite normal. The best thing to do is to ventilate thoroughly once the air is saturated (around 99% humidity). We did this three times a day (before work, after work, and again before going to bed). For our windows, we used a window vacuum cleaner, and for windowsills and similar areas, old towels. It’s important to hang everything outside to dry, otherwise the moisture will end up back inside the house.
We heated for a total of 4 weeks and then ventilated for another 4 weeks without heating. After that, the house was dry enough to lay the floor and move in.
We also had a portable heater back then because we had issues with delivery times for our heat pump. We got the electricity meter just before drying the screed, and when we moved in it showed just under 3500 kWh for 140 m² (1,507 sq ft) of living space. You should expect around 6,000–7,000 kWh until moving in for your house size. I recommend signing up for a cheaper electricity tariff through the usual comparison platforms to save a good amount. It will still cost around €2,000. With a large house like yours, these costs are normal.
Having a sauna-like environment for several weeks is quite normal. The best thing to do is to ventilate thoroughly once the air is saturated (around 99% humidity). We did this three times a day (before work, after work, and again before going to bed). For our windows, we used a window vacuum cleaner, and for windowsills and similar areas, old towels. It’s important to hang everything outside to dry, otherwise the moisture will end up back inside the house.
We heated for a total of 4 weeks and then ventilated for another 4 weeks without heating. After that, the house was dry enough to lay the floor and move in.
We also had a portable heater back then because we had issues with delivery times for our heat pump. We got the electricity meter just before drying the screed, and when we moved in it showed just under 3500 kWh for 140 m² (1,507 sq ft) of living space. You should expect around 6,000–7,000 kWh until moving in for your house size. I recommend signing up for a cheaper electricity tariff through the usual comparison platforms to save a good amount. It will still cost around €2,000. With a large house like yours, these costs are normal.
N
nordanney23 May 2025 12:46jrth2151 schrieb:
We heated the house for a total of 4 weeks and then continued airing it out without heating for another 4 weeks. After that, the house was dry enough to lay the floor and move in.Besides functional heating (the initial "heating up"), there is also finishing heating as part of the process.M
MachsSelbst23 May 2025 19:04When performing functional heating, the temperature should be increased gradually. The purpose is to allow the screed to expand and contract once, so you can observe whether it works properly or if it cracks.
There’s no issue with raising the temperature up to 40 or 50°C (104 or 122°F). Higher temperatures mean more water is released. The moisture you drive out now won’t need to be removed later when living inside.
A floor heating system requires exactly the supply temperature it was designed for. There are still many general contractors and heating engineers who, unless the customer specifies otherwise, use supply temperatures above 38°C (100°F) because this allows for significantly less piping. This either reduces costs for the customer or increases the installer’s profit. Both are correct practices; there is no strict requirement to keep the supply temperature at 30°C (86°F) or lower.
For your 270 m² (2,900 ft²) screed, around 3,000 liters (790 gallons) of water have been introduced into the building, and it all needs to be removed.
Tilted windows might help, but they are not always effective. It’s better to open windows wide for 3-4 minutes several times a day and wipe off any condensation.
In the end, I bought paper towels to dispose of the moisture because soaking wet towels didn’t dry between ventilation periods.
A 20 kW heater doesn’t run at full 20 kW power continuously. Its temperature control keeps the setpoint around 35°C (95°F).
Using construction dryers (dehumidifiers) would cost you even more electricity... and you have to empty them at least once, often several times a day.
By the way, I have never seen a heat pump placed directly on the screed. The unit, including a 300 to 500-liter (80 to 130-gallon) tank, weighs over half a ton.
PS:
And finally, a delay of four weeks before moving in can easily cost you 1,500 EUR (approx. $1,600) in rent, construction interest, and possibly standby interest fees.
There’s no issue with raising the temperature up to 40 or 50°C (104 or 122°F). Higher temperatures mean more water is released. The moisture you drive out now won’t need to be removed later when living inside.
A floor heating system requires exactly the supply temperature it was designed for. There are still many general contractors and heating engineers who, unless the customer specifies otherwise, use supply temperatures above 38°C (100°F) because this allows for significantly less piping. This either reduces costs for the customer or increases the installer’s profit. Both are correct practices; there is no strict requirement to keep the supply temperature at 30°C (86°F) or lower.
For your 270 m² (2,900 ft²) screed, around 3,000 liters (790 gallons) of water have been introduced into the building, and it all needs to be removed.
Tilted windows might help, but they are not always effective. It’s better to open windows wide for 3-4 minutes several times a day and wipe off any condensation.
In the end, I bought paper towels to dispose of the moisture because soaking wet towels didn’t dry between ventilation periods.
A 20 kW heater doesn’t run at full 20 kW power continuously. Its temperature control keeps the setpoint around 35°C (95°F).
Using construction dryers (dehumidifiers) would cost you even more electricity... and you have to empty them at least once, often several times a day.
By the way, I have never seen a heat pump placed directly on the screed. The unit, including a 300 to 500-liter (80 to 130-gallon) tank, weighs over half a ton.
PS:
And finally, a delay of four weeks before moving in can easily cost you 1,500 EUR (approx. $1,600) in rent, construction interest, and possibly standby interest fees.
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