ᐅ Condensation or puddles on pipes – despite controlled mechanical ventilation and dehumidifiers
Created on: 31 Dec 2021 11:06
A
Abzug86Hello everyone,
In August of this year, we took over a single-family house from the general contractor. It was planned together with us. A brief overview of the situation: we have 202 m² (2172 sq ft) of usable floor space (approximately 185 m² (1991 sq ft) of living area + 17 m² (183 sq ft) for technical/utility rooms), two full stories, an unfinished hipped roof, and no basement. Heating is provided by a heat pump with underfloor heating, although some rooms (e.g., technical/utility rooms) are unheated. We also installed a central ventilation system from Helios (controlled residential ventilation 500EC), including a ground-source heat exchanger (brine circuit) and an enthalpy heat exchanger. All rooms receive fresh air supply or have extracted air—this applies, for example, to the technical/utility rooms. Our ventilation system runs continuously at the set “nominal level.”
Now to the problem: since the outdoor temperature dropped below 10°C (50°F), we have experienced heavy condensation on practically all pipes in the technical/utility rooms. This includes, for example, the fresh water supply pipes, the pipes of the brine circuit, and also the supply air duct of the ventilation system. The condensation is sometimes so severe (worsening with colder temperatures) that puddles form at the base of the pipes and under critical points of the horizontally running pipes. I have attached several photos that show the situation at that time. The relative humidity was around 55–60%. From my understanding, this is relatively high but not excessively so—especially for an unheated room where washing and drying take place.
The general contractor has attributed the issue to excessive humidity due to construction moisture and advised us to ventilate more frequently. We naturally questioned why we have a ventilation system costing nearly 26,000 EUR if we still need to ventilate manually. Their response was, “It’s only at the beginning because of the construction moisture.” I would like to point out that in all other rooms of the house, under similar temperatures, the humidity levels are around 40–45%. So, I cannot detect any significant construction moisture elsewhere in the house.
Since we both work and cannot ventilate throughout the day, we purchased a larger dehumidifier and additionally ventilate in the mornings and evenings. Since then, the humidity has remained consistently below 50% (usually around 47–48%). However, the condensation issue has hardly improved or only marginally. As a result, the general contractor insulated many of the pipes. You can find photos of this in the attachments as well. The effect is that the condensation now appears on other uninsulated spots or that water is accumulating behind the insulation (when I press against the insulation, my fingers get wet).
Both the contracted installer and Helios are at a loss as to what else can be done. In the current condition, I consider mold growth within a few years to be likely, which of course must be avoided. Do you have any ideas on what else I can try? Many thanks in advance!
Regards
Micha
In August of this year, we took over a single-family house from the general contractor. It was planned together with us. A brief overview of the situation: we have 202 m² (2172 sq ft) of usable floor space (approximately 185 m² (1991 sq ft) of living area + 17 m² (183 sq ft) for technical/utility rooms), two full stories, an unfinished hipped roof, and no basement. Heating is provided by a heat pump with underfloor heating, although some rooms (e.g., technical/utility rooms) are unheated. We also installed a central ventilation system from Helios (controlled residential ventilation 500EC), including a ground-source heat exchanger (brine circuit) and an enthalpy heat exchanger. All rooms receive fresh air supply or have extracted air—this applies, for example, to the technical/utility rooms. Our ventilation system runs continuously at the set “nominal level.”
Now to the problem: since the outdoor temperature dropped below 10°C (50°F), we have experienced heavy condensation on practically all pipes in the technical/utility rooms. This includes, for example, the fresh water supply pipes, the pipes of the brine circuit, and also the supply air duct of the ventilation system. The condensation is sometimes so severe (worsening with colder temperatures) that puddles form at the base of the pipes and under critical points of the horizontally running pipes. I have attached several photos that show the situation at that time. The relative humidity was around 55–60%. From my understanding, this is relatively high but not excessively so—especially for an unheated room where washing and drying take place.
The general contractor has attributed the issue to excessive humidity due to construction moisture and advised us to ventilate more frequently. We naturally questioned why we have a ventilation system costing nearly 26,000 EUR if we still need to ventilate manually. Their response was, “It’s only at the beginning because of the construction moisture.” I would like to point out that in all other rooms of the house, under similar temperatures, the humidity levels are around 40–45%. So, I cannot detect any significant construction moisture elsewhere in the house.
Since we both work and cannot ventilate throughout the day, we purchased a larger dehumidifier and additionally ventilate in the mornings and evenings. Since then, the humidity has remained consistently below 50% (usually around 47–48%). However, the condensation issue has hardly improved or only marginally. As a result, the general contractor insulated many of the pipes. You can find photos of this in the attachments as well. The effect is that the condensation now appears on other uninsulated spots or that water is accumulating behind the insulation (when I press against the insulation, my fingers get wet).
Both the contracted installer and Helios are at a loss as to what else can be done. In the current condition, I consider mold growth within a few years to be likely, which of course must be avoided. Do you have any ideas on what else I can try? Many thanks in advance!
Regards
Micha
What are the temperatures like in the utility room? Why is it designed without any heating elements, inside the heated building envelope? It’s obvious that this will lead to condensation. The heat pump hardly produces any waste heat, and the other appliances behave similarly. In my opinion, ventilating the utility room would help. That means not only extracting the air but also supplying fresh air from the system.
Alternatively, you could consider heating the utility room.
Alternatively, you could consider heating the utility room.
Mycraft schrieb:
What are the temperatures like in the utility room? Usually somewhere between 19 and 21°C (66 and 70°F), which in my opinion is perfectly normal.
Mycraft schrieb:
IMHO, ventilating the utility room would help. I mean not just extracting air but also supplying fresh air from the system. The room is indirectly supplied with fresh air, basically from other rooms that have fresh air intake. We never really get the feeling that it’s musty or anything in that room.
When condensation occurs, it means the dew point has been reached. Therefore, there are only two possible causes: either it is too cold, too humid, or both combined.
Abzug86 schrieb:That is clear, as this is the usual approach. But in your case, it might not be sufficient, and that is why the problem could be solved by adding an additional supply air vent in the room.
The room is indirectly supplied with fresh air, basically from other rooms that have supply air.
Abzug86 schrieb:So, is it 19 or 21? Or maybe 18? And when do these temperatures occur?
between 19 and 21°C (66 and 70°F)
Mycraft schrieb:
So, 19 or 21? Or maybe 18? And when do which temperatures occur?Well, as is often the case when many appliances are running (washing machine, dryer, photovoltaic storage, inverter, etc.), it’s around 21°C (70°F). If not, and it’s very cold outside and I may have ventilated before, then it’s about 19°C (66°F). I haven’t noticed any values outside this range so far.
So I can neither confirm the coldness in the room mentioned by you nor the excessively high humidity. However, the fact is that the inside of the water/ground loop pipes and the supply air duct, depending on the outside temperature, are naturally very cold inside and condensation forms on the outside due to the large temperature difference.
If you have only just taken over the house, there can still be some moisture inside, even if it isn’t immediately noticeable.
When we moved in in October 2021, the moisture meter didn’t show any significant dampness, yet the printer paper in the office became wavy. We then set up a dehumidifier for a while, which extracted several liters of water from the air—specifically in the office.
Our utility room is heated, and at the very beginning, we also had some occasional condensation around the heat pump area. However, this was only temporary and cleared up after 1–2 weeks.
Today, the central ventilation system works perfectly, and laundry dries very quickly in that room.
But back when we took over the house, we were also advised to ventilate additionally during the first few months because of residual moisture. This is normal, even with a mechanical ventilation system with heat recovery (MVHR / HRV).
When we moved in in October 2021, the moisture meter didn’t show any significant dampness, yet the printer paper in the office became wavy. We then set up a dehumidifier for a while, which extracted several liters of water from the air—specifically in the office.
Our utility room is heated, and at the very beginning, we also had some occasional condensation around the heat pump area. However, this was only temporary and cleared up after 1–2 weeks.
Today, the central ventilation system works perfectly, and laundry dries very quickly in that room.
But back when we took over the house, we were also advised to ventilate additionally during the first few months because of residual moisture. This is normal, even with a mechanical ventilation system with heat recovery (MVHR / HRV).
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