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COLD. is a family of products for cooling the inlet air in central MHVR systems. It is mainly intended to prevent overheating and excessive supply of humidity into any house during warm and humid summer days, however it can also be used for heating, especially during transitional periods.
To achieve this there are two main types available:
- COLD.W is a water (glycol) heat exchanger, primarily intended for combination with a heat pump;
- COLD.X is a gas (refrigerant) heat exchanger that operates in combination with the outdoor unit of an air conditioning system.
Addition:
- COLD.R (air) is a complement to the first two and allows usage in existing ventilation systems where the ducts are not insulated, which would cause the occurrence of surface condensation.
Concept
We at Remty-R believe the COLD. systems designed for cooling (and heating) in MVHR systems are an efficient and logical step forward in ensuring the well-being and comfort of the residents. Read more about the concept behind COLD. products below.
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Frequently Asked Questions
How does the COLD. system compare to a typical fan coil or mini-split AC system?
The COLD.X system is specifically designed for cooling (and heating) residential MVHR systems with airflows up to 600m³/h (353 CFM). Mini-splits or fan coils cool or heat spaces locally, requiring units in each room for comfort. The COLD.X system, on the other hand, cools or heats the air before it enters rooms via a distribution system, providing fresh, cool (or warm) air conveniently and silently to every room.
I already have an MVHR system installed but would like to have cooling. Can I use the COLD. system?
Yes, you can. In this case, COLD.R must be used in combination with either COLD.X or COLD.W. This combination will prevent condensation on the inlet distribution elements.
What is the typical power capacity of the COLD. system?
Power capacity depends heavily on the inlet air conditions and airflow. Under typical summer conditions with inlet air (after heat recovery) of 27°C (80.6°F) and 60% RH, with an airflow of 400m³/h (235 CFM), the total cooling power is typically around 2.5kW (9000 BTU). Under the same conditions with an airflow of 600m³/h (353 CFM), the total cooling power is approximately 3.5kW (12000 BTU).
Are there any requirements for minimal or maximal airflow?
With COLD.W, there is no minimum airflow limitation. With COLD.X, the minimum airflow is 180m³/h (106 CFM). The maximum airflow for both COLD.W and COLD.X is 600m³/h (353 CFM).
Which outdoor AC units can be used with the COLD.X system?
COLD.X is designed for use with AC split outdoor units with capacities up to 3.5kW (12000 BTU). There are no brand limitations, but the AC outdoor unit must have the option of external control of the capacity (0-10V) and be suitable for 0.7l indoor unit volume.
I have a newly built nZEB home with a heat pump, radiant floor heating/cooling, and an MVHR system. While I generally have good comfort, I experience high humidity in the summer despite relatively normal indoor temperatures. If I add the COLD. system, what results can I expect?
Adding COLD.W or COLD.X will significantly reduce the humidity introduced by the MVHR system. In existing buildings where insulating the inlet duct branch is typically not feasible, a good combination is to implement COLD.W or COLD.X with COLD.R. This will supply slightly warmer(less cold) but dehumidified air to the rooms. Radiant cooling can still be used to maintain stable building construction temperatures.
What is the typical inlet air temperature when the COLD.X system is working?
This heavily depends on air conditions, water temperature or outdoor unit type, and outdoor conditions. Typical figures are: in cooling mode, inlet air temperatures range from 10°C (50°F) to 15°C (59°F). When combined with COLD.R, the inlet air temperature ranges from 17°C (62.6°F) to 19°C (66.2°F). In heating mode, inlet air temperatures typically range from 40°C (104°F) to 48°C (118.4°F).
What is the average reduction of absolute air humidity in summer?
Normally, we can dehumidify the inlet air by 4 g/kg to 5 g/kg of air. For example, if we use an MVHR system without the COLD. system in summer, we may supply air at 25°C (77°F) and 70% RH (15 g/kg absolute humidity). With COLD. system, we will supply air with 5 g/kg less absolute humidity. At the same temperature (25°C / 77°F), the relative humidity is 48%.
Is the COLD. system sufficient to maintain stable indoor temperatures during summer, eliminating the need for additional cooling?
This largely depends on the building’s size, airflow capacity of the MVHR unit, climate conditions, and the residents’ comfort preferences. Based on real-world experience, a COLD. system can adequately cool a near-zero energy building (nZEB) family home up to 160 square meters, provided there’s sufficient shading. It would be even more effective for a Passive House. Larger or less energy-efficient buildings may benefit from supplementary radiant cooling. In such cases, the COLD. system should serve as the primary cooling source, and the radiant cooling system’s water temperature must be set to prevent condensation under the building’s worst-case dew point conditions.
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- Cesta II. grupe odredov 54, 1261 Ljubljana, Slovenia