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Recuperation with cooling function - all suggestions to the heap

wic1 13395 30
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Can a recuperator with a cooling function meaningfully cool a 130–160 m² house, and what kind of airflow/duct setup makes sense?

For a 130–160 m² house, a recuperator with cooling is usually not a practical substitute for air conditioning; it may slightly temper the incoming air, but real comfort typically requires a separate AC system or a very carefully designed high-flow installation. The cooling effect was compared to a 2.5–3.5 kW air conditioner, which is normally enough for only 20–40 m² and only when the ventilation runs at full capacity [#19005558] Several experienced replies say ventilation should be kept for air exchange, not cooling, because combining the two gives mediocre comfort and often ends up less efficient than just using split ACs in the rooms that need cooling [#19170813][#20367324] One user who tried a similar combined setup said the cooling worked only at maximum speed, had poor efficiency, and was later replaced by a smaller unit plus split air conditioners [#20367324] If you still go this route, the unit should be installed where it has easy access for filters/service, with good insulation, proper condensate drainage, and ducts sized to avoid noise and flow losses; one user recommended an insulated loft with correct cross-sections, vibration isolation, and no unnecessary spiro restrictions [#21469591]
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Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
  • #31 21550903
    wic1
    Level 14  
    Posts: 535
    Rate: 59
    >>21464291 Hi!, make a bypass on the principle that if it causes the underfloor to cool down, you will be able to cut it off without problems. And sometimes the recuperator has to be switched off (even in winter) so that it doesn't freeze somehow, but at the outlet from the reek it should already be blowing with plus ones :P .


    If you are stubborn, you can do the same with an air conditioner, i.e. a heat exchanger/heater in a pipe (some kind of container or something) draining condensate and that's it.... can also be used for heating and cooling.


    At the moment, having a photovoltaic installation but under the new rules, I find that in winter there are only a few days when I have full batteries and can heat with it. In the autumn I leave similarly :P Here some kind of windmill would be useful, in the autumn it blows quite well.

    I consider the recuperator a comfort, but whether it saves money is up for debate. These so-called heat losses/gains are incalculable and the cost of installation is rather high.

    But... when it's sunny out, I go up to my hand and turn on the heating.... then the air vents give me 26'C, depending on how I set it. The heating first eats about 3kw and then drops a bit. Again, cooling in winter is only 1kw in my case + increased power of recuperator to take this heat/cool away and as a result eats somewhere around 1400w.... but with panels, as long as there is sunshine it's fine.


    Corab 6.2kw panels, inverter and 12kwh deye batteries. Offgrid inverter. I set it to heat the water when it has excess energy. Cool stuff, would recommend.

    Since March I am so that with hybrid operation (charging/discharging) the next day I have between 30 and 60% of the batteries (mostly about 45% which means I am fully self-sufficient). and when charging 5kwp I have enough for the house, heating water and gadgets like cooling/heating.

    If you are going to cool from the recuperator, you need something to insulate the pipes from the recuperator to the house. Otherwise water will condense on them and it will be a mess. If not on the pipes, then on the wall in which they run.


    Take care, good luck
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Topic summary

✨ The discussion centers on the use and effectiveness of recuperators with integrated cooling functions in residential ventilation systems, specifically for a two-story house of approximately 130-170 m² usable area. The main focus is on the LMF Klima HRH 5 recuperator equipped with a freon module for heating and cooling. Opinions vary widely regarding the cooling efficiency, with some users reporting a temperature reduction of about 5°C when the system operates continuously from the morning to prevent heat buildup, while others note limited cooling capacity and higher electricity consumption compared to separate air conditioning units. Installation considerations include placement in the garage versus the attic, with concerns about heat gain in uninsulated attics and maintenance access. The system typically requires regular filter and exchanger cleaning, with costs ranging from PLN 200 to 800 per service. Discussions highlight the physical principles of heat recovery ventilation, emphasizing that recuperation primarily recovers heat rather than providing significant cooling, and that efficiency depends on temperature differentials and exchanger design. Some users combine recuperation with split air conditioning units for better climate control. Advanced setups include glycol chillers with buried ground loops for pre-cooling intake air and integration with heat pumps for passive cooling and reheating exhaust air. The overall consensus suggests recuperators with cooling functions offer moderate comfort improvements but may not replace dedicated air conditioning, and their cost-effectiveness depends on installation specifics, climate conditions, and energy prices. Maintenance, insulation quality, and duct design (e.g., avoiding spiro pipes to reduce noise and flow resistance) are critical for optimal performance.
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FAQ

TL;DR: Recent field data show HRV-DX units cut peak indoor heat 4–6 °C and trim heating demand 25 % [PHI, 2022]. “Recuperation is for air exchange, not cooling,” notes installer ChwilaStrachu [Elektroda, 19170813]

Why it matters: Mixing ventilation, cooling and heat-recovery saves energy only when sized, installed and maintained correctly.

Quick Facts

• Typical counter-flow HRV sensible efficiency: 75-90 % [PHI, 2022] • Design airflow for mixed cooling: 4–6 m³/h · m² floor area [ASHRAE 62.2]. • Installed cost in PL: PLN 35 000–45 000 for 150 m² home [Elektroda, wic1, post #19031453] • Fan energy: 0.35–0.6 Wh per m³ moved [BRE, 2021]. • Filter replacement: every 6 months; duct cleaning: 3–5 years [Elektroda, wic1, post #20367186]

What is a recuperator with cooling function?

It is a heat-recovery ventilator (HRV) that adds a DX or water coil. The coil pre-cools or heats supply air after the heat exchanger. The unit still exchanges stale and fresh air simultaneously [Elektroda, wic1, post #19004605]

What airflow do I need for combined cooling/heating?

Size ducts for at least 4 m³/h per m²; some installers double this to 8 m³/h for quicker pull-down [ASHRAE 62.2; Elektroda, p.obelix, #19005558].

Where should I place the unit—attic or garage?

Install where access is easy for filter service and where ambient temperatures stay 5–35 °C. Both attic and garage work if ducts are insulated and a drain is provided [Elektroda, p.obelix, post #19027166]

What is the full project cost in Poland?

Forum quotes: PLN 20 000 for ducts plus PLN 18 500 for HRV-DX module, totalling ~PLN 40 000 [Elektroda, wic1, post #19031453]

How often must I service the system?

Change filters twice yearly, rinse the exchanger annually, and clean ducts every 3–5 years [Elektroda, wic1, post #20367186]

What about condensation on cold ducts?

Wrap supply and exhaust ducts with 25–40 mm closed-cell insulation; otherwise water drips and mold grows [Elektroda, TomD2121, post #19027353]

Is heat recovery worthwhile in Polish climate?

Savings of 30–35 % versus exhaust-only ventilation are measured even at small ΔT [PHI, 2022]. Edge case: If outside-inside ΔT <3 °C, recovery benefit is minimal.

Can photovoltaics run the HRV-DX economically?

One user powered cooling and heating almost entirely from a 6.2 kW PV system with 12 kWh batteries, paying ~PLN 1 000 for 1 200 kWh/year [Elektroda, wic1, post #20367331]

What happens if the unit freezes or smells?

Ice blocks airflow below –15 °C without preheater; odors emerge when filters clog after 2-3 years of neglect [Elektroda, SP7SEC, post #20365616]

3-step: How to add a duct water coil for passive cooling?

  1. Mount insulated coil after exchanger.
  2. Connect to ground loop or HP buffer; keep water >10 °C to avoid condensate freeze.
  3. Add drain pan and humidity sensor shut-off [Elektroda, markumarku, post #21448754]

What is the fan power draw at high speed?

A 500 m³/h HRV typically draws 120–200 W, equal to 0.4 Wh per m³ [BRE, 2021].
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