Hello everyone,
I’ve heard different opinions about this. What do you do with the ventilation system in summer, turn it off or leave it running?
In the past few days, when it was warm outside, I noticed that heat was also coming in through the ventilation system. The supply air was about 24°C (75°F) even though the outside temperature was around 28°C (82°F), so it’s no surprise the house gets warm.
How do you handle this?
I’ve heard different opinions about this. What do you do with the ventilation system in summer, turn it off or leave it running?
In the past few days, when it was warm outside, I noticed that heat was also coming in through the ventilation system. The supply air was about 24°C (75°F) even though the outside temperature was around 28°C (82°F), so it’s no surprise the house gets warm.
How do you handle this?
@Bieber0815
Since I can’t provide a link, I can only say that the information comes from their website.
And yes, I assume these are just typical manufacturer specifications based on some lab conditions. But if everyone misleads a bit, at least they remain comparable, as long as they all fudge in a roughly similar way.
I understand that the enthalpy heat exchanger performs the compensation described but also releases excess moisture when the membrane saturates. Is that correct? If so, it should help against excessively humid air.
Since I can’t provide a link, I can only say that the information comes from their website.
And yes, I assume these are just typical manufacturer specifications based on some lab conditions. But if everyone misleads a bit, at least they remain comparable, as long as they all fudge in a roughly similar way.
I understand that the enthalpy heat exchanger performs the compensation described but also releases excess moisture when the membrane saturates. Is that correct? If so, it should help against excessively humid air.
Hello,
It would be nice:
First of all, I wouldn’t be sure if the membrane lets water molecules pass equally in both directions; there are membranes that work more like a one-way valve.
Also, this only works up to equilibrium. With some design tricks in the heat exchanger, you can shift the equilibrium slightly but not to the extent that the moisture would conveniently accumulate in the exhaust air while the supply air remains dry.
The vapor pressures would also have to be quite similar. Outside air is around 20°C (68°F) at 60–70% relative humidity, and the exhaust air is approximately 23.5°C (74°F) at 50–55% relative humidity. I don’t have time to calculate details now, but the differences are not that large.
As I said, an enthalpy exchanger is meant to balance extreme imbalances (mostly in winter) to humidify the dry outside air. It doesn’t really function as a dehumidifier. Otherwise, why do climate control systems still include a dehumidifier if it were really that simple...?
Best regards,
Andreas
It would be nice:
Bieber0815 schrieb:
From what I understand, the enthalpy exchanger always balances the moisture between both sides (because it has a membrane that allows water vapor molecules to pass through). This should work in both directions like heat exchange (exhaust air to fresh air / fresh air to exhaust air), always from the side with higher vapor pressure to the side with lower vapor pressure.
First of all, I wouldn’t be sure if the membrane lets water molecules pass equally in both directions; there are membranes that work more like a one-way valve.
Also, this only works up to equilibrium. With some design tricks in the heat exchanger, you can shift the equilibrium slightly but not to the extent that the moisture would conveniently accumulate in the exhaust air while the supply air remains dry.
The vapor pressures would also have to be quite similar. Outside air is around 20°C (68°F) at 60–70% relative humidity, and the exhaust air is approximately 23.5°C (74°F) at 50–55% relative humidity. I don’t have time to calculate details now, but the differences are not that large.
As I said, an enthalpy exchanger is meant to balance extreme imbalances (mostly in winter) to humidify the dry outside air. It doesn’t really function as a dehumidifier. Otherwise, why do climate control systems still include a dehumidifier if it were really that simple...?
Best regards,
Andreas
K
Knallkörper31 May 2017 09:59You would need enormous surface areas to allow any significant moisture exchange through a membrane given the vapor pressure differences. I looked for specifications or graphs on this but couldn’t really find anything.
B
Bieber081531 May 2017 22:04andimann schrieb:
Then something like that only works up to equilibrium. Equilibrium, meaning equal vapor pressures on both sides, is achieved with an infinitely large enthalpy exchanger (membrane area). In practice, equilibrium is of course never fully reached. This is entirely analogous to heat transfer (temperature equalization).
andimann schrieb:
It doesn’t really work as a dehumidifier.I never claimed that it did.Similar topics