ᐅ Is Moisture Recovery Useful in Controlled Residential Ventilation?
Created on: 4 Dec 2015 14:54
W
world-e
Hello everyone,
Does moisture recovery in a mechanical ventilation system with heat recovery make sense? I have read different opinions on this. Without moisture recovery, the air can be too dry in winter, especially for allergy sufferers. On the other hand, some say that in timber frame houses, it is better to keep the moisture outside and that the additional cost for moisture recovery can be avoided.
What is your opinion on this? Thank you
Does moisture recovery in a mechanical ventilation system with heat recovery make sense? I have read different opinions on this. Without moisture recovery, the air can be too dry in winter, especially for allergy sufferers. On the other hand, some say that in timber frame houses, it is better to keep the moisture outside and that the additional cost for moisture recovery can be avoided.
What is your opinion on this? Thank you
# Mycraft:
I have to agree with you about the choice of systems, although there are huge price differences when it comes to heat exchangers. For my Paul Novus 300, one costs around 800 euros (about half the price), while other manufacturers charge nearly twice as much.
I also understand that the air doesn’t become more humid, but the effect of a ground heat exchanger, which makes the air drier and therefore more comfortable in summer, is reduced. I would let the moisture condense in the brine (or air) heat exchanger and then re-humidify it inside the unit. To me, that doesn’t make sense...
In winter, all ventilation systems dry out the houses. But this also happens if I were to ventilate properly through the windows. In the end, doesn’t the heat and moisture exchanger just delay this effect?
If you’ve studied this topic more closely, maybe you can tell me what else besides water is recovered through these special membranes. I know it depends on the size of the molecules what passes through.
I have to agree with you about the choice of systems, although there are huge price differences when it comes to heat exchangers. For my Paul Novus 300, one costs around 800 euros (about half the price), while other manufacturers charge nearly twice as much.
I also understand that the air doesn’t become more humid, but the effect of a ground heat exchanger, which makes the air drier and therefore more comfortable in summer, is reduced. I would let the moisture condense in the brine (or air) heat exchanger and then re-humidify it inside the unit. To me, that doesn’t make sense...
In winter, all ventilation systems dry out the houses. But this also happens if I were to ventilate properly through the windows. In the end, doesn’t the heat and moisture exchanger just delay this effect?
If you’ve studied this topic more closely, maybe you can tell me what else besides water is recovered through these special membranes. I know it depends on the size of the molecules what passes through.
S
Sebastian7921 Dec 2015 12:09The membranes are coated and eliminate all germs/bacteria – the air will not be more contaminated than the outside air you breathe.
And why would the effect be delayed – the people in the house sweat and breathe, so this moisture is partly recovered.
And why would the effect be delayed – the people in the house sweat and breathe, so this moisture is partly recovered.
So if a heat exchanger ends up costing nearly half of the new system, in my opinion, it simply doesn’t make sense to first install one without and later add moisture recovery... that is just a waste of money... but well, one learns from mistakes, as they say...
The membrane contains a high proportion of salt and absorbs the water vapor like a sponge. On the cold air side, the water evaporates at the membrane surface and is taken up by the drier airflow. The salt is chemically bound to the membrane material and is not dissolved or flushed out by the water.
The membrane transports water molecules due to their high dielectric (non-conductive) constant and small size. Microorganisms cannot penetrate the membrane because they are much larger compared to water molecules. Additionally, the high salt concentration in the membrane acts antibacterially. Bacteria, yeast, mold, and all microorganisms die off on the membrane surface.
The membrane contains a high proportion of salt and absorbs the water vapor like a sponge. On the cold air side, the water evaporates at the membrane surface and is taken up by the drier airflow. The salt is chemically bound to the membrane material and is not dissolved or flushed out by the water.
The membrane transports water molecules due to their high dielectric (non-conductive) constant and small size. Microorganisms cannot penetrate the membrane because they are much larger compared to water molecules. Additionally, the high salt concentration in the membrane acts antibacterially. Bacteria, yeast, mold, and all microorganisms die off on the membrane surface.
I consider enthalpy heat exchangers to be completely unnecessary.
We also had the problem of somewhat dry air. I simply reduced the air exchange rate by assigning different fan speeds to the ventilation stages.
This way, during the cold/dry winter, we achieve 40-45% relative humidity instead of 30-35%.
We also had the problem of somewhat dry air. I simply reduced the air exchange rate by assigning different fan speeds to the ventilation stages.
This way, during the cold/dry winter, we achieve 40-45% relative humidity instead of 30-35%.
Everyone is different... for some, a 30% level is no problem, while others already feel uncomfortable at 40%. For example, we manage quite well with a simple heat exchanger, but when it gets close to 30%, I do occasionally wish for some humidity recovery. However, these are usually only a few days per year.
Mycraft schrieb:
... however, once it gets close to 30%, I do occasionally wish for some humidity recovery... but that’s usually just a few days per year...And for those few days per year, we use a small portable humidifier. It’s usually placed in the bedroom and runs for a while before going to bed.
My partner has some issues with dry air due to allergies and similar sensitivities.