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Garald

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  1. Yes, I think so. The general contractor says the existing ducts (which carry the positive-pressure air from the PIV to the first and second floors) are too narrow for conventional MVHR. Hence my interest in cascade MVHR. Cool, thanks. Do they also install things (in France) or would I have to work with a local plumber or ventilation person?
  2. Pretty much what says on the headline. Situation: I have part of the ground floor, all of the first floor, and all of the attic for a total of about 175m^2, or 120m^2 counting only the surface in which one can stand (the rest is the sides of the attic, or staircases, which don't count for the official total either). I suppose I'd need three cascade systems, or two if I'm very lucky (since I have only a bit of the ground floor, and the staircase is quite large). (Currently I have PIV, which I am not very happy with; it hasn't even been installed all that well - it's nearly impossible to change the filter without destroying it.)
  3. ERST20D-VM6D PAC-ISOCH MITSUBISHI UE ECODAN SPLIT ZUBADAN SILENCE 12KW 1PH R32 ZUBADAN SILENCE Won’t they just cool a thin layer of air at the bottom? Will have it, don’t have it yet.
  4. The model doesn’t. Mitsubishi models that could used an older, more polluting cooling fluid - and all installers I talked to expressed profound skepticism as to whether producing cold water was ever useful, particularly without underfloor heating (I have radiators).
  5. Well, obviously, the humidity will go up, but the temperature should go down. If by "cooling" you mean lowering the heat, then yes, obviously and tautologically. If by "cooling" you mean lowering the temperature, no, not necessarily. Without refrigerative means, the wet-bulb temperature will not go down, but the temperature may and in fact should be lowered as humidity is added, no? >Something your ASHP is likely capable of doing? Nah, it's not reversible. (It's air-water; if it had a different, more polluting refrigerant coolant, it could produce cold water).
  6. I'm still trying to figure out how to make my attic comfortable during heat waves. I live in the Paris area, where heat waves are comparatively dry (in fact, they are the only time when it is comparatively dry). So, I decided to get a medium-sized evaporative cooler: https://www.amazon.fr/KLARSTEIN-Skyscraper-Rafraîchisseur-Humidificateur-Refroidisseur/dp/B085HM8N2Z?th=1 It does produce a cool breeze, so I suppose it is helpful if you stand or sit literally in front of it and quite close to it. I didn't notice enough of an effect if sitting at 1-2m from it. So, wanting to determine the truth, I ran an experiment. My attic consists of two compartments (not counting the bathroom): I closed the windows in both, and ran an evaporative cooler (Klarstein Skyscraper ICE) in one of them; I put a thermometer/hygrometer in each compartment. After a while, - the half without the cooler was at 30.9 C, 50% humidity, - the half with the cooler was at 30.9 C, 60% humidity. That's a remarkably total and precise failure! The cooler was humidifying without cooling. My question is: how is this even possible? Wouldn't a simple decorative indoor fountain do better than this? How can a tool manage to be so bad? How do you set out to make an evaporative cooler that doesn't work? (Some data (from https://www.kwangu.com/work/psychrometric.htm😞 30.9 C at 50% corresponds to a wet-bulb temperature of just 22.75 C (i.e., we could be very comfortable if were just willing to do math while wrapped in wet towels). An evaporative cooler that keeps enthalpy constant (I thought that was a reasonable assumption - these are low-powered devices, so the heat they dissipate by operating is likely negligible) would keep wet-bulb temperature constant. Then, at 60% humidity, we would have expected the temperature to be lowered to 28.7C, a significant change.) I ran the experiment again the following day. Starting conditions (at 4:50pm): outside temperature 28C, attic room with cooler: 32.8C, 42% humidity; attic room without cooler, 32.9C, 47% humidity. End conditions (at 11:25: attic room with cooler - 30.3C, 60%, attic room without cooler - 31.2C, 51%). All right, this time, the cooler did *something*, but it seems to be remarkably bad at what it does.
  7. Well, I hope that this is the one and only renovation I will do in my life, so any knowledge I acquire is useless to me *except* for academic knowledge (which is a nice way to review undergraduate physics, learn what our friends in finite element analysis do after all, etc.).
  8. If you wish, but where do I read up about these models?
  9. Well, can you tell me where to look up those models (and the physical reasoning behind them)?
  10. I haven't vanished! At any rate, I take the DIN this-and-that models are very simple 1-D models one can do with pencil and paper?
  11. Are these things likely to work with efficiency close to what is claimed (88%)? https://www.econology.fr/extracteur-air-double-flux-econoprime-dfd.html?gad_source=1&gclid=CjwKCAjw1emzBhB8EiwAHwZZxUfYNCLDDGeyKXbT61jEQ-mJwDtcp4l_nM0XAGxf3fgPYK3h9JNteRoC4e8QAvD_BwE I imagine installation costs double the price or so, but even then things would remain very reasonable. My situation: a) I'm towards the end of a long renovation. b) I have PIV and I'm rather frustrated that double-flux wasn't offered as a possibility early on. It's most likely too late to install central MVHR. c) I have a habitable (and lived-in) attic that (i) is rather open (one large open space, one room, one bathroom) (ii) most likely doesn't get adequately ventilated by the PIV (there are only skylights, and apparently ventilation exits weren't built into them); the place feels a bit stuffy when hot; d) On the first floor, I have one large library where in fact does have ventilation exits in the window frame (or so I'm told - I haven't been able to find them); I wouldn't mind closing them, as they lead to a noisy road; I might be able to put a ventilation exit on a side wall. I suppose a MVHR in each room in the attic does not enter into conflict with the PIV - it would just makes it more or less superfluous, no? PS. Added advantage if this MVHR-in-the-attic plan works: I'll be able to soundproof the doors in the attic. Right now, there's about 1cm of empty space at the bottom, necessary for the PIV to work (to the extent it works at all). PPS. Are there single-room MVHR units with filters? I live 10 min away from a highway, so pollution is non-trivial, and then there is pollen.
  12. I've got a quote for insulating a wall on the outside using rockwool. (I've got similar quotes for polystyrene, but I think there are good reasons to prefer rockwool, one of them being permeability to water vapour.) What is being proposed is 16cm thickness, for an R of 4.55. Is there such a thing as too much rockwool on the outside? If not, why not go up to 18cm, or 20cm? (Sure, there is the matter of cost, but only 1/3 of them are the cost of the insulating material itself. Going from 16 to 18cm should correspond to an increase in price of less than 5%.) I have a further motivation - the wall is already insulated on the inside (I know, I know, not the best decision for a northern wall - the pseudoarchitect overruled both the builder and me on that, back before I knew she was no architect). Now, Ubakus tells me that just a little bit of insulation on the outside will be enough to forestall the risk of condensation, but, until I get WUFI to run and/or understand condensation myself, it's best to work with safety margins. Around here, people go by a "the R on the outside should be at least twice the R on the inside" rule - that seems like an exaggeration, but who knows?
  13. I've read Ubakus really uses a very simple model to predict condensation. So, what is it, and where can I read about it? What do more sophisticated models (such as the one used by WUFI, which I can't use, as I don't have Windows - just failed to run it using WINE) really do? TL;DR: I would like to install outside insulation on a wall that is already insulated on the inside. I want to actually understand (the physics behind) how to make choices so as to prevent condensation - I can't just follow rules of thumb such as the "1/3-2/3 rule" and "at least 5 times as much resistance to water vapor on the inside as on the other" as they can't really be simultaneously obeyed in this sort of situation.
  14. OK, here is the composition of the wall: - wall itself: some sort of masonry from the 1930s (not concrete) - inside insulation: ISOLIN HPV (reflective insulation) + 45mm Biofib Trio + hygrovariable vapor barrier (Proclima) + 13mm fireproof plaster
  15. Important point: the wall is insulated from the inside with materials permeable to water vapor (though I'd think there's also a barrier). Does this nale polystyrene unadvisable?
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