Green Building Bible, Fourth Edition |
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment. PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book. |
Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.
1 to 28 of 28
Posted By: martinhobsonChecking out 'You Tube' there are plenty of people (mainly USA & Canada) making these units (panels?) out of mainly scrap cans or aluminium downpipe or aluminium sheeting and ducting hot air directly into buildings but as yet I can't find anyone combining them with MVHR.There's a good reason for that. As evan said, pre-heating the external air input to an MVHR merely increases the exhaust air temperature. In other words, it increases the external air temperature as seen by the MVHR unit & thereby helps protect it from frost, but very little of the additional heat will be transferred into the house. If the MVHR heat exchanger is 90% efficient then around 10% of the additional heat makes it into the house, the other 90% will come out of the exhaust.
Posted By: evanI can see it helping in the case of a cold and frosty day but with good sunshineYes, this is a good point & I have considered a number of such schemes myself of varying complexity. The Sunwarm products from Nuaire in particular allow various forms of solar capture. One of these allows the solar air collector to act as a frost protection pre-heater for the MVHR unit & it will bypass the MVHR altogether if warmer air is available from the solar air collector. However, solar heating is best done by passive means &, for an airtight house requiring continuous ventilation, I think you need frost protection which doesn't rely on the sun being there. So I prefer frost protection based on ground-brine-air heat exchangers, electrical resistance pre-heaters or ground-air pre-heater ducts, in that order.
Posted By: martinhobsonI really find this forum frustrating at times; presumptive, obscure and even mocking answers, another thing is that people eg Viking House assume that I am not doing all the other stuff anyway AND that I am about to spend money on a 'gadget'. If I do attempt to use this idea, it'll probably cost about £20 at most. I expect to be able to ask questions which may end up being stupid without being patronised. I'm trying to work something out. Perhaps you all do know more than I do, but even if you do, have some respect. Sorry guys but this feels like being bullied at school. I've had some very helpful answers (sometimes) but on other occasions, like this one, the 'GBFcollective' really tests my patience.Apologies Martin. I had no idea your solution was so cheap, I hope this information is of use to you, we transferred the air intake pipe from the north wall of a house to inside the garage last winter and it increased the temperature of the air entering the living room by 1.5 degrees. The house we built with the most efficient HRV is the one that first takes the air into the south facing sunroom and then draws the air into the house from there. So it seems to act like a buffer zone!
Posted By: martinhobsonI really find this forum frustrating at times; presumptive, obscure and even mocking answersI hope you didn't find my answers presumptive, obscure or mocking; that certainly wasn't the intention. I was simply trying to say that for a 100% efficient MVHR heat exchanger:
Posted By: evanHang on a minute, doesn't it split the difference in temperature, even if it's 100% efficient?Another way to think about this is that a heat exchanger is just a metal or plastic plate separating two airflows going in opposite directions. The heat is transferred from one air flow to the other by conduction from one face of the plate to the other. One end of the plate is at the inlet air temperature the other end is at the extract air temperature.
Posted By: Viking HouseLast winter we were getting 18 degrees supply air when it was 20 degrees inside and 0 degrees outsideI guess this is because the heat exchanger is 90% efficient.
Posted By: rhamducountercurrent heat exchangers
1 to 28 of 28