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So the smell seems to be completely gone this winter. Maybe it was related to the coil being wet, because we basically have almost never run heating/cooling for upstairs for months.
So I think the ERV isn't ideal for my climate. This month, my RH at around 20 degrees has been sitting around 60% the entire time. Realistically that's probably fine, but 50% would definitely be better, and I assume HRV is more likely to achieve that? Especially since my main problem seems to be having higher dew point indoors (albeit very slightly). Although today, outside has a Dew point of 15 degrees, due to the rain.
Considering Auckland's mild climate, I assume HRV would be better in all cases except the hot parts of summer. Basically anytime I need to run cooling, the ERV would be better. But even then, only a tiny bit, because technically it's also less efficient energy wise (although the hot attic probably makes that point mute).
So not sure what I want to do. Will probably try this next summer and see how it goes. Tempted by a ducted dehumidifer, as mentioned in this thread, but my attic has enough complexity in it as is. Swapping out to an HRV would probably be far too expensive, unless the installer took on most of the costs by trying to sell the ERV unit.
Here's stats for this month:
tweake:
sorry, just a quick comment. i think erv is ideal for the climate, i just think everything else isn't.
hrv may make it worse, or it may be better. it depends on what the source of humidity is. is it cause by people inside or by air leakage. hrv's tend to be more suited to areas that have good outdoor humidity levels. eg a lot of south island is far better suited than auckland is.
i would borrow or buy a regular dehumidifier, one that has a humidistat, set it to 50% and let it run. once the humidity level in the house comes down to 50%, see how much it has to run to maintain it.
That was a great idea thanks. I managed to borrow a residential humidifier for my room. Running it for a while, the humidity drops as expected. One thing I notice though is that the disparity of my humidity sensor and the dehumidier's sensor seems massive. They're very close to each other and they can be 10% RH apart.
So I ran the dehumidifier this morning and got the dew point below the outside. I'm at work now, but just checking my sensor in home assistant, the dew point is much larger than outside. This could be a mix of the room being a high temperature (24 degrees, hot roof, open blinds) and maybe the fact my house is still releasing moisture? (only built just over a year ago).
I definitely need to get a new sensor and compare to see how inaccurate it is. Or try the salt test to calibrate it.
Here's a graph of my room from overnight using Aircon at 20 degrees set point, with ERV on Lossnay mode with the 25% fan speed (lowest for that unit).
You can see it gets the dew point down, as expected.
For some weird reason, every single day, the humidity starts climbing at around 4am. The only reason I could think of, is that the entire unit turns off at that time and humidity builds up from breathing (we sleep with the door closed). I probably need some power sensors to detect when the compressor is running and the attic unit etc.
Edit: It's possible some of problems are coming from pressuring the room since we close the doors. Hmmmm. They are decently cut at the bottom and I avoid having the damper fully open for that room, but maybe it's still a problem, causing negative pressure in other parts of the house. Or maybe the unit itself is just not well balanced and negative pressure is everywhere? Not sure how to test this!!!
Hi
Yes if you use this as an example diagram, you can see the lossnay with the Red Return , that's the default approach, it feeds into the aircon. you can see the two Orange bypass vents, i would put a damper on that line so that it is open or closed depending on aircon running, essentially it allows air to bypass
i asked BDT about this and they were not in favour
"We wouldn’t recommend this setup, as it can easily cause backflow, pressure imbalance, or even block the airflow of the AC unit, which is not safe."
I'm unclear how those would occur with a electronic damper, ( unless the damper failed? ). Interested in other peoples thoughts on this.. but this is how you could reuse the vents and achieve a bypass. Its somewhat dependant on the Baffle i guess you have set up, do you have a small number of main lines that you could tap into to reduce the number of electronic baffles and Y connectors :) But im a layman so i know nothing in this space so take with a grain of salt.
mrhaboobi:
Hi
Yes if you use this as an example diagram, you can see the lossnay with the Red Return , that's the default approach, it feeds into the aircon. you can see the two Orange bypass vents, i would put a damper on that line so that it is open or closed depending on aircon running, essentially it allows air to bypass
i asked BDT about this and they were not in favour
"We wouldn’t recommend this setup, as it can easily cause backflow, pressure imbalance, or even block the airflow of the AC unit, which is not safe."
I'm unclear how those would occur with a electronic damper, ( unless the damper failed? ). Interested in other peoples thoughts on this.. but this is how you could reuse the vents and achieve a bypass. Its somewhat dependant on the Baffle i guess you have set up, do you have a small number of main lines that you could tap into to reduce the number of electronic baffles and Y connectors :) But im a layman so i know nothing in this space so take with a grain of salt.
This seems like a lot of work and cost when you could just run the ducted unit on 'fan only' mode at lowest fan speed and the lossnay on to get the same result.
mrhaboobi:
Hi
Yes if you use this as an example diagram, you can see the lossnay with the Red Return , that's the default approach, it feeds into the aircon. you can see the two Orange bypass vents, i would put a damper on that line so that it is open or closed depending on aircon running, essentially it allows air to bypass
i asked BDT about this and they were not in favour
"We wouldn’t recommend this setup, as it can easily cause backflow, pressure imbalance, or even block the airflow of the AC unit, which is not safe."
I'm unclear how those would occur with a electronic damper, ( unless the damper failed? ). Interested in other peoples thoughts on this.. but this is how you could reuse the vents and achieve a bypass. Its somewhat dependant on the Baffle i guess you have set up, do you have a small number of main lines that you could tap into to reduce the number of electronic baffles and Y connectors :) But im a layman so i know nothing in this space so take with a grain of salt.
So that orange duct is a supply? And the red ones on the left are 2 returns?
Also, shouldn't the ERV/HRV intake/outtake be on the same side of the house for pressure balance reasons? Due to wind etc? Not sure how important that is in practice, but supposedly a thing?
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