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tweake:
where on the heat pump unit does it go? on the return side or the outlet (air to bedrooms) side.
Hmmmm on the return side....
AlDrag:
Hmmmm on the return side....
well thats weird.
normally you put it into the outlet side, but these don't have a single pipe outlet. also the downside is it fights against the heat pump fan.
i kinda see the logic behind doing both into the return. as the heat pump fan is always on (or should be setup that way) it will work as the heatpump fan flows a lot more air. however you have the heat pump fan assisting the fresh air side and fighting against the fan on the exhaust air side. normally the exhaust side would be coming from the bath rooms and fresh air get put into the return.
but it doesn't explain the noise unless the exhaust side is struggling fighting against the heat pump fan, which will get worse as the main return filter clogs up.
it would be interesting to see the difference in flow rates of the erv in/out.
a simple test would be to take the exhaust side off the return and see if the noise changes.
tweake:
well thats weird.
normally you put it into the outlet side, but these don't have a single pipe outlet. also the downside is it fights against the heat pump fan.
i kinda see the logic behind doing both into the return. as the heat pump fan is always on (or should be setup that way) it will work as the heatpump fan flows a lot more air. however you have the heat pump fan assisting the fresh air side and fighting against the fan on the exhaust air side. normally the exhaust side would be coming from the bath rooms and fresh air get put into the return.
but it doesn't explain the noise unless the exhaust side is struggling fighting against the heat pump fan, which will get worse as the main return filter clogs up.
it would be interesting to see the difference in flow rates of the erv in/out.
a simple test would be to take the exhaust side off the return and see if the noise changes.
I had no idea, so very glad you told me thanks.
Maybe I can compare the noise by adjusting the fan speed on the heatpump? Unless that also affects the fan speed of the lossnay unit.
I don't know to remove ducting, but I can watch some youtube videos and see how it's done. I might talk to the installer too, but I'm assuming they're going to prefer their current install. Still need them to come over and fix a leaky damper (Dampers suck).
tweake:
weird for a joiner. most joiners i've used you can pull on the duct right up to the center. that insulates it as well. its usually 3 way joins or dampers that are tricky but they often come with their own insulation.
unfortunately i don't know what the air temps typically are for ducted heat pumps. normally with aircon you always want ducts insulated, not because of efficiency but rather to avoid condensation on the ducts. you don't want condensation dripping onto the ceiling.
So I asked the installer about it, and apparently the insulation is there, they just taped over it to compress it.......doesn't that void the use of the insulation completely? You're not supposed to pack it down....
what ever the thickness the insulation is compressed to is its effectiveness. eg take 4" compress it to 1", its only as good as 1" insulation.
in this case is it enough to cause a problem? i have no idea. if you have a thermocouple temp sensor you can put that on and see what temp its gets to. then you can work out dew point and get an idea of if it will condensate or not.
i would get them to check the noise and why its noisy. if the return is a bit undersized, it might cause the erv fan to go noisy.
the other thing is to work out what flow the erv should be and check its set for that. normal would be half the volume of the bedrooms per hour (or half of the house if you have the downstairs vent). set that as medium, set the lower one at 1/3 the volume, and the high one 2/3 volume.
tweake:
i would get them to check the noise and why its noisy. if the return is a bit undersized, it might cause the erv fan to go noisy.
the other thing is to work out what flow the erv should be and check its set for that. normal would be half the volume of the bedrooms per hour (or half of the house if you have the downstairs vent). set that as medium, set the lower one at 1/3 the volume, and the high one 2/3 volume.
Ok, they're coming on Friday so will get them to take a listen. So if the return is undersized, that could be creating positive pressure? Or maybe just making it work harder.
I don't know how to work out what the flow should be, but I assume the settings you are talking about are via the Lossnay controller?
if return is undersized, the heat pump fan will cause a bit of suction that the erv exhaust fan has to fight against. it just depends on the spec/type of fan they use, which is have no idea of. by disconnecting that exhaust duct the erv fan no longer fights against the heat pump fan. if the sound goes quiet, "theres your problem".
by mem settings are normally done through lossnay controller, probably through the heat pump controller as well. i would have to read the manual again.
working out the what the flow rate should be is easy. work out the volume of the bedrooms in liters, half that and you have the flow in l/hr. if you have downstairs vent, then use the volume for the whole house. then its finding the erv specs and workout what fan speed you need to get that flow. if in doubt post up the room/house sizes.
Ok I think I have an idea of all my issues now, I just need a Lossnay and Heatpump controller to solve them, but jesus christ they are so overpriced. Over $500 just for a Lossnay controller!
- Lossnay Fan speed: Apparently my Lossnay unit is set to fan speed 4, which is the highest speed, by default (according to the manual). This might be a bit too much for my smaller PEAD 50 heatpump unit.
- Lossnay Bypass Dampler: running fan mode only I noticed humidity increases above 60%. I think the bypass damper for the Lossnay is basically always on because I think it's reading temperature from the heatpump return which is always higher than the outside temp. I need to be able force the bypass damper off!
- Static Pressure setting: My heatpump unit's static pressure is set to 50 by default. Doing some reading, supposedly this default is for simple installs with minimal ducting? Could be wrong, but I wouldn't mind trying 70 or 100.
- Bends in the duct: due to my lossnay unit being directly above the heatpump unit, there's lots of bends in the duct. They're gentle bends, but still bend 360 degrees in total. The Lossnay supply that leaves the lossnay unit bends immediately for example so it can reach the heatpump's return on the other side.
- Airtouch and Lossnay is bad: Airtouch automatically adjusts dampers depending on temperatures per room. When the temperatures are met, the dampers fully close. However, this is a big assumption by me, I think Mitsubishi Electric is configured to run ventilation only once set point has been reached. But since Airtouch closes all the dampers, the ventilation just runs through the heatpumps bypass damper. This means zero supply is going into the house and yet the central return is still running, potentially pulling in outside air into the house through gaps.....although I haven't actually checked any pressure from the return when this happens. It's possible I'm just hearing the bypass damper exhausting to the outside through the Lossnay. I might be able to solve all these issues through Home Assistant automations and scripting...
- Polyaire bypass dampers leak: I have leaks again from the Polyaire dampers. Chatting to some guys on a Unofficial Polyaire Facebook group, seems most dampers leak a little and is normal. Maybe it doesn't cause enough issues to be noticeable, but it's something that bothers me.
So my goal is to try and find a cheap controllers somewhere, otherwise I'm going to have to just bite the bullet. Trying to get my installer to find one though as I'm pissed they through the existing one away.
Flow rate calculation:
Assuming I don't need to include the hallway for the calculation:
My 3 rooms total to about 76m3 for my 2.55m high ceilings.
This means the flow rate should be about 38L/hr (I think it's meant to be 38L/s?) So if my Lossnay unit (LGH-25RVX3-E) really is on the highest fan speed, it'd be pushing 69 L/s.
Well damn, this may also explain a lot....this is 2 months worth of use on the inline sock filter for the Lossnay fresh air (I requested a box filter, but whatever).
https://www.level.org.nz/energy/active-ventilation/
"The ventilation rate for houses is often described as the number of air changes per hour (ach). This is how many times a volume of air equal to the house volume has entered and left the house in 1 hour. A healthy ventilation rate is 0.35–0.5 ach. In other words, one third to one half of the volume of air in a house is replaced each hour."
3 bedrooms and they are only 30sqm total ??? thats pretty small.
i'm guessing for your whole house will be less than 100l/hr (assuming about 200sqm total). at the lowest speed, LGH-25RVX3-E runs at 1020l/hr. its massively oversized, its 10x the amount of air flow for the whole house at its lowest possible speed. someone really screwed up the airflow calcs.
thats really going to screw with the house let alone on full speed. i would go pull the plug on it until you get things sorted.
AlDrag:
Well damn, this may also explain a lot....this is 2 months worth of use on the inline sock filter for the Lossnay fresh air (I requested a box filter, but whatever).
not surprised when your sucking in 40-50x the required airflow. you have had 80-100 months worth of normal airflow through it.
tweake:
https://www.level.org.nz/energy/active-ventilation/
"The ventilation rate for houses is often described as the number of air changes per hour (ach). This is how many times a volume of air equal to the house volume has entered and left the house in 1 hour. A healthy ventilation rate is 0.35–0.5 ach. In other words, one third to one half of the volume of air in a house is replaced each hour."
3 bedrooms and they are only 30sqm total ??? thats pretty small.
i'm guessing for your whole house will be less than 100l/hr (assuming about 200sqm total). at the lowest speed, LGH-25RVX3-E runs at 1020l/hr. its massively oversized, its 10x the amount of air flow for the whole house at its lowest possible speed. someone really screwed up the airflow calcs.
thats really going to screw with the house let alone on full speed. i would go pull the plug on it until you get things sorted.
Yea the rooms are only 3 x 3. The master only slightly larger.
And we didn't duct the entire house. Downstairs is about 6 x 6. The stairs/landing/hallway probably adds up to about 5 x 5 in total maybe.
Well shit, that's depressing... Both disappointed by both the Lossnay and the Airtouch. Massive waste of money.
I assume if I turn off the Lossnay unit at the wall, the rest of the system will work just fine? Don't need to remove any ducts or anything? Not sure if the unit itself has smart dampers to stop airflow.
I'm an idiot and paid up ages ago, as I did think it was mostly ok. They wouldn't understand the flow rate is too high, so maybe I just need to cut my losses. Sell the Lossnay unit if I don't think it adds much to our quality of life.
give me a mo, i've not had enough coffee because i stuffed up the figures. but something still doesn't look right, i wonder if mitsi printed wrong specs. brb.
i screwed up there, sorry for the heart attack !
you need 38m3/h or 38000l/h or 10.5l/s.
add in the hallway, about 25l/s, so putting it on low speed would be about right...........i need more coffeeee.
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