Panasonic vs Mitsubishi ducted heat pump and ventilation solutions

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2391 posts

Uber Geek

#3317322 5-Dec-2024 19:15

AlDrag:

I guess if someone ran a super hot shower for 30 mins without running the extractor fan, all that humidity would fill the house.

So the impression I'm getting, if I don't have a dehumidifer, is that with an ERV, we are able to have a dryer home, as it avoids bringing in Auckland humidity from the outside, but you run the risk of appliances in the house circulating humidity everywhere. Can get the humidity get too low?

HRV will always maintain the same humidity as outside, but probably a little lower due to the a/c. But obviously humidity won't get as low as ERV. I assume no where near as low.

Is this accurate? Sorry if I'm slow in understanding.

roughly put, the erv will maintain the humidity. if the indoor humidity is high or low depends on whats going on in the house and machines (dehumidifier, aircon etc). the erv won't send moisture out, but it also won't bring it in. so your not using the ventilation to dry the house like we typically get told to do. hence the need to monitor it (which costs like $10).

an hrv will bring in whatever humidity it is outside. no different to having a window open in that respect. same issue with positive pressure systems. i found reducing the ventilation lowered the humidity in the house, which is the opposite of what we typically get told.

AlDrag

247 posts

Master Geek

#3317324 5-Dec-2024 19:25

tweake:
roughly put, the erv will maintain the humidity. if the indoor humidity is high or low depends on whats going on in the house and machines (dehumidifier, aircon etc). the erv won't send moisture out, but it also won't bring it in. so your not using the ventilation to dry the house like we typically get told to do. hence the need to monitor it (which costs like $10).

an hrv will bring in whatever humidity it is outside. no different to having a window open in that respect. same issue with positive pressure systems. i found reducing the ventilation lowered the humidity in the house, which is the opposite of what we typically get told.

That totally makes sense. Thanks for being patient.

So I guess the only remaining problem is the garage. I assume the return in the upstairs ceiling will pull air from the not-so-well-sealed-garage. I could probably improve this by putting a draft stopper on the internal door to the garage.

Ugh so frustrating building companies skimp on this shit. Thin walls, thin floors and no heating/cooling solution upstairs. At least I have a massive attic I guess. Can stand up within a 10 x 2.4m2 area.

tweake

2391 posts

Uber Geek

#3317330 5-Dec-2024 19:56

with the garage it should have an external rated (ie outdoors) door on the house side. ie it has all the weather proofing and seals. you want it to air seal.

having bedrooms above garages is really poor. you really want to makes sure the garage is well ventilated. all that water that clings to a wet car, plus the residual heat, means a ton of moisture gets put into the garage and it all wants to go up. thats up into the bedroom. not to mention car fumes, petrol fumes etc. having a loose fitting garage door allows some ventilation in/out.

AlDrag

247 posts

Master Geek

#3317331 5-Dec-2024 19:58

tweake:
with the garage it should have an external rated (ie outdoors) door on the house side. ie it has all the weather proofing and seals. you want it to air seal.

having bedrooms above garages is really poor. you really want to makes sure the garage is well ventilated. all that water that clings to a wet car, plus the residual heat, means a ton of moisture gets put into the garage and it all wants to go up. thats up into the bedroom. not to mention car fumes, petrol fumes etc. having a loose fitting garage door allows some ventilation in/out.

Like most kiwis, we won't be putting a car in the garage haha. Ours is far too small for that anyway. But our master bedroom is above the garage. Pretty sure the fletcher standard is to insulate any internal wall (and hopefully floor) that touches a garage....

tweake

2391 posts

Uber Geek

#3317332 5-Dec-2024 20:01

AlDrag:

Ugh so frustrating building companies skimp on this shit. Thin walls, thin floors and no heating/cooling solution upstairs.

pretty normal for nz.

HVAC is still a pretty new idea for nz. its going to take a few decades for people to click that its better to build the house to work with those systems rather than retrofit.

AlDrag

247 posts

Master Geek

#3317547 6-Dec-2024 12:33

Install is basically booked in this month. Can't wait.

So for the Lossnay ERV, I ain't going to do the fresh air downstairs yet. Maybe in the future if I feel like we need it. Just too much going on at the moment.

So if I did add the extra fresh air vent downstairs, that would mean I'd need a bigger lossnay unit (supposedly). Is there a negative to having an oversized lossnay? Because I could get the bigger one now for "future proofing". The installer didn't seem to think so, just said it means more fresh air would be coming into the system.

timmmay

20575 posts

Uber Geek

Trusted

Lifetime subscriber

#3317575 6-Dec-2024 12:56

Doing things in future can be more difficult / expensive than you expect. Do it now or don't bother.

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AlDrag

247 posts

Master Geek

#3317579 6-Dec-2024 13:07

timmmay: Doing things in future can be more difficult / expensive than you expect. Do it now or don't bother.

Hahaha yea...i just don't know if I need it or not. Especially since it's a little intrusive.

timmmay

20575 posts

Uber Geek

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Lifetime subscriber

#3317580 6-Dec-2024 13:09

Getting ducts downstairs would be annoying, and take up space on the top floor. I probably wouldn't bother personally.

AlDrag

247 posts

Master Geek

#3317582 6-Dec-2024 13:12

timmmay:
Getting ducts downstairs would be annoying, and take up space on the top floor. I probably wouldn't bother personally.

Yea it'd go through one of the wardrobes. It's small, 150mm, but yea still annoying. Plus not sure if it'll produce any extra noise in the rooms or not. Hmmmm. I guess we have the garage downstairs anyway Hahaha....

tweake

2391 posts

Uber Geek

#3317624 6-Dec-2024 16:45

AlDrag: Install is basically booked in this month. Can't wait.

So for the Lossnay ERV, I ain't going to do the fresh air downstairs yet. Maybe in the future if I feel like we need it. Just too much going on at the moment.

So if I did add the extra fresh air vent downstairs, that would mean I'd need a bigger lossnay unit (supposedly). Is there a negative to having an oversized lossnay? Because I could get the bigger one now for "future proofing". The installer didn't seem to think so, just said it means more fresh air would be coming into the system.

i would check in the closets if you can actually do it. check the mail pattern on the floor to see if there is a joist under that spot. ceiling can be harder as the paint often hides the nails, but a stud finder works. if there is a joist of truss in the way then you can't do it so go for the smaller unit.

if i remember right the lossnays are now all ec motors and should be all variable speed both sides. so you can vary the airflow amount
(so you can get the correct ventilation rate) and vary the supply and return so you can match the flow rates or deliberately have more supply to make up for an air leaky home (its better to have air leaking out than air leaking in).

something i completely forgot about is if they have boost mode. for that to work you need a unit that can flow more than what you need.

AlDrag

247 posts

Master Geek

#3317635 6-Dec-2024 19:01

tweake:
i would check in the closets if you can actually do it. check the mail pattern on the floor to see if there is a joist under that spot. ceiling can be harder as the paint often hides the nails, but a stud finder works. if there is a joist of truss in the way then you can't do it so go for the smaller unit.

if i remember right the lossnays are now all ec motors and should be all variable speed both sides. so you can vary the airflow amount
(so you can get the correct ventilation rate) and vary the supply and return so you can match the flow rates or deliberately have more supply to make up for an air leaky home (its better to have air leaking out than air leaking in).

something i completely forgot about is if they have boost mode. for that to work you need a unit that can flow more than what you need.

That's if I can even control the Lossnay speed due to airtouch haha. Seems like I can't have both controllers...

Researching about erv vs hrv, seems like ERV is better than HRV in almost every single aspect. Apparently if the indoor does get more humid than the outside, which was your concern I think, ERV still can balance the moisture by exchanging the moisture between the incoming and outcoming air? So it seems perfect for Auckland.

Someone told me HRV is better as indoor humidity in their home is usually higher than the outside, but again, seems like ERV perfectly solves that?

ERV are just more expensive due to their permeable core.

tweake

2391 posts

Uber Geek

#3317645 6-Dec-2024 20:33

AlDrag:

Researching about erv vs hrv, seems like ERV is better than HRV in almost every single aspect. Apparently if the indoor does get more humid than the outside, which was your concern I think, ERV still can balance the moisture by exchanging the moisture between the incoming and outcoming air? So it seems perfect for Auckland.

Someone told me HRV is better as indoor humidity in their home is usually higher than the outside, but again, seems like ERV perfectly solves that?

ERV are just more expensive due to their permeable core.

erv is better but it can't "balance the moisture" as you suggest. it cannot dry a house via ventilation. it keeps indoor moisture indoors. as humans produce moisture indoors, the erv doesn't allow that moisture to escape via ventilation. that moisture can be removed via air leakage, other air outlets like range hood and dehumidifiers/aircon.

this is why i mention dehumidifiers. in a typical setup an erv is paired with a dehumidifier. instead of ventilation drying the house the dehumidifier is, and the erv makes that easier by keeping outdoor moisture out. your only dehumidifying inside the house, not the whole country side. if you have a good air tight house, you set the dehumidifier to 50% and it will stay there.

an hrv is fine if your outdoor humidity is ok as it will bring outdoor humidity into the house. but it will push indoor moisture outside. if the climates humidity is fine, an hrv will work just fine. if not an erv is a better choice.

AlDrag

247 posts

Master Geek

#3318825 10-Dec-2024 16:20

Ok I finally had a call with BDT.

They suggest HRV is better. Lossnay HRV to be fair does seem way more user friendly. Filters are more accessible for example and apparently it costs more...

They suggest it reduces humidity by I think running the exhaust air (which would be cold in summer) on it that would condense the water or something? Because an HRV has a drain. But then this goes against all the reading I've been doing that suggests ERV would be better for Auckland.

He said ERV when paired with aircon is fine if trying to reduce costs over HRV. He stated he has an HRV in his home.

Like there is so much contradictory information in this sector, it's messed up.

tweake

2391 posts

Uber Geek

#3318844 10-Dec-2024 18:08

AlDrag:

Ok I finally had a call with BDT.

They suggest HRV is better. Lossnay HRV to be fair does seem way more user friendly. Filters are more accessible for example and apparently it costs more...

They suggest it reduces humidity by I think running the exhaust air (which would be cold in summer) on it that would condense the water or something? Because an HRV has a drain. But then this goes against all the reading I've been doing that suggests ERV would be better for Auckland.

He said ERV when paired with aircon is fine if trying to reduce costs over HRV. He stated he has an HRV in his home.

Like there is so much contradictory information in this sector, it's messed up.

yeah the sector is messed up all right. big part of that is from salespeople talking crap to push whatever product they have to sell. but also because there is a lot of variables and every situation is different.

HRV reduces man made moisture through ventilation, just like opening windows.

the drain is there for when the airflow on one side is cold and the other side is damp and it gets condensation in the core. eg cold winter morning, very cold incoming air and someone takes a shower. moisture from shower goes through, hits the cold core and condensates a bit. or house is airconditioned extremely cold and very humid outside air, humidity will condense. but its a real stretch to claim "it reduces humidity".

erv/hrv filters should not need to be changed much because the incoming air should have its own separate filter (did they leave that out of the quote?) its the return side that should get dirty the most and that depends on how clean your house is. they are only there to protect the core, so they are a low grade filter. its a modern salesman thing to try and use that filter to clean the air, which causes restriction and sometimes a non-standard size (you have to buy their filters).

"ERV when paired with aircon is fine", that depends on the house. thats down to how air leaky the house is (outside humidity coming in), how hot the house is (lack of insulation and nz love affair with big windows), the size of the aircon and how you use the air con. basically they are using the aircon as a dehumidifier.

"ERV.....if trying to reduce costs over HRV. " true but cost isn't really the issue. ERV with aircon/dehumidifier will get you lower humidity, where as HRV with aircon/dehumidifier will not, because HRV brings in outside humidity.

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