Recommend inline filter box with drop in easily replicable HEPA / charcoal filters?

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#3310338 18-Nov-2024 20:14

nzben: comes with a standard MERV filter, not sure what the differences are to HEPA, but the specs on what microns it can filter out appears to be better than HVAC HEPA filters.

https://herbals.co.nz/products/inline-air-filter-box-6-150mm-ac-infinity?_pos=1&_sid=32c8c1dc9&_ss=r

another option. seams to use a common usa hvac filter. not sure on availability here.

it doesn't list the filters rating at all, their mention of microns is just BS.

an F7 filter is equal to a merv 13 filter. f9 = merv 16, then your into hepa filters.

tweake

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#3310343 18-Nov-2024 20:20

AlDrag:

With the lossnay system, do you end up removing the filters from that and instead rely on the filters for this one to avoid further inefficiency?

with loosnay you would keep their basic filter. if they have options, get their low grade filter. its only there to protect the core from house hold stuff (cat fur, sucked into the return) or if the main inlet filter is split, put in badly etc.

Kickinbac

427 posts

Ultimate Geek

#3310358 18-Nov-2024 21:31

AlDrag:
With the lossnay system, do you end up removing the filters from that and instead rely on the filters for this one to avoid further inefficiency?

I’ve left them in to protect the heat exchanger core. I haven’t put better additional filters on the exhaust (yet). I have three return grilles so costly to add filter grilles!

Additional filters increase the pressure drop and the energy consumption.

Something for you to consider is access to get to the filters in the Lossnay. The bathroom grilles won’t have filters so dust and lint is going to end up in the Lossnay filters. There’s two filters on supply and exhaust. So you’ll want the Lossnay to be fairly close to the access hatch.

This is a reason why most domestic AC units have filter return grilles, so that they are easy to access for cleaning and replacement.

timmmay

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#3310676 19-Nov-2024 15:54

Thanks all for the thoughts. It seems like two have two filters I need two housings, none that I've found can do two filters - I'd like HEPA or similar for dust / pollen / etc and carbon or similar for smells. That makes things quite a bit more expensive.

The AC Infinity stuff looks good if you want a single filter. I already have smart vent stuff with a fairly poor way of attaching the ducts which involves springs and duct tape, a filter box would be a step up in ease of use. The SIMX filter boxes take the same kind of filters I already have, but it's a much nicer way to mount them.

timmmay

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#3380309 3-Jun-2025 21:40

I've found a decent looking filter that has pre-filter, activated carbon filter, and HEPA filter - pdf specs link, website link, Ali Express link. The 200mm diameter ducted version is NZ$383, going down to $222 for the 100mm version, but I have 200mm ducts. Filter refills $100 per set here, or $150 here - but it's a bit confusing. I've emailed them to ask about it.

For domestic ventilation with 200mm ducts, it probably makes sense to get the 200mm version. However, I wonder if we'd get away with the 150mm version and duct adapters to reduce the duct size, to drop the cost from NZ$383 to NZ$211 and reduce the size of filters. Airflow would be lower, but I guess it would still be ok. I guess the larger filter would probably last longer given the larger surface area, given the same running time. Thoughts?

zenourn

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#3380365 4-Jun-2025 09:45

I'd go for a system with as large a surface area as possible - so the 200mm. I've now had my cleanaire filter bag system with GU4 and charcoal filters with over 1m^2 of filter area for over two years and it provides great performance and the filters aren't showing any signs of being clogged.

timmmay:

I've found a decent looking filter that has pre-filter, activated carbon filter, and HEPA filter - pdf specs link, website link, Ali Express link. The 200mm diameter ducted version is NZ$383, going down to $222 for the 100mm version, but I have 200mm ducts. Filter refills $100 per set here, or $150 here - but it's a bit confusing. I've emailed them to ask about it.

For domestic ventilation with 200mm ducts, it probably makes sense to get the 200mm version. However, I wonder if we'd get away with the 150mm version and duct adapters to reduce the duct size, to drop the cost from NZ$383 to NZ$211 and reduce the size of filters. Airflow would be lower, but I guess it would still be ok. I guess the larger filter would probably last longer given the larger surface area, given the same running time. Thoughts?

timmmay

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#3380387 4-Jun-2025 10:26

Yeah, larger with more surface area is better. @zenourn can you buy just the Cleanaire filters? I had a look on their website but couldn't see anything.

I have my ventilation system bringing air in from outside as the ceiling cavity space is a bit old and smelly at times. Currently I have the filter between the inlet and the motor, but doing things that way if the filter box isn't 100% sealed it can suck dirty ceiling air into the house. If I put the filters after the motorso it's pushing filtered air that might increase air quality, but also leaves the motor without a filter before it. Apparently filter before the pump is most normal, and for critical applications you can have a pre-filter before the motor then HEPA filter afterwards, but that increases the number of filters and costs. Any thoughts on that?

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zenourn

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#3380398 4-Jun-2025 11:21

timmmay:

Yeah, larger with more surface area is better. @zenourn can you buy just the Cleanaire filters? I had a look on their website but couldn't see anything.

I'd give them a call, they were rather helpful when I visited them. I'm going to contact them to get spare bag filters for when it comes time to replace mine.

I have my ventilation system bringing air in from outside as the ceiling cavity space is a bit old and smelly at times. Currently I have the filter between the inlet and the motor, but doing things that way if the filter box isn't 100% sealed it can suck dirty ceiling air into the house. If I put the filters after the motorso it's pushing filtered air that might increase air quality, but also leaves the motor without a filter before it. Apparently filter before the pump is most normal, and for critical applications you can have a pre-filter before the motor then HEPA filter afterwards, but that increases the number of filters and costs. Any thoughts on that?

I have my filters between the outside inlet and motor. In my case the filter system has an excellent seal so I don't have the issue of taking in air from the ceiling. In general I'd highly recommend having the filter before the motor as dust can reduce the lifespan of the motor.

tweake

2391 posts

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#3380484 4-Jun-2025 17:38

timmmay:

I've found a decent looking filter that has pre-filter, activated carbon filter, and HEPA filter - pdf specs link, website link, Ali Express link. The 200mm diameter ducted version is NZ$383, going down to $222 for the 100mm version, but I have 200mm ducts. Filter refills $100 per set here, or $150 here - but it's a bit confusing. I've emailed them to ask about it.

For domestic ventilation with 200mm ducts, it probably makes sense to get the 200mm version. However, I wonder if we'd get away with the 150mm version and duct adapters to reduce the duct size, to drop the cost from NZ$383 to NZ$211 and reduce the size of filters. Airflow would be lower, but I guess it would still be ok. I guess the larger filter would probably last longer given the larger surface area, given the same running time. Thoughts?

the 150mm versions filters are to small. you will need the larger size. however first thing is to go find the filters and check air flow specs (and availability).

timmmay

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#3380566 4-Jun-2025 19:51

tweake:

the 150mm versions filters are to small. you will need the larger size. however first thing is to go find the filters and check air flow specs (and availability).

The larger size has more than double the filter surface area. There's no airflow specs available - I'm more concerned with filtration than airflow, I can always turn the motor up as it's running at half speed right now. Filters seem to be available easily from the company, plus I've learned recently when I called SmoothAir you can get custom sized filters made in NZ.

Can anyone see a good reason that I wouldn't buy this filter / filter box? It'd cost $230 or so for a basic plastic filter box with a decent filter in NZ, this one costs $380 and is almost exactly what I was looking for.

tweake

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#3380569 4-Jun-2025 20:01

timmmay:

The larger size has more than double the filter surface area. There's no airflow specs available - I'm more concerned with filtration than airflow, I can always turn the motor up as it's running at half speed right now. Filters seem to be available easily from the company, plus I've learned recently when I called SmoothAir you can get custom sized filters made in NZ.

Can anyone see a good reason that I wouldn't buy this filter / filter box? It'd cost $230 or so for a basic plastic filter box with a decent filter in NZ, this one costs $380 and is almost exactly what I was looking for.

you may find that even turning up the fan, you generate more noise than airflow. with hepa filters, size is king. the 150mm size is ok if it wasn't hepa. (typical ventilation filter is 300x300 roughly)

the other downside, and a project i need to do, is to insulate the outside of the metal box.

timmmay

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#3380574 4-Jun-2025 20:16

tweake:

you may find that even turning up the fan, you generate more noise than airflow. with hepa filters, size is king. the 150mm size is ok if it wasn't hepa. (typical ventilation filter is 300x300 roughly)

the other downside, and a project i need to do, is to insulate the outside of the metal box.

These filters are 430 x 300 so about 1/3 larger.

If I have the filter box in the ceiling space, and it's pulling air from outside, the filter box will usually be warmer than the air coming in. Doesn't that mean condensation will form on the outside of the filter box? Insulating the outside might reduce the condensation, or I could just put something underneath it to catch drips.

tweake

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#3380825 5-Jun-2025 17:29

timmmay:

These filters are 430 x 300 so about 1/3 larger.

If I have the filter box in the ceiling space, and it's pulling air from outside, the filter box will usually be warmer than the air coming in. Doesn't that mean condensation will form on the outside of the filter box? Insulating the outside might reduce the condensation, or I could just put something underneath it to catch drips.

the 150 dia is only 295 x 170.

insulation is not about condensation. its about stopping the ceiling space heating up the ventilation air. most pps use a temp sensor in the fan for the air temp to control fan speed. even with mine which takes air from outside and i have all insulated ducting, the fan and filter gets heat soaked enough to turn off from high temps. keep the fan cool so it can keep going.

timmmay

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#3380868 5-Jun-2025 20:22

True. The larger size has 2.2 times the surface area. The 430 x 300 are about 1/3 larger than the standard 300 x 300.

My positive pressure system is extremely simple. It's a duct from the eaves through a filter, to a motor, through a splitter to two rooms. The fan speed is constant, and it's on a WiFi timer. Really simple. I'd have thought with the fan being inline the air from outside would keep it cool either way. Glad I don't have to bother with insulation! I'm likely to order that system, it looks pretty good.

Kickinbac

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Ultimate Geek

#3381055 6-Jun-2025 09:30

For the Ali express filter, there is no information on the pressure drop of the filter(s), this could be considerable with the filter, carbon filter and hepa filter. The higher the filtration grade, the higher the pressure drop.

Timmmay - we don't know the airflow of your system, but I'm going to assume it's no more than 50 l/s.

When designing a system we look at the pressure drop of all the system components and check that against the fan curve to slect the right fan for the job. For example, the fan may deliver something like 50 L/s @ 100 pa. If the clean filter has a pressure drop of 80 Pa that leaves 20 Pa for all the duct work. As the filter gets dirty, the pressure drop increase so the airflow reduces.

Bearing that in mind I often allow a velocity over the filter at no more than 2.5 m/s.

The construction of the unit looks very similar to the SIMX filter I have, shown earlier in this post. I like that it has the prefilter, its good to have this to catch the big stuff and keep the hepa clean for longer. I'm going to do some testing this weekend and measure the pressure drop and airflow of the my Lossnay system. Being the great professional that I am I've never done this at home, and I have all the testing equipment needed. 🙄

A magnehelic differential pressure gauge like this is good to monitor the condition of filters. I've never seen one installed in a home ventilation system, you can, but its just for ventilation geeks! They are commonly installed on Air Handler Units (AHU) in say a hospital to monitor the condition of the filters. This means the filters are generally only replaced when needed when the pressure drop is too high. Its also good for reducing energy use. In these systems we often have the control system monitoring the pressure drop across the filters and the fan speed increases to maintain a constant airflow. But you need to know what the pressure drop is clean and then dirty.

https://www.aliexpress.com/item/1005003717813308.html?spm=a2g0o.productlist.main.4.3262J4KCJ4KCLm&algo_pvid=e1d72728-eea3-47c6-a0df-4c383abad4d6&algo_exp_id=e1d72728-eea3-47c6-a0df-4c383abad4d6-3&pdp_ext_f=%7B%22order%22%3A%2288%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21NZD%2126.07%2126.07%21%21%2115.42%2115.42%21%402101ea7117491579471665682e7268%2112000034116489994%21sea%21NZ%21798135583%21ACX&curPageLogUid=iVhzrNoWwimY&utparam-url=scene%3Asearch%7Cquery_from%3A

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