Recommendations to replace a 3-in-1 Light/Fan/Heatlamp in bathroom

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CrazyM

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#299322 29-Aug-2022 16:12

Hi,

My house has those rectangular 3-in-1 heat/fan/light units in the bathrooms. The heatlamps have no value for me (I have replaced with large LED globes to great effect), and the exhaust fan is so weak it may as well not be there. Below is a similar model to what I have.

https://www.mitre10.co.nz/shop/aerlite-heat-fan-light-100mm-white/p/165312

My goal is to have much better extraction. Does anyone have any recommendations for a light/fan unit that fits in the same rectangular hole, or is larger? I dont want to have to patch and repaint the ceiling if I can help it.

Cheers

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#2960838 29-Aug-2022 17:21

Those integrated units aren't great. If you have space get something from Fantech or Ming Fans, which will put a diffuser in the room and the actual fan up in the ceiling somewhere. Add LED downlights separately.

If that be too difficult I wonder if you can connect a duct to the existing vent and connect it to a more powerful extraction fan from one of the vendors above.

neb

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#2960842 29-Aug-2022 17:39

timmmay:
Those integrated units aren't great.

That's a novel way to spell "absolute garbage".

There's two in the Casa as well, kludged in, like everything else here, by previous owners. As with @CrazyM, the heat lamps were replaced with LED lights long ago, and the fan seems to have no effect at all apart from the rattling drone it makes.

Mind you, it seems like every house more than a few decades old is a cowboy palace. Was talking to one of the neighbours a few days ago and got to hear of the ceiling insulation that gave you a slight tingle when you touched it (bare wire ends twisted together under the insulation), the 1.5mm lighting wire with eight power points wired up to it (he realised that it was feeding more than just a lighting circuit when he noticed that it was very warm to the touch), the two-way light switch that used the earth wire as a second active wire, the mass of wires soldered together and jammed into a 32A circuit, the deck where they'd skipped the hangers to save a bit of time and money, the ...

lxsw20

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#2960849 29-Aug-2022 18:09

Have you had a look in the ceiling to make sure the pipe has a good run outside? No dips in the pipe that could be filling with water? Is there a good air supply getting into the room when the door is closed? Can you feel an airflow under the door when the fan is on?

CrazyM

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#2960966 29-Aug-2022 20:20

Thanks for your comments guys.

I had hoped there might be a rectangular unit out there with a big extract grill in the middle and lights on the side. Sounds like I should just do the extract separate.

Maybe I’ll leave the current combo unit in there just as the lights and then get the separate fan wired onto the existing fan/light/heat switch.

timmmay

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#2960974 29-Aug-2022 20:40

That sounds like a good idea. I've had two fans now, one wore out after about 8 years. The first was this one (manrose pro), the second I can't remember. I have the diffuser directly over the shower, as that's the main place steam is created, which happens to be on the opposite side of the room from the door.

neb

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#2960982 29-Aug-2022 21:26

timmmay:
That sounds like a good idea. I've had two fans now, one wore out after about 8 years. The first was this one (manrose pro), the second I can't remember.

Holy cow, nearly $300 for a (say) 120mm fan and a bit of plastic duct? I've got a spare 120mm Panaflo I could solvent-weld into a piece of ducting for a total cost of under $10, or maybe $30 total if I had to buy the fan first.

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#2960983 29-Aug-2022 21:33

CrazyM: Thanks for your comments guys.

I had hoped there might be a rectangular unit out there with a big extract grill in the middle and lights on the side. Sounds like I should just do the extract separate.

Maybe I’ll leave the current combo unit in there just as the lights and then get the separate fan wired onto the existing fan/light/heat switch.

That's what I've done. Disconnected the small fan unit, and installed a 150mm high flow in-line fan (think it was 400m3 / hour) with the vent over the shower. Reused the old fan switch.

The flow of the new unit must be 10x or more than the pathetic thing built into the light unit was.

I've kept the heat lamps because it's quite nice on a cold day to have some instant heat when you jump out the shower.

timmmay

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#2960986 29-Aug-2022 21:41

neb:
timmmay:
That sounds like a good idea. I've had two fans now, one wore out after about 8 years. The first was this one (manrose pro), the second I can't remember.

Holy cow, nearly $300 for a (say) 120mm fan and a bit of plastic duct? I've got a spare 120mm Panaflo I could solvent-weld into a piece of ducting for a total cost of under $10, or maybe $30 total if I had to buy the fan first.

I think with install cost it was more like $600 installed. The fans aren't cheap but they're powerful, dual speed, made for damp air, and last many years.

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#2960988 29-Aug-2022 21:45

timmmay:
Those integrated units aren't great. If you have space get something from ...Ming Fans, which will put a diffuser in the room and the actual fan up in the ceiling somewhere. Add LED downlights separately.....

http://www.mingfans.co.nz/index.php/product/index/id/52.html
This is what HRV use if you go with their "Vortex" option for bathrooms. Nice find!

I also got my sparky to add a timer to my fan, so it runs for another 7 minutes after I turn the switch off.

neb

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#2960989 29-Aug-2022 21:47

timmmay: The fans aren't cheap but they're powerful, dual speed, made for damp air, and last many years.

That was my only concern, would a standard PC cooling fan handle damp air? Power and longevity aren't a problem, they're designed for continuous operation over a period of years, the only concern is how well they deal with damp air. The Panaflos claim sealed bearings, but I'm not sure what that says about the fan as a whole.

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#2961002 29-Aug-2022 22:34

A PC fan is way, way less powerful than a dedicated bathroom fan. I'd have to look up specs but I'd say they're not even in the same ballpark in terms of throughput.

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#2961005 29-Aug-2022 22:45

timmmay:
A PC fan is way, way less powerful than a dedicated bathroom fan. I'd have to look up specs but I'd say they're not even in the same ballpark in terms of throughput.

That really depends on what you're comparing it to. A asthmatic 80-year-old moves more air than our current bathroom fan...

But in general, sure, PC fans don't move that much air compared to a serious 240V one.

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#2961033 30-Aug-2022 07:07

I just did a quick calculation, I'm surprised how well the PC fan did. It's only 30% the throughput of the 150mm Manrose we have, but that's better than I expected. However, the PC fan probably assumes in free air, whereas the Manrose spec is probably with some length of ducting attached. So maybe not directly comparable. It does make sense that a big 230V fan is a lot more powerful than a small PC fan that's optimised for being quiet.

Panaflo NMB 120x120x38mm High Speed Fan FBA12G12HL 103.8 CFM = 176 m3/hr
Manrose 125mm: 125mm: 320m3/hr
Manrose 150mm: 597m3/hr

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#2961224 30-Aug-2022 16:32

A couple of years ago I replaced the (actually broken) fan from an old bathroom heat/light/fan combo unit with one of these:

Weiss Intelli-Flow Automatic Extraction System - ER08P

https://www.weiss.co.nz/extraction/er08p-intelli-flow-extraction-system

I really rate it. It's much quieter than the old fan (when it was working) - new fan unit is in ceiling with ducting going to new vent hole above shower.

Instead of a fixed length timer, it has a moisture sensor that governs how long it runs for.

It's made the bathroom MUCH drier - I haven't seen any signs of mould since it was installed, and the bathroom mirror takes a lot longer to fog up & clears up really quickly once shower is over.

A quick google & it looks like they are still available from the usual suspects (Mitre10, Trade Depot, Plumbing World, Mico, Placemakers etc).

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#2961312 30-Aug-2022 21:00

timmmay:
I just did a quick calculation, I'm surprised how well the PC fan did. It's only 30% the throughput of the 150mm Manrose we have, but that's better than I expected. However, the PC fan probably assumes in free air, whereas the Manrose spec is probably with some length of ducting attached. So maybe not directly comparable. It does make sense that a big 230V fan is a lot more powerful than a small PC fan that's optimised for being quiet.

Panaflo NMB 120x120x38mm High Speed Fan FBA12G12HL 103.8 CFM = 176 m3/hr
Manrose 125mm: 125mm: 320m3/hr
Manrose 150mm: 597m3/hr

The PC fan rating is almost certainly free-air, but then they're also designed to push air into or pull air out of a mostly-sealed PC case so they can certainly move air in the presence of a lot of back pressure.

Given that they're mostly silent and fairly low-power, it'd be interesting to have one operating at each end of a duct, so the one in the bathroom ceiling pushing air into a low-pressure zone created by the one at the exit point. You could just run them for a longer period (because of the low noise and power) and cycle out all the air in the room.

Any fluid dynamics experts here?

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