Dehumidifier that will run at a given time each day

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#2956558 19-Aug-2022 12:24

timmmay:

I find it better to prevent the causes of moisture rather than fixing problems. Good extraction in the bathroom, rather than the tiny integrated units. An extractor in the kitchen. Plastic ground sheeting under the house. Ventilation is still important, we have positive pressure which we run on a timer.

But with all that done, or as a stopgap, dehumidifiers are ok.

Thats all good and should be done, but, especially up north, is ventilation can only dry it down to the outsides humidity level. If your 85% humidity & 22c (so your not running air con or heating), then ventilation doesn't do a whole lot and your in the mold danger zone. Only way your getting that humidity down is a dehumidifier. To keep it down you will also need a fairly air tight house (preferably with an ERV) otherwise all the air leakage and ventilation air just fills the house up with moisture again.

sparky1685

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#2956630 19-Aug-2022 16:44

We have a Goldair dessicant dehumidifier GD330, and if I switch that off at the wall then turn the power back on, it resumes on the same settings it was at, so that seems as if it would work with a timer switch.

neb

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#2957172 21-Aug-2022 05:33

Another option I'd initially skipped because it looked a bit gimmicky but recently had another look at is the Midea Cube, which gets pretty good reviews across multiple forums. This has an ingenious 12L tank that's just a big square bucket that it sits on top of, as opposed to the dinky little 3L or so tanks that standard dehumidifiers have which you have to wrestle into and out of the side of the case and that you need to empty every day or two in the worst case. It's also much, much cheaper than the Goldair and Breville ones, and despite needing a custom Midea control app rather than Breville's Home Connect it's no worse than the Goldair which also needs a custom app.

Wakrak

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#2957178 21-Aug-2022 07:57

neb: Another option I'd initially skipped because it looked a bit gimmicky but recently had another look at is the Midea Cube

Use code AFTERPAYDAY20 if you're going to buy from the Midea site ($329 + Shipping or free c&c Auckland / Christchurch).

$314.10 + Shipping with code TMXLK524 on The Market

SATTV

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#2957202 21-Aug-2022 09:04

Why not get a heatpump installed?

They have a dehumifying function and drains outside, set and forget.

Even the cheapest ones have timers to turn on and off at specified time. You also get the added bonus of a heater if you need it, a cooler if you need it and a fan if you need it.

John

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tweake

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#2957207 21-Aug-2022 09:30

SATTV:

Why not get a heatpump installed?

They have a dehumifying function and drains outside, set and forget.

Even the cheapest ones have timers to turn on and off at specified time. You also get the added bonus of a heater if you need it, a cooler if you need it and a fan if you need it.

John

They are not a dehumidifier. the dry function is basically running the air con on low fan speed. So they cool the room down which can make things worse (moisture can now condense on room surfaces). Obviously they will only run down to a certain temp, then they typically wait until the temp rises before running. In a basement that will never happen.

The dry function is made for high temp high humidity situations like summer humidity, where you cool the room down and the sun heats the room back up. However i find this really doesn't work well because standard homes are often to air leaky allowing the humidity in much faster than the heat. ie the heat pump won't run enough to dehumidify the room. Imho its better to use separate machines for separate jobs. Dehumidifier to dry the room, heatpump to heat/cool.

richms

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#2957261 21-Aug-2022 13:36

neb: Another option I'd initially skipped because it looked a bit gimmicky but recently had another look at is the Midea Cube, which gets pretty good reviews across multiple forums. This has an ingenious 12L tank that's just a big square bucket that it sits on top of, as opposed to the dinky little 3L or so tanks that standard dehumidifiers have which you have to wrestle into and out of the side of the case and that you need to empty every day or two in the worst case. It's also much, much cheaper than the Goldair and Breville ones, and despite needing a custom Midea control app rather than Breville's Home Connect it's no worse than the Goldair which also needs a custom app.

Does it have a lid on the big square bucket with just a small entry to it? Doesnt look it since it seems to have the mecanical half sitting inside it in some of the photos. My dehumidifiers all have absurd open containers making it a right pain to carry them without water slopping out of them.

Richard rich.ms

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mudguard

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#2957269 21-Aug-2022 14:03

I always wondered about that. What does a dehumidifier do that a heat pump can't?

I run our bedroom one on dry and it pulls the humidity down by almost twenty percent?

neb

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#2957273 21-Aug-2022 14:12

Wakrak:
neb: Another option I'd initially skipped because it looked a bit gimmicky but recently had another look at is the Midea Cube

Use code AFTERPAYDAY20 if you're going to buy from the Midea site ($329 + Shipping or free c&c Auckland / Christchurch).

$314.10 + Shipping with code TMXLK524 on The Market

Damn, saw this right after I'd ordered it. If anyone else was thinking of getting one though it's definitely a good deal.

tweake

2391 posts

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#2957277 21-Aug-2022 14:27

mudguard: I always wondered about that. What does a dehumidifier do that a heat pump can't?

I run our bedroom one on dry and it pulls the humidity down by almost twenty percent?

A dehumidifier will keep working. A heat pump will stop when it gets to cold. Having a cold room can cause condensation issues.

Heating. A dehumidifier will heat the room which in turn helps dry it. In winter thats fine as it saves you a bit of heating from your main heat source. A heat pump costs you to cool/dry, then you need to heat the room back up again which costs you.

For summer its often fine if your using aircon anyway. dry mode is simply aircon with low speed fan anyway.

One thing often overlooked is walls actually get condensation inside them (Branz has an article on it). if you make the room to cold that can increase the condensation to a point where mold starts growing inside the walls. Our walls are not air sealed on the outside so we can get moist outdoor air coming into the wall and hitting the cold gib, when it condensates. typically it get soaked up by the gib and dries out.

So don't go crazy on the room temps.

neb

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#2957392 21-Aug-2022 20:03

richms:
Does it have a lid on the big square bucket with just a small entry to it? Doesnt look it since it seems to have the mecanical half sitting inside it in some of the photos. My dehumidifiers all have absurd open containers making it a right pain to carry them without water slopping out of them.

No, no lid, but it's a 12L bucket and you can tell it to stop at some arbitrary point before it fills it to 12L, at which point it'll ping you and tell you to empty it.

neb

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#2957393 21-Aug-2022 20:12

tweake:
A dehumidifier will keep working. A heat pump will stop when it gets to cold. Having a cold room can cause condensation issues.

There's also very little around about the effectiveness of a heat pump as a dehumidifier that isn't written by heat pump vendors. Given the absence of any quoted figures it seems more like a y'all-watch-this than something it's well suited to, what it looks like it's doing is forcing the evaporator to frost up after which the compressor shuts off and the air flow melts the frost, drawing moisture out of the air as it warms back up to the dew point. Once it's warmed up the compressor starts up again and the cycle repeats. So while it's possible to do this with a heat pump, is it actually sensible to do so compared to a dedicated dehumidifier that's specifically designed to do the same thing?

tweake

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#2957402 21-Aug-2022 21:10

neb:
tweake:

A dehumidifier will keep working. A heat pump will stop when it gets to cold. Having a cold room can cause condensation issues.

There's also very little around about the effectiveness of a heat pump as a dehumidifier that isn't written by heat pump vendors. Given the absence of any quoted figures it seems more like a y'all-watch-this than something it's well suited to, what it looks like it's doing is forcing the evaporator to frost up after which the compressor shuts off and the air flow melts the frost, drawing moisture out of the air as it warms back up to the dew point. Once it's warmed up the compressor starts up again and the cycle repeats. So while it's possible to do this with a heat pump, is it actually sensible to do so compared to a dedicated dehumidifier that's specifically designed to do the same thing?

Not really. They don't frost, thats why they have evap temp sensors. Pretty common tech to drive air temp down to just above freezing anyway. For normal room temps it doesn't go that cold, i did test it at one stage. The main problem comes from the fact that its a split unit, so its pumping heat outside instead of keeping it inside. You run out of room temp which stops it from running. Its not made for dehumidifying as such, at least on mine they do not advertise it as such, its a tweak to increase moisture removal in hot humid conditions.

neb

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#2957852 22-Aug-2022 15:08

Interesting seeing what the dehumidifier is actually doing, from the device itself you just getting running/not running (via noise levels) but this is the actual effect:

The set point is 55%, so it's overshooting by a few percent below 55, then waiting till it creeps up again by a few percent over 55, and then cycling (hysteresis management, so it's not continuously toggling around the set point like too many heat pumps do).

neb

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#2960262 27-Aug-2022 17:39

sparky1685:
We have a Goldair dessicant dehumidifier GD330, and if I switch that off at the wall then turn the power back on, it resumes on the same settings it was at, so that seems as if it would work with a timer switch.

With the Midea one I'm now using, the second warning after the initial "don't exceed the rating of the power outlet" is "don't operate or stop the unit by switching the power on or off". So while it may work, the manufacturers seem to be warning against it quite strongly, and it may be a warranty-voiding mode of operating it.

There's also this sage advice:

Possibly machine-assisted translation, there's a word form "culu" which can mean a range of things that includes "rough" but also "rude".

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