Meaco Dehumidifer readings too low

tomp2494

I've had my dehumidifer for just under two years.
Yesterday it returned from repair under warranty, as it was displaying an error message on the screen. I also paid extra to have it serviced/cleaned.

Since turning it on yesterday I think the humidity readings on the screen are far too low.

It's currently displaying 48%. 
Since purchase in 2021 it struggles to get to 52% and turn itself off. 

The baseline humidity in my flat is around 70% 

I have a cheap indoor tempreature and humidity sensor. It says the humidity is 63% as I type. It's usually on 70% but the dehumidifer has been on for 2 hours.

Prior to sending the dehumidifer back they were both within 5% of each other all the time. 

My bedroom wall is still damp as a result of condensation from breathing. The dehumidifer is in the room next door, and the door to the room is open.
There's no way the humidity is 48% surely? 

It is possible to have over calibrated the humidity sensor at the repair shop?

I understand that there's no really accurate humidity sensor, but for there to be a 15% difference suddenly seems a bit odd.

My room temperature hasn't changed either, it's 21c as per indoor sensor or 21
5c as per heating thermostat 

FreeBear

tomp2494 said: I have a cheap indoor tempreature and humidity sensor. It says the humidity is 63% as I type. It's usually on 70% but the dehumidifer has been on for 2 hours.

There is an easy way to check the calibration of your cheap humidity sensor.

Take a small cup and fill it half full with common table salt. Add enough water to create a thick slurry. Place the cup along with the sensor in to an airtght container and leave for 12-24 hours. Between 20°C and 40°C, the relative humidity will remain fairly constant at 75%.

Using different salts, you can calibrate different levels of humidity fairly accurately. With any salt, the level of curacy is not to laboratory spec, but certainly good enough for a domestic environment.

If you are interested, a list of saturated salt solutions and the associated humidity levels - https://www.engineeringtoolbox.com/salt-humidity-d_1887.html - Three on the list are fairly common. Sodium Chloride (table salt), Potassium & Sodium Nitrate (fertilizer). and Potassium Hydroxide (caustic potash - not as common). Forget trying to get your hands on Sodium Dichromate - Sales to the public has been banned (very toxic stuff), although you might find a ebay seller or two peddling the stuff.

ThisIsWeird

Is there anything FreeBear doesn't know!

FreeBear

ThisIsWeird said:

Is there anything FreeBear doesn't know!

High energy particle physics, rocketry, DNA splicing....

Or it could be multiple people posting using the same FreeBear account.

sim42

Same issue with a Meaco, except it’s brand new. Did you ever resolve this?

tomp2494

sim42 said:

Same issue with a Meaco, except it’s brand new. Did you ever resolve this?

Got it resolved once. Problem re-occurred, out of warranty.
Ditched Meaco in favor of a Honeywell dehumidifier. 

bornjoyful

Late answer to this…..
My new Arete 2 is 29 days old and was reading on average 10%rh out compared to a cheap hygrometer.
I also noticed that when the arete was reading 40rh there was still condensation on my bathroom windows and doors.

In order to be sure I bought 2 Inkbird TH-5 which can be calibrated and I also bought a Bodeva 75%rh calibration pack which is purified salt and purified water and is more accurate than the ‘salt test ‘ above.
I also bought ten more cheap hygrometers.
my 11 cheap hygrometers once in the calibration oack for 24 hrs  have a range of  +\3 and cannot be calibrated and the Inkbirds are now calibrated.

Don’t laugh but I also bought another Meaco - a DD8L Junior!

Meaco say their machines are +/- 3 %

I set up both dehumidifiers in the same 75m3 room at 17-18c within 2ft of each. The humidistat sensors of each machine were NOT facing each-other  (they  are at the back behind the filter.) All the hygrometers were placed 3 ft away from the dehumidifiers and  the radiator was not near this experiment.

I set the DD8 to 60%rh (one drop) and the Arete to 60
Then I set each dehumidifier to 50%rh
Then 40%rh and finally to 35%rh

I did this twice over 2 days for repeatability. First day took 8 hrs and second day took 6 hrs.

The result was that the DD8L turned off  at each setting  and all hygrometers read 1-3 %rh of that reading and the Arete readings were way lower. 8-14% lower.
14% lower at 60rh and 8% at 50rh 

The room temp increased to 20-21 as the DD8L is a dessicant and pumps out warmer air - however the warmer it gets the more efficient a dehumidifier works 
The other interesting number was that after 14 hrs of running at different settings the DD8L collected 1200ml and the Arete only 400ml

The main issue is that the best rh is between 50 and 55rh for households and that currently that meansI would have to set the Arete to 40-45 rh to get that result

BUT when I need clothes drying which is 35rh the Arete would need to be at 25% and it does not go that low
It turns iff when it reads +/- 3% of 35rh which according to all my hygrometers and the DD8L is in reality somewhere between 42rh and  48rh and this is not even enough to deal with the condensation after a shower.

Meaco are collecting the Arete tomorrow but the senior customer service person has said that despite my evidence ( photos and video and charts)  they may decide there is nothing wrong with it

I will update the forum in a few days 

UPDATE. It came back today- a week later.They DID change the sensor and although it has only been running fifteen minutes it is now reading close enough to the Meaco DD8 and all my hygrometers. Hurrah.

UPDATE- no Hurrahs
I left the Arete 2  and the DD8 running all night set to come in if it went above 60%rh .They are next to each other but not so that either sensor would catch the air from the other dehumidifier.
and this morning the EXACT same issue.
DD8 turns on and off at between 55-60%rh and has collected more than a litre.
The hygrometers read between 55-58%rh
The Arete must have turned off not long after i went to bed as it is reading 46%rh and has not collected even a drop of water.
I have emailed the CEO  Chris Michael as his direct email is in their blog  and I have informed the shop where I bought it that if Mr Michael doesn’t contact me by Monday , I will  be returning for a full refund and leaving every detail of how difficult it has been to get to talk with anyone other than  the front line customer service staff and my full experience on Truspilot.

slysy

bornjoyful said:

Just wondering if you got any further with this? Did he contact you and what was the outcome?