New dehumidifier required.

Good morning All,

My "ProBreeze PB-10" desiccant dehumidifier has finally given up the ghost. It has provided several years of reliable service in my unheated double garage workshop. I only noticed something was amiss when light rust started to appear where I'd not seen it before.

Any suggestions please, before I trawl the internet and some dubious performance claims?

The PB-10 doesn't appear to be available anymore and I'm considering the "EcoAir DD128". The Dehumidifier needs to be the desiccant variety (low ambient temp), have continuous drain and preferably a front removable reservoir.

The Meaco DD8L gets good reviews IIRC.

I bought a DD8L Junior some years ago and was sufficiently happy with it to buy a similar replacement when it gave trouble outside the warranty period.

I have an Inventor Rise dessicant dehumidifier that has civen good service over the last 2-3 years.

Probably newer models now but the Inventor range seems well reviewed...

I had a desiccant type, it worked well for nearly one year. Unless the filters are very good, and you change them, all the workshop 'fine crud' ends up on the silica gel, which needs a clean surface if it is going to work. And my workshop is comparatively clean.

I had the silica gel swapped by the manufacturer (it was all glued together inside so not DIY friendly !) and they said it was filthy dirty. Waste of money because it all failed again after another year.

So now, for several years, I have had a 14inch square x 18inch high compressor type and it keeps purring away, on for perhaps a quarter of the time, with around 100ml/hour condensed water piped directly outside. My wall mounted RH meter usually reads between 55-65% RH.

Edited By norm norton on 26/02/2023 11:28:37

Thank you norm,

As I understand it, desiccant dehumidifiers work at lower ambient temperatures (as low as 1deg. C). Ideal in my unheated garage during the winter, when most of the moisture problems manifest themselves, so I've dismissed the refrigerant type.,

I have had four of those. All purchased as basket cases or not working.

Easy fixes, but still unreliable. I have made three working machines from the four and always keep at least two operational. While on holidays I set two running (for less time than the usual single unit) for two reasons - firstly both are unlikely to fail during that period and secondly to allow collection of 4 litres of water before they stop.

These are obviously older second hand units and cost me peanuts. That said, the one I am currently using has not failed in more than the a year, only runs for an hour each night (on low setting) and will have collected less than four litres of condensate this month.

That the humidity is maintained adequately low and the workshop has not needed much other heat - only some use of a chinese diesel air heater (mostly while I am in situ, on colder days) - makes the outlay very much worthwhile.

Current nightly running cost is just over 7.5p, since shell increased their unit charges at the beginning of the year.

+1 for the Medco DD8L, I have had mine for over ten years and it hasn’t given any trouble, I would certainly buy another one.

NDIY:

I have sent you a PM.

The 20L Meaco Low Energy Dehumidifier, (no model number other than that description), is a refrigerant type, and has been very good. It cost several hundred quid from Argos, but unlike reviews of cheaper models and manufacturers, this one works very well, and was well worth it in my book.

It has a 20L water container, or can have an external hose fitted to drain externally, and you can set the required humidity for the room or garage.

Has been working without problems for a couple of years now.

Edited By John Doe 2 on 26/02/2023 20:25:24

Hi All,

Many thanks for your thoughts. Time to spend some lolly.

Yes you are right, that is the theory. But my workshop drops to 4degC overnight in these cold spells, then I warm it to 14deg during the day. In the early mornings the RH is often in the 45-55% range because the cold air from outside that leaks in is much less able to carry moisture, The dehumidifier still runs and does not seem to freeze up.

If your workshop is left at near zero degrees for a few days then, of course, the compressor dehumidifier can achieve nothing. But the air outside is not saturated at those temperatures.

We got a compressor type from Machine Mart years ago, it has worked perfectly including being left running in the hallway of my Mother in Law's empty house for several months with only the occasional emptying. Good source of soft water for irons/loco boilers/etc - why pipe it outside? Any decent unit should shut itself off if the reservoir gets full. Also great for clothes drying when too wet outside (not in the workshop though!).

That 20l referred to the daily water collection (at standard conditions - likely warm and high humidy). The collection tank, therefore, may need emptying four times each day.🙂

Piping to a drain is very handy if one does not wish to keep emptying the tank - or are away for a period of time. There is only so much collected water that can be used up. Most of mine goes in a 200l water butt or for watering plants.

My desiccant type helps to keep the workshop warm as well as keeping the humidity down. A compressor dehumidifier would be more energy efficient for hot, humid conditions.

I have run a Delonghi compressor type for quite a few years and it seems to pull quite a lot of water out of the air. Although the compressor type are poor performers in the very cold it seems to me that I don’t have condensation problems when it is cold. The nightmare scenario is when everything in the workshop has dropped to a very low temperature and the the weather changes to a warm wet wind and as soon as this gets in the workshop the water drops out on to all the cold metal surfaces. As soon as the air is warm and wet the dehumidifier gets to work but water condensing on the cold machinery is near instant but the dried air from the dehumidifier seems to absorb the moisture. Of course humans produce moisture so removing the moisture we produce is useful to prevent it condensing on cold surfaces. The dew point seems a very complicated thing to calculate but there seems to be two important ways of combating it, heat everything above it or dry the air so the moisture doesn’t condense. Continuous heating is expensive and wasteful if the air is dry and not going to unload its moisture. I imagine a control system could be designed to run heating and a dehumidifier to keep a well insulated room always dry. One thing I notice is that items in still corners of the workshop can get rusty so air movement is probably useful to make sure the moist air gets dried.

Mike

Edited By Mike Poole on 27/02/2023 17:12:38

I have two Electriq ones from Appliances Direct, one for workshop and one for clothes drying etc.

Fast delivery, easy to attach an overflow pipe, modest electricity consumption, plenty of sensible and useful controls.

Even the smaller one can drop the humidity of my workshop by a few tens of percent and it's 17 x 16.

Neil

I originally bought our dehumidifier because we used to live near the sea, and had a subterranean garage. The temperature in there only rarely went below 12°C all year, but I did not want my tools to rust with the moist sea air that of course rushed in whenever I opened the door. So I kept the dehumidifier running 24/7 to keep the garage down to around 40% RH. (It automatically shuts off when it reaches the target RH, and tests the air every 30 mins to see if it needs to come on again). After a week or so, the garage and all the wood inside it had dried and reduced in RH and the unit only came on occasionally.

Initially though, there was a lot of water and it became a chore to go outside and into the garage to empty the container, so I fixed a hose to the outlet supplied and simply piped it outside. Yes, you can use the demineralised water for irons, and car windscreen washers etc.

Now we have moved, and use our dehumidifier in the spare room to dry our clothes, which is much cheaper than heating the room or tumble drying.

The Meaco 20 L model we have is fully automatic and goes through a defrost cycle if it ever needs to. Yes, it also shuts off when its collector tank is full. A very good unit and worth the money.

Edited By John Doe 2 on 28/02/2023 12:14:47