Workshop dehumidifier with HEPA filter

[harvestbarn]

After some research Meaco recommended their 20l low energy model with the optional HEPA filter fitted as the only model in their range that was suitable for a woodworking environment . I have purchased this model and in the first 24hrs it has dropped the humidity from 84% to 68%.. The workshop is well insulated with 70mm Celotex lined with 18mm plywood all on 9" hollow concrete blocks well filled with concrete as it was a bull pen originally and is within a barn. The inner roof is filled with about 8"of mineral wool with 9mm ply ceiling and tongue and grooved flooring above. The barn roof is then above this and air drying timber can be stored on top. I have had no problem with rust the machine beds are waxed despite only heating when occupied. This winters weather has been so wet the humidity has been approaching 90% regularly.

Oak that I have been using has been moving and I believe this is the reason, currently I have dialed in 55% as the target humidity do you think this is an optimum level.

Has anyone tried using HEPA filters in a Dehumidifier and if so have they been a problem clogging up, I intend to vac them regularly. My workshop has ducted chip collection with a modified Axminster single bag collector having a Thein separator in the middle. A large twin motor vac is used for sanders etc so dust levels are tried to be reduced if this is not working there is also a Ventaxia 12" wall mounted but this cools the workshop in the winter.

 

[CHJ]

If you run the ventaxia at the same time or close to running the ventaxia then you are just trying to dry the planet, as you are just pulling replacement moist air into the shop.

Your wood will be conditioned to your storage area unless you bring it into your shop or house for several weeks before use. A dry shop will do little to condition fresh wood other than encourage it to move around.

Hepa filter? think this is just going to keep dust out of the chilling coils and fan system and be swamped by the workshop dust environment, more in keeping for use in a clean finishing room I would have thought just to reduce circulating fine dust.

 

[harvestbarn]

Hi, thank you for your comments the Ventaxia was installed for occasional use mainly when assembling Lances for the sport of Tent Pegging (for any one interested see http://cotswoldsport.co.uk/shop/index.php?main_page=product_info&cPath=127&products_id=624) the fumes from the Araldite can get a little strong though I do generally wear a face mask with suitable filters.

The wood for the current project has been conditioned in the workshop for over six months which is why I suspect the high humidity has been the problem.

The HEPA filter removes particles down to 0.3 microns at a cost of 9% reduction in dehumidification and a 5% increase in energy cost. The Record AC2 Workshop Air cleaner removes down to 5.0 microns and has a larger surface area so you may well be correct that it may clog up quickly. On the plus side both the pre-filter and the HEPA filter are easy to get at and should only take a few minutes to vacuum out and the workshop is less than half the volume the Record unit is rated to clean and only used intermittently.

The unit uses just 255watts /hour and the tank holds 6 liters of water and will switch off if full. It looks as if the workshop will reach 55% humidity tomorrow although it is currently raining hard which may not help.

 

[CHJ]

The wood for the current project has been conditioned in the workshop for over six months which is why I suspect the high humidity has been the problem.
.

If the wood has been in working shop conditions for that long I suspect you are just harvesting the consequences of reaction wood or poor initial drying.

See this post for some comments about the problem.

 

[jimmy_s]

I would be surprised if its a proper HEPA filter. They are expensive and clog quickly. Normally with HEPA's they would be protected by a number of upstream filters to improve their lifespan. They are normally replaced not cleaned. The only times we would normally come across HEPA filters is when working with clean rooms either in pharmaceutical or electronics environments where cleanliness is very important or the other application has been nuclear extract where the air must be cleaned before being exhausted to the environment.

Also I would have thought you would want to bring the RH in your workshop down gradually as surely a rapid drop in RH will cause your timber to move quickly possibly resulting in defects?

 

[lurker]

I think you are seeing a change in relative humidity. A slight change in temperature has a massive effect on RH.
There are tables so you can compare the apples with the oranges

My guess is the machine is just warming up the air.

Anyway as CHJ says, unless you have a near air tight building you are just trying to dry the planet

 

[harvestbarn]

Thanks to all that have responded.

With regard to the filters Meaco states :-
The HEPA filter has proved to be a very popular extra with most people buying the HEPA filters when they buy the dehumidifier. The filters are what are called True HEPA filters which means that they conform to international standards and capture 99.97% of particles that have a size of 0.3µm or larger. This makes a huge difference to those that suffer from allergies and also will prolong the life of your dehumidifier.

This model was the "Which best buy" in September 2014 so one would expect it to meet specification. It does have upstream filtering and the HEPA are supplied in packs of three . I was told they should be changed every 4 months. The manual says the filter should be cleaned every two weeks. We will have to see how it goes.

You may be right about slowing the rate of change.

The workshop temperature has remained within a 1 Deg C but agree dehumidifying it is going to be heating the workshop a little. Less once the selected level is reached as it will then stop and sample the air every half hour. I am aware that I could have dropped the humidity by heating but this will be much more expensive in running costs. The workshop is very well sealed just the minimal gaps around the one door and any leakage through the Ventaxia shutters. The concrete and painted floor also has a DPC but no insulation, there is one small fixed double glazed window only. Fluorescent lighting is used at all times the whole inside is painted white.

 

[harvestbarn]

These links regarding HEPA filters might be of interest to owners of suitable shop vacs

Lee Valley http://www.leevalley.com/en/wood/page.aspx?cat=1,42401&p=64681

and a You Tube cleaning review https://www.youtube.com/watch?v=8j_9PO2aEf8

If anyone knows if a HEPA filter using this washable polymer filter material can be obtained to fit the Meaco 20L low energy dehumidifier please advise.

 

[harvestbarn]

A further update from Chris Michael who foundered Meaco in 1991 :-

Ours is a true HEPA filter and is very important that they are in place otherwise the dust will clog up the inside of the machine, they are though not designed to be washable. Within the HEPA family there are different types of MERV ratings for HEPA filters and we have carefully selected one to maintain the correct air pressure. We would not therefore recommend the use of a third party filter.

When the dehumidifier reaches the set point the fan is turned off and it is no longer reads the room relative humidity but the internal relative humidity of the machine, this is why the reading increases. When the fan turns back on it will read the relative humidity of the room again.

 

[Matt@]

interesting to read this thread. I am looking for a dehumidifer at the moment. I've had experience of these machines going back years but it is only recently I realised that the standard dehumidifier that runs like a fridge is not much good at temps under 15degrees whilst the dessiccant ones are good at low temperatures. I was thinking of going with an Econair but will take another look at the Meaco. Filtering dehumidifiers is a huge issue in woodworking workshops - even when you think you have no dust, they clog up like hell..

OP what are your running costs on the Meaco, do you know and which model did you buy - I'm assuming it is the dessicant one?

 

[harvestbarn]

Non of the desiccant type dehumidifiers I could find are recommended for a woodworking workshop environment as the controls will clog up. When I spoke to Econair they had no model they could offer. This Meaco 20l low energy was the only model they could recommend provided the HEPA filters were fitted. This unit extracts down to 3 Deg C but will be less efficient at this low temperature I intend to keep a 5 Deg minimum in the workshop using an oiled filled electric radiator.

The workshop is currently at 56% moisture with the dehumidifier set at 55% their are slight variations daily but considering the wet conditions we have had I am very pleased with it. I examined the machine at seven days and all the filters are very clean but the workshop has only been lightly used mainly for some wood turning. The sanding was done with a 4" chip extractor collecting the dust. The 6 litre water container is a joy both in size and ease of emptying.

I also have a Meaco 8l desiccant in another smaller building it is also a fine machine and has been in use a number of years if I were purchasing again I would buy another Meaco low energy model but may not fit the HEPA filters, it would be considerably cheaper to run.

 

[Matt@]

ok thanks for the info, is it a hot defrost model then?

 

[harvestbarn]

Yes once the room temperature reduces to 16 Deg C it goes into this mode. I understand if the temperature was allowed to fall below freezing it would all freeze up and switch off. I think it would be best not to let this happen as it is outside the expected operating parameters for this unit.

 

[Matt@]

thats sounds good, I'm going to ring up about one of these next week.....

 

[harvestbarn]

I bought mine from http://www.airconcentre.co.uk/Shop+By+Brand/Meaco+Store free delivery and a 3 year Warrenty excellent service it arrived next day. The unit has a set of castors and a substantial carrying handle and is not too heavy

 

[Matt@]

it seems a lot better than the piece of junk I bought from Ebac via screwfix. Ebac = noisy, resonating metal casing, no filter, no defrost, no LED display, rubbish performance below approx 15deg, castor falling off, leaked after 6 mths, leaked in same place 1 week after returning from Ebac for repair and finally when I sent it back to Ebac for repair I was told by Ebac to just put it in a cardboard box no packing, no protection, no bubblewrap - how can you transport a mini fridge with no protection??? A shame as Ebac I know is known as a well regarded UK manufacturer - I would never buy another one......Meaco 20L - £229. Ebac 25L £349. UK manufacturing at its best, not..

 

[RogerS]

Dehumidifier in the workshop?

Begs the question......

...Why?

 

[custard]

Dehumidifier in the workshop?

Begs the question......

...Why?

Helps keep your tools and machinery rust free and holds your timber at humidity levels that are closer to that which they'll experience indoors so there's less warping and shrinking with your finished furniture.

That's why I run dehumidifiers 24/7/52

 

[Matt@]

also it gives a much more pleasant working atmosphere ie takes that horrible cold damp feeling out of the air....

 

[RogerS]

Dehumidifier in the workshop?

Begs the question......

...Why?

Helps keep your tools and machinery rust free and holds your timber at humidity levels that are closer to that which they'll experience indoors so there's less warping and shrinking with your finished furniture.

That's why I run dehumidifiers 24/7/52

I don't have any of those problems and I don't run a dehumidifier.