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Humidity/damp and storage of PA equipment

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Humidity/damp and storage of PA equipment

Postby forumuser637535 » Sat Aug 16, 2014 3:57 pm

I store my PA systems in a groundfloor cupboard in my communal stairwell. It used to be a coal cupboard.

Possibly due to leaking pipes in neighbouring flats, or something else entirely, the humidity in the cupboard is registering at 82% (installed a meter the other day), even with a dehumidifier running. After a day, the dehumidifier has about 100ml of water in it...

Is this level of water in the air likely to be damaging my equipment? I've got a low wattage greenhouse heater that triggers if the temperature drops below about 10 degrees c, so cold/condensation isn't a significant issue.

Anyone have experience of this? Most of my gear is in hard or soft cases of some description (except some of my larger passive PA speakers). I've got some dynacord powerstations in there which are probably my biggest concern, but I'm not sure what is a risky level of humidity...

Any thoughts?
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Re: Humidity/damp and storage of PA equipment

Postby tacitus » Sun Aug 17, 2014 12:40 pm

I can't speak with any degree of technical competence about this but I would certainly be looking elsewhere to store my kit.
My PA's stored in an outhouse and although the temperature varies, it's still not too hot in summer. Important (to me) is that it's not the least bit damp and I haven't had anything go mouldy or whatever in the 6 years I've used it.

I think I'd start looking for an alternative solution.
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Re: Humidity/damp and storage of PA equipment

Postby Exalted Wombat » Sun Aug 17, 2014 1:39 pm

Your gear won't mind the cold. It will mind the damp.
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Re: Humidity/damp and storage of PA equipment

Postby forumuser637535 » Mon Aug 18, 2014 8:40 am

What constitutes "too damp" though? Finding an alternative solution involves serious cost - easier to fix the problem with the damp, I think.
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Re: Humidity/damp and storage of PA equipment

Postby James Perrett » Mon Aug 18, 2014 8:58 am

It is condensation that does the real damage - especially when the temperature suddenly changes like when you take your gear out of storage into a warm room. Don't try to use your gear until any condensation has evaporated.
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Re: Humidity/damp and storage of PA equipment

Postby mick.n » Mon Aug 18, 2014 10:09 am

Would a generous amount of these silica crystal bag type thingys be helpful?
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Re: Humidity/damp and storage of PA equipment

Postby forumuser637535 » Mon Aug 18, 2014 12:18 pm

I've used about 5 or 6 of those moisture trap devices (much more aggressive than silica gel) and they get used up pretty fast.
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Re: Humidity/damp and storage of PA equipment

Postby Jorge » Mon Aug 18, 2014 1:45 pm

You definitely don't want mold growing on your PA equipment, especially wood speaker cabs, paper speaker cones or other porous cellulose-based materials. 82% humidity is too damp and can support mold growth when there is cellulose around for the mold to live on. Mold is bad for many reasons and its growth indoors should be avoided. The problem seems to be moisture leakage into the cupboard space and its surrounding walls and ceiling, not condensation from warm damp air hitting cold PA hardware.

A dehumidifier draws a lot of power (similar to an air conditioner or refrigerator) and running one with enough capacity to keep the room air dry can become expensive. Your observation of 100 ml of water per day is clearly an underestimate of the amount of moisture that needs to be removed. When I run a dehumidifier in my 4m x 5m x 2m basement rehearsal studio in the summer, it typically collects between 3 and 8 gallons of water in a 24 hour period. Unless you have a drain hose setup, emptying gallons of water per day from the dehumidifier pan can be a pain.

Finding and fixing the leak to completely eliminate the source of moisture is the first thing you should try. If there is no leak, the moisture could possibly be from condensation on cold water pipes that run through or above the space. That could be fixed by insulating the pipes to prevent humid air from contacting the cold surface. If eliminating the moisture source is impossible, consider simply ventilating the space with a fan and a vent. Essentially you want to bring dryer air in from the surrounding room and remove humid air from the cupboard space. To do that you need 2 holes in the cupboard wall, one with a fan blowing in (or out) and the other with a vent to let the air out (or in). How many air changes per hour (ie, cubic feet per minute of ventilation / volume of cupboard) depends on the amount of moisture leaking in. Unless you can accurately estimate the air changes per hour needed before you put the fan in, you may want to get a multispeed fan since fan speed is related both to noise and cost of electrical power. If you can vent to inside the house, that will save some money. If you vent the air out to the outside of the house, you will essentially have to heat an equal volume of air that gets drawn into the house, and pay for that heating energy.
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Re: Humidity/damp and storage of PA equipment

Postby forumuser637535 » Mon Aug 18, 2014 2:56 pm

This is super helpful, thanks!

Three possible places that the moisture is coming from.

1. The exposed ground at the bottom of the cupboard - this could be the very foundations of the property, with no basement level underneath. Currently, I have runners which slightly raise the plywood floor off the ground, and allow a little air to circulate.

2. There is a hole in one wall which connects to the basement under a neighbour's flat. The hole is around 8-10" wide - a few bricks-worth. I've tried to cover that over as much as possible, but it's not airtight. There are some pipes I can see on the other side of that wall (in their basement) and one of them looks like it has had a bit of a leak, and has been taped up. It's not dripping or anything, but it looks damp to the touch (and ew, I'm NOT touching it). The airflow doesn't seem to come INTO the cupboard from that hole, but I suspect that changes depending on whether they have their windows open in their flat.

3. The moisture is just coming from the air in the stairwell. There is a bit of airflow from the back door which is 2m from the cupboard, but the stairwell itself never feels like there is much moisture in the air. It would surprise me if the air getting into the cupboard (e.g. under the door) was causing that level of humidity.

Do you recommend that I try to seal off the floor with e.g. plastic sheeting and sealant, and do the same with the wall adjoining the neighbour's flat?

I've drilled some holes in the door of the cupboard to add a little airflow, and there are some holes in the stairwork that forms the roof of the cupboard, but these are all pretty small.

I just don't know whether it's better to try and seal it all up or to increase airflow as much as possible!
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Re: Humidity/damp and storage of PA equipment

Postby James Perrett » Mon Aug 18, 2014 4:00 pm

Thinking about it - if it used to be a coal cupboard then it would have been designed to be dry. I wonder if anyone has blocked up any air bricks or other ventilation in the intervening years?
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Re: Humidity/damp and storage of PA equipment

Postby Exalted Wombat » Mon Aug 18, 2014 7:02 pm

James Perrett wrote:Thinking about it - if it used to be a coal cupboard then it would have been designed to be dry.

Design is one thing...
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Re: Humidity/damp and storage of PA equipment

Postby forumuser637535 » Mon Aug 18, 2014 7:29 pm

Is it possible that blocking up the hole in the wall that connects to the flat's basement is making it worse?
I suppose I could open that hole again and see whether the humidity meter has a better reading...
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