Heating a garden shed / gym to avoid condensation

[functor]

Hello,

I am setting up a gym in a rather large (4mx4m) wooden shed in my garden. I haven't noticed any condensation yet, it has 4 windows and looks like it is well insulated. It is not that cold usually but I am afraid of frost temperatures in the winter causing condensation and rusting the equipment.

Should I get:

http://www.screwfix.com/p/winterwarm-tubular-wall-hung-heater-60w/80336

Or

http://www.screwfix.com/p/winterwarm-tubular-wall-hung-heater-120w/71539

And let them run overnight?

Thanks

 

[mointainwalker]

I don't believe these will prevent condensation as there is simply not enough heat and you will -presumably -be adding sweat to the normal moisture load. Look at the link for dew-points.

http://www.dpcalc.org/

These heaters are basically to prevent freezing pipes i.e. keep temp a few degrees above 0 C

 

[functor]

I see, so I need a radiant heater that dries the air? Any way to do this economically and safely? (so the shed doesn't burn down)

Is there maybe another way? Since it is insulated and sealed, will a dehumidifier be better?

 

[mointainwalker]

Any way to do this economically and safely

Economically ? No , not in my opinion.

Since you would presumably be using this occasionally, this could be one time when a humidifier would be exactly right.

I'm not sure of the costs but maybe a reversible wall-mounted air-con unit might be an alternative as these can heat and ( you need to check this out as I'm not sure ) maybe also incorporate a de-humidifying function.

 

[functor]

What about getting a Temp, RH and DP monitor, and turning on a big oil heater whenever the values are unacceptable?

 

[mointainwalker]

and turning on a big oil heater whenever the values are unacceptable

...because oil-heaters ( paraffin ) generate 1 litre of water vapour per litre of fuel burned.

 

[functor]

These ones do?

http://www.amazon.co.uk/dp/B002DGTM...de=asn&creative=22218&creativeASIN=B002DGTMJO

 

[mointainwalker]

If you want an electric heater then sure but you asked how economical................

 

[functor]

I was weighing this vs an air con, I know for example that air cons are very very electricity expensive, so I was hoping perhaps I could run this electric oil heater at low when the T/RH/DP values were at risk, I guess it's not economical but I don't have a choice right?

 

[mointainwalker]

It depends if you need heating at all. The more you heat the greater the condensation problem will be.

To illustrate it with an extreme, if you left the doors open so it was at ambient temp/humidity, there would be no humidity ever.

 

[functor]

The problem is, there is also humidity in the air (more so than indoors?), and from what I understand condensation is only created during the time where there is a big difference of temperature (which is why it's advised not to seal outbuildings, to create an air flow). I have another outbuilding (brick) which is ventilated, but it always feels damper than the wooden one.

 

[mointainwalker]

Sorry if I have created confusion functor, the sentence should have read...

there would be no condensation ever.

 

[big-all]

What about getting a Temp, RH and DP monitor, and turning on a big oil heater whenever the values are unacceptable?

oil or compressed gas give out loads off moisture when burning

you need at least 3 kw off heat if you wish to use the room in the winter
insulation just reduces the the speed the heat moves

if the outside temperature is say -3 at night and plus 3 during the day your shed will hover around o degrees as the average off the 2
if you add say 200w heater the average will rise by maybe 2 or 3 degrees

if its well insulated opening the doors and window during the heat off the day on sunny days will heat it up a bit and vent the moisture thats providing the area around the shed isnt in shade if you have any heating on in the previous 24 hours you wont gain any heat but you will still remove moisture

my shed is fully insulated with 3" loft insulation if the inside is say 3 degrees it can take the best part off 40 mins to raise to 12 degrees with a 2.5 kw heater but then its full off metal tools and machinery
my shed is 3m x 3.6 x 2.2 average height so 24cu metres

if i assume your shed is 4 x 4 x 2.6 that 41.6 so 75% more volume

 

[functor]

So you keep yours heated all the time or just during winter and when you use it?

 

[big-all]

if i am not using it i have a log burner that i light up around 6pm if the temperature is below around 5 degrees

i then spend around 1 1/2 to 1 3/4 hours bringing the temperature up to around 22 degrees this ensures all the metal work is warm to the touch i then close down the burner to smolder for the next 2 or so hours then i come and check everything is ok at around 10pm to a lovely 24 degrees
then thats it for 48 hours as the residual heat will start the next evening warm enough [8 degrees plus] to not need a fire

i dont use the fire during day light hours out off respect for others
if i am working during the day i just use the fan heater to raise the temp to 12 degrees and no more as that the 4 % above minimum for the glue i use[8% min]

i just make sure the temperature is abouve 3 degrees at all times for the sake off the glues/silicons fillers varnishes and paints

if the shed temperature is abouve 8 degrees i do nothing if not in use
heres a picture or two before the insulation
http://s21.photobucket.com/albums/b270/bigall2005/