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Thread: Condensation
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28-11-2020, 09:02 AM #1
Condensation
What do others do to prevent , avoid , remove condensation in their sheds / grow on rooms etc.
I've a quarantine tank 300 gallons and a grow on tank 120 gallons both heated 15 degrees and 22 degrees and getting lots of condensation throughout the shed . Its about 14 feet by 8 feet .
One window slightly ajar . Walls insulated but not the roof.
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freddyboy Thanked / Liked this Post
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28-11-2020, 09:37 AM #2
It's all about getting the right balance of temp, insulation and ventilation.
If I were setting up a filter room/grow on, then I would plan to insulate roof, walls and floor. Install a heat source, along with a small through the wall heat exchange unit.
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28-11-2020, 11:29 AM #3
Currently all that warm moist air coming from your quarantine and grow on will condense on anything cooler than it, just like it does in the home on windows and cold corner walls. Its worth remembering that warm air holds more moisture than cold air so ventilation to allow moisture laden air out and less humid air in coupled to insulation of anything cooler than the general indoor air temp is perhaps one way forward.
If you don't mind the running cost a dehumidifier could help, but I'd imagine it will be working hard given the environment it will be in.
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28-11-2020, 11:51 AM #4
Think you're right, an industrial sized dehumidifier/building drier would be needed in that environment and they are costly to run.
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arceye Thanked / Liked this Post
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28-11-2020, 12:04 PM #5
When building an indoor swimming pool - not as irrelevant as it sounds - you have relatively very warm water compared with a ambient room temperature, condensation is something that can't be ignored.
Simply, if the room surfaces are at a lower temperature than the water you can get condensation. If the actual air temperature is less than the water temperature can get visible mist.
In a swimming pool at 28C you can begin to see the problem - which is why dehumidification is a thing here.
There are several suggestions I could make in your case:
1. I won't suggest continued extra ventilation in this instance because at this time of year the outside air can be both cold and humid - not what you want in there.
2. Properly insulate the shed (at least the roof and walls) with no gaps. This will bring the shed ambient temperature up nearer to water temperature and reduce amount of condensation. The water will be a large heat store and will be heating the shed anyway.
3. Cover any "open water". I presume you have air pumps/circulation so water O2 levels shouldn't be a problem - this will reduce evaporation (which supplies the a lot of extra water vapour to condense).
4. Consider a shed heater for when it gets really cold - again to reduce differential between water/shed temp.
5. You could consider dehumidying the air - but that will be an uphill battle and so unless money is no object I'd not bother with this.
I hope this has been of use.Last edited by Ukzero; 28-11-2020 at 12:08 PM.
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28-11-2020, 12:09 PM #6
Also, would covering the quarantine and grow on with polycarb help, I know there would have to be some open area left for gas / air exchange but it could possibly reduce the amount of moisture that is currently escaping to air? or not? just a thought.
Post crossed with above...Last edited by arceye; 28-11-2020 at 12:17 PM.
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RS2OOO Thanked / Liked this Post
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28-11-2020, 12:43 PM #7
I agree with the majority of this, but have a slightly different view on point 1 regarding ventilation. Cold air can indeed have a high relative humidity but assuming heating is also being used it is surely better to vent some of the very humid warm air though this will bring in the mentioned humid cold air.
The relative humidity of cold air can indeed be high, however on heating the air that relative humidity would drop significantly.
example... air at 0c with a R/H of 69% would if warmed to 20c only have a relative indoor humidity of 18%, a more extreme example is air at -8c with a relative humidity of 100% which is heated to 20c would have a R/H of just 15%.
I think there is a need to replace some of the humid indoor air, and this of course can only be done by bringing in another source of air, this is still beneficial assuming some heating is present.
I'm not suggesting a gale blowing through but I do believe there is a need for some ongoing ventilation in order to replace the heavily moisture laden air of the environment.
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28-11-2020, 01:08 PM #8
Ventilation is a tricky one in our relatively small filter rooms/sheds in the depths of Winter.
It's a question of balance as has been said, which can be surprisingly difficult to achieve with constantly varying outside temperature and humidity - which is why I was trying to suggest ways to reduce the condensation at source as it were.
I don't disagree with any of the suggestions for more ventilation, it's just that getting the amount right can be a fine art.
I remember a car salesman once moaning about the fact that on some "dry" days when he opened the tailgates to ventilate his used cars the interior condensation would dry out and on others they would actually get worse.
Perhaps a fan system using internal and external RH sensors would be the ultimate answer to maximise ventilation when it would be of most benefit
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arceye Thanked / Liked this Post
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28-11-2020, 01:15 PM #9
hi i have a 500 gallon qt grow on. and no covers on the tank. as i don t like them. i have my tank temperature at 21c and i heat the shed above that temperature with a electric heater.
and i get no condensation what so ever. the electric heater runs on a timer 4 hours on and 2 hours off. roughly. and it works in my shed. i have one of those cheap plastic vents in the shed door.
fred
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29-11-2020, 07:51 AM #10
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29-11-2020, 08:01 AM #11
Lots of interesting posts above. Spent the day yesterday insulating roof and walls which hadn't been insulated before.
Also covered both tanks.
Like the idea of ventilation as it does feel very humid and whilst the air outside will be colder I think it will be a lot less humid.
Has anyone used a bathroom extractor style fan or would that not be suitable ? They normally have timers but I think they can be overridden and an external switch / timer can be incorporated or even a humidity sensor??
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29-11-2020, 09:04 AM #12
My 350 gal grow on is in the garage and I cover the top with clear 25mm polycarbonate to keep the heat in and no problems,when I need to look at the fry it just hinges up I get some stem coming out but no condensation.
You have a nice set up there Graeme.John
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29-11-2020, 09:26 AM #13
Then I would recommend a small fan linked to one of these:
https://www.ebay.co.uk/i/22245028453...waAqRBEALw_wcB
I have used one in my garage linked to a dehumidfier to prevent condensation and rust on my classic'ish car which is SORN'ed over Winter. Of course the garage doesn't haver all that water present so a dehumidifier makes more sense here.
A small fan should be OK because the stat will run it for as long as needed.
You would need to play around with a sustainable RH value. You can also double check to see how much RH reduces wit the fan on.
The same device could also be linked to a small heater which would also help.
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29-11-2020, 09:27 AM #14
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arceye Thanked / Liked this Post
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29-11-2020, 09:29 AM #15
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30-11-2020, 01:55 AM #16
you want a heat exchanger unit in there, initial outlay is expensive, but the running cost is a very low powered fan.
no point dumping the warmth you have paid for,
a smaller version of that would be the ideal
https://www.ebay.co.uk/itm/Vent-axia...AAAOSwJZ5fw7G6the slow pond build thread
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02-12-2020, 03:15 PM #17
Condensation
I would not want to just ventilate with an extractor.
You are going to have to heat the room, and loose all that heat, get a HRVU
The cost may be about £500 for a single room system, about £300-400 for the unit plus ducting and controls.
I have a whole house system in my house, and they are fantastic. Running cost are tiny as you will recover 95% of the heat you have put into the room, and they cost so much less to run than a dehumidifier.
The big advantage is they dump the moisture it’s removed from the air directly to outside, and then bring in a small amount of fresh air from outside to mix with the recovered warm air.
You still need to insulate the roof.
Heat Recovery Ventilation Unit HRVU DHV-04/100B | Heat Exchanger for Low Energy Consumption & Reduced Condensation https://www.amazon.co.uk/dp/B00OQH8E..._b95XFb0JMA3SQ
Sent from my iPhone using TapatalkLast edited by Dudley; 02-12-2020 at 03:17 PM.
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02-12-2020, 03:53 PM #18
Roof and all walls fully insulated now. See pic.
Have also used clear polycarbonate 10mm over the two tanks and condensation has improved considerably. It tends to catch on the polycarbonate and when lifted goes back in.
Early days but lots of good options from above thread.
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02-12-2020, 04:15 PM #19
Looking good Graeme,the sheets of polystyrene what thickness?
Like the colour scheme must have took you ages to do all those black dots
Seriously looks great and will keep it warm in there.John
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freddyboy Thanked / Liked this Post
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02-12-2020, 04:28 PM #20
The Daily pond temp thread
Pond still covered, currently 11.6C Been really mild this year as far as pond temps go. ...