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How important is negative pressure?

#negativepressure #exhaust

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#21 madgoose

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Posted 16 October 2020 - 12:12 AM

Or you could introduce an aircon unit that's what I would / and have done in the past... There absolute pennies and work fantastic ...

 

I bought a second hand domestic 4.5KW A/C unit a few years back to help combat the temperatures in the summer, luckily I was working in the main bedroom which was on the north side of the building so it never got direct sunlight on it. After buying the unit (which weighed a ton) I realised i could not use it in the tent because, a) it was to big to get in there, and B) if i had of been able to get it in there I had no way of filtering the extracted air from it without pumping out "smelly" air. The result was that I used it to cool the ambient temperature of the room extracting the hot air out through the ceiling to the loft space. If you have used tents then you know that they are like having massive radiators in the room. As i was able to extract out through the ceiling and draw fresh air in from outside of the building for both of the tents so  I had a slight advantage, but cooling the ambient temperature of the room made a big difference. Unfortunately when i bought the unit all of the refrigerant in it had leaked. A "friendly" engineer was recommended but he had problems re-charging it and ended up putting two new valves on it trying to charge it. It did pump out very cold air for a couple of months but it continued to leak and lost all of the gas. I still have it and my car mechanic says he should be able to recharge it for me but i don't want to use that much electric for A/C on top of what i am already consuming.

 

UPDATE:

 

Wednesday I went shopping and picked up some 50mm key rings and zinc screw hooks. This will allow me to gain about 250m and raise the lights as high as possible doing away with the cable ties and EZ rollers. Temperatures have been pretty constant at 29.5C to 30.5C and the humidity have been between 30-35%, I would still like the humidity to be higher at between 45-55% and i have some ideas on how to raise it passively. I had a lazy day Thursday as my back was playing up so didn't do anything other than feed the plants and refill the humidifier. Tomorrow I plan to reposition the lights at the same time raising them to as high as possible because I will lose so much headroom when i re-pot the plants in the 78 liter planters. After that I have some work to do in the kitchen fitting another light under the shelf I fitted earlier in the week. Then I have to refit my 1.2 x 1.2 tent in the dining room so I can bring in my tomato and scotch bonnet pepper plants that are in grow bags inside to ripen them as the weather will just rot the fruit on the vine. After that is complete hopefully i can go out and pick up some Perlite so i can re-pot what I need to over the weekend. I will try and take some photos so you can see what I am up to.


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#22 symbol 22

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Posted 16 October 2020 - 01:33 PM

As an example got ducting too to expel air .... Just a thought like ..

https://www.heatersh...vxoC_ywQAvD_BwE
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#23 madgoose

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Posted 16 October 2020 - 08:17 PM

As an example got ducting too to expel air .... Just a thought like ..

https://www.heatersh...vxoC_ywQAvD_BwE

 

When I got the unit the guy did not have the remote control, the attachment for venting out of the window or the flexible ducting, which was cool because I did not need any of that and gave me some room to knock the price down some more. I was able to use the regular 150mm flexible ducting that we use connecting it to the back of the unit then to a fabricated right angled piece of ducting and then more 150mm flexible ducting vertical to a piece of MDF board that had a 150mm hole cut in it. I then connected the ducting to the MDF board using a spigot. I then drilled a couple of holes in the right angle and bolted some screw eyes to it and two screw eyes to the MDF board, I tied some washing line to the screw eyes and placed the MDF board on top of the open loft hatch. I then adjusted the lengths of the washing line to take the weight of the ducting off of the spigot. If I had of been able to work out how to filter the air running through the A/C unit i would of been happy, I guess now looking back I could have fitted an Ozone generator in the exhaust ducting but never having used one I was a bit unsure of the best way to go about it. I think venting out to the loft and using the A/C to cool the ambient temperature of the room was my best option at that time.


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