Ventilation system

[Lars Kurth]

Hi,

am having problems again with my greenhouse. The Biogreen Nevada heater that I have been using as a ventilator (the heating element has died a long time ago) keeps on tripping my RCD. So it has to go. I didn't have a good experience with any Biogreen products, so am looking for an alternative.

The setup before worked extremely well gfor circulation and to reduce my heating cost. The fan was installed in the gable and an airduct would take warm air to the greenhouse floor. At the bottom I had a duct that of the greenhouse I had a permeable airduct positioned in parallel to the 1.5m long heater that is installed on the floor. Air would be released along the duct blowing air over the heater, helping to distribute the heat.

I want to replicate this set-up, but am not sure about the products. The two which look promising are:

• Duct extractor fan kit
• Circulation fan with heat recovery tube

Does anybody any experiences with these products, or alternative suggestions?

Thank you

Lars

[RosieC]

Sorry I can't help Lars, just giving you a bump

It sounds a really interesting idea though. My greenhouse has been in since Feb and has so far been unheated. I've got a guy coming in the next couple of weeks to get me a power outlet though. This makes me really think about air circulation once the windows have to stay closed, which is not something I had thought of.

[Lars Kurth]

Rosie, air circulation is crucial. It avoids condensation, fungal attack and reduces heating costs.

I just ordered a hotbox fan. I read in one of my books that the recommended volume for orchids is 40-60 cubic meters of airflow per cubic meter of the greenhouse per hour. In the upper range if you are growing cool plants such as Zygos, Masdies, etc.

This means that both of the solutions I linked to don't have enough power for my setup.

Make sure the electrician is doing a good job and gives you a certificate. I did not ask for it, the electrician did a bodge job and I had lots of problems and eventually had to have the electricity redone. There is no point saving any money: just imagine you get an electrical fault in the winter and have nowehere to put your plants.

[stonedragonfarms]

Lars:
If I read your post correctly you are looking for a way to circulate the warm air from the peak of your gh to the floor area; the heater at floor level then also has a fan placed behind/over it to provide further circulation of the heat...
I wonder if you have thought about making use of a power tube fan at the peak, simply punching holes in the tubing to direct airflow toward the floor. You might use this in conjunction with the fan that circulates air over your heater.
I'm curious, do you run circulation fans in your gh all the time? I have a large fan that circulates air from the peak of my gh 24/7, this is used in conjunction with my power vents & exhaust fan (which runs pretty much constantly throughout the summer) & my forced air furnace.
At any rate, let us know how it goes...

As an aside, do you have any Norwegian relatives? A friend of mine shares the same surname.
Adam

[richardb]

Lars
I installed a Hotbox circulation fan in each of my greenhouses earlier this year. They are not cheap, but they are really excellent. In fact I have no ducting, but when I closed the door and watched I could see ferns on the gravel floor waving from the fan installed high in the apex. I guess that the tubular structure of the fan draws air from behind and thus up through the staging.
I thoroughly recommend.
Richard