Adding a second window to GH ?

**Martin H** · 23-12-2014, 10:30 PM

Personally I think one window isn't really enough. The greenhouse heats up so quickly in the summer and can cook your plants in no time. So if you can get two automatic openers in the roof it will be better.

I think that the low level vents (louvres usually) are less important to automate. You can keep them open whenever it's not frosty and not worry too much about getting it wrong.

**Alison** · 23-12-2014, 11:18 PM

You do really need two openings. In find a roof opening and a side louvre works well on mine but two windows would be fine too to ensure air flow.

**Damian Jay** · 24-12-2014, 12:02 AM

The greenhouse I have has only one window in the top. Would it be easy to add a second window ?

**Aberdeenplotter** · 24-12-2014, 07:48 AM

Simple answer is yes but sourcing one may not be so easy.
If you have the name of the manufacturer , that should be your first port of call

.

**Bigmallly** · 24-12-2014, 08:07 AM

I agree with AP, it would be a lot easier & cheaper to buy louvre vents. They are easy to fit & will vent the greenhouse adequately.

**Damian Jay** · 24-12-2014, 08:23 AM

Thanks AP and BM.

I'll have a look at all the 'bits' and see if I can find a manufacturer. I won't hold my breath on that one. But I'll google louvre vents as well
Thank you for your comments :-)

**Kristen** · 24-12-2014, 09:58 AM

Originally posted by Bigmallly View Post

They are easy to fit & will vent the greenhouse adequately.

Personally I think smaller greenhouses are harder to ventilate [than larger ones, say 10' x 12' and bigger] and I would want roof vents on either side (so can take advantage of the wind coming from either side) and also a louvre in the wall (perhaps back wall, opposite to door) so that Louvre plus Roof Vents can be used for convection cooling, when temperatures are "moderate", which causes the plants much less transpiration stress than forced cooling, by opening the door, which will be necessary when the temperatures are higher - delaying when that becomes necessary, towards summer, and reducing how often will help with raising the plants IMHO

Agree may be hard to source though, particularly if the greenhouse is old or of unknown brand.

**Potstubsdustbins** · 24-12-2014, 02:47 PM

If you find the roof window hard to come by consider a low level louvre sited as far away horizontally from the top vent as possible.

The cold air (heavier) entering at the bottom will naturally push the hot air (lighter) up through the top vent.

**Bigmallly** · 24-12-2014, 04:42 PM

You do say things so much more eloquently than I Potty..............

**Damian Jay** · 24-12-2014, 06:28 PM

Oooo thanks for the tips. *Adds Louvre vents to the to do list for Jan 2015*

I think the easier option will be to add the louvre vents as I can't remember seeing a manufacturers plaque or markings anywhere on the framework when I dismantled it. Then again, it was given to me and I only had a couple of hours to get it dismantled and loaded on the van. So I didn't pay too much attention.

I will have another look when we put the frame back up. Never had a greenhouse before, is there a specific place manufacturers place their mark?

**veggiechicken** · 24-12-2014, 07:52 PM

I have 4 GHs (3 Freebies

) and only one has a maker's mark - and its just a building, not a name - above the door.
Most aluminium GHs are of the same sort of construction with the panels 2' wide. Roof pitches may differ but shouldn't affect the window opening.
Alternatively, you could remove a pane of glass from the door in summer and cover it with mesh. This would give you some ventilation.

**Aberdeenplotter** · 24-12-2014, 09:44 PM

WHATEVER MAKE OF GREENHOUSE, ALUMINIUM ROOF LIGHTS/WINDOWS GENERALLY OPERATE (scuse caps, not retyping) with a pipe sliding inside a fixed tube with a slot in it or a tube with a slot in it sliding over a fixed pipe. Hope that makes sense. Whatever, different brands use different diameters so it would be almost impossible to mix and match. With that in mind, louvred side panels would probably be the best idea. one of my greenhouses has 18" panes of glass rather than 2ft and beware some manufacturers will have gone metric. new fittings may be 600mm whereas 24" is closer to 610mm

**Alison** · 24-12-2014, 10:20 PM

Originally posted by Aberdeenplotter View Post

WHATEVER MAKE OF GREENHOUSE, ALUMINIUM ROOF LIGHTS/WINDOWS GENERALLY OPERATE (scuse caps, not retyping) with a pipe sliding inside a fixed tube with a slot in it or a tube with a slot in it sliding over a fixed pipe. Hope that makes sense. Whatever, different brands use different diameters so it would be almost impossible to mix and match. With that in mind, louvred side panels would probably be the best idea. one of my greenhouses has 18" panes of glass rather than 2ft and beware some manufacturers will have gone metric. new fittings may be 600mm whereas 24" is closer to 610mm

But surely the OP is wanting to fit an entirely new window first anyway so the auto opener is somewhat irrelevant. I'd agree with the post further up this thread, if the greenhouse is standard 2" wide panels then it'll be pretty standard so quite easy. Re auto openers, I quite happily use a cheapo generic one and it's fine, lasted for years with the only attention being that I remove it each winter and keep t frost free and give it a blast of WD40 each spring before refitting.

**Aberdeenplotter** · 24-12-2014, 10:32 PM

as you say Alison, the auto opener is irrelevant which is why I didn't mention it

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