Lock for sash window whilst open

This is for a sash window that opens out onto the street.
So security is foremost.
Unfortunately it is the only means of room ventilation so it is important that the window can be left partially open, especially in this weather.
Can anyone suggest an affordable way of allowing the window to have an option of being open say 4 inches, where it is impossible or very difficult to open any further from the outside?
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On 03/07/14 14:03, Fredxxx wrote:

Search for "Sash Locks" - pretty sure I've seen some that do exactly this - they mount part the way up the frame and can be unlocked to allow full opening.
The other option is to fit secure louvre shutters either inside or outside to allow air through whilst the window is open.
I think shutters are a great idea - which I had them.
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On 03/07/2014 14:03, Fredxxx wrote:

A variant on a piece of wood or a removable block that prevents the opening window moving up past a certain point (eg four inches up).
A similar trick can be used on patio doors by adding a drop in wooden baton to the inside rail track so that no amount of forcing the door from the outside will do anything apart from exhaust the would be thief.
--
Regards,
Martin Brown
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writes

These are what I use and these guys appear to best value ATM:
http://www.lockshop-warehouse.co.uk/acatalog/era-822-sash-window-stop.html
or http://preview.tinyurl.com/osybg7r
They are effective and are available in satin or brass finish. They require a 10mm hole behind the post and I used beefy no. 12 fixing screws in place of the lightweight ones provided.
Other ones I have seen have various security flaws or require inordinately large holes to be drilled in the sashes, these provide a good balance. Their flaw is that you mustn't overtighten the post when screwing it in as it will wear out the key/post fit and eventually result in it spinning. You then just replace the key and post.
If you want similar security with the window closed then fit a second set of plates below the first.
--
fred
it's a ba-na-na . . . .
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On 03/07/2014 14:03, Fredxxx wrote:

The sash stops mentioned are about the best you can do, but they do allow the sashes to be forced apart sufficiently to clear the stops. Screwing (rather than nailing) the staff beads may delay the casual burglar a little, which is the most you can hope for with most domestic security. I'm a great believer in the little battery operated impact alarms. Any force sets them off and the burglar is not to know the full extent of the alarm system.
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Interesting
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On 03/07/2014 14:03, Fredxxx wrote:

Thanks for the ideas.
I can see a Yale/Chubb lock that should do the trick, bit for what it is it seems incredible pricey, and there is an extra charge for keys. (Amazon.com product link shortened)
There are others that seem to have a flip-out type of stop that are much cheaper yet look more difficult to fit. http://www.ironmongerydirect.co.uk/products/window_and_joinery_hardware/vertical_sash_window_hardware/800/weeks_sash_stop/426616
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On 03/07/2014 14:03, Fredxxx wrote:

Difficult! Sash windows are only really secure when they're closed and locked together in the middle. If you have something which prevents the top sash from moving down too far (say) by having a protruding bit which sits on the top of the bottom sash, there's not a lot to prevent someone from pushing both sashes up and creating an equivalent space at the bottom - which would be more of a security risk.
You really need something which independently locks the bottom sash shut *and* limits the movement of the top sash at the same time. I suppose that if you *never* wanted to open the bottom sash, you could screw it shut and then fit something to restrict the motion of the top one - but that wouldn't work if you needed it as a fire escape.
--
Cheers,
Roger
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How about fitting one of those mechanisms banks have to quickly put a barrier up between the desks and celing in a robbery,
have a sensor that detects someone putting their fingers in the gap, then 'blam' down goes the sash, the bonus is you catch the scrote as well as protect the property,
kinda reminds me of that video of the feral youth kicking in a panel in one of those concrete sectional fences,
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On 04/07/2014 17:10, Gazz wrote:


http://www.youtube.com/watch?v=vPjUvNW6QUU

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Bet that would see the local kids triggering it deliberately once they realised it had been installed.

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