[Tech1] Air con

Thu Jul 22 03:20:36 CDT 2021

Effective ventilation can keep a house much cooler in the hot weather, but it also can allow flies and mosquitoes in.  A friend of mine used to swear by fine screens stretched across windows but my house has a number of windows which aren’t suitable for self adhesive strips to hold the mesh.

Some of my windows have stone mullions with Crittall steel window frames.  These pose two problems, one is that I don’t like the idea of sticking self adhesive Velcro to stone, the other is that the window doesn’t have a window stay to hold it open.  There is supposed to be a friction adjustment in the hinge, but the adjusting screw has long since jammed up.

I made wooden frames to fit the windows and recessed a number of 6mm magnets into them to hold the frame onto the steel window frame.  The mesh is stretched over the frame and the whole assembly easily lifts on and off in a moment. 

Keeping the window open called for more ingenuity.  I tried several approaches but ended up using magnets again, but these are very strong 25mm diameter magnets in a metal shell with an M5 male thread. I found an aerospace supplier on eBay who sold what I believe are throttle linkages. It’s a sort of ball bearing joint with an M5 male thread at one end and a female thread at the other. Another eBay supplier sold me thick walled aluminium tube which was just the right size for tapping M5, leaving plenty of material to maintain it’s strength.  

I’ve attached a picture and you can see how it all goes together.  I optmised the exposure to show the mesh as best as I can, but in reality, the tightly stretched black mesh is almost invisible in most lighting conditions.

Another window posed multiple challenges. That one is a round window, again supposedly with a friction mechanism to keep it open, but the adjusting screw is jammed solid.  The mesh screen over that window was the easier challenge.  I made a ring of MDF with a smaller ring behind it, the mesh is trapped between the two.  Holding it in position looked to be tricky to achieve neatly until I started making the smaller ring.  Although the window is circular, by the time the plasterer had smoothed it neatly, the inside aperture was slightly eccentric, even though it looked circular. The inner ring was scribed to exactly fit the shape and when the rings and mesh are offered up to the window, you only need to twist it slightly and it locks firmly into place like a cam.

Keeping the window open was much more tricky.  The wooden frame meant that magnets were no use and the position of the window makes it awkward to reach any mechanical clamp. Furthermore, adjusting the window was going to be a little tedious if it meant removing the frame which holds the mesh in order to tweak the clamp. 

I ended up buying a 12v linear actuator from eBay ( intended for operating things like windows, seats and mirrors in cars - cost about £16 ). I had hoped to mount the actuator vertically with one end screwed to the frame and the other screwed to the window, but when the window was shut, the disadvantageous leverage meant that the weather seal made it too stiff to break that seal.  I ended up having to mount it pushing the window directly and it works really well, although in hindsight, I should have got an actuator with a longer travel. The actuator is operated by a generic car window switch mounted on a standard 1 gang blanking plate and as it’s in a bathroom and there isn’t power readily available there, it’s powered from a 12v lead acid gel battery inside a cupboard. I have several of these batteries for my audio gear.  I don’t know how long it goes between recharges, but make a point of operating it every day and four months on, it’s still going strong.  The next battery is charged up and ready to be dropped in and connected by it’s 4pin XLR.

The next task is to get it connected via HomeKit.  It will need mains power instead of the battery, but suitable controllers are excessively pricey, so I’ve got a couple of ideas about doing it more affordably.

…. and yes Graham, CAT 6 cabling is great to have routed around the house.  We have stone walls, solid floors and beamed ceilings, therefore running cables inconspicuously calls for some ingenuity. Whenever a room is being refurbished or a floor taken up, I try to install CAT6 cables for future use.  Sometimes used for ethernet data purposes and other times to distribute A/V signals via adaptors. Having said that, wireless systems are getting more practical these days.  Fortunately our new router means that WiFi works well throughout the house, but it struggles to pass  through the external walls so we use a separate sender for the garden.

Alan Taylor

> On 22 Jul 2021, at 01:05, Graham Maunder via Tech1 <tech1 at tech-ops.co.uk> wrote:
> 
> One of the several “innovative” things I did when we built our house 16 years ago was to install a ‘fresh air ventilation system’ which has been invaluable since we moved in. As well as supplying a constant changing of the fresh air in all rooms it combines with a heat exchange unit to keep warm air inside in the winter and outside in the summer. When we installed it I went to the extra expense of upgrading the pipe work to allow for an external air conditioning unit to be added later but we’ve never felt the need to do this as even during the hottest days outside the house is cool inside. The extra bonus has been really good air quality as it’s also git a great filtration system.
> Building from scratch also gave me the opportunity to put in a central vacuum system so the main unit is in the garage and vacuuming becomes a magically silent thing to do.
> Also, despite protestations at the time from the electrician I’m also very grateful that I put CAT 6 cables through the whole house as due to the solid floor construction conventional wifi was really poor early on.
> By the end of the build I never wanted to see another builder in my life but we’re just looking at doing it all again somewhere new!! Time is a great healer.
> 
> Graham Maunder
> 07831 515678
> 
> Sent from my iPhone 
> 
>>> On 22 Jul 2021, at 07:27, Roger Long via Tech1 <tech1 at tech-ops.co.uk> wrote:
>>> 
>> We live in a thick walled stone cottage from 1760.
>> The southwest face gets to high 30s ,we open front and back doors , and the temperature differential drives a cooling  breeze through the ground floors.
>> The best airco I have ever experienced  , silent and cool.
>> 
>> Roger
>> 
>> Sent from my iPhone
>> 
>>>> On 21 Jul 2021, at 22:54, Bernard Newnham via Tech1 <tech1 at tech-ops.co.uk> wrote:
>>>> 
>>>  Long ago I bought a portable aircon machine for my young son's bedroom, which is on the sunny corner of the house and doesn't have good ventilation. 
>>> 
>>> Twenty years on, it's here behind me in my small "office", with the tube stuck out the window. It's the only room in the house where it's comfortable to be, though it's jolly noisy.  In a few days it will go back into it's corner till next year.
>>> 
>>> B
>>> 
>>> 
>>> 
>>> 
>>> On 21/07/2021 21:30, techtone via Tech1 wrote:
>>>> With all this talk of plumbing and pipework, I suddenly wondered if any of you have an air con unit at home. When we lived in Chalfont St. Peter, one of our neighbours had air con in his lounge, but it was seriously noisy when running, and I think the noise would have made a good night's sleep difficult if it was necessary to run it during the night.
>>>> 
>>>> So, any thoughts on keeping cool indoors during this weather (considering the possibility of more of the same in future years)?
>>>> 
>>>> TeaTeaFN - Tony
>>>> 
>>>> Sent with ProtonMail Secure Email.
>>>> 
>>>> 
>>>> 
>>> 
>>> -- 
>>> Tech1 mailing list
>>> Tech1 at tech-ops.co.uk
>>> http://tech-ops.co.uk/mailman/listinfo/tech1_tech-ops.co.uk
>> -- 
>> Tech1 mailing list
>> Tech1 at tech-ops.co.uk
>> http://tech-ops.co.uk/mailman/listinfo/tech1_tech-ops.co.uk
> -- 
> Tech1 mailing list
> Tech1 at tech-ops.co.uk
> http://tech-ops.co.uk/mailman/listinfo/tech1_tech-ops.co.uk
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://tech-ops.co.uk/pipermail/tech1_tech-ops.co.uk/attachments/20210722/802a1eae/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image0.jpeg
Type: image/jpeg
Size: 35135 bytes
Desc: not available
URL: <http://tech-ops.co.uk/pipermail/tech1_tech-ops.co.uk/attachments/20210722/802a1eae/attachment.jpeg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image1.jpeg
Type: image/jpeg
Size: 32004 bytes
Desc: not available
URL: <http://tech-ops.co.uk/pipermail/tech1_tech-ops.co.uk/attachments/20210722/802a1eae/attachment-0001.jpeg>