Hanging a condensing unit

[Abe]

I am posing a question regarding the hanging of condensing unit on a " New Build"

By New Build I refer to modern day bricklaying techniques and especially the type of bricks employed.

In the UK is is now customary to use a solid concrete block, or one made of ash, usually Newtons. Then a gap which is filled with an insulation fibre and then the outside with a face brick. The face brick is not solid, rather has three holes within it.

Now when it comes to fixing a bracket against this wall, you will find the rho bolt will not secure tightly if per chance the drilled hole goes through the hole opening.

The integrity of the bracket holding is in my opinion not guaranteed in this case, and if the condensing unit is located high up, there exists the possibility of it falling off at some point, the whole shebang crashing to the ground.

I am inclined to secure the bracket not only through the brick, but by use of a threaded rod, right through the block as well for added security.

Your thoughts please

[nh3wizard]

Sounds like how I would do it, but are there any concerns with heat transfer from the threaded rods causing ice build up? Ambient to freezer

[Andy AC]

I use a M8 x 70mm hex head coach screw with Fischer S12 plugs and zip them in quickly with my impact driver, then give them an extra tweak up by hand if necessary. Very rarely fails, if it does I change the coach bolt for the hex head screws they sometimes bolt condensers down to the pallets. Even works quite well on celcon blocks.

Andy

[Brian_UK]

Hi Abe, register at this site...
http://www.fixingscfa.co.uk/index.asp
(it's a simple entry form and no passwords etc)
Login to the site and go to 'Guidance Notes', there is a note on fixings to perforated bricks so hopefully wil shine a light on your choices.

[eggs]

Fix into the motor joint with m10 rawlbolt fixings, as long as the brick/block is tied in at the top you will be fine. Three on the heavy side, two on the wimps side.

Job done! home for dinner.

eggs

[AcidSlasher]

we use chemset to fix the bracket to the wall. drill the holes out (14mm, careful not to punch through the back of the brick) fill it with chemset and insert the 12mm bolts, let it set, thenput the brackets and nuts on and she aint going nowhere.

[Argus]

.

Abe, I think your question concealed another one that is more fundamental - one that I would direct at a structural engineer, being the acknowledged expert in this area..

That is, how substantial is a single course brick curtain wall as you described it?

Will it support the prolonged weight of a live load and its brackets?

This is typical of a lot of modern building in the UK; these walls are usually an infill between concrete beams and are not, in my opinion, load-bearing - especially in a lateral direction with a condensing unit supported on it. You only have to consider the type of brick you described and other lightweight composition material.

Even more, I think that these things hanging over public thoroughfares, as is often the case, are a liability.

.

[expat]

I like this stuff.

http://www.hilti.co.uk/holuk/modules/prcat/prca_navigation.jsp?OID=-27372

You drill a 16mm hole, if memory serves, then you blow out the hole and push in a mesh sleeve. The sleeves I have can clip together according to the depth of the hole.
Then you cut a piece of threaded rod to length or you use Hilti's standard bolts. The sleeve is disigned in such a way as to hold the bolt square.
Now you squirt the chemical in and then push the bolt in. The chemical will have pushed it's way out through the mesh sleeve into any hollows and it turns to rock in 40mins at 20°c.

This could be the sort of solution you're looking for.

[SkyWalker]

We use the Horemann Coach bolt stlye fixing, 16mm hole bash her in and Job done, these things hold serious weight!

my personal worst nightmare when it comes to out door units is mounting on a cladded building!!! how/what do you guys use for this?

[Abe]

I like this stuff.

http://www.hilti.co.uk/holuk/modules/prcat/prca_navigation.jsp?OID=-27372

The chemical will have pushed it's way out through the mesh sleeve into any hollows and it turns to rock in 40mins at 20°c.

This could be the sort of solution you're looking for.

Expat

Noted, thank you for some very useful info indeed
I have also taken on board the views of other members, Argus, thanks for reminding us that this is a serious issue and one all engineers must consider very carefully when locating and hanging units.

I read a report last week that in Korea a unit dislodged and the bracket fell down killing a women.

[Abe]

We hung the outdoor unit today. Used 12mm threaded rod.
A hole was drilled through both face brick and internal block.

A channel ( uni strut) was placed in the inside, against the block with 4 x rods bolted to it.

The bracket is very very secure. For added measure used a couple of Rho Bolts as well to boot, on the face side holding rail.

No way is this unit falling off.

[Argus]

We hung the outdoor unit today. Used 12mm threaded rod.
A hole was drilled through both face brick and internal block.

A channel ( uni strut) was placed in the inside, against the block with 4 x rods bolted to it.

The bracket is very very secure. For added measure used a couple of Rho Bolts as well to boot, on the face side holding rail.

No way is this unit falling off.



That’s belt and braces, Abe.:D

I hope that it wasn’t the MD’s office wall! It'll make a mark on his wallpaper.

.

[taz24]

Expat

Noted, thank you for some very useful info indeed
I have also taken on board the views of other members, Argus, thanks for reminding us that this is a serious issue and one all engineers must consider very carefully when locating and hanging units.

I read a report last week that in Korea a unit dislodged and the bracket fell down killing a women.

One thing I would like to remind you of is not to overtighten the bolts if you choose to use them.
With the cavity wall if you over tighten the bolts you stand the risk of pulling the two walls together and damaging them.
(from experience)

taz.

[Abe]

One thing I would like to remind you of is not to overtighten the bolts if you choose to use them.
With the cavity wall if you over tighten the bolts you stand the risk of pulling the two walls together and damaging them.
(from experience)

taz.

My over "exuberant" engineer who came up with the idea did the tightening.

And he has a history of overtightening things. I keep telling him not to overtighten flare nuts. But he swears that he tightens till they cant move any more.

Now Im thinking of that poor wall...........More sleeepless nights for me.

[Argus]

My over "exuberant" engineer who came up with the idea did the tightening.

And he has a history of overtightening things. I keep telling him not to overtighten flare nuts. But he swears that he tightens till they cant move any more.

Now Im thinking of that poor wall...........More sleeepless nights for me.



............. back to my point about the strength of the masonery.

If the wall is that weak, it's not strong enough to hang a unit on.

.

[aza]

Hi Guys, can i just say that if you use uni strut and cantilever arms you can bolt the uni to the wall and say thats not going anywhere, but, the cantilever arms are being held on by 4 x m10/m12 bolts and 4 x m10/m12 zebberdies!

Now what does it take to strip these threads or to snap a bolt???

[frank]

Now what does it take to strip these threads or to snap a bolt???

Well, it takes in excess of 40 metric tons to shear a 1/4" bolt, but I can't say 'owt about stripping a thread as I've never seen anything over M4 stripped - unless it was cross threaded.

[expat]

No offense meant Aza as I did not completely understand your post, but I must say that there is an important issue here.

We are not talking about the tensile strength of the fixations used, but more the resistance of the support.

Abe, the work you have done has covered your back, and will decisively stand the test of time...I only wish I had your powers of persuasion so that my clients would believe me when I say that a condenser unit falling on your head really hurts!

[expat]

One thing I would like to remind you of is not to overtighten the bolts if you choose to use them.
With the cavity wall if you over tighten the bolts you stand the risk of pulling the two walls together and damaging them.
(from experience)



You're right Taz, but what can I say. Don't send a boy to do a man's job!

[expat]

You're killin' me Frank...a pint'a harvest, mmm.

Right I'm off to the fridge!