25mm core for 22mm outside frost resistant hot and cold tap...

[GoodDIYjob]

Very straight forward question but not sure why it seems so limited or I have lost my googling abilities..... There seems to be very few 25mm cores to go through a brick and block cavity wall circa 300mm..

The supply tails on the outdside hot and cold tap, which incorporate the valves, run back inside the property thermal envelope and can't be changed and they are 22mm OD. And go all the way through the wall. So 2 x cores required.

My obvious go to would be a 25mm core for 22 mm pipe. Last time I did an almost identical job at our old house, I used a 25mm mansonary bit on the sds which must have meant I couldn't find a core then either. 22mm yes, 28mm yes... The cheapie long reach masonary bit got though ok, but made a bit of a mess of the hole and exit point....

I suppose I could sleeve and go higher diameter, what would I use, 28mm copper, but the nearest core that would allow insertion would be 32mm wouldn't it? Last time I just wrapped the two fixed tail in electrical tape just to give them some barrier to cement // lime.

FYI the outside tap is a woodford model 22, very useful for outside warm water demand, the dog also demands it after November hits!

 

[Deluks]

Pilot through with a 6mm, then drill through from both sides, step up with increasing diameter bits until you get to 25mm.
Pipe collar over the resulting hole to seal around the pipe.

 

[Madrab]

As suggested - why core - just use a good quality 25mm masonry bit and back off with the pressure on the gun when getting to the outside wall

 

[Razor900]

They are readily available....

Amazon.co.uk

 

[GoodDIYjob]

They are readily available....

Amazon.co.uk

Yeah ok. Thanks. Just quite rare and not in a brand I recognise but I may just go with it. On the cheap side. But I am only doing 2 holes!! Is that a normal arbor thread or is it for a specific core drill. I will do some searching... Tks

Thanks for the other replies as well. Yes, I could use my 25mm masonary bit and sds and be a bit more careful. It did try last time and I did pilot hole it as well.... I can't do a hole from inside without completely removing the vanity and concealed WC cistern and WC pan....

Photos attached...

and this was the inside of the finished job last time.... Which also didn't lend itself to using a core from the inside! the outside bricks were as hard as nails. Southern water branded engineering bricks on a 1980s extension!!

 

[GoodDIYjob]

Ok thanks @Razor900 and @Madrab.

I already had the long sds plus masonry bits so I did as before and suggested here. Pilot 10mm, then 20mm, then 28mm. Before going through the plaster inside I turned to drill only without percussion. All turned out fine. Thanks. Few photos.

Now for connecting up. I think I'll probably resort to compression or tectite classic for the tees and they are in a lightly awkward position and close to the plastic soil pipe. My soldering is ok but not brilliant and gets worse in tighter locations....

I'll probably pack the end partition with some rockwool and of course seal around the inside of the entry holes but the valves for the tap are actually internal in the very end of the tail pipes - quite a smart design. they're on a slightly down slant, so when you turn the tap off they drain as there is also an air entry in the top of the tap...

Thanks again.

 

[tbcnsg]

I had almost the exact same problem when I ran a pair of 22mm insulated tails through a 9" wall for an outdoor mixer tap. Couldn’t find a proper 25mm core anywhere either — seems they just skip that size completely!

I ended up using a 28mm core bit, then sleeved the pipes with short bits of 28mm copper tube - worked a treat. Gives you just enough wiggle room and some protection against mortar contact.

If you want to be neat, you can also push a bit of expanding foam or silicone around the sleeve ends once you’re done, keeps the draught and damp out.

So yeah, 28mm core + sleeve is probably the most practical way.

And totally agree about the Woodford taps - once you’ve had warm water outside, you’ll never go back!