125mm non-standard bends?

[phatboy]

Hi all,

 

I am finally fitting the last pipe to my system -  the 5" intake.

 

Where it exits the soffit, I had hoped to use a 45' bend, but sadly this is ever so slightly too wide, and hits the back of the MHRV unit, when it needs to pass just behind it.

 

I can use flexi pipe, but was hoping not to, as it will be a small weakness in the otherwise carefully detailed system and also require more physical supports.

 

Does anyone know of a supplier of, say, 40' bends?  In my mind its like plumbing, and you don't often want a true 45 or 90!

 

Can't even get away with partially inserting the connector, with the type I have.

 

Thanks

Tim

Edited July 13, 2019 by phatboy

[MJNewton]

I can't quite picture your exact setup/scenario from your description but I have found that plastic ducting (assuming that's what it is?) can be persuaded into taking on a slightly different shape/bend if heated with a hairdryer or heat gun if that'd help?

[PeterW]

Make one ..??

 

Have you got a length of 125mm pipe..? Cut the pipe at 20 degrees, rotate it 180 degrees and glue them together - gives you your 40 degree elbow. 

 

If  you then smear with CT1 and tape with decent foil tape it will be fine. 

[phatboy]

3 minutes ago, MJNewton said:

I can't quite picture your exact setup/scenario from your description but I have found that plastic ducting (assuming that's what it is?) can be persuaded into taking on a slightly different shape/bend if heated with a hairdryer or heat gun if that'd help?

 

This is true..... some plastic angle i had to fit the other day happily deformed in the heat, so I may be able to persuade a 1m length to do the same, a bit

 

4 minutes ago, PeterW said:

Make one ..??

 

Have you got a length of 125mm pipe..? Cut the pipe at 20 degrees, rotate it 180 degrees and glue them together - gives you your 40 degree elbow. 

 

If  you then smear with CT1 and tape with decent foil tape it will be fine. 

 

This is the sort of lateral thinking I'm lacking the past few weeks.  Lot's of CT1 and gorilla foil tape is in stock!

[MJNewton]

Just now, phatboy said:

 

This is true..... some plastic angle i had to fit the other day happily deformed in the heat, so I may be able to persuade a 1m length to do the same, a bit

 

 A five degree bend over a 1m length should be easy.

[Jeremy Harris]

Bear in mind that you must have short lengths of flexible duct at the connections to the MVHR, in order to isolate vibration.  If you fit rigid duct to the MVHR then there is a risk that the vibration from the fans will pass into the ducting.  Most MVHR MIs include mention of this, but even if they don't it's good practice, as is mounting the MVHR itself on some form of vibration isolating mount.  The need for short lengths of flexible duct may get around your bend problem.

[Russell griffiths]

We regularly used to make a bonfire out of cement bags and gently rotate pipe over it to make it fit what we needed. 

[phatboy]

Got through this finally today....  already had a flexible section in the duct close to the unit, but opted to just insert another one at the other end of the run, on the end of a 45degree piece, job done!