Jump to content

Incoming mains water: 20mm or 25mm MDPE? Best bet?


oranjeboom

Recommended Posts

In this 'renoextension' the original MDPE supply was 20mm which I had to pull out during structural works and now looking to pull back in. It's a private water supply coming in from landowner next door in 20mm MDPE (no chance to replace that all the way to source at the moment). Not noticed any issues with water pressure living in the static, but I recall reading somewhere on BH that it's probably best to opt for 22mm in the house itself (after stopcock) if there is a chance of low incoming pressure.  The landowner next door rents out various commercial units units next door (so there is a potential for a drop in pressure but I haven’t noticed so far) so just want to insure myself against pressure issues.

 

I need to get my UFH pressure tested soon, so just need a connection in the house again and may as well get it right from the very beginning. I was looking to go for 20mm MDPE to 22mm but options seemed very limited (though typically did find an option last night, typically here https://www.drainagepipe.co.uk/products/mdpe-water-pipe-fittings/mdpe-to-universal-copper-adaptor/20mm-x-15/22mm/)

 

I can either stick with the 20mm MDPE or would it be best to replace my incoming MDPE from the boundary with 25mm?

 

Not sure what I'm going for in terms of UVC, boiler, TS etc etc but was reading that 20mm is a safer bet (for runs to bath at least), but that will be more questions in another post.

 

TIA

Link to comment
Share on other sites

I have 20mm MDPE from under the road to our water meter and then into the bungalow. I have teed off that in 25mm MDPE to the new house and then used a 25mm MDPE to 22mm adapter.

Edited by PeterStarck
Link to comment
Share on other sites

3 hours ago, Nickfromwales said:

Can you do a flow rate. ? Get a bucket and a stopwatch. 

I was hoping for an easy answer @Nickfromwalesas I did not want to venture out in this not so fine weather. But my flow rate a la bucket method is 14L in 20secs, so 42L/minute, so does not seem to be an issue. However, like I said, I have a number of commercial units next door so maybe the flow rate is improved by the landlord during the day, so I will do another test a bit later this evening. So okay to stick to the original 20mm MDPE?

Edited by oranjeboom
Link to comment
Share on other sites

19 hours ago, Onoff said:

I've got 25mm coming up into a 22mm stopcock. It then tees off to an outside tap so no loss of pressure. Then a PRedV. Goes to 15mm at the mo. Will shortly change to 22mm.

 

 

 

Thanks!  Those Honeywell's aren't cheap are they!!! Just found one on fleabay for around £17 (*unused*....)

 

16 hours ago, PeterStarck said:

I have 20mm MDPE from under the road to our water meter and then into the bungalow. I have teed off that in 25mm MDPE to the new house and then used a 25mm MDPE to 22mm adapter.

 

Well if it works for you! I thought there may be issues going from 20mm-->25mm MDPE and then 22mm. Off to the 'station to get my adaptors then!

Link to comment
Share on other sites

17 minutes ago, oranjeboom said:

Thanks!  Those Honeywell's aren't cheap are they!!! Just found one on fleabay for around £17 (*unused*....)

 

I could not, for love not money get the 25mm MDPE to stopcock joint to seal until I got some Jet Blue Plus.

 

SAM_4102

 

SAM_4099

 

http://www.plumbcenter.co.uk/product/center-center-jet-blue-plus-500-g/

 

Wouldn't use anything else now.

 

Link to comment
Share on other sites

2 hours ago, Onoff said:

 

I could not, for love not money get the 25mm MDPE to stopcock joint to seal until I got some Jet Blue Plus.

 

 

http://www.plumbcenter.co.uk/product/center-center-jet-blue-plus-500-g/

 

Wouldn't use anything else now.

 

Now you tell me!! Just got back from the 'station. Actually, yes, I saw you had problems with yer plumbing in another post. Will see how/if mine has the same issues. Thanks!

Link to comment
Share on other sites

@Onoff I see that you installed the PRV vertically like I intend to also (MDPE up through the slab, then copper vertically up the whole into attic). However, now in receipt of my Honeywell PRV and I see the instructions state it can be fitted vertically or horizontally but "In vertical installation position spring bonnet with adjustment knob facing upwards". Not had a drop tonight but if I follow that instruction, then the flow in the PRV will be in the wrong (downwards) direction. :SHave you had any issues with this @Onoff? Wondering whether that will affect the pressure setting/reading and also debris collection filter? Maybe the resident plumber, @Nickfromwales can clarify?

 

My preference is to have a nice straight run, rather than adding in a horizontal section.
 

Link to comment
Share on other sites

22 minutes ago, oranjeboom said:

@Onoff I see that you installed the PRV vertically like I intend to also (MDPE up through the slab, then copper vertically up the whole into attic). However, now in receipt of my Honeywell PRV and I see the instructions state it can be fitted vertically or horizontally but "In vertical installation position spring bonnet with adjustment knob facing upwards". Not had a drop tonight but if I follow that instruction, then the flow in the PRV will be in the wrong (downwards) direction. :SHave you had any issues with this @Onoff? Wondering whether that will affect the pressure setting/reading and also debris collection filter? Maybe the resident plumber, @Nickfromwales can clarify?

 

My preference is to have a nice straight run, rather than adding in a horizontal section.
 

 

Problems, yes, it doesn't seem to be working properly as in it's bending the needle and twiddling the green knob doesn't seem to have any effect. Just assumed it needs a clean out which I've never done.....

 

I might need a scan of your instructions!

Link to comment
Share on other sites

If you read the words to the letter, it says 

 

5. Assembly
5.1. InstallationsGuidelines
It is necessary during installation to follow the installation instructions, to comply with local requirements and to follow the codes of good practice.
• Horizontal and vertical installation position possible 

 

"Codes of good practice" are the forces at work here. I'd say they're open to interpretation and the valve could be mounted and operate properly in the opposite orientation. It doesn't say that it won't work the other way, and it doesn't say it need to be mounted that way to comply with regs. 

I'd say it's a recommendation only to make service and repair most practical, and nowt else. ;)

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...