Plastic pipe for HP?

[Beelbeebub]

I know everyone says "don't use speedfit/Hepco plastic pipe because it restricts the flow, use copper"

 

But if I was going to use 22mm copper for the primary feeds, what about using 28mm plastic. The internal diameter of the 28mm plastic is a little bit more than the 22mm copper.

 

22mm copper is about the same per meter as 28mm plastic but I may have some long and difficult to access routes where pulling though a (pre insulated) length is pipe is easier than jointing then insulating 3m lengths in somewhat awkward conditions.

 

Any thoughts?

 

Should add, I was planning on doing the final runs off the primary in copper, 15 or 22mm to suit.  This is just for a run from the unit outside through a loft space and possibly down a stairwell.

Edited December 11, 2023 by Beelbeebub

[JohnMo]

My piping runs are (6kW ASHP) bit of a mixed bag.

 

First 4m is 28mm copper (to stop mice eating it and for valves etc), I go into a shed where I tee off, in 15mm for approx 6m in Hep2O to garden room (2x UFH 50m loops, no pump or mixer). The main run is converted to 28mm Hep2O 5m in a shed, then 4m underground, when I get to the house I convert back to 28mm copper (2m) up to 3 way valve in house. From 3 way valve it is copper 22mm to UFH (1m) and 22mm Hep2O to cylinder (8 to 10m away).

 

Did all the pressure loss calcs all good, but required a return pump on the cylinder loop.

 

Do pressure loss calc, use what material suits your application. One or two sharp bend is worse than many metre of slightly to small a pipe with shallow bends.

Edited December 11, 2023 by JohnMo

[sharpener]

4 minutes ago, JohnMo said:

Do pressure loss calc, use what material suits your application. One or two sharp bend is worse than many metre of slightly to small a pipe with shallow bends.

 

Yes, the advantage of plastic is you may be able to get away with bends, and it is good for angles that are not 45 or 90 deg. But when new CH was installed in previous house they still had copper mentality and used lots of elbows quite unnecessarily.

 

This calculator is quite useful for various comparisons.

 

 

[Beelbeebub]

2 hours ago, JohnMo said:

My piping runs are (6kW ASHP) bit of a mixed bag.

 

First 4m is 28mm copper (to stop mice eating it and for valves etc), I go into a shed where I tee off, in 15mm for approx 6m in Hep2O to garden room (2x UFH 50m loops, no pump or mixer). The main run is converted to 28mm Hep2O 5m in a shed, then 4m underground, when I get to the house I convert back to 28mm copper (2m) up to 3 way valve in house. From 3 way valve it is copper 22mm to UFH (1m) and 22mm Hep2O to cylinder (8 to 10m away).

 

Did all the pressure loss calcs all good, but required a return pump on the cylinder loop.

 

Do pressure loss calc, use what material suits your application. One or two sharp bend is worse than many metre of slightly to small a pipe with shallow bends.

Good point about the mice.  We are 5 floors up in an attic, but the little blighters do get about.....

[JohnMo]

16 minutes ago, Beelbeebub said:

mice.  We are 5 floors up in an attic, but the little blighters do get about.....

Our 15mm goes under two sheds, it is insulated and then placed inside some gutter downpipe, the exposed bits are foil tape wrapped and painted, to keep the bug***s out.

 

Plus we have bait boxes dotted about.

Edited December 11, 2023 by JohnMo

[ReedRichards]

My mice, which are field mice overwintering in the loft, love to chew up pipe insulation but so far have not touched the foil-covered phenolic type which I have used predominantly.

[JohnMo]

29 minutes ago, ReedRichards said:

My mice, which are field mice overwintering in the loft

I got these from Amazon

 

Roshield External Tamper Proof Rodent Boxes & Wax Bait Rat Killer.

 

Have got though 6kg of bait so far. So some hungry mice about. But the mice seem to be disappearing, we were getting over run by them, prior to this.

[ReedRichards]

I live trap my field mice; live if I get to them in time, that is.  Apparently it's not legal to poison them.  If I'm prompt enough and the mouse is still alive it gets relocated to several miles away in the countryside, where it ought to have taken winter quarters in the first place.

[Jenki]

Mice, don't like sticky traps, quick- break back traps for me, and the chickens love fighting over them, so they don't go to waste🙈

[saveasteading]

I think there are rats in the roof space, judging by the sounds, so yesterday i got out the old ice cream tub where i keep the bait, from a wall cupboard.

I found a small hole in the bottom of it and an empty sachet that had been  blue wheat. The only way into the cupboard is via a cable entry. I'm going to measure it for interest. 

I stopped using catch and release after i once forgot.