Ducted insulated twin pipe - best supplier

[HughF]

I need approximately 18-20m of insulated twin ducted pipe for my ashp flow and return. 
 

Rehau rauthermex duo seems to be much cheaper than the uponor product and is slimmer overall at 110mm for the 2x32 duo.

 

Does anyone have any recommendations either way about what to use?

[yebaws]

We used Rauthermex for our biomass installation. Not cheap, but at the time (8 years ago now) generally accepted as the best. Be aware that it has a very wide maximum bending radius. You'll need to put joints is to get round most corners.

[HughF]

8 minutes ago, yebaws said:

We used Rauthermex for our biomass installation. Not cheap, but at the time (8 years ago now) generally accepted as the best. Be aware that it has a very wide maximum bending radius. You'll need to put joints is to get round most corners.

That was my understanding of rauthermex from the data sheet. It appears to be a fully bonded product unlike the uponor which looks like it allows for the cores to slip as you bend it.

 

I need to do 2 90’s but they can be wide sweeps as they’re in the garden at one end and under the floor at the other. I can come out the ground at 45 at one end and transition to 32mlcp for the hidden run alongside the shed. 
 

 

[Nick Laslett]

10 hours ago, HughF said:

I need approximately 18-20m of insulated twin ducted pipe for my ashp flow and return. 
 

Rehau rauthermex duo seems to be much cheaper than the uponor product and is slimmer overall at 110mm for the 2x32 duo.

 

Does anyone have any recommendations either way about what to use?

My system is not yet commissioned, so hard to tell the performance of the pipe. I went with this product, CaldoPEX from Enerpipe, which I think was better value than Rehau or Uponor. The specs looked comparable. There may have been some other factors which I don’t remember now. But something made me choose this over the other options. 
 

https://ingoodnic.uk/25-25-90mm-16.html

 

They have longer lengths. 
 

https://www.enerpipe.de/en/produkte/14262/pre-insulated-pipe/pa/?p=2

 

On reflection, perhaps the flexibility of the pipe after thermals should be considered. They are very hard to bend. 

Edited September 17, 2022 by Nick Laslett

[HughF]

13 hours ago, Nick Laslett said:

My system is not yet commissioned, so hard to tell the performance of the pipe. I went with this product, CaldoPEX from Enerpipe, which I think was better value than Rehau or Uponor. The specs looked comparable. There may have been some other factors which I don’t remember now. But something made me choose this over the other options. 
 

https://ingoodnic.uk/25-25-90mm-16.html

 

They have longer lengths. 
 

https://www.enerpipe.de/en/produkte/14262/pre-insulated-pipe/pa/?p=2

 

On reflection, perhaps the flexibility of the pipe after thermals should be considered. They are very hard to bend. 

I was looking at that product as Ingoodnic appear to have the best prices around. It looks identical to the Rehau product, with a fully bonded pu foam inside a heatshrink type outer. 
 

My biomass installing ex-neighbour said that the fully bonded product behaves better when it leaves the ground with less risk of differential expansion along the pipe runs causing the inners to push out of the outers.

 

I like the fact it’s around 110-120mm OD too as I need to fit one end through a cored hole in the foundation.

 

0.9m bend radius, I can live with that as I’m only needing to bend it to 90 degrees in the horizontal plane, I can do the out of ground transitions at 45 degree or less, gently coming out of the ground as I need these ends to be horizontal.

[SteamyTea]

On 18/09/2022 at 08:03, HughF said:

0.9m bend radius

Can add a lot of extra length, as heat loss is proportional to length, may be better to use angles if you can.

Possible affect flow rate though.

[Nickfromwales]

OK.

So, for a potential project I am considering what could be a good idea, or it could also be the 'other kind' of idea.... @SteamyTea / others, sharpen your best pencils please.

 

I would like to install ~50m of 4x 25mm 'cores' pre-insulated pipe EXAMPLE in a trench of X depth ( assuming 750mm-1000mm atm ) carrying central heating flow and return and DHW + DHW/HRC. This would be to supply services to an single residential annex from a centralised, remote plant room. Assume bags of available heated water from a remote but local ~1000L buffer tank fed from a large oil boiler.

 

No room in the annex for any kind of cylinder / tank etc, so ideally I wanted to pipe the ( already available ) significantly sized services via an umbilical aka district type arrangement as that seems the obvious route atm.

 

I've ruled out a PHE due to the much higher flow temps that would be required to go a-la 'full district' setup; eg via a 2-pipe umbilical pipe arrangement + PHE for DHW, and the fact that the buffer would need to be heated all year round just to give the annex DHW.

 

Summer ideally wants to see the oil boiler and its buffer tank hibernating, ergo the full district setup seems unsuitable / non-cost-effective. The large plant UVC will be kept hot 24/7/365 from an oil boiler + strategic electrical injection via immersion(s) on TOU + Solar PV excess being used to offset DHW running costs; standing losses of UVC plus losses from umbilical. ( 4kWp of existing solar, likely to be upscaled to 8 or 12 if 3ph becomes available ).

 

Annex ( relatively small ) will be lived in all year round ( retired occupants ).

 

Crappy retrofit UFH to GF and brand new convector rads FF. Old stone cottage with OK 2G doors / windows, it is what it is. Will be improved over time, I'm told.

 

I will need to convey; 

CH flow and return - flow temp assume 65^oC .

DHW + HRC - 'flow' temp assume 55^oC ( will be a fair bit higher in summer I expect, with the source UVC boosted by PV divert ).

30 year proposal / running costs to meet.

 

Q;

I am specifically after a bit of help understanding the expected heat losses from the umbilical insulated pipe, please.

 

Options would be;

1. stick with the pre-insulated pipe, burying it in the ground in a 300mm wrap of sharp sand, as is.
2. stick with the pre-insulated pipe, boxing it ( 4 sides around ) inside an EPS 'trunking' ( 100mm thickness or more ) with subsequent air gaps foamed, eg to further reduce losses as best practicable.
3. ditch the uber expensive pipe, do these runs in Hepworth aka Hep2o, insulate them manually with 25mm wall Armaflex, and box them inside 200mm thick EPS trunking + foam
4. open to other better / more cost-effective methods etc
5. lend of a scientific calculator plus simplified instructions for use........

 

 

Silence in the room please, the exam has now started.

 

 

[SteamyTea]

3 minutes ago, Nickfromwales said:

I am specifically after a bit of help understanding the expected heat losses from the umbilical insulated pipe, please.

You can treat the heat loss from a pipe as exactly the same problem as a wall.

Hot side, Cold side, Surface area and Thermal Properties.

 

Dig a trench, pour in some polystyrene beads, lay pipe, more beads, then cover with a foot of dirt.

Plant grass.

If water table is a problem, pour in two part expanding PU foam and cover with paving slabs, then earth and seed.

[Nickfromwales]

4 minutes ago, SteamyTea said:

You can treat the heat loss from a pipe as exactly the same problem as a wall.

Hot side, Cold side, Surface area and Thermal Properties.

 

Dig a trench, pour in some polystyrene beads, lay pipe, more beads, then cover with a foot of dirt.

Plant grass.

If water table is a problem, pour in two part expanding PU foam and cover with paving slabs, then earth and seed.

I was expecting rows of digits etc.

 

Ground averagely permeable, not 'water-logged'.

 

So EPS box and pipes inside good as anything? Pre-insulated pipe would be north of £5k, was thinking home-made would halve the cost ( assuming trench dug either way, just dug a wee bit more to allow for the EPS is chicken-feed once there and at it ).

[SteamyTea]

5 minutes ago, Nickfromwales said:

I was expecting rows of digits etc.

I could, but working on a load of more interesting data ATM.

 

The main thing is to make sure air and water does not reach the pipes.  Polystyrene is a pretty good insulator, just make sure that you dig the trench large enough to separate the pipes by at least 100 mm.  Make the separators of polystyrene.

 

If you open an account with a 'bead expander' there are a few on here that will buy extras off you, seems the only way to get them is to 'be in the trade'.