navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address. Following continuous spam/hack attempts on the forum, "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1] 2   Go Down
  Print  
Author Topic: Cheapest option for flexible plastic pipe to carry hot water  (Read 5947 times)
Ivan
Hero Member
*****
Offline Offline

Posts: 2262


« on: February 11, 2015, 04:39:43 PM »


I need to move hot water underground about 40metres, so was looking for something around 32-50mm that will take hot water. On the cheap, I was thinking about using 100mm unperforated land-drain type pipe and filling the void with expanding foam, then surrounding it in the trench with offcuts of kingspan, which I can free locally.

I had wondered about using MDPE, but I think 70C would be touch-and-go as to whether the pipe would take it. Needs to be available on the roll to avoid underground joints, and be cheap!
Logged

www.epogee.co.uk - Solar PV & Solar Thermal Training / MCS
Fintray
Hero Member
*****
Offline Offline

Posts: 909



« Reply #1 on: February 11, 2015, 05:08:15 PM »

 Looks like 28mm Polypipe would be the "cheapest" nearest option but still 100+ per 50m roll. Normal MDPE pipe wouldn't likely survive hot water (Central heating?) temps might be ok for UFH type temps.
« Last Edit: February 11, 2015, 05:56:13 PM by Fintray » Logged

3.87kWp PV
10.24kWp PV SolarEdge system
Tesla Powerwall 2
100 x 47mm Navitron tubes (still being installed!)
MK2 PV router DHW diverter
Morso 5kW WBS
Nissan Leaf
stannn
Global Moderator
Hero Member
*****
Offline Offline

Posts: 5541



« Reply #2 on: February 11, 2015, 05:24:58 PM »

http://www.engineeringtoolbox.com/pe-pressure-grades-d_668.html
Logged

2.45 kWp PV (Navitron supply), 40 evacuated tubes (Navitron supply), Clearview 650 log burner with back-boiler heating cottage and water, 2 off 50W border collies, 1 off 35W cat, 1 off 25W cat.
Nickel2
Hero Member
*****
Online Online

Posts: 1869


Sunny North-East Hampshire


« Reply #3 on: February 11, 2015, 05:57:40 PM »

My pipe-run from house to workshop is 14M (plus return = 28M). I used 22mm polyplumb grey barrier pipe,  (good for 90c and pressure), at 50 for a 25M roll. 2 rolls means no joints for reliability issues. From a ground temperature of 11 degrees up to maximum results in expansion of 83mm each leg. (last pic) I used full-flow 22mm braided flexible hoses to deal with expansion. The entire pipe-run including the inside of house and wshop is approx. 2 1/2 gallons, which needs to be heated for every cycle.
I copied Ken Boak's arrangement; 22mm polybutylene pipe inside climflex-style (Wickes) insulation inside 68mm rainwater down-pipe. The whole lot (underground) is boxed inside 50 mm Grey 'Jablite' polystyrene sheet, sliced up to suit. As I have no sharp joints in the outdoor section, the flow resistance is very low, so the water can be moved at fairly high speed with low friction and low noise. Some pics:














N2
Logged

1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
guydewdney
Hero Member
*****
Offline Offline

Posts: 4320



« Reply #4 on: February 11, 2015, 09:26:58 PM »

What pressure?
Logged

Pic of wheel on day 1
7.2kW Waterwheel and 9.8kW PV
mr smith
Full Member
***
Offline Offline

Posts: 233



WWW
« Reply #5 on: February 11, 2015, 09:41:01 PM »

I ran 25mm cold water inside 80mm unperforated land drain and just put normal pipe insulation around it.
Logged
Ivan
Hero Member
*****
Offline Offline

Posts: 2262


« Reply #6 on: February 11, 2015, 09:56:32 PM »

The static pressure would be fairly low - head of water, so maybe 0.25bar. Depending on the resistance to pumping, the pump will cause some increase in pressure, though I've no idea how much. I'm guessing it would be under 1 bar.

Polypipe sounds like the way to go - but is 28mm the largest size available? It could do with being 32mm or better still 40mm.
Logged

www.epogee.co.uk - Solar PV & Solar Thermal Training / MCS
guydewdney
Hero Member
*****
Offline Offline

Posts: 4320



« Reply #7 on: February 11, 2015, 10:09:09 PM »

I bet mdpe will gake that. 70 isnt hot, think of a black mdpe pipe in the sun, in a sunny field....
Logged

Pic of wheel on day 1
7.2kW Waterwheel and 9.8kW PV
Fintray
Hero Member
*****
Offline Offline

Posts: 909



« Reply #8 on: February 11, 2015, 10:11:21 PM »

28mm seems to be the biggest they do, you could always double up to give you a greater capacity.
Logged

3.87kWp PV
10.24kWp PV SolarEdge system
Tesla Powerwall 2
100 x 47mm Navitron tubes (still being installed!)
MK2 PV router DHW diverter
Morso 5kW WBS
Nissan Leaf
Ivan
Hero Member
*****
Offline Offline

Posts: 2262


« Reply #9 on: February 11, 2015, 10:22:00 PM »

It is quite a distance - I think about 40metres, so doubling up might work out expensive, as that's 4 pipes in the trench.

MDPE is certainly an attractive proposition, and you're right 70C is probably close to what a pipe sat in the sun would get up to in July. I can't find anywhere that says what the maximum temperature for low pressure applications would be. I can always use a mixer and blend it to something lower, but of course, it might not be needed.
Logged

www.epogee.co.uk - Solar PV & Solar Thermal Training / MCS
offthegridandy
Hero Member
*****
Offline Offline

Posts: 1007



« Reply #10 on: February 12, 2015, 06:29:52 PM »

Hi Ivan,

I think MDPE could be considered if as you say you blend the water to keep stable temp in system. Blue pipe is available in a range of larger sizes.  From my notes I think the max recommended temp for blue MDPE is 60" it actually starts to melt at 110 '.  Have you considered expansion of the pipe. 8mm per 6mtr length per 10' temp rise so not impossible to live with but need to make sure no connections at either end are fixed rigid.

I looked this stuff up a few yours ago when a church mouse I knew needed a rayburn plumbing in.  I had mdpe a plenty and he had no money.  I plumbed most of the system using 25mm blue mdpe and fittings of which I have 100's .  Obviously not used adjacent to tank and rayburn. So I got the above gen from a manufacturer to work out what was safe to do.

Good luck.

Andy 
Logged

8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw WT H Piggot design 4.5 Mtr Dia AC coupled
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 K wood stove
rogeriko
Hero Member
*****
Offline Offline

Posts: 1445



WWW
« Reply #11 on: February 12, 2015, 07:55:26 PM »

Here you go its only 99p for 100 meters!!  http://www.ebay.co.uk/itm/100metres-32mm-mdpe-blue-water-pipe-/271771956971?pt=LH_DefaultDomain_3&hash=item3f46def6eb
Logged

sb79
Sr. Member
****
Offline Offline

Posts: 356


« Reply #12 on: February 12, 2015, 08:21:38 PM »

Ivan you could always try to blag a 'sample' of heat main out of watts industries or rehau..... 'Yes of course we want to sell it. Honestly'....
 
Logged
knighty
Hero Member
*****
Offline Offline

Posts: 2831


« Reply #13 on: February 12, 2015, 10:51:45 PM »

how much heat do you need to shift ?

40m of nice smooth pipe won't cause much flow restriction

all depends how much heat you need to shift, and the flow/return temps?
Logged
Philip R
Hero Member
*****
Offline Offline

Posts: 1691

South Cheshire


« Reply #14 on: February 12, 2015, 11:04:27 PM »

As you want to transport hot water, allow expansion loops to cater for the thermal expansion of the pipe, otherwise your fittings will start to leak.
Philip R
Logged
Pages: [1] 2   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!