Tue, 09 Jun 2026 10:57:52 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175103#Comment_175103 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175103#Comment_175103 Wed, 01 May 2013 20:59:06 +0100 Mike George https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175107#Comment_175107 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175107#Comment_175107 Wed, 01 May 2013 21:36:07 +0100 DarylP ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175108#Comment_175108 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175108#Comment_175108 Wed, 01 May 2013 21:46:59 +0100 arnyj
I managed to get him to run both hot and cold water 6" away from outside wall so I could install internal insulation behind them and alongside them, then clad walls with ply to form my "Internal Shed"

arny]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175152#Comment_175152 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175152#Comment_175152 Thu, 02 May 2013 09:39:17 +0100 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175160#Comment_175160 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175160#Comment_175160 Thu, 02 May 2013 10:22:05 +0100 rhamdu
In practice this means looking wherever there is a temperature difference and asking "why would I *not* insulate there?"]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175168#Comment_175168 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175168#Comment_175168 Thu, 02 May 2013 10:37:12 +0100 fostertom Posted By: rhamduAnything that is not expressly permitted is forbidden.I thought that was Switzerland? Or is that 'anything that's not forbidden is compulsory'?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175174#Comment_175174 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175174#Comment_175174 Thu, 02 May 2013 11:16:28 +0100 tony
A cold pipe will over a long period ie a few hours warm up to room temperature and so will a WC cistern.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175184#Comment_175184 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175184#Comment_175184 Thu, 02 May 2013 13:24:14 +0100 Simon Still
And in some ways it's a very good approach. You can only park in marked bays which means a much much less cluttered streetscene. No need for yellow lines all over the place for a start...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175195#Comment_175195 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175195#Comment_175195 Thu, 02 May 2013 15:20:19 +0100 barney
regards

Barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175202#Comment_175202 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175202#Comment_175202 Thu, 02 May 2013 16:56:35 +0100 djh Posted By: tonyA cold pipe will over a long period ie a few hours warm up to room temperature and so will a WC cistern.
I wonder if anybody has ever calculated exactly how many hours, or better yet done an experiment to measure it?

With a cistern, the other thing insulation does is to raise the surface temperature enough to stop condensation on the cistern. It's worth doing for that reason, IMHO. I guess the same is true for pipework although that is more out of sight, out of mind.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175205#Comment_175205 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175205#Comment_175205 Thu, 02 May 2013 17:36:02 +0100 Ed Davies
This surprises me. The slug of water in the cold hot pipe which seems to go uninsulated under the floor here gets pretty chilly in the time between me running some water for my shave and then running a bit more to rinse off afterwards.

[Edit: I meant hot water pipe - which goes out into the cold weather]]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175207#Comment_175207 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175207#Comment_175207 Thu, 02 May 2013 17:44:49 +0100 barney
I'd go along with those numbers Ed - bearing in mind we are only going up by about 10C in total.

I've measured the time taken for a CWS pipe in ceiling void running near HWS pipes in a healthcare building to rise from approx 10 - 12C to about 22C ambient and it's not actually that long - half an hour wouldn't be unusual.

regards

Barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175220#Comment_175220 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175220#Comment_175220 Thu, 02 May 2013 19:42:18 +0100 SteamyTea Posted By: djhI wonder if anybody has ever calculated exactly how many hours, or better yet done an experiment to measure it?It is in the units W.m^-1.K^-1

W=J.s^-1
s= time t
K=T[1]-T[0]

Follows dT/dt = -k(T[1]-T[0])
This leads to
T=e^(-kt) (Newtons Law of Cooling)
Where k is the system properties, or the surface area of the pipe, the thermal properties of the material. Sometimes the surface area is put before the e

I have 3 iButtons on my desk, I could do a test, shall use a bit of T-Towel as an insulator.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175224#Comment_175224 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175224#Comment_175224 Thu, 02 May 2013 19:58:03 +0100 barney
In a former life, we used to use mugs of hot instant coffee - and no soap

take a few swigs and then when you just had enough to cover the razor - away you go - some guys used to drink the last drop as well after shaving - I couldn't face that myself

similar to the cold pipe warming, your hot pipe is cooling exponentially (ST's newtonian cooling above) - from a much greater delta T - so it don't take long to get chilly.

Not green to keep the hot tap running whilst shaving though - nor the cold tap running to brush teeth !!

regards

Barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175228#Comment_175228 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175228#Comment_175228 Thu, 02 May 2013 20:02:28 +0100 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175234#Comment_175234 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175234#Comment_175234 Thu, 02 May 2013 20:22:13 +0100 barney
Or are you actually going to measure the discharged water temp after x time

Regards

barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175239#Comment_175239 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175239#Comment_175239 Thu, 02 May 2013 21:37:27 +0100 SteamyTea Not really a long enough test, but can do some on the cold pipe and the cistern tonight as that is easy to get to.
This is what I have so far.
It is temp differences (from ambient) over time.
Added two trend lines per curve, linear and exponential, though 20 minutes was not really long enough]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175240#Comment_175240 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175240#Comment_175240 Thu, 02 May 2013 21:47:26 +0100 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175244#Comment_175244 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175244#Comment_175244 Thu, 02 May 2013 21:56:20 +0100 Sprocket
If I could bear to rip up all the floorboards again I would definitely insulate all the cold pipes.
I would also insulate the central heating pipes as well as the hot water pipes.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175248#Comment_175248 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175248#Comment_175248 Thu, 02 May 2013 22:39:30 +0100 Ed Davies
Still, the 22 mm seems it cools at about half the speed I estimated (16 °C to 8 °C in an hour where I'd have said 16 °C to 5 °C in 40 minutes).

My assumption I'd be least confident in would be the heat loss coefficient. I assumed 10 W/m²·K but that's probably too high. Copper seems to have a pretty low emissivity, for starters:

http://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

Also, a relatively smooth surface would be less good at conduction, I'd have thought, than the sort building materials that 10 W/m²·K figure is typical for.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175253#Comment_175253 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175253#Comment_175253 Fri, 03 May 2013 07:53:40 +0100 SteamyTea Quite amazed just how stable the temperature is in my bathroom overnight.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175278#Comment_175278 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175278#Comment_175278 Fri, 03 May 2013 13:44:03 +0100 djh Posted By: Ed DaviesThe pipe will warm at an exponentially decreasing rate. Making a few assumptions I reckon the time constant (i.e., the time it takes to get about 2/3rds of the way to room temperature) would, for uninsulated 15 mm copper pipe, be about 25 minutes. For 22 mm, nearer 40 minutes.
What about for an insulated pipe, though? (critical thickness insulation, before you ask!)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175279#Comment_175279 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175279#Comment_175279 Fri, 03 May 2013 13:45:36 +0100 djh Posted By: SteamyTeaMeasured a hot pipe and see how it cools (was easy to get to and had insulation I could take off)
I don't understand in your graph why the uninsulated case starts at a lower temperature at time 0?

Surely the two lines should start at the same point, and then we'd expect the uninsulated one to drop more steeply.

What am I missing?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175297#Comment_175297 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175297#Comment_175297 Fri, 03 May 2013 16:07:17 +0100 SteamyTea Posted By: djhI don't understand in your graph why the uninsulated case starts at a lower temperature at time 0?All I can think of is that an uninsulated pipe looses heat very rapidly, too fast for the 1 minute sampling to capture.
It would account for an uninsulated pipe seemingly to loose temperature at a slower rate, but that is to do with starting at a lower temperature.
So it seems to loose the first 15°C in under 1 minute, then near as damn it at the same rate.
All I can think.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175301#Comment_175301 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175301#Comment_175301 Fri, 03 May 2013 17:31:48 +0100 barney
The physics wuld support that as well - higher rate of heat loss with the biggest delta T

regards

barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175314#Comment_175314 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10615&Focus=175314#Comment_175314 Fri, 03 May 2013 22:49:35 +0100 SteamyTea