Insulating pipes

[MortarThePoint]

Am I imagining it or did I read somewhere that hot and cold water pipes should be insulated even within the building's insulated envelope? I hope I did ?

[TonyT]

Yes,  helps keeps heat loss down on hot pipes and condensation on cold pipes.

 

climaflex comes in varying thickness so allow for this when running pipes , with suitable pipe clips.

Edited March 10, 2021 by TonyT

[MortarThePoint]

Hot water: Part L requires insulation. If the water is 38C warmer than ambient then a 22mm pipe losses heat at 53W/m [link]. The heat capacity of water is 4.2KJ/KgC. The volume is 0.38l/m giving 0.38kg/m. That will therefore cool at a rate of 53J/sm / (4200 J/KgC * 0.38kg/m) = 0.033C/s or 2C/min. The temperature difference half life will be something like LN(2) / (0.033/38) = 800s about 13minutes.

 

Table 5 of https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697525/DBSCG_secure.pdf

Table 6.1.1 of http://www.timsa.org.uk/TIMSAHVACGuidance.pdf

 

Insulated to achieve the 9W/m figure would slow the heat loss to about 0.33C/min. The temperature difference half life will be 13*53/9 = 77minutes of 1.25hours.

 

I wonder if that's worth it for the family bathroom where chances are all activity happens in a flurry and then nothing for many hours. Probably makes sense for a downstairs loo where the usage is more constant with the tap going about once an hour or more (depends who's cooking).

 

Cold water: Is this a building regulations requirement or guided by good practice?

 

[jfb]

I would say that the benefit of insulating internal pipes is limited (coming from someone who lagged the lot religiously!).

I guess there is some benefit for the hot pipes but only if taps are being used reasonably close together in time as otherwise the heat just escapes into the house.

[TonyT]

Good practice as far as I’m concerned and in the Scottish Technical standards too

 

‘Every building must be designed and constructed in such a way that temperature loss from heated pipes, ducts and vessels, and temperature gain to cooled pipes and ducts, is resisted’

[Nick Laslett]

I’m planning on running hot & cold water pipes in 50mm ducting that is inside the concrete of an insulated slab foundation. 
 

I assume that it is difficult to add insulation to these pipes and get them through the duct. 
 

Back in 2020 when all this stuff was being planned, this is the approach I adopted. I can’t remember if these pipes did need insulation. 
 

Any advice appreciated. 

[Nickfromwales]

2 hours ago, Nick Laslett said:

I’m planning on running hot & cold water pipes in 50mm ducting that is inside the concrete of an insulated slab foundation. 
 

I assume that it is difficult to add insulation to these pipes and get them through the duct. 
 

Back in 2020 when all this stuff was being planned, this is the approach I adopted. I can’t remember if these pipes did need insulation. 
 

Any advice appreciated. 

50mm duct per single insulated pipe? Or a pair of hot and cold per duct?

[Radian]

The number of times I thought I'd found a leak in a kitchen cupboard - only to find it was condensation forming on mains cold feed pipes. Doesn't seem to happen on cold from loft storage tank. Obviously I need more loft insulation.😖

[Thorfun]

how is it possible to insulate pipes when they're running in a service cavity? even with 47mm x 47mm battens as a service cavity will be tight to insulate water pipes. so do you only insulate between the posi-joists and don't bother in the walls? seems pointless that way though.

[Nickfromwales]

2 hours ago, Thorfun said:

how is it possible to insulate pipes when they're running in a service cavity? even with 47mm x 47mm battens as a service cavity will be tight to insulate water pipes. so do you only insulate between the posi-joists and don't bother in the walls? seems pointless that way though.

When the systems I've put in for clients have been fine ( in Hep2O ) the question has to be asked where it is applicable and where it's not. If it's in a cold drafty home, fair enough. In an airtight high-spec dwelling the delta is often not so converse, plus the issues seem to be far less with plastic vs copper. I always insulate at the plant, and for the larger primary distribution eg to the manifolds, but after that I only ever insulate the hots and the hot returns tbh.

Systems where there is a water softener and some larger bore primary stuff, the stored ambient in there often staves off the slug of ice-cold mains water that usually causes this problem, so it is horses for courses, not just a one answer for all afaic. 

[Nick Laslett]

10 hours ago, Nickfromwales said:

50mm duct per single insulated pipe? Or a pair of hot and cold per duct?

I have 1x50mm duct per single pipe.  Hot and cold to kitchen island. Hot and cold to utility room, hot and could to downstairs shower room. The 50mm ducts run along the bottom of the 150mm concrete raft on top of 300mm of Kore EPS. This is a Tanner designed foundation. 
 

Reading a few more threads and I thought there was not much value in insulating these pipes even if it was possible. 
 

 

Edited April 2, 2022 by Nick Laslett

[Jilly]

I love sheepswool and have discovered Topsleeve do a product, but it looks like it should have been slipped on before  the pipes were placed. Is there another way or shall I sew them on? !

[Iceverge]

Having insulated the living daylights out of some 26mm pipes in the hope that it would preserve some heat in the pipes I would say it's of limited value in a radial system. ( Hot circulation loops might be different)

 

Even with 2 layers of pipe insulation well taped at all joints ( it looked like an elephants leg) the water cooled very quickly, about 20 mins. Insulation only slows the heat loss it doesn't stop it. so unless you use your taps super frequently i wouldn't bother insulating outside the plant room. 

 

Running 10mm and 15mm Hep20 to reduce the volume of the dead leg worked a treat to have hot water quickly. 

 

[Adam2]

Is there not benefit in insulating hot pipes to reduce heat loss in transit? Or is that so minimal to not make much difference either way?