Cold tap running warm for 20 secs

[nhold86]

New build job, 4 zones, unvented cylinder and boiler on top 3rd floor, cold main in 28mm comes up through voids were it could be picking up heat from sec return and heating circs. These voids are well insulated.
The builder is saying the pipes should have been lagged everywhere to stop heat transfer, am not so sure that would work/ would help, is it a regulation?
Has anyone else had this and has anyone thought of a fix other than re-routing pipes?

 

[ShaunCorbs]

I would be surprised if they are lagged depends on builder but I find most new builds arnt

Was yours a big development?

 

[centralheatking]

New build job, 4 zones, unvented cylinder and boiler on top 3rd floor, cold main in 28mm comes up through voids were it could be picking up heat from sec return and heating circs. These voids are well insulated.
The builder is saying the pipes should have been lagged everywhere to stop heat transfer, am not so sure that would work/ would help, is it a regulation?
Has anyone else had this and has anyone thought of a fix other than re-routing pipes?

The problem as see it is that a slight warming of the cold water supply which ultimately will be drunk, and brushing teeth is the potential for naughty bacteria to thrive in such a temperature range which is never heated properly like the hot water supply. Maybe not so dangerous on a day to day basis but more dangerous when the occupants go on holidays. centralheatking

 

[nhold86]

I would be surprised if they are lagged depends on builder but I find most new builds arnt

Was yours a big development?

Yes 5 bed 5 bathroom house, not sure what else could have been done other than lagging pipes but what about the drops in walls.

 

[townfanjon]

Cold main must be separated from any hot pipe , basic plumbing , pipe should be lagged .

 

[Millsy 82]

With the way they insulate houses now hot and cold have to be lagged especially if you have a secondary return.

I did a job when I worked for a company just before christmas rip out all old and install new plumbing. I ran the cold in the old heating notches and I ran the hot and secondary with the heating pipes 2ft away I thought no issues with that as it miles away. I had to go back once the customer had moved in take up carpets as I removed the carpet you could feel the heat on the underlay and once I removed the underlay the floor was like a radiator. This was the only room that had the downstairs ceiling taken down and the ceiling void had to be insulated. In the landing area though where there was no insulation the heat could disperse under the floor.

From now on I will fully insulate hot and cold in new builds

 

[Scott_D]

Is the cold piped from the balanced cold?
Secondary return piped correctly?

 

[Chuck]

The Water Regulations (1999) Schedule 2 says that:

9. Any pipe supplying cold water for domestic purposes to any tap shall be so installed that, so far as is reasonably practicable, the water is not warmed above 25°C.

So I think that the installation will need to be improved. If the void is "well insulated" and hence permanently warm, you'll need good quality insulation or possibly even to re-route the cold so it doesn't share space with the heating pipes.

 

[oz-plumber]

What temperature is the water coming out of the taps during the first 20 seconds?

 

[nhold86]

With the way they insulate houses now hot and cold have to be lagged especially if you have a secondary return.

I did a job when I worked for a company just before christmas rip out all old and install new plumbing. I ran the cold in the old heating notches and I ran the hot and secondary with the heating pipes 2ft away I thought no issues with that as it miles away. I had to go back once the customer had moved in take up carpets as I removed the carpet you could feel the heat on the underlay and once I removed the underlay the floor was like a radiator. This was the only room that had the downstairs ceiling taken down and the ceiling void had to be insulated. In the landing area though where there was no insulation the heat could disperse under the floor.

From now on I will fully insulate hot and cold in new builds

Is the cold piped from the balanced cold?
Secondary return piped correctly?

Cold main must be separated from any hot pipe , basic plumbing , pipe should be lagged .

From now on I would insulate all Pipework even in ceiling spaces. The cold is run on the bottom which is how I’ve always done new builds and never had this issue, but the insulation in this house seems over the top and unfortunately I haven’t taken that into account

 

[OffshoreGas]

Cold main must be separated from any hot pipe , basic plumbing , pipe should be lagged .

Is there a requirement to lag cold water pipes? Is that for frost protection?

Just seen Chucks post

 

[centralheatking]

From now on I would insulate all Pipework even in ceiling spaces. The cold is run on the bottom which is how I’ve always done new builds and never had this issue, but the insulation in this house seems over the top and unfortunately I haven’t taken that into account

nice touch that cold below hot, learning all the time thank you
centralheatking

Is there a requirement to lag cold water pipes? Is that for frost protection?

It was but now its double important centralheatking

 

[Chuck]

Is there a requirement to lag cold water pipes? Is that for frost protection?

Cold pipes need to be protected from frost, keep their contents below 25°C and not suffer from condensation. Not easy (perhap not possible?) to achieve all three without lagging in modern houses, which tend to be well-insulated and poorly ventilated.

 

[OffshoreGas]

nice touch that cold below hot, learning all the time thank you
centralheatking

It was but now its double important centralheatking

From now on I would insulate all Pipework even in ceiling spaces. The cold is run on the bottom which is how I’ve always done new builds and never had this issue, but the insulation in this house seems over the top and unfortunately I haven’t taken that into account

Quite a neat idea running the cold at the bottom, I wounder what practical difference it makes if pipes are in a double clip 10mm apart.