Condensation on mdpe pipe in kitchen

[gambo]

New floor and everything rerouted to allow for more space and different kitchen cabinet layout but I spotted that the mdpe pipe is wet (just below the paper towels). I did a few observations and after sticking lots of towels into the hole I think it's just condensation.

What's the best way to prevent it? Covering with kitchen cabinets will probably reduce it but shall I put some close cell foam into the hole?

[Conor]

Dont use foam. Just use a length of pipe insulation.

[JohnMo]

It was obviously flowing cold water - so pipe surface below dew point. If it's a concern just insulate it, with the grey pipe insulation you can pickup anywhere 

Edited October 9 by JohnMo

[gambo]

My worry is that when I close it with cabinet on top the condensation may cause mould.

[gambo]

I've covered the pipe to see if this helps but also to make sure condensation comes from kitchen.

To my surprise the foil is completely dry on outer side but wet on inner. Does the condensation come from the ground? Or is this some dpc issue? Shall I just cover it like this?

[andyscotland]

If you've just taped that patch over the hole and there's a void below (I assume?) then the air from whatever that void is can still get to the pipe surface and if the pipe is colder than the surrounding air it will likely condense. You need to completely enclose the pipe.

[gambo]

51 minutes ago, andyscotland said:

If you've just taped that patch over the hole and there's a void below (I assume?) then the air from whatever that void is can still get to the pipe surface and if the pipe is colder than the surrounding air it will likely condense. You need to completely enclose the pipe.

The pipe goes from the meter to the house and exits through this gap. I could probably put a bit of sleeve insulation from kitchen side but this would likely be a very short piece only.

I don't really understand what this issue is. Is it the concrete/screed "breathing", a leak or a hole somewhere?

 

 

[JohnMo]

What is in the hole other than the pipe? Do you have a solid floor or suspended floor?

 

[gambo]

29 minutes ago, JohnMo said:

What is in the hole other than the pipe? Do you have a solid floor or suspended floor?

 

Just pipe and the duct to run the pipe through.

its late 80s house with concrete + 40-50mm of screed + Ditra matt.

Water meter is on the other side of the house (8-10m from the kitchen).

 

Edited Monday at 09:51 by gambo

[Nickfromwales]

It’s just the time of year, with lower cold water temp vs heated homes.

 

The foil patch is the worry thing you can do.

 

Just put grey pipe insulation (13mm wall thickness minimum) on the blue pipe and the copper pipe, and it’ll solve the majority of the problem. You’ll still get condensation on the stopcock, but that should be above the units not below, ideally.

[gambo]

1 minute ago, Nickfromwales said:

It’s just the time of year, with lower cold water temp vs heated homes.

 

The foil patch is the worry thing you can do.

 

Just put grey pipe insulation (13mm wall thickness minimum) on the blue pipe and the copper pipe, and it’ll solve the majority of the problem. You’ll still get condensation on the stopcock, but that should be above the units not below, ideally.

Due to the shape of the run it's difficult to put pipe insulation. Lets say I fit a sleeve up to the duct will this not move the condensation to bottom of cabinet or before the insulation? 

Why covering it is bad? I get that in general condensation shouldn't be covered but right now it feels like it's going wrong way round, ie from cold to warm area.

Stopcock at the moment is planned to be under the unit to gain space in cabinet. I could reroute to run on the wall behind the unit.

 

[JohnMo]

6 minutes ago, gambo said:

Why covering it is bad? I get that in general condensation shouldn't be covered

You condensation is only forming because pipe is not covered. Once insulated the air doesn't get to the cold pipe, so water formation doesn't occur.

 

19 minutes ago, Nickfromwales said:

Just put grey pipe insulation (13mm wall thickness minimum) on the blue pipe and the copper pipe, and it’ll solve the majority of the problem. You’ll still get condensation on the stopcock, but that should be above the units not below, ideally

As said above. 

 

You need ready access to a stop cock, hiding under units, isn't the correct thing to do. The actual stop cock should be inside the cabinet.

[Nickfromwales]

18 minutes ago, gambo said:

Due to the shape of the run it's difficult to put pipe insulation. Lets say I fit a sleeve up to the duct will this not move the condensation to bottom of cabinet or before the insulation? 

Why covering it is bad? I get that in general condensation shouldn't be covered but right now it feels like it's going wrong way round, ie from cold to warm area.

Stopcock at the moment is planned to be under the unit to gain space in cabinet. I could reroute to run on the wall behind the unit.

 

You just need to put some thin insulation on the pipework. That is the solution here.
 

Covering with a foil patch will just cause it to ‘sweat’, and that’ll harbour damp forevermore.
 

The hole in the floor needs to be open to the room, with just some rockwool stuffed down it, so it’s about 50mm below the tiles, to prevent draughts.

 

If you can move the stopcock then do so, as replacing to would be a painful job after you build a kitchen over it.

 

You can ask the plumber to fix a 90° bend at the point the blue pipe exits the floor, and then convert the blue pipe to 22mm copper and then go to a new 22x15mm stopcock in the unit, with all pipe under the slab insulated and forgotten about. 

[gambo]

@JohnMo @Nickfromwales

I've done the plumbing myself so may not be perfect but I do have another ball valve further up which is easily accessible. I did it to avoid doing 90 degree mdpe bend and run it on the wall (I dont want to loose space by having the pipe running through the middle of cabinet.

My view is that if I insulate the pipe with pipe insulation it will not go to deep, so the sweating can still occur before the insulation (deeper in the hole). If I stuff rockwool will it not get very wet overtime?

[Nickfromwales]

11 minutes ago, gambo said:

@JohnMo @Nickfromwales

I've done the plumbing myself so may not be perfect but I do have another ball valve further up which is easily accessible. I did it to avoid doing 90 degree mdpe bend and run it on the wall (I dont want to loose space by having the pipe running through the middle of cabinet.

My view is that if I insulate the pipe with pipe insulation it will not go to deep, so the sweating can still occur before the insulation (deeper in the hole). If I stuff rockwool will it not get very wet overtime?

Once the air gap is gone, the condensation won’t form. 
 

Does the pipe have some sort of duct, or is it straight out of the ground? 

[gambo]

5 minutes ago, Nickfromwales said:

Once the air gap is gone, the condensation won’t form. 

How is it different from covering it with foil and not allowing the air to move both ways? Alternatively I was thinking about putting 75mm PIR on top of the pipe (with a groove for the pipe) to keep the hole colder.

5 minutes ago, Nickfromwales said:

Does the pipe have some sort of duct, or is it straight out of the ground? 

Yes, there is a ducting but it ends under the tiles.

[Nickfromwales]

1 hour ago, gambo said:

How is it different from covering it with foil and not allowing the air to move both ways? Alternatively I was thinking about putting 75mm PIR on top of the pipe (with a groove for the pipe) to keep the hole colder.

Yes, there is a ducting but it ends under the tiles.

Because the too will be warm, at room temp, and will pull the moisture up to it. 
 

It’s an odd thing (not really a phenomenon) but I saw this with a thermal (foil) underlay for laminate flooring, and it was sopping wet under it.

 

The PIR idea is a bit OTT, and doesn’t wrap around and remove the air gap, unless you use foam to seal as well…. but messy and complicated. 

[gambo]

15 minutes ago, Nickfromwales said:

Because the too will be warm, at room temp, and will pull the moisture up to it. 
 

It’s an odd thing (not really a phenomenon) but I saw this with a thermal (foil) underlay for laminate flooring, and it was sopping wet under it.

 

The PIR idea is a bit OTT, and doesn’t wrap around and remove the air gap, unless you use foam to seal as well…. but messy and complicated. 

I don't mind OTT just but i like if i can remove something easily. Putting foil first and gluing the PIR with expending foam is a good idea.

Are you saying that because the hole now has a higher temperature by being warmed up it pulls the air/moisture up? But once i isolate it to keep it at lower temp it will be fine?

[Nickfromwales]

11 minutes ago, gambo said:

Putting foil first and gluing the PIR with expending foam is a good idea.

I don’t think it is. The pipe just needs simple pipe insulation. Wrap the insulation with duct tape to stop the seam opening and that’s it. Simple! 

[gambo]

8 minutes ago, Nickfromwales said:

I don’t think it is. The pipe just needs simple pipe insulation. Wrap the insulation with duct tape to stop the seam opening and that’s it. Simple! 

duct and pipe is buried in the ground/concrete. It has some very low temperature comparing to temp of the house. The duct ends in the hole and the pipe goes out of the hole. I have no idea where the humid air comes from but assuming it comes from somewhere deeper I don't understand why insulating the final run of the pipe would improve it.

[-rick-]

Nick's suggestion should work. It's a very cheap thing to do (<£10) so why not try it and come back if it doesn't work?

 

You just need to stop warm air touching cold surfaces.

Edited Monday at 14:57 by -rick-

[Nickfromwales]

51 minutes ago, gambo said:

duct and pipe is buried in the ground/concrete. It has some very low temperature comparing to temp of the house. The duct ends in the hole and the pipe goes out of the hole. I have no idea where the humid air comes from but assuming it comes from somewhere deeper I don't understand why insulating the final run of the pipe would improve it.

Humid air is in the house. That hits the cold pipe and condenses. 
 

It’s coming from the depths of your house lol 😜. People breathing, washing machine, tumble drier, dishwasher etc.

 

Please don’t go digging the floor up to look for the source, you’re the source.

[gambo]

But if it's from the house then it should not penetrate the foil easily or at least I should have moisture on top of the foil too, but the foil is dry.

[Nickfromwales]

4 hours ago, gambo said:

But if it's from the house then it should not penetrate the foil easily or at least I should have moisture on top of the foil too, but the foil is dry.

Ok then. Let’s stay up and fight this out! 
 

If there’s a duct, that means atmospheric conditions can / will exist there, plus ground moisture (damp); so you’ll have it from ‘both ends’ if you create a barrier with the foil.

 

The condensation on the pipe comes from you / the house air, sweat from the ground would collect on the underside of the foil from the subterranean aspect.

 

Just give me your bloody postcode and I’ll bring some pipe insulation and fit it for you, then it’s off to the pub for beer. You’re paying 🍻   

 

The top of the foil will be dry because there’s now an air gap between it and the pipe. 

[gambo]

Iim more than happy to give you my postcode but it's a rabbit hole with lots of other issues waiting for a separate threads.

Anyway, I do have pipe insulation just don't understand what I'm gaining by installing it.

If I read your answer correctly, each side of the tile has its own reason for moisture so I can't cover it up but by covering the pipe with insulation I'm moving it further up to the next cold spot (stopcock)?