Localised condensation on pipes.

[Aire]

Hi guys, installed a water softener last week and I've been called back to it today with heavy condensation round the pipework. I've attached a photo which now shows the pipes lagged but only these pipes are forming condensation. The other pipes in the unit that feed the kitchen sink are fine. The pipes from the softener run under the units the are surface fixed accross some skirting board where they attach to the existing feed to the house, and again these are fine with no signs of condensation. I could have put it down to a fault with the softener passing water but I would have thought that would only cause the inlet to condensate but both the inlet and outlet are condensing. Any ideas

 

[ShaunCorbs]

somethings flowing

 

[Aire]

somethings flowing

That's what I thought, bathroom is new and I've checked everything, nothing is dripping, toilet isn't running, boiler pressure isn't rising so filling loop isn't passing, I'm baffled. All pipes are surface fixed and above floor so no hidden leaks.

 

[ShaunCorbs]

easy way to tell close the valve open the bypass

 

[Aire]

Could do, that would rule out the softener at least.

 

[Chuck]

That's what I thought, bathroom is new and I've checked everything, nothing is dripping, toilet isn't running, boiler pressure isn't rising so filling loop isn't passing, I'm baffled. All pipes are surface fixed and above floor so no hidden leaks.

If everything you say is correct (no offence intended) then it seems likely that the humidity in that cupboard is higher than it should be for some reason. Was the installation process nice and dry or did the area get wet when you cut in to the existing pipework? Have a careful look for small but long-term leaks from the drains and WM/DW connections and outlets. Is that white stuff on the shelf some sort of mould? Is the pointing on the outside wall okay? Is the chipboard/MDF bone dry?

Does the problem go away if they leave the cupboard door open for a few hours/days?

Sometimes these problems are long-standing and only get noticed when something new is installed and the homeowner starts looking in places that they have previously ignored...

 

[Aire]

Not sure what the white stuff is, it's a fairly old unit so could be caused by anything. Installation was dry and no washing machine/dishwasher wastes nearby. The thing about possible humidity in the cupboard, is that the pipes feeding the sink in the same cupboard are fine.
The kitchen is in an old converted outhouse, no cavity just twin brick, there was 2 air bricks outside leading to the back of the units so I sealed these up and lagged the pipes hoping this might cure it, which I will wait to see when the customer rings me tomorrow.

 

[Chuck]

there was 2 air bricks outside leading to the back of the units so I sealed these up and lagged the pipes hoping this might cure it, which I will wait to see when the customer rings me tomorrow.

Your pipes only have to be a couple of degrees colder than the others under the sink to attract the lion's share of any condensation. Lagging your pipes has a good chance of curing the symptoms. Ventilation is your friend when it comes to to condensation so I'd have probably left that alone. If you've got a humidity / dew-point meter that would probably allow you to pinpoint the root cause. But even if you know the root cause fixing it may be tricky as it could well be down to the fact that outhouses were not built to be warm and dry...

I'd still keep the possibility of a leak of some sort causing flow in your pipes as suggested by ShaunCorbs in mind. You only need a very low flow coming in from the main to reduce the pipe temperature significantly. Have you had a close look at the water meter with everything turned off?

 

[Pickwickpick]

Not sure what the white stuff is, it's a fairly old unit so could be caused by anything. Installation was dry and no washing machine/dishwasher wastes nearby. The thing about possible humidity in the cupboard, is that the pipes feeding the sink in the same cupboard are fine.
The kitchen is in an old converted outhouse, no cavity just twin brick, there was 2 air bricks outside leading to the back of the units so I sealed these up and lagged the pipes hoping this might cure it, which I will wait to see when the customer rings me tomorrow.

I'd be worried that sealing up the airbricks could make the problem worse, have come across condensation problems caused by people sealing air bricks in a couple of properties. Saying that lagging the pipes should sort it.

 

[Frelon]

easy way to tell close the valve open the bypass

I agree with Shaun, however we should ask the question "Was there any condensation on the rising mains before you installed the softener?
With the softener by passed the water into and out of it will equate to the same temperature as it's surroundings = should be no condensation. However you may find that the rising mains will have condensation and you will have solved your problem!

 

[Aire]

There's no water meter so can't do that test.

The sealing of the air bricks was a trial, I've only done it with silicone so will be easy to pull out if i need too.

There was no condensation on the main before I installed the softener, but the stop tap is about 3m of pipe away from the softener, I've came off the stop tap round some skirting, under the plinth and into the unit, and then back again to re attach to the supply pipe. The stop tap still isn't condensing and neither is the pipe returning from softener once it's left the unit. It only seems to be localised on the manifold I've installed in the unit.

I haven't heard anything from the customer today so either the lagging has sorted it or I'll be getting a call tomorrow.