BS: any ideas on this Damp Control system ?

Subject: BS: any ideas; home Damp Control system ?
From: GUEST,punkfolkrocker
Date: 28 Mar 06 - 09:54 AM

hi..

anone here have any experience or knowledge on this home damp control system from Holland ?

do you think its an effective system worth consideration..

or a useless rip off.. ?


any ideas ??

http://www.schrijver-systeem.com/


Btw, our house is a uk west-coast town centre Victorian mid-terrace..

[climate and conditions perhaps very similar to reclaimed areas of Holland]


cheers...

Subject: RE: BS: any ideas on this Damp Control system ?
From: JohnInKansas
Date: 28 Mar 06 - 10:32 AM

The page linked gives no information without clicking on unlabelled buttons. Maybe this is a Dutch tradition, but I'm reluctant.

I see a warning flag in the: NATIONAL PRIZE WINNING INVENTION AS SEEN ON TV. In the US that normally means "the only information available is what we say in our ads."

It may be a good enough system, but I'm not gonna click blind buttons to find out.

The most common humidity "reducers" use some form of cooling to a sufficiently low dew point to wring the moisture out of the air. Units are available that attach to a central heating/cooling system (best used with forced air systems) and also as stand-alone/roll-around units for smaller room-sized areas. They're quite commonly available, in-season, from local suppliers in my (US) area, and models from major appliance suppliers seem to be of fairly consistent and acceptable quality.

I haven't heard of any new miracles changing the laws of physics to make the few other kinds of "absorbers" etc competitive with the refrigeration/reheat kind. I'll wait for someone's description of why this one is "different."

John

Subject: RE: BS: any ideas on this Damp Control system ?
From: Bunnahabhain
Date: 28 Mar 06 - 11:18 AM

John in kansas, look left! The blind buttons are non-functonal decor, the infomation was on links behind the headings on the left, with titles like 'The problems of damp' etc.


As to if it will work, well maybe. Assuming the figures quoted based on reality, then it does it appear to achive a significant drop in the mositure content of the wall, and the air inside. It appears to be a forced draft system, to draw relativly dry air into a cavity, and increase evaporation. It's simply wind driven, so (presumably) has no running costs.

Assuming your mid-Victorian terrace has been properly maintained, and has reasonably close fitting windows, then you shouldn't have many drafts, so could well find this system effective.

The alternatives are:

Open a window or two, and put on some warmer clothes

Get a standard dehumidifier. I've used them in bathrooms, and other areas that got very steamy, and they work.

Move to an older, drafty house, and the moist air will escape through the cracks in the walls...

Subject: RE: BS: any ideas on this Damp Control system ?
From: Amos
Date: 28 Mar 06 - 11:19 AM

John:

The little squares aren't buttons. The contents panel to the left gives the links in a normal way. The little squares represent the installed units along the wall of ahouse, I think. The description is interesting but I haveno idea whether it would work or not.

A

Subject: RE: BS: any ideas on this Damp Control system ?
From: Bert
Date: 28 Mar 06 - 12:45 PM

It would depend on the cause of the dampness. I wouldn't think that it would help the most common causes of dampness.

1. Rising Damp.
which is usually dealt with by the installation of a damp course.
2. Seepage into a basement.
3. Outside ground higher than the ground floor.
These last two can be cured by a combination of tanking and landscaping.

Some electrolytic systems are also available which can be retrofitted to an old house.

Subject: RE: BS: any ideas on this Damp Control system ?
From: GUEST,TIA
Date: 28 Mar 06 - 01:34 PM

I read the blurbs. I can see how it will remove moisture from the outside air that flows through the stone chamber (stone has a huge thermal inertia and will stay cool all day even in warm weather), but how does the moisture from inside the house get out? Maybe I'm reading someting on their diagrams wrong.

Subject: RE: BS: any ideas on this Damp Control system ?
From: JohnInKansas
Date: 28 Mar 06 - 10:44 PM

Okay. I assumed the link would be to where the informatin was. They fooled me with the sidebar layout - putting the info where the ads for other stuff typically appears.

I'm afraid I'm not impressed with their "technical description." It appears to have been written by an ad department (or a bricklayer) with only a vague concept of physical phenomena, and uses pseudo-tech-speak to impress without actually saying anything (correct) technical.

The kind(s) of construction for which this appears suited are not too often seen in my parts of the US, but porous stone in contact with any source of moisture can absorb and hold rather large amounts of moisture. In the structure shown, where there are two separate "stone walls," ventilating the space between them will help to keep excess moisture from being held in the inner wall, where small changes in temperature can cause the absorbed moisture to be released and drip on either the interior side – into the room – or on the outside – into the cavity between walls.

Too much ventilation would destroy any insulating effect of the outer wall. Too little ventilation would fail to remove sufficient moisture. Based on a few installations, an appropriate compromise should be fairly easy to reach, and it's possible that the spacing of these vent devices has been "tried" enough to be a useful approximation to an "adequate installation" for typical walls.

With two holes connecting to a single cavity, wind blowing across both holes will usually produce very little circulation through the cavity. The main effect is to "pump up" the cavity without much through-movement. The baffle between the two holes helps to produce a pressure drop, if the flow is restricted slightly where it goes over the end of the baffle. That probably contributes to more air actually moving through the cavity. The flow cross section through the restriction (at the end of the baffle) must be a bit smaller than either of the two external holes, so the air velocity there will be higher than at either the inlet or the outlet hole, and will in fact be slightly cooled.

The amount of cooling to be reasonably expected is miniscule, and in fact would be counter-productive if it were to be significant. Cold air simply holds less moisture, and hence can pick up less moisture when it flows over a damp surface.

The higher velocity where the air flows past the baffle does probably increase the amount of moisture that can be entrained, simply because it reduces the thickness of the boundary layer of stagnant air that's always present adjacent to a surface with air flowing over it. The faster the air flows, the thinner the boundary layer gets. A more effective "drying" effect would in fact be obtained if the air could be heated, rather than cooled; so the bit of babble about cooling the air so it picks up more moisture is bassakward to what really helps.

The bottom line is that ventilating the airspace adjacent to a water retaining inner wall in this way will help to remove some water locally where the air contacts the inner wall. Moisture from other parts of the wall should "wick" toward the dryer areas fairly efficiently, so if these vents work at all, the whole wall should (eventually) be somewhat drier. (And the ability of stone to act as a wick to transfer water from inside to outside answers TIA's question - the water goes through the wall.)

These vents appear to incorporate a suitable baffle to help with pumping some air through the embedded chambers. Note that with wind from the other direction, the air flow will go the other way through the chambers, so the assymetrical structure – insulated on one side and not on the other – would only work half the time; but that's almost irrelevant if, as I suspect, that part of it doesn't really do much of anything.

The "technical notes" are, so far as I can tell, pretty much BS. I don't get the impression they actually understand how it works; although it probably does provide some ventilation.

The "tests" are too vaguely described to really tell whether they did something. They did measure RH at a few places, and the results indicate a benefit from the ventilation. There is no comparison with other methods of ventilating the space between the two walls, so no conclusion can be made about whether this is better or worse than other options. The only comparison is between walls with these devices and walls with NOTHING.

The "references" cited:

Various advisory groups recommend using the Schrijver Systeem®. This is due to comments by satisfied customers and good reviews in the media. In Holland and Belgium the system has been shown on television and various newspapers have published articles on the Schrijver Systeem®. You can write for a (translated) copy of the articles and references.

Anectdotal customer BS, and some media printed some of them? Shown on TV (BFD). Newspapers have published articles. ???? Great sources of factual and technically accurate information. (Don't miss the sarcasm.)

Again: They're wall vents. Wall vents work. They typically install a lot of wall vents. Lots of wall vents is good, if you don't loose too much heat through them.

They do sound a bit expensive, but its a fair assumption is that retrofitting into existing walls is going to incur some cost.

Have you talked to the guys at the local building supply *dealership, to ask how they'd do it?

* Not the ones who sell this item.

John

Subject: RE: BS: any ideas on this Damp Control system ?
From: Don Firth
Date: 29 Mar 06 - 12:46 AM

Depends?

(Sorry, but somebody had to do it. . . .

Subject: RE: BS: any ideas on this Damp Control system ?
From: robomatic
Date: 29 Mar 06 - 11:39 PM

JohnInKansas reaction sounds more believable to me than anything in the website.

In simple terms, it sounds as if they are using ventilation to remove moisture, because modern homes are so well insulated they have limited ventilation.

The problem is, then, that in bringing back ventilation to remove 'damp' (dehumidify the atmosphere), you are reversing what you put all that insulation and vapor barrier for, to save heating energy. You spend most of your heating budget heating air. The term I've heard for the amount of air moving through a room is 'air changes'. You need enough air changes to keep the atmosphere clean and comfortable. However, you are heating and then losing all that heated air to the outside (in the cold months of temperate climates).

The device that can counter the loss of energy would be a heat-exchanger unit, this is some kind of metallic baffled system with a fan to blow your 'old' air out but transfer as much heat as possible to the 'new' air coming in. The trick is to make something that will do the job efficiently without wearing out, collecting condensation, and costing too much. They exist, and are still pretty rare in new housing.

So, the Schjriver system may or may not work, but without more information it may work at a great cost.

And does it work in warm muggy environments like New England summers?