Reply
 
Thread Tools Search this Thread
 
Old 23 December 2010, 12:12   #1
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
Dehumidifier output

Bit of a 'how long is a piece of warp' question really, but I could do with knowing roughly how many pints a domestic dehumidifier would draw out of the air per day in an unheated, unoccupied 1 bedroom flat of say 800sq ft.

I realise there are many variables such as humidity, temperature, airtightness of building, quality of machine etc. The question relates to a flat with a suspected damp problem that a colleague is trying to investigate, but we have no gauge on how much water a dehume would pull out in a 'dry' flat. Any thoughts oh wise ones?
Erin is offline   Reply With Quote
Old 23 December 2010, 12:31   #2
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,021
3.142



:d
__________________

__________________
martini is offline   Reply With Quote
Old 23 December 2010, 13:17   #3
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
Thank you for your extremely helpful post . I see a certain resemblance to a well known theorum, and I'm not entirely sure it fits this particular application
Erin is offline   Reply With Quote
Old 23 December 2010, 14:39   #4
Member
 
martini's Avatar
 
Country: UK - Channel Islands
Town: jersey
Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
MMSI: 235067688
Join Date: Jun 2005
Posts: 3,021
It rang a bell but I could be getting mixed up with something else...

Difficult one to answer, as you know much better than me, there is no "damp" or "dry", just an infinite number of degrees of damp/dryness.

I used to live in an old brick house, no d/g or c/h etc. My bedroom had damp problems, mould on the walls etc, my dehum. could get up to about 500ml just from that average sized room as a starting point for you.

Might be worth putting the dehum in one room at a time with the door shut, might give you a better picture of whats going on.
__________________
martini is offline   Reply With Quote
Old 23 December 2010, 14:49   #5
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,928
RIBase
Quote:
Originally Posted by Erin View Post
Thank you for your extremely helpful post .
Well, you can't have your Pi and eat it
__________________
willk is online now   Reply With Quote
Old 23 December 2010, 17:05   #6
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
Quote:
Originally Posted by martini View Post
could get up to about 500ml just from that average sized room as a starting point for you.
That's the kind of info I was hoping for . Apparently this particular property has some evidence of rising damp and some penetrating, and to confound matters there was a plumbing leak a month or so ago.

I gather 2 dehumidifiers had been set up and are collecting about 2 pints per day (not sure if that is each or total) but the problem was, we didn't know if that was normal for a dehume to produce, or indicative of a serious damp/humidity problem. Obviously the ideal would be to set them up in a known dry property and see what they collect, but that won't be possible due to time constraints. So if you collected 1 pint from a single occupied room, then 2 pints from a flat may not be particularly exceptional given that it is unoccupied/unheated and we are in winter and outside humidity levels are currently 85%.
Erin is offline   Reply With Quote
Old 23 December 2010, 17:18   #7
Member
 
Country: Finland
Town: Helsinki
Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
Join Date: Oct 2009
Posts: 896
Regarding how it moves inside a wall its generally considered that it goes inside a wall
typically from warm surface towards cold surface, unless something is restricting the passage. Thats why in summertime it might be a worse issue than in winter.

Regarding damp in the air, I don't have the tables any more but it's pretty straight forward how much water air can hold in a certain temperature

here is a calculator, Vaisala is pretty pro so it should be ok. Its a downloadable file that need to be installed:

"http://www.vaisala.com/humiditycalculator/Vaisala%20Humidity%20Calculator.msi

Its important, when tracing the issue, to measure simultaneously the humidity both inside and outside, as then you can see if there is a source for topping on the humidity in the air inside( leak, but also normal activities like a shower will do the same).

Typically You should have less relative humidity inside than outside as the warmer air can hold more moisture. Difficult to say how much water the dehumidifier will collect as so many moving parts.

Accurate measurement of the air moisture content might tell plenty about the situation and potential issues.

Good luck!
__________________
fun on a boat is inversely proportional to size...sort of anyway
C-NUMB is offline   Reply With Quote
Old 23 December 2010, 17:33   #8
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
Thanks for the help C-Numb. I am in fact a Chartered Building Surveyor and understand the technical aspects quite well. We have damp meters, wet and dry bulb thermometers and hygrometers along with the psychometric chart you are referring to for establishing dew-point etc and interstitial condensation, although at this stage we've just been asked for some basic advice so don't want to get too technical.

We know that there is dampness in the structure, but my colleague wasn't sure if the dehumidifiers were extracting anything more than just typical airborne moisture. I was hoping there'd be some ribnetters who would have some experience of basic dehumdifiers and be able to say whether 2 pints per day was either alot or not very much.
Erin is offline   Reply With Quote
Old 23 December 2010, 17:37   #9
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,841
We sell the big industrial dehumes. Ebac BD150, Rhino RD4S,Dantherm CDT50, Andrews Sykes HD500 etc, etc. These knock out around 40-50Ltrs per day depending on air temp and humidity.
Domestic dehumes are ok for cloakrooms etc. You need building dryers as mentioned above for decent results. Give me a shout if your in the market.
__________________
Mollers is offline   Reply With Quote
Old 23 December 2010, 17:48   #10
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
Quote:
Originally Posted by Mollers View Post
Give me a shout if your in the market.
Thanks, but luckily it ain't my problem and I suspect it will be a hire shop visit if anything.

Quote:
Originally Posted by Mollers View Post
We sell the big industrial dehumes. Ebac BD150, Rhino RD4S,Dantherm CDT50, Andrews Sykes HD500 etc, etc. These knock out around 40-50Ltrs per day depending on air temp and humidity.
I think if they had one of these running it'd start sucking the water table up through the concrete floor . Goes to show that 2 pints from a domestic is pretty much naff all.

Cheers
Erin is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 14:58.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.