Login Join Maker Pro
Or sign in with

# Dehumidifier power

N

#### Nottnick

Jan 1, 1970
0
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick

A

#### Anthony Matonak

Jan 1, 1970
0
Nottnick said:
Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.
Currently extracts about 0.7 litres / day. (so not working itself too hard)
However it is running most of the time = quite a lot of money per month.
Is there a more cost effective method?

Perhaps you could add an external humidistat to only turn
the unit on when the humidity exceeds a certain level.

An alternative would be to use a desiccant, like silica gel,
that is available in bulk. Every so often you'll need to
"recharge" it, typically by baking. This baking/drying step
could be done in a solar oven or solar dehumidifier.

If you want to go completely automated you could use desiccant
discs like they use for building cooling. They slowly spin
between two chambers that have air flowing through them. The
one chamber has heated air that dries the desiccant and the
other has air that is dehumidified. The heat could be supplied
by a solar thermal collector of some sort. If you want it to
work when the sun doesn't shine you could use some kind of
burner (natural gas, propane, wood).

Anthony

M

#### Mary Fisher

Jan 1, 1970
0
Nottnick said:
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too
hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick

A relative humidity controlled, low wattage, low noise, extractor fan might
be an answer.

Low running cost and only works when the air is damp - unless you prefer to
use it any other way.

We have a Vent-Axia 459051 low watt fan with humidistat in our bathroom and
are very well pleased. They have an enormous range of equipment and would
probably be able to advise for your specific problem.

From their site:
The Technical Service Department is available for your calls from 8:45 to
17:00 BST, Monday to Thursday and 8:45 to 16.30 BST Friday, providing best
practice installation and product selection advice over the phone. Using the
latest information systems our Technical Support Team members can instantly
fax or e-mail you product information, typical application drawings or
specific wiring diagrams.
All technical enquiries
Tel: +44 (0)1293 526 062 Domestic and Commercial Support
Tel: +44 (0)1293 455 196 Industrial Support
Fax: +44 (0)1293 551 188
e-mail: [email protected]

We found them very helpful and eventually bought our fan from a local
supplier.

Mary
Leeds, Yorkshire

N

#### [email protected]

Jan 1, 1970
0
Nottnick said:
Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Yes. Ventilate with outdoor air when its vapor pressure
is less than the basement air vapor pressure.

Nick

N

#### [email protected]

Jan 1, 1970
0
Mary Fisher said:
A relative humidity controlled, low wattage, low noise, extractor fan might
be an answer.

If the basement air and the outdoor air were the same temperature, we might
ventilate when the basement air has a higher RH. We might make equal temps
by caulking a thin foamboard box to a basement window, with small holes at
the top and bottom to let a little basement air flow through the box and
warm to the outdoor temp through the low thermal resistance of the glass.
We might have one RH sensor in the box and another RH sensor outdoors.

Nick

N

#### Nick Hull

Jan 1, 1970
0
Nottnick said:
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick

An air conditioner is usually more efficient at dehumidifying than a
dehumidifier.

M

#### Mary Fisher

Jan 1, 1970
0
Nick Hull said:
An air conditioner is usually more efficient at dehumidifying than a
dehumidifier.

And frightfully power hungry.

Mary

J

#### JoeSP

Jan 1, 1970
0
Nottnick said:
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too
hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick

Atmospheric humidity is a variable. One day it might extract 16 litres, and
it might be 0.7 the next. A humidistat and a few bags of dessicant should
do the trick. Is there a steady flow of humid air into the room? Reduce it
if you can.

S

#### samc

Jan 1, 1970
0
Nottnick said:
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick
there are 2 main systems for stopping damp/flooding in cellar's .
(1) a vapour barrour is placed on the walls/floor with a sump in the
center of the floor for the water to be extracted with a pump .
(2) the earth is dug away from the sides of the cellar out side and a
inpervious barryour is appleyd to the out side walls .
prob not what you wanted to hear I know .

N

#### Nottnick

Jan 1, 1970
0
Yea I knew that was the case. We are just making the best of things -
hopefully cheaper to pay for power than all tanking work (although as I
said, power isn't so cheap!!).

N

#### Nottnick

Jan 1, 1970
0
JoeSP said:
Atmospheric humidity is a variable. One day it might extract 16 litres,
and it might be 0.7 the next. A humidistat and a few bags of dessicant
should do the trick. Is there a steady flow of humid air into the room?
Reduce it if you can.

Hi Joe

So I just buy loads of dessicant and re-charge it regularly.
How much dessicant?

Any thoughts as to what is reasonable humidity to try to obtain? I have a
digital weather gizmo in front of me right now and it gives humidity as a
percentage (44% in my study at the moment).

Only air flow is through 2 air bricks and I think I need to have a bit of
air flow available (or maybe not?).
Thanks

Nick

J

#### JoeSP

Jan 1, 1970
0
Nottnick said:
Hi Joe

So I just buy loads of dessicant and re-charge it regularly.
How much dessicant?

Any thoughts as to what is reasonable humidity to try to obtain? I have a
digital weather gizmo in front of me right now and it gives humidity as a
percentage (44% in my study at the moment).

Only air flow is through 2 air bricks and I think I need to have a bit of
air flow available (or maybe not?).
Thanks

Nick

The cheapest way I know is to use rock salt in burlap sacks. Every few
months, you can change them out. As long as your airflow isn't excessive,
it should keep the air fairly dry. The best way to measure humidity is with
a wet-dry bulb humidity meter.

N

#### Nick Hull

Jan 1, 1970
0
Mary Fisher said:
And frightfully power hungry.

For equal power an AC is better at dehumidifying than a dehumidifier

M

#### Mary Fisher

Jan 1, 1970
0
Nick Hull said:
For equal power an AC is better at dehumidifying than a dehumidifier

Still frightfully power hungry.

Mary

M

#### Mary Fisher

Jan 1, 1970
0
Nottnick said:
In UK

Have drum room in cellar.
Need dehumidifier to keep air dry.
Current model rating = 400W Max 16 litres/day.

Currently extracts about 0.7 litres / day. (so not working itself too
hard)

However it is running most of the time = quite a lot of money per month.

Is there a more cost effective method?

Advice appreciated.

Nick

Where in UK are you, Nick?

Mary

J

#### John

Jan 1, 1970
0
If your unit is not working at rated capacity you might want to open the
thing up and check the coils for dust and dirt build up. Most dont have
filters on them.I have found several that were thrown away and that was
all that was wrong with them

N

#### Nottnick

Jan 1, 1970
0
Neon John said:
Before you go off on this ill-advised tangent, consider the physics
and do a little math. See how much desiccant it's going to take to
remove even one gallon per day and then figure up the work involved in
rejuvenating it every day or two. Then, of course, there's the
energy. It takes more than the heat of vaporization of water to drive
it from the desiccant so the energy consumption will actually be
higher than with a high efficiency refrigeration-type dehumidifier.

You really only have two options - refrigeration-based
dehumidification and ventilation. The second option is only available
if there is a source of dry air available. If the outside air is as
humid as indoors then ventilation will do you no good.

It takes a relatively large amount of energy to dehumidify simply
because water has such a high heat of vaporization. That heat has to
be absorbed to condense the water vapor into liquid water. That's
something we're stuck with. The only way to reduce the power
consumption is to find a more efficient refrigeration unit and/or
reduce the moisture influx.

You may find as I did that a high SEER window AC is more efficient
than a typical dehumidifier. I found that an 8000 BTU 11 SEER window
unit was considerably more efficient than any dehumidifier available
on the local market AND it removed much more water AND it was a LOT
cheaper (about $90 vs over$200 for typical dehumidifier). I have it
sitting on a platform over the floor drain in my basement. I drilled
a hole in the bottom to let the condensate drain to the floor drain
and blocked the little tube that normally carries the condensate to
the condenser to be evaporated outside. I have an external humidistat
wired to the unit to turn it off in the unlikely event it ever dries
the basement below 50% RH.

The way to evaluate the efficiency is in terms of water removed per
unit of energy. That would normally be grams/ounces/gallons of water
per kilowatt-hour. The nameplate power consumption is, in my
experience, usually higher than actual. Actually measuring the power
consumption using a Kill-a-Watt (KAW) or equiv is the way to
accurately determine efficiency.

When I was choosing my AC unit, I carried my KAW to the various stores
and actually operated each unit under consideration.

There is one limitation to using an AC and that is the limit of
humidity reduction. ACs are designed to never bring the evaporator
below freezing and typically don't go below about 38 degs. That means
that the humidity can't go below about 40 deg wet bulb which is about
38% RH for a dry bulb temperature of 70 degrees. If you need to go
below that you'll have to get a freezing dehumidifier. This type of
dehumidifier is designed to freeze the evaporator and periodically
thaw it. Only go that route if you need the lower humidity, for the
freezing style is a little less efficient.

The best return on investment will be dollars spent reducing the
moisture influx. Sealing the concrete floor and walls, for instance,
can dramatically reduce the moisture that diffuses through them.

As part of my moisture reduction program I had the dirt next to the
house dug out to below the foundation, coated the blocks with tar and
black poly, installed a french drain and backfilled a foot or two with
gravel before replacing the dirt. I also graded the fill away from
the house to ensure that rain water didn't flow back against the
walls. I painted the inside walls with that water sealer paint that
the home improvement stores sell and I coated the floor with cement
floor paint.

It is far too humid to rely on ventilation where I live so the
moisture reduction program and the dehumidifier were the techniques
necessary. My basement went from having billowing growths of mildew
and other fungus growing on the floor studs to being pretty much as
dry as the house.

John

---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain

Thanks John

Really useful information.

Nick

N

Jan 1, 1970
0
N

#### [email protected]

Jan 1, 1970
0
Neon John said:
You may find as I did that a high SEER window AC is more efficient
than a typical dehumidifier. I found that an 8000 BTU 11 SEER window
unit was considerably more efficient than any dehumidifier available
on the local market... The way to evaluate the efficiency is in terms
of water removed per unit of energy... When I was choosing my AC unit,
I carried my KAW to the various stores and actually operated each unit
under consideration.

Fascinating. How did you measure the water removed? Sounds like that would
take a long time, and there might be trapped pockets, and the store air
might be so dry that an AC couldn't remove any water.

Nick

M

#### m Ransley

Jan 1, 1970
0
To run all the time and not remove near rated water amount it might be
low on freon, also at cooler temps less water is removed and the coil
can freeze. Many dehumidifiers will freeze the coil below 65F, does
yours freeze up. You first need an accurate humidistat, get a digital
unit or analog you can and do calibrate. Did you use an amp meter or
Kill a watt to measure draw and overall power used. I would bet you
could use a new efficient dehumidifier, unless you can get yours checked
and charged cheaply.

Replies
6
Views
394
N
Replies
8
Views
2K
N_Cook
N