Spec me a dehumidifier please?

koolpc said:
Running cost for a dehumidifier vs a PIV system?
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The zambezi dehumidifier is 351w (not sure if that's average or slow speed though) but the PIV I have when checking the envirovent website is 4w! That's without the heater bit, they don't say what it is with it on though.

That's about £11.25 for the PIV and £984 per year for the dehumidifier lol. At about 32p per KW/h as of now.

Edit: Presuming 24/7 runtime but the dehumidifier will use less when the target humidity is reached.
 
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Nemiyen said:
The zambezi dehumidifier is 351w (not sure if that's average or slow speed though) but the PIV I have when checking the envirovent website is 4w! That's without the heater bit, they don't say what it is with it on though.

That's about £11.25 for the PIV and £984 per year for the dehumidifier lol. At about 32p per KW/h as of now.

Edit: Presuming 24/7 runtime but the dehumidifier will use less when the target humidity is reached.
Click to expand...

Waw! Big difference in running costs.

Is it very noticeable running the PIV without the heater and is it audible? Ta
 
koolpc said:
Waw! Big difference in running costs.

Is it very noticeable running the PIV without the heater and is it audible? Ta
Click to expand...

You also need to factor in the cost to heat the air up from the PIV via your heating system as it would fall under an indirect running cost.

The specific heat capacity of air under constant pressure is 1.005 kJ kg-1 K-1, we can use this with the flow rate of the PIV to caculate how much energy you'd need to use per hour to heat the air coming in. For an example i just picked one of the nuaire models, it suggests a speed setting of 4 for a 3 bedroom house, which is 40 litres/s. Lets say the average temp of the air coming in from the loft/outside is 10c (this might be a little high when including the depths of winter..). The density of air at that temp is 1.2466 kg/m3. Assuming it runs constantly for an hour it'll move 144,000l of air, which is 144m3. So for our calc we'll need 179.5kg of air (1.2466*144). Its then simply a case of multipling our mass of air by the specific heat capacity by how many degrees to raise (target temp of 18, so an increase of 8 degrees), so 179.5*1.005*8 = 1443.18kJ of energy. Energy (J) / Time (S) = Power (W), so we get 1443180/3600 = 400.9w. So we require 0.4kWh of energy input from having the PIV running per hour, assuming a 24/7 operational time that'll be 9.6kWh of extra heat input. Roughly £1 of gas at todays prices in a worst case senario, the likely hood is that it'll be a bit less as the PIV should turn off when it reaches a RH goal from the control unit
 
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We have this one it uses half the power of desiccant one.
  • Just 165 Watts rated power consumption

www.meacodehumidifiers.co.uk

Meaco 12L Low Energy Platinum Dehumidifier – Free 3 Year Warranty

The Meaco 12L Low Energy Dehumidifier delivers outstanding efficiency, using just 157 watts and costing only 4p per hour (based on 22.36p/kWh). This Quiet Mark award-winning unit operates at a mere 41dB, making it perfect for smaller homes without disrupting daily life. With versatile 2-in-1...
www.meacodehumidifiers.co.uk www.meacodehumidifiers.co.uk
 
koolpc said:
Waw! Big difference in running costs.

Is it very noticeable running the PIV without the heater and is it audible? Ta
Click to expand...

We kept ours on because when we bought the house it needed major mould renovations! BUT, their lifestyle choices were what made the house so bad.

We turned ours off earlier this year to see how things went and so far, apart from condensation on the windows, which is generally normal for this time of year, we haven't had any mould problems... Touch wood!

The unit we have now I ran on the high setting (not boost) and you could hear it when you were under it but not when in one of the bedrooms. I'm going to turn it back on but keep it on low over winter because it's one of those things where when you see mould, it's too late!

I'm hoping the dehumidifier will help as well but I do need to turn the PIV back on.

I turned it off because it did cause the house to get colder. If it's 3 degrees outside then it's supposed to temper the air to 10 degrees when it comes in (assuming my heat element is working, I can't see how I could tell apart from opening it up!) which is still cold in my opinion! I didn't notice a massive increase in my electric bill with the new unit vs the old one that didn't heat the air.

The unit we have doesn't switch off when the RH hits a certain amount, ours just runs 24/7 and that's it. In summer if it gets hot it will turn off but it doesn't turn off any other time. The new models might do something better though.

See gammawolfs post for the energy costs to heat that air, I've not done any sanity checking on the maths but I'm guessing it is right :D
 
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The cost comes back to efficiency of the dehumidifier type vs how quick you want the humidity to drop vs your house temperature.

Compressor ones work great in high humid reasonably high temperature houses. I keep reading 20-25 degrees is best for a compressor type.

Desiccant ones will work perfectly fine at a much lower or higher temperature like garages, conservatories or cold houses like ours. :D

It's a case of running a 165w compressor at 3 hours to get the same moisture out of the air vs 1 hour of a desiccant running at 351w that is more efficient at 18 degrees or lower. I've made these times up so it's not exactly that but I don't think it is far apart.

A house with 100 percent humidity at 30 degrees then a compressor type would be amazing! But a house or garage with 71 percent humidity at 16 degrees, a compressor type would struggle to match a desiccant one for extracting moisture.
 
The compressor ones can be quite effective at lower temps than 20-25, i was actaully looking at that comparison recently because i bought a MeacoDry Arete® One 20L Dehumidifier for downstairs inside a coat closet (its got underground external walls and that floor is generally colder than the rest of the house (14.5c) so the RH is around 75% all the time, issues with eventual mould growth on used coats (not dirty i promise!) and stuff if they stay in there long enough)

Anyway this was comparing the data provided by Meaco for two of their models (so assuming constant test methodology, you can view the full tables in the extract rate tab on the links), both cost £259. The Arete is the compressor and the Zambezi is the desiccant.
I believe lower than 10c is where the compressor ones start to really fall off a cliff though because you can realistically only run the cooling coils so low before theres not enough differential in temps and they start to frost up. Then it spends most of its time defrosting the coils

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www.meaco.com

MeacoDry Arete® One 20L Dehumidifier / Air Purifier

Quiet Mark awarded & a Red Dot Winner: Britain's best-selling family of dehumidifiers, the Arete® One 20L. Dry clothes fast. Free next day delivery. Shop now.
www.meaco.com www.meaco.com
www.meaco.com

Meaco DD8L Zambezi Dehumidifier

Advanced 8L desiccant dehumidifier for any sized home, garage, boat, conservatory or basement. Manage home humidity & dry clothes fast. Free next day delivery.
www.meaco.com www.meaco.com
 
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Gammawolf said:
The compressor ones can be quite effective at lower temps than 20-25, i was actaully looking at that comparison recently because i bought a MeacoDry Arete® One 20L Dehumidifier for downstairs inside a coat closet (its got underground external walls and that floor is generally colder than the rest of the house (14.5c) so the RH is around 75% all the time, issues with eventual mould growth on used coats (not dirty i promise!) and stuff if they stay in there long enough)

Anyway this was comparing the data provided by Meaco for two of their models (so assuming constant test methodology, you can view the full tables in the extract rate tab on the links), both cost £259. The Arete is the compressor and the Zambezi is the desiccant.
I believe lower than 10c is where the compressor ones start to really fall off a cliff though because you can realistically only run the cooling coils so low before theres not enough differential in temps and they start to frost up. Then it spends most of its time defrosting the coils

0fxXjxP.png

www.meaco.com

MeacoDry Arete® One 20L Dehumidifier / Air Purifier

Quiet Mark awarded & a Red Dot Winner: Britain's best-selling family of dehumidifiers, the Arete® One 20L. Dry clothes fast. Free next day delivery. Shop now.
www.meaco.com www.meaco.com
www.meaco.com

Meaco DD8L Zambezi Dehumidifier

Advanced 8L desiccant dehumidifier for any sized home, garage, boat, conservatory or basement. Manage home humidity & dry clothes fast. Free next day delivery.
www.meaco.com www.meaco.com
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That's giving me buyers remorse! I went with the zambezi as it was beating all the other compressor models that I could find so I pretty much didn't do a great comparison of the Meaco compressor types!

At least the Zambezi ones uses more electric so it generates more heat for the house! :D
 

EcoAir DD1 Simple Blue Desiccant Dehumidifier | Rotary Control | 7.5 L/Day | Quiet 34dBA | Silver Filter | Laundry | 6Kg | Home Garage Basement Boat​

5 years and still going strong. Not used as much in last 2 years but still going strong. Used mainly for laundry these days rather than full house treatment
 
Nemiyen said:
That's giving me buyers remorse! I went with the zambezi as it was beating all the other compressor models that I could find so I pretty much didn't do a great comparison of the Meaco compressor types!

At least the Zambezi ones uses more electric so it generates more heat for the house! :D
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Don't be! As with everything there are downsides and it depends on your use for it. The compressor one is a much bigger machine and also comes in weighing 2x as much. So if space / transporting it were an issue thats a consideration. I didn't list it just for the sake of keeping the table simpler for a power comparison with similar extraction rates but that rate is not the Zambezis max extraction at 10c where as the compressor will be max extraction. It can do 7.5litres per day at fan speed 3 for a power usage of 663 watts. If you need that kind of extraction rates (for larger spaces/floors) at those lowerish temps then the Zambezi does win out as you'd have to have two of the other machines in order to get close to the same performance at 10c. So if you need to be pulling 7.5l a day this makes the Zambezi cost half as much to buy effectively and use 33% of the floor space.

I have had a desiccant before and it served its purpose well but it sadly broke and my usage had also changed. I used to use it in a shower room downstairs (again underground walls, so no windows). The heat and increased power use was actually wanted for me. I'd turn on the dehumidifier before starting a shower and it would do its thing as well as heat the shower room, which on its own is around 14c, so not pleasant to step in to when wet. The reason i went compressor this time around was we no longer use that shower and I keep it on 24/7 in a 2m by 2m coat/storage closet so i don't need those higher extractions rates at the lower temps. It occasionally will come out into the the spare room on the same floor if someone is staying over just so it doesn't feel damp, space is also not an issue as it was before in that shower room
 
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Gammawolf said:
Don't be! As with everything there are downsides and it depends on your use for it. The compressor one is a much bigger machine and also comes in weighing 2x as much. So if space / transporting it were an issue thats a consideration. I didn't list it just for the sake of keeping the table simpler for a power comparison with similar extraction rates but that rate is not the Zambezis max extraction at 10c where as the compressor will be max extraction. It can do 7.5litres per day at fan speed 3 for a power usage of 663 watts. If you need that kind of extraction rates (for larger spaces/floors) at those lowerish temps then the Zambezi does win out as you'd have to have two of the other machines in order to get close to the same performance at 10c. So if you need to be pulling 7.5l a day this makes the Zambezi cost half as much to buy effectively and use 33% of the floor space.

I have had a desiccant before and it served its purpose well but it sadly broke and my usage had also changed. I used to use it in a shower room downstairs (again underground walls, so no windows). The heat and increased power use was actually wanted for me. I'd turn on the dehumidifier before starting a shower and it would do its thing as well as heat the shower room, which on its own is around 14c, so not pleasant to step in to when wet. The reason i went compressor this time around was we no longer use that shower and I keep it on 24/7 in a 2m by 2m coat/storage closet so i don't need those higher extractions rates at the lower temps. It occasionally will come out into the the spare room on the same floor if someone is staying over just so it doesn't feel damp, space is also not an issue as it was before in that shower room
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That's pretty much my thought process and ideally I'd want it to extract as much as possible but with the least amount of cost! :D

The size / weight is a consideration but I'm used to lugging the delonghi dragon radiators up and down the stairs so I'm used to that lol.

The Zambezi came today and it's already got the upstairs rooms down from 74 percent humidity to 55 percent or so but that's on full power for the last 4 hours so I don't want to see my electric bill!
 
Why do the desiccant ones use much more power, I thought they were just an absorbent material rather than a compressor one which actually has mechanical moving parts?

Woke up to 80% Rh this morning in my house at around 17 degrees C. No condensation on windows though but musty smell. Other days we've had window condensation at lower humidity and no smell.
 
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danlightbulb said:
Why do the desiccant ones use much more power, I thought they were just an absorbent material rather than a compressor one which actually has mechanical moving parts?

Woke up to 80% Rh this morning in my house at around 17 degrees C. No condensation on windows though but musty smell. Other days we've had window condensation at lower humidity and no smell.
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The desiccant ones have to heat the desiccant to remove the moisture, which is why the rooms get nice and toasty when using them. :D

Edit: Creating heat from electric isn't very efficient. We need a heat equivalent of the LED bulb!

The compressor ones don't use heat as such because they just create a really cold plate / surface and the water condenses on that. Sort of like when you bring a cold beer into the room when you've kept it in the fridge.
 
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Nemiyen said:
The desiccant ones have to heat the desiccant to remove the moisture, which is why the rooms get nice and toasty when using them. :D

Edit: Creating heat from electric isn't very efficient. We need a heat equivalent of the LED bulb!

The compressor ones don't use heat as such because they just create a really cold plate / surface and the water condenses on that. Sort of like when you bring a cold beer into the room when you've kept it in the fridge.
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A heat equivalent of LED.
That would be a backwards step.
 
If I get a dehumidifier - how do you stop it just dehumidifying the outdoor air. Do you then keep all windows and vents closed, improve house air tightness overall?

My older house has airbricks all over the place especially in the kitchen. I don't want to be wasting money fighting a problem that can't be solved if all those air inputs are bringing in humidity?
 
danlightbulb said:
If I get a dehumidifier - how do you stop it just dehumidifying the outdoor air. Do you then keep all windows and vents closed, improve house air tightness overall?

My older house has airbricks all over the place especially in the kitchen. I don't want to be wasting money fighting a problem that can't be solved if all those air inputs are bringing in humidity?
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Solid wall victorian house and have learnt a lot from dotting a few of these monitors round the house as good to get an idea of the changing humidity levels and affects of open windows cooking etc. problem areas and how quick they recover. Big struggle here to get down to 50% .....I am going to concede at 55% max

Main internal humidity issues are of course cooking/ boiling the kettle kicks out a whole load of humidity as well as whatever you are getting up to in the bathroom (good extraction works well in both areas to an extent but can be dependent on outdoor humidity). Even Asleep you producing humidity!

In the winter months my windows remain entirely sealed shut and block off the one airbrick in bathroom (that keeps agood deal of the outside humidity at bay) but have plenty of minor drafts from chimney and font door.
 
robj20 said:
A heat equivalent of LED.
That would be a backwards step.
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I've sort of said that wrong. We went from crappy inefficient incandescent bulbs to super efficient LEDs for light.

Yet we've stuck with the same way of generating heat by sending electric through a heating element since forever.

We need mini non meltdown nuclear thermal generating radiators. Or something similar :D
 
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