Dehumidifier running costs
Discussion
I had a new garage built earlier this year. It's 20ft x 15ft concrete sectional garage and was built predominantly to store a Porsche 997 C2S that I've had for years but no longer use as a daily and two motorcycles. All was well when the garage was installed. I delayed painting the floor as the builders told me I should allow 1 month per inch of concrete for it to dry out thoroughly (it's 10 inches thick in parts due to sloping ground. So, I've fitted electrics so that I can use battery conditioners and I've also put LED lighting in.
A few weeks ago I happened to go in there and to my horror there was a large puddle of water on one side. The timber above the door (It's a Hanson Duchess model with the faux tiled front) was covered in mould, the roof sheets, that have a flock finish to reduce condensation were soaking wet and the steel C shape girders had water in them.
The car and bikes were covered up for winter, all the covers were soaking.
I removed the covers, brushed the water out and borrowed my father in laws old compressor type dehumidifier and set about drying the place out. It took around 4 days to dry out. during that time I bought my own dehumidifier, A 10l Probreeze, It's a desiccant dehumidifier from Amazon.
I set it up running and a day later was surprised to see that it was still showing to be above 80% humidity. So then I bought a hygrometer with a sender so that I could monitor from inside the house.
A couple of days later, the rain came again which resulted in another puddle. This lead to a quick inspection. I found that the foam fillets at the top of the rood where the metal sheets go under the faux tiles at the apex weren't fully under the profile, this was causing them to become saturated and then drip down onto the ply (the mouldy ply) that was below them. When standing in the garage as it rained I could see drips. I also found a random screw through one of the faux tiles that had no weather protection grommit. There were a few other things too. I've reported these to Hansons customer service team and I'm waiting for them to reply with a date for a remedial visit.
Over the past week I've read so much about the options of ventilation or seal up and dehumidify and decided that for winter I'd seal up and dehumidify and then for the warmer months I plan to fit exhaust fans on humidistats to get rid of any high humidity air. I'm not convinced that the dehumidifier is up to the job or even working correctly so over the weekend I made some changes. I insulated both the main door and the pedestrian door with two layers of the foil adhesive bubble type stuff. I also fitted the fillets on the roof correctly and sealed this errant screw that I'd found. I also fitted a rubber threshold strip to the main door. We've had heavy rain since and the good news is, there are no longer any leaks. At least none that I can see.
Here's my problem though, and I'm hoping someone can share some insights or a similar experience with a solution. So, today as I write this, the outside temp is 5.8c and RH is 99%. The temp inside the garage is 7.6c and the RH is 80%. Bear in mind, the desiccant dehumidifier has been running none stop at full power, that means it's using 680w which at todays prices. is over 23p per hour, or £5.55 per day, an eye watering £166 per month. That's simply untenable. The problem seems to be that it's just not reaching anything like the 60% target that I have it set to. If it's not raining, it'll get down to around 65% and it'll flick itself into low mode (370w - £90.60 per month) but the moment it rains, the humidity rises again.
So I understand that during winter, the RH figure will always be higher as cold air can't hold the same amount of water, and the dew point is always a few degrees lower, so what are my options? I'm thinking of sending the desiccant dehumidifier back and getting a compressor type, I've seen some Ebac models that work down to 3 degrees and have a hot gas defrost feature. They only use 190w and therefore with constant running will only cost £46.50 per month. I can live with that. I could even put an 80w tube heater on a timer for evenings, that would still work out more cost efficient than what I'm currently trying to achieve.
Sorry for the long post, hoping someone can relate and help me to decide what my best course of action is (knocking it down isn't an option)
A few weeks ago I happened to go in there and to my horror there was a large puddle of water on one side. The timber above the door (It's a Hanson Duchess model with the faux tiled front) was covered in mould, the roof sheets, that have a flock finish to reduce condensation were soaking wet and the steel C shape girders had water in them.
The car and bikes were covered up for winter, all the covers were soaking.
I removed the covers, brushed the water out and borrowed my father in laws old compressor type dehumidifier and set about drying the place out. It took around 4 days to dry out. during that time I bought my own dehumidifier, A 10l Probreeze, It's a desiccant dehumidifier from Amazon.
I set it up running and a day later was surprised to see that it was still showing to be above 80% humidity. So then I bought a hygrometer with a sender so that I could monitor from inside the house.
A couple of days later, the rain came again which resulted in another puddle. This lead to a quick inspection. I found that the foam fillets at the top of the rood where the metal sheets go under the faux tiles at the apex weren't fully under the profile, this was causing them to become saturated and then drip down onto the ply (the mouldy ply) that was below them. When standing in the garage as it rained I could see drips. I also found a random screw through one of the faux tiles that had no weather protection grommit. There were a few other things too. I've reported these to Hansons customer service team and I'm waiting for them to reply with a date for a remedial visit.
Over the past week I've read so much about the options of ventilation or seal up and dehumidify and decided that for winter I'd seal up and dehumidify and then for the warmer months I plan to fit exhaust fans on humidistats to get rid of any high humidity air. I'm not convinced that the dehumidifier is up to the job or even working correctly so over the weekend I made some changes. I insulated both the main door and the pedestrian door with two layers of the foil adhesive bubble type stuff. I also fitted the fillets on the roof correctly and sealed this errant screw that I'd found. I also fitted a rubber threshold strip to the main door. We've had heavy rain since and the good news is, there are no longer any leaks. At least none that I can see.
Here's my problem though, and I'm hoping someone can share some insights or a similar experience with a solution. So, today as I write this, the outside temp is 5.8c and RH is 99%. The temp inside the garage is 7.6c and the RH is 80%. Bear in mind, the desiccant dehumidifier has been running none stop at full power, that means it's using 680w which at todays prices. is over 23p per hour, or £5.55 per day, an eye watering £166 per month. That's simply untenable. The problem seems to be that it's just not reaching anything like the 60% target that I have it set to. If it's not raining, it'll get down to around 65% and it'll flick itself into low mode (370w - £90.60 per month) but the moment it rains, the humidity rises again.
So I understand that during winter, the RH figure will always be higher as cold air can't hold the same amount of water, and the dew point is always a few degrees lower, so what are my options? I'm thinking of sending the desiccant dehumidifier back and getting a compressor type, I've seen some Ebac models that work down to 3 degrees and have a hot gas defrost feature. They only use 190w and therefore with constant running will only cost £46.50 per month. I can live with that. I could even put an 80w tube heater on a timer for evenings, that would still work out more cost efficient than what I'm currently trying to achieve.
Sorry for the long post, hoping someone can relate and help me to decide what my best course of action is (knocking it down isn't an option)
F20CN16 said:
A 680W dehumidifier, are you sure? That sounds like a lot. Is it huge?
I know, crazy isn't it, I'll be honest, I didn't give it a thought when I bought it. Apparently all desiccant dehumidifiers use a lot more energy as they have a small heater on board. If you do a Google search for ProBreeze 10l you'll see it. It's just a regular domestic dehumidifier that doesn't seem that efficient. 2 sMoKiN bArReLs said:
There must be cheaper to run dehumidifiers?
I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
Three! wow that must be some size garage, can I ask what brand/model you run and is the garage heated?I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
Just looked at my electricity bills
For example
Total
April 2021 (no dehumidifiers) £79, May 2021 (no dehumidifiers) £56
April 2022 £96, May 2022 £87
But rates have gone up by 30%, So April 2021 equivalent is £102 & May 2021 equivalent £73
So no change really.
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
For example
Total
April 2021 (no dehumidifiers) £79, May 2021 (no dehumidifiers) £56
April 2022 £96, May 2022 £87
But rates have gone up by 30%, So April 2021 equivalent is £102 & May 2021 equivalent £73
So no change really.
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
G2ADY said:
2 sMoKiN bArReLs said:
There must be cheaper to run dehumidifiers?
I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
Three! wow that must be some size garage, can I ask what brand/model you run and is the garage heated?I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
2 sMoKiN bArReLs said:
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
A more efficient refrigerant dehumidifier will be less effective (and less efficient) in the colder temperatures of this garage. A dessicant dehumidifier is the right type for this job, but can't be cost effective if there's rain water coming in constantly.F20CN16 said:
Ah fair enough. I didn’t know they had a heater, and that’ll be why. I use a compressor one in my garage that runs at 165W, but admittedly it isn’t meant to run below 5 degrees so no comparison.
How do you keep the garage above 5 degrees? This is my preferred route now I think but I need a contingency for the few weeks of the year where it will dip below that temp. OP first thing's first, get the garage sealed up and stop the water coming in. Once it's sealed you'll find the dehumidifier much more efficient as it's not constantly battling an incoming stream of water.
I run one in my unheated single-skin garage over winter, it's got a pretty poor door seal, but it doesn't face the incoming weather so it's relatively dry.
Last winter it used about £15 of electricity, this year I'm expecting x2 that.
I run one in my unheated single-skin garage over winter, it's got a pretty poor door seal, but it doesn't face the incoming weather so it's relatively dry.
Last winter it used about £15 of electricity, this year I'm expecting x2 that.
2 sMoKiN bArReLs said:
Just looked at my electricity bills
For example
Total
April 2021 (no dehumidifiers) £79, May 2021 (no dehumidifiers) £56
April 2022 £96, May 2022 £87
But rates have gone up by 30%, So April 2021 equivalent is £102 & May 2021 equivalent £73
So no change really.
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
Thanks for the figures, I don't have economy 7, I didn't realise that it was still a thing, I'll look into it. For example
Total
April 2021 (no dehumidifiers) £79, May 2021 (no dehumidifiers) £56
April 2022 £96, May 2022 £87
But rates have gone up by 30%, So April 2021 equivalent is £102 & May 2021 equivalent £73
So no change really.
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
Evanivitch said:
2 sMoKiN bArReLs said:
Get a more efficient dehumidifier must be your start point? Do you have economy 7?
A more efficient refrigerant dehumidifier will be less effective (and less efficient) in the colder temperatures of this garage. A dessicant dehumidifier is the right type for this job, but can't be cost effective if there's rain water coming in constantly.Garage is 10m x15m, fairly new with well insulated walls with 3mm x 2m x3m plastic covering all round . The doors are also internally insulated along with a rubber sealing strip along the bottom edges. The floor is commercial carpet. All I use is a 350w PowerDry dehumidifier with external outlet. It seems very economical to run..
2 sMoKiN bArReLs said:
G2ADY said:
2 sMoKiN bArReLs said:
There must be cheaper to run dehumidifiers?
I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
Three! wow that must be some size garage, can I ask what brand/model you run and is the garage heated?I run three in my garage.
I have two running during economy seven hours, and one with a preset RH % of 60% 24/7.
I've had this set up since March & I haven't noticed an increase in electricity costs.
Krikkit said:
OP first thing's first, get the garage sealed up and stop the water coming in. Once it's sealed you'll find the dehumidifier much more efficient as it's not constantly battling an incoming stream of water.
I run one in my unheated single-skin garage over winter, it's got a pretty poor door seal, but it doesn't face the incoming weather so it's relatively dry.
Last winter it used about £15 of electricity, this year I'm expecting x2 that.
That’s what I found, the first few weeks i put mine in it was on constantly, once it had dried out the garage it’s rarely working tbf I run one in my unheated single-skin garage over winter, it's got a pretty poor door seal, but it doesn't face the incoming weather so it's relatively dry.
Last winter it used about £15 of electricity, this year I'm expecting x2 that.
This Winter it isn’t constantly on and the humidity is around the the 60* or less
Dehumidifier is pissing in the wind when rain is leaking in.
May even make things worse, it's 'free' water and more heat in the space.
It's not much better if there are significant draughts.
Most garage doors don't seal well enough for a dehumidifier to work efficiently, so it will run 24/7 if you're not careful.
With no rain leaks, a reasonably damp proofed floor and a fair attempt at draught proofing the door, mine runs a few hours a day in a double garage sized space, in typical manky autumn weather.
I only use it when weather dictates, I.e when the outdoor humidity is fairly high.
May even make things worse, it's 'free' water and more heat in the space.
It's not much better if there are significant draughts.
Most garage doors don't seal well enough for a dehumidifier to work efficiently, so it will run 24/7 if you're not careful.
With no rain leaks, a reasonably damp proofed floor and a fair attempt at draught proofing the door, mine runs a few hours a day in a double garage sized space, in typical manky autumn weather.
I only use it when weather dictates, I.e when the outdoor humidity is fairly high.
Something about this doesn't sound right. Are you sure the garage isn't still leaking? There's no real reason why the humidity should rise so drastically when it's raining, unless water is still making its way inside and evaporating owing to the slightly warmer temperature. Additionally, perhaps it's too well sealed? We rented a council lockup years ago for storage, which had an asbestos roof on a metal frame and no weather sealing at all; there was a gap of about half an inch between roof and walls all the way round! The entire structure was bone dry all year round, probably because any damp air that did get in would immediately get out again. Dusty as Hell in there, though.
My money is on a small amount of water getting in to OP's garage, and then having no effective means of getting out again.
My money is on a small amount of water getting in to OP's garage, and then having no effective means of getting out again.
I just popped out to the garage to have a look at mine.
I have one of the below running full time in my double garage.
The garage is a detached brick, block, tiled roof structure with a timber side door and insulated sectional garage doors with a rubber seal on the bottom that closes onto a rubber seal on the floor. I went to some effort to seal it pretty well.
https://www.amazon.co.uk/EcoAir-DD122-Simple-Desic...
It’s set at halfway around the dial.
It’s a horrible persistently wet day and evening and the Relative Humidity in the garage now is just under 60%.
The unit is running but the whole house is running at 24p/ hour on the smart meter.
I had a normal compressor one but it just used to freeze up and be ineffective when it got colder.
I reckon your garage is letting in the rain and probably not sealed at DPC level as well, get that right then as air tight as possible, then I would recommend the above dehumidifier with a perm discharge pipe through the wall.
Good luck.
I have one of the below running full time in my double garage.
The garage is a detached brick, block, tiled roof structure with a timber side door and insulated sectional garage doors with a rubber seal on the bottom that closes onto a rubber seal on the floor. I went to some effort to seal it pretty well.
https://www.amazon.co.uk/EcoAir-DD122-Simple-Desic...
It’s set at halfway around the dial.
It’s a horrible persistently wet day and evening and the Relative Humidity in the garage now is just under 60%.
The unit is running but the whole house is running at 24p/ hour on the smart meter.
I had a normal compressor one but it just used to freeze up and be ineffective when it got colder.
I reckon your garage is letting in the rain and probably not sealed at DPC level as well, get that right then as air tight as possible, then I would recommend the above dehumidifier with a perm discharge pipe through the wall.
Good luck.
I had a Hanson garage built 8 years ago and remember similar water ingress under the cement fillet they put down around the inside edge. I bought a few tubes of frame sealant and ran a bead + smoothed around the outside edge where the panels sit on the base.
I run a desiccant machine in mine too, however I insulated the walls and roof (placed a vapour barrier underneath the wall insulation to stop damp coming through from the outside…whether that’s the right thing to do or not, garage is nice and dry ever since )
I run a desiccant machine in mine too, however I insulated the walls and roof (placed a vapour barrier underneath the wall insulation to stop damp coming through from the outside…whether that’s the right thing to do or not, garage is nice and dry ever since )
Humidifiers generally have few mode. One we have is with 5 modes including two laundry modes and the 650w figure on our model is for for the highest of the two laundry modes.
As someone said its difficult to seal garage doors properly. You might be better off with better ventilation rather than trying to seal and dehunidify.
As someone said its difficult to seal garage doors properly. You might be better off with better ventilation rather than trying to seal and dehunidify.
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