Heat house with dehumidifier - Page 2

ecomodded · 10-17-12, 11:19 AM

Quote:

Originally Posted by Daox

I see where he is getting the heat from the conversion of water vapor into water. That makes sense. However, the energy to do that must come from somewhere. The energy is going to come from the dehumidifier.

This is the statement that is incorrect.

While he has used 3.87 kWh, not all of that is turned to heat. Some of it is running a motor for the compressor, some of it is pumping fluid through the heat pump system, some of it is being lost as heat energy. So, only a portion of that 3.87 kWh is being returned as heat energy. The rest is doing actual work and converting the energy from the phase change of water. There is no other source of energy to do it.

A funny thing with energy is it never goes away, it only changes form.
Which is why a closed loop system like the refrigeration system is 100% efficient at turning all of its mechanical energy into heat.

Good call Ryland ! I found the same info yesterday, also the condensation Btu's are part of the 13 degree increase in the exhaust temperature.

Turns out the Author was 100% correct.
A day spend without learning is a day wasted.

I cleaned my dehumidifiers filter yesterday, that night it only 'made' 1 liter of water.
The night before with a dirty filter it made 3 liters.
My thought is the dirty filter was acting as a pre cooler for the air.
Now i plan on making a pre-cooler by attaching wire mesh to one side of the condenser then in the pre air flow over to the other side of the condenser.
I will be taking the cold off the sides of the condenser where it is hardly utilized , moving it to the front where it will be 100% utilized.

I would love to make a heat pipe and add it to the system.
If i do i will remove the dehumidifier from its case permanently.

Found a sticker behind the water catch container that has the dehumidifiers specs on it. My unit uses 600 watts at peak, as Ryland posted, a 600w dehumidifier on average consumes 300w.

ecomodded · 10-17-12, 03:24 PM

I solved the problem of waste heat in the waste water and the inefficiency of the fan.

Perpetual extraction

What could be done so there is a 'perpetual' reintroduction of the waste water is have the water drain to the back of the dehumidifier
where it will be absorbed by a cotton cloth that is strung across the path of the exhaust air.
By doing this the fans mechanical wasted energy is utilized by the evaporation of the waste water allowing continuous repeated extractions.

Fast and dirty

Re-use the waste water by wetting a wool blanket and reintroducing the water to the environment.

This dehumidifier is going to save electricity, no doubt about it.

I have the case off of it now for my planned modification, i will add my pre cooler today and plan for the water extraction construction.

Daox · 10-17-12, 04:33 PM

And where is the energy coming from that is turning that water back into a gas? The fan isn't going to heat up the water. The air passing over the cloth will heat it up though, the nice warm air of your house... So, the enrgy is going to come from the atmosphere and that means sucking the heat back out of the air.

Really, I don't see this working. Number one, you want humidity in your house in winter to be comfortable so running a dehumidifier is counter-intuitive in the first place. Assuming you just have a massive amount of water to take out of the air, and electric heating is your only other source of heating, its still isn't more than 100% efficient because of the fan and pump losses.

The only way I can see this actually working is to use it like an actual heat pump and pull heat from outside the house to the inside.

ecomodded · 10-17-12, 10:02 PM

ahh ha, i see my perpetual humidity device is not at all possible.
I do see the problem, it takes heat not wind to cause evaporation, as the process consumes the Btu's lost in the condensation process.

The losses you speak of with the compressor is non existent.

A funny thing with energy is it never goes away, it only changes form.
Which is why a closed loop system like the refrigeration system is 100% efficient at turning all of its mechanical energy into heat.

I can buy a 12,000 Btu portable air condition , dehumidifier combo that with high humidity will make up to four times the heat energy as a electric heater .
Its a common consumer facts that dehumidifiers make more heat then a electric heater. I have read enough ads and spec sheets as of late to know.

People over here in B.C have a excess of humidity not at all like the dry air of back east.

Warm and wet is a typical winter over here with a chance of snow on the ground for 1 week 2 weeks tops and a average annual rainfall of 75 inches.

ecomodded · 10-18-12, 03:33 PM

Earlier I mentioned that the dehumidifier condensed only a liter of water over night, as it turned out there was .7 liters water in ice build up that melted later.
I ran it with its cover off to see when it frosts over,
It took 5 hours to freeze to a point before restricting the airflow with the house at 19 c.

The evaporator is getting too cold, I think i can fix that.
I can absorb some cold away from the evaporator coils into some added mass.
For a cold sink I decided on 15 layers of galvanized chicken wire, wired together, 2 of them one inside the top one in the bottom of the evaporator (photo)
I am testing it now to see if it will reduce ice buildup and create more condensation from its increased surface area.

When i removed the case off the dehumidifier i found a very dirty condenser, I modified a vacuum end to vacuum it.

I have more chicken wire planned for testing on the outside of the evaporator.

jeff5may · 10-20-12, 01:09 PM

Ok, so here's the simple version:
All properly designed phase change refrigerating systems move more energy than the compressor consumes. The performance of the system depends on what we do with that moving energy. If we are trying to heat, the cold must be disposed of somehow. The opposite is true for cooling.
In your dehumidifier heater, the air flowing through is cooled to condense water vapor, and cold water drops out. The cold air is then reheated and exits the unit above ambient, since dry air heats up faster than wet air. If you were disposing of the cold condensate, you would pick up a little heat gain from the condensing/cooling energy stolen from the water vapor(until you run out of excess water in the air). As it is, you are saving the water and reheating it with the dry air, literally evaporating your heat gain.

jeff5may · 10-20-12, 01:41 PM

Now here's a general idea of what to do with this unit:
1. Drain your cold condensate
2. Enclose the evaporator coil and dispose of cold air to someplace you're not trying to heat.
3. Be amazed at your creation and its potential
A good many posters on this site started out with a unit much like yours. Look around on the site to see what worked and what didn't. Good luck.

ecomodded · 10-20-12, 02:58 PM

That is exactly what i am planning.
I read up on how the' air heat pump' uses the same components as a refrigerator or dehumidifier only with the evaporator outside the home with the condenser on the inside.

My plan is to make a plywood box enclosure around the evaporator, with the intake and exhaust running threw it from the outdoors ,with a fan.
I am also going to need a defrost heater.
I could use some ideas on what to use for that.
So far my idea is to use a heated wire to wrap around the evaporator with ?
I want it to be a low heat defroster because of the construction materials, i could if need be make the case and vents out of metal.
And i will need to have a drain running to the outside to remove the condensed cold water.

jeff5may · 10-20-12, 08:28 PM

Ok, I have some ideas for you.
I see you are in Canada. I'm guessing it gets pretty cold there in winter. For this reason, you will want to minimize cold air getting into your house. Also, you want your condensate going into a drain inside the house, as not to create a sheet of ice outside somewhere.
So try this: find an airtight tupperware/rubbermaid container sized slightly larger than your evaporator. Chop, cut, wrangle it in around the evaporator so you can snap the lid on in between the two coils. Fasten a computer fan to the lower outside of the container so that will suck cold air from the evap coil inside. Blow this cold air thru a shop-vac style hose outside, trying to keep the hose length short. Poke some holes in the container for airflow/drainage.
As for defrosting, most dehumidifiers have a built-in defrost thermostat. Look for a small sensor on the evap coil or the suction line between the compressor and evap coil. If yours has none, you can get defrost thermostats on ebay for 5 bucks shipped.

ecomodded · 10-21-12, 11:20 AM

My plan is to keep it simple and cheap.

Reuse the drip tray with a added drain hose.
Reuse the 120W fan with a added 3-speed switch( i have one) for the evaporator outdoor ventilation.

I will make a evaporator airflow box out of plywood (have it) covered with vapor barrier, a 10" intake and exhaust venting(fan is 8") with a easy access inspection hatch.

For defrost i am going to weave in a 6 or 9 ft , 7 watt per ft water pipe heater cable between the evaporator coils. With 2 timers (have them)synchronized to turn the dehumidifier on & off with the defrost cycle.
To spread the heat i will use 4 large computer fans( have 2 now)
The condensed water can be drained directly outdoors in this case as the unit will not be used or even function when its below zero.

So for supplies i need some venting 2 more large computer fans and a 6-9ft. heater cable. Costs expected to be $30-$40.

edit: found better fans,left over from previous renovations.
I plan on using a bathroom exhaust fan to pull air threw the condenser and a 8" inline exhaust fan for the evaporator outdoor vent.

10-17-12, 03:24 PM	#12
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	I solved the problem of waste heat in the waste water and the inefficiency of the fan. Perpetual extraction What could be done so there is a 'perpetual' reintroduction of the waste water is have the water drain to the back of the dehumidifier where it will be absorbed by a cotton cloth that is strung across the path of the exhaust air. By doing this the fans mechanical wasted energy is utilized by the evaporation of the waste water allowing continuous repeated extractions. Fast and dirty Re-use the waste water by wetting a wool blanket and reintroducing the water to the environment. This dehumidifier is going to save electricity, no doubt about it. I have the case off of it now for my planned modification, i will add my pre cooler today and plan for the water extraction construction. Last edited by ecomodded; 10-17-12 at 03:30 PM..

10-17-12, 04:33 PM	#13
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	And where is the energy coming from that is turning that water back into a gas? The fan isn't going to heat up the water. The air passing over the cloth will heat it up though, the nice warm air of your house... So, the enrgy is going to come from the atmosphere and that means sucking the heat back out of the air. Really, I don't see this working. Number one, you want humidity in your house in winter to be comfortable so running a dehumidifier is counter-intuitive in the first place. Assuming you just have a massive amount of water to take out of the air, and electric heating is your only other source of heating, its still isn't more than 100% efficient because of the fan and pump losses. The only way I can see this actually working is to use it like an actual heat pump and pull heat from outside the house to the inside. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-17-12, 10:02 PM	#14
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	ahh ha, i see my perpetual humidity device is not at all possible. I do see the problem, it takes heat not wind to cause evaporation, as the process consumes the Btu's lost in the condensation process. The losses you speak of with the compressor is non existent. A funny thing with energy is it never goes away, it only changes form. Which is why a closed loop system like the refrigeration system is 100% efficient at turning all of its mechanical energy into heat. I can buy a 12,000 Btu portable air condition , dehumidifier combo that with high humidity will make up to four times the heat energy as a electric heater . Its a common consumer facts that dehumidifiers make more heat then a electric heater. I have read enough ads and spec sheets as of late to know. People over here in B.C have a excess of humidity not at all like the dry air of back east. Warm and wet is a typical winter over here with a chance of snow on the ground for 1 week 2 weeks tops and a average annual rainfall of 75 inches. Last edited by ecomodded; 10-17-12 at 10:46 PM..

10-18-12, 03:33 PM	#15
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	Earlier I mentioned that the dehumidifier condensed only a liter of water over night, as it turned out there was .7 liters water in ice build up that melted later. I ran it with its cover off to see when it frosts over, It took 5 hours to freeze to a point before restricting the airflow with the house at 19 c. The evaporator is getting too cold, I think i can fix that. I can absorb some cold away from the evaporator coils into some added mass. For a cold sink I decided on 15 layers of galvanized chicken wire, wired together, 2 of them one inside the top one in the bottom of the evaporator (photo) I am testing it now to see if it will reduce ice buildup and create more condensation from its increased surface area. When i removed the case off the dehumidifier i found a very dirty condenser, I modified a vacuum end to vacuum it. I have more chicken wire planned for testing on the outside of the evaporator. Attached Thumbnails Last edited by ecomodded; 10-18-12 at 03:39 PM..

10-20-12, 02:58 PM	#18
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	That is exactly what i am planning. I read up on how the' air heat pump' uses the same components as a refrigerator or dehumidifier only with the evaporator outside the home with the condenser on the inside. My plan is to make a plywood box enclosure around the evaporator, with the intake and exhaust running threw it from the outdoors ,with a fan. I am also going to need a defrost heater. I could use some ideas on what to use for that. So far my idea is to use a heated wire to wrap around the evaporator with ? I want it to be a low heat defroster because of the construction materials, i could if need be make the case and vents out of metal. And i will need to have a drain running to the outside to remove the condensed cold water. Last edited by ecomodded; 10-20-12 at 03:08 PM..

10-20-12, 01:09 PM	#16
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Ok, so here's the simple version: All properly designed phase change refrigerating systems move more energy than the compressor consumes. The performance of the system depends on what we do with that moving energy. If we are trying to heat, the cold must be disposed of somehow. The opposite is true for cooling. In your dehumidifier heater, the air flowing through is cooled to condense water vapor, and cold water drops out. The cold air is then reheated and exits the unit above ambient, since dry air heats up faster than wet air. If you were disposing of the cold condensate, you would pick up a little heat gain from the condensing/cooling energy stolen from the water vapor(until you run out of excess water in the air). As it is, you are saving the water and reheating it with the dry air, literally evaporating your heat gain.

10-20-12, 01:41 PM	#17
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Now here's a general idea of what to do with this unit: 1. Drain your cold condensate 2. Enclose the evaporator coil and dispose of cold air to someplace you're not trying to heat. 3. Be amazed at your creation and its potential A good many posters on this site started out with a unit much like yours. Look around on the site to see what worked and what didn't. Good luck.

10-20-12, 08:28 PM	#19
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Ok, I have some ideas for you. I see you are in Canada. I'm guessing it gets pretty cold there in winter. For this reason, you will want to minimize cold air getting into your house. Also, you want your condensate going into a drain inside the house, as not to create a sheet of ice outside somewhere. So try this: find an airtight tupperware/rubbermaid container sized slightly larger than your evaporator. Chop, cut, wrangle it in around the evaporator so you can snap the lid on in between the two coils. Fasten a computer fan to the lower outside of the container so that will suck cold air from the evap coil inside. Blow this cold air thru a shop-vac style hose outside, trying to keep the hose length short. Poke some holes in the container for airflow/drainage. As for defrosting, most dehumidifiers have a built-in defrost thermostat. Look for a small sensor on the evap coil or the suction line between the compressor and evap coil. If yours has none, you can get defrost thermostats on ebay for 5 bucks shipped.

10-21-12, 11:20 AM	#20
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	My plan is to keep it simple and cheap. Reuse the drip tray with a added drain hose. Reuse the 120W fan with a added 3-speed switch( i have one) for the evaporator outdoor ventilation. I will make a evaporator airflow box out of plywood (have it) covered with vapor barrier, a 10" intake and exhaust venting(fan is 8") with a easy access inspection hatch. For defrost i am going to weave in a 6 or 9 ft , 7 watt per ft water pipe heater cable between the evaporator coils. With 2 timers (have them)synchronized to turn the dehumidifier on & off with the defrost cycle. To spread the heat i will use 4 large computer fans( have 2 now) The condensed water can be drained directly outdoors in this case as the unit will not be used or even function when its below zero. So for supplies i need some venting 2 more large computer fans and a 6-9ft. heater cable. Costs expected to be $30-$40. edit: found better fans,left over from previous renovations. I plan on using a bathroom exhaust fan to pull air threw the condenser and a 8" inline exhaust fan for the evaporator outdoor vent. Last edited by ecomodded; 10-21-12 at 10:00 PM..