YES you CAN dry your laundry with your OWB, here's how!

[zeek]

Howdy all!I finally have a few minutes here to share with you guys something that will save you money on drying laundry. I have a friend who is a master tinkerer, this guy is a genius, anyway he is the person that got me started with this project. I must mention Stihl310, without him I would never have completed this project, we exchanged many LONG emails about the circuitry.

I have read many naysayers about drying your laundry with your Outdoor Wood Boiler (OWB) but they are simply wrong because I have been doing it for months now. Oh, yes, it does take longer, but I don't have to use the 20 Amp, 5000 watt (or so) electric heating element . . . unless I want to. You can convert ANY dryer, gas or electric, and maintain the ability to use the factory setup so you can still dry clothes when the OWB is not burning, so here goes . . . .

The idea is simple: force air over a heat exchanger into the dryer, I have an electric dryer.

First you need get some parts, my friend gave me a 12 Volt DC blower and A/C evaporator from a Mercury Capri, but you can use an evaporator from any car and you can get them on eBay. But don't get something that is too big because you have to mount it behind, or above, your dryer in a box. You can build a box from sheet metal, or even buy a return register box from Home Depot, and mount your evaporator in there.

Next you will need a fan that will connect to the box you just made/bought so that it will blow over the evaporator, which will have hot water from your OWB flowing through it. You could even use an inline, Duct Booster Fan, but be sure it has enough CFM to really blow the hot air into the dryer. I am not sure what would work, but my 12 Volt DC Mercury Capri blower does great. Since mine is 12 Volt DC I had to buy this.

Mine looks like this:
View attachment 269046

Now that you have your evap/blower ready it is time to supply it with HOT water, which is easy. I just used heater hoses from Carquest and hose clamped then to the evaporator, but I had to cut the fittings off so the hoses would fit. I have 3/4" PEX lines from the OWB and I just crimped a connector to the end of the PEX and clamped the heater hoses.

At this point all you have is a little self contained forced air furnace . . think about it, yu have the exchanger (evaporator) and a blower fan, just like your forced air furnace for the home.

Time to ask your wife to leave . . . you will be modifying the dryer and that may make her nervous, lol. At this point a picture explains it all, but a simple point of caution for electric dryers. Be certain, ABSOLUTELY certain that any screws/rivets/fasteners do not touch the element that is inside the long skinny duct or bad things will happen. For gas dryers I think it is pretty much the same, but I have never done it and if you are attempting this project then you can figure it out I'm sure.

View attachment 269051

Here is a wide view from the back so you can see it all put together . . .
View attachment 269053

A few notes: mounting all of this stuff will push the dryer out from the wall, but if you don't have the space you can hide the evap/blower in between the wall studs (as my friend did) or even mount it in the ceiling and use metal, flexible dryer vent to carry the hot air to the dryer.

Also, while your dryer is apart you need to do some wiring, but since all dyers are slightly different I cannot tell you how to do it. But basically what I did was I cut the hot wire wire going to the electric element and put a switch on the wall behind the dryer. I used a 30 Amp single throw disconnect I found in the garage, but what ever you use it must be able to handle 20 Amps! The point of this switch is so that when the OWB is out we can flip the switch turn the electric element on so we can still dry the laundry. For gas you can just shut the valve off, as you should have a shut off at the end of th egas line where your yellow gas line connects.

I will comment more on the wiring at the end of the post.

The next issue is getting the hot water to the evaporator, which is easy, just scoop tee off the OWB supply line and return it to the system. BUT, you must create a pressure differential so the hot water will flow to the evaporator at the dryer. All I did was cut the line from the OWB that brings the hot water in, put a Tee, then a valve that I slightly closed in order to create a pressure differential that forces the water into the Tee. There are probably better ways to do this, like a manifold, but this works for me. A picture explains it better:
View attachment 269055

The rest of the project is relays and wiring and I will try to explain.

I have 4 relays running this beast and it was a challenge, but we got it! Basically here is what happens: When my wife starts the dryer 2 events take place.

The 120 Volt drum motor hot wire was tapped so that when it is energized that electricity is sent to a 120 Volt AC relay that turns on the 12 Volt DC power supply that makes the Mercury Capri blower turn on. Got it? So the button is pushed and the blower blows!

The second event that happens is the Taco 009 pump in the OWB comes on to pump hot water to the evaporator.

I know what you're thinking . . . what happens when the OWB is out and you turn on the dryer? You don't want cold air being forced in! You are correct, so for that what I did was put a single pole switch on the hot wire for the signal that goes to the 120 Volt AC relay that turns on the 12 Volt DC power supply. If the OWB is out then she just flips that switch and turns off the signal to relay.

So what about that circulator pump? That too is on a relay, and the relay is connected to the same relay that is connected the 120 volt drum motor signal, so that when that switch on the front of the dryer that I put in is off then no power to any relay and no pump and no 12 Volt DC blower.

It does get a bit complicated because I only have one pump that is controlled by two appliances, the house furnace and the dryer. You have to try every combination to be sure you have set up right. What if there is a call from the dryer to turn on the circ. pump and then a few minutes later the thermostat calls for heat, and of course the circ. pump. which is already on. Test that situation.

What about when there the thermostat calls for circ. pump, then the dryer calls for circ. pump?

I had all kinds of crazy problems, like when the furnace came on and so did the 12 Volt DC blower! Or when the dryer came on first, then the furnace, the furnace would never shut off! It was pretty comical at times!!

Finally, my ultimate goal is to hook all this up to a PLC that will control EVERYTHING for me! And I mean EVERYTHING!! I want the PLC to take the OWB water temperature and decide whether or not to use the dryer in standard mode, or wood mode, it will also control my electric hot water tank, so that when the OWB temperature is sufficient enough it (the PLC) will turn off the hot water tank, open a valve and circulate the water through the OWB, or when the OWB tempertaure not high enough the PLC will turn on the hot water tank, close the valve and run it normal, until the OWB temperature rises! But that will be a while . . .

Yes it does take longer to dry the clothes, but I am saving about $45-$50 per month by not using the electric element!

Hope you all try this out because it is pretty fun!

 

[Stihl310]

Glad to see you got it all working, congrats. Now for the PLC!

 

[morewood]

I put mine in front of a kickspace heater I have and hang them on racks. Wife doesn't like them being stiff as a board. Your idea is pretty cool. Might have to give it some thoughts. I probably have most of that stuff. Thanks for all the details on the job you did.

Shea

 

[brenndatomu]

I put mine in front of a kickspace heater I have and hang them on racks. Wife doesn't like them being stiff as a board. Your idea is pretty cool. Might have to give it some thoughts. I probably have most of that stuff. Thanks for all the details on the job you did.

Shea

I think I remember reading that to much soap and not enough rinse causes SADC (stiff air dried clothes) I dunno, just sayin...

Do I win anything if I'm the first to post laundry tips on AS?!

Sweet mod there zeek!

 

[zeek]

Glad to see you got it all working, congrats. Now for the PLC!

Yeah, my buddy got that PLC we looked at and is tinkering. He has all the temp sensors I need for what I want to do, so now I just need to get him over here . .

 

[Stihl310]

If he needs a sample program to look at for reference let me know. Getting the BASIC and ladder logic to comm together can be tricky. You'll also need to download the free programming software from Comfile.

 

[zogger]

We use nuclear fusion here, delivered for free.

So do you, just yours works when it is raining out! Plus it took a lot of nerdish skillz!

Our electric dryer went out two years ago, hauled it to a shop, they went out of business and no dryer..hmm..had the outside line up, used it some of the time, told GF to just use that until I got another one, and...never needed the dryer. So didnt replace it. We just avoid doing laundry on rainy days, besides that, use it year round, even in the winter.

When I was growing up as a kid in the 50s, all my mom had was a wringer washer and the solar dryer, seemed to work. I remember helping quite a bit with that, being the oldest (along with every other household chore stuff). That freeze drying effect in the winter is a hoot.

I guess I dont mind the stiffer laundry, and I like the sun and air dried towels a lot.

 

[zeek]

We use nuclear fusion here, delivered for free.

So do you, just yours works when it is raining out! Plus it took a lot of nerdish skillz!

Our electric dryer went out two years ago, hauled it to a shop, they went out of business and no dryer..hmm..had the outside line up, used it some of the time, told GF to just use that until I got another one, and...never needed the dryer. So didnt replace it. We just avoid doing laundry on rainy days, besides that, use it year round, even in the winter.

When I was growing up as a kid in the 50s, all my mom had was a wringer washer and the solar dryer, seemed to work. I remember helping quite a bit with that, being the oldest (along with every other household chore stuff). That freeze drying effect in the winter is a hoot.

I guess I dont mind the stiffer laundry, and I like the sun and air dried towels a lot.

Well we also hang to dry when we can, but with 7 people in the house and being on a farm, we can really got through some laundry. In fact the clothes dryer is rather unique to the US, and if you go to other industrialized countries they do not have dryers. Even high rises in China hang to dry, but in the house!

 

[8433jeff]

Most dryers already have limit switches installed in them. The fancier the dryer, the more switches needed, for the different cycles. It should be possible to filter the incoming air to the dryer blower and use that to suck the warmed air in. IDK what your line temp is on your OWB, but doubt its hotter than the coolest dryer setting.

Of course, my days with appliance repairs ended a while ago. Good for you in trying it. Are you heating the water for the house also?

 

[zeek]

Most dryers already have limit switches installed in them. The fancier the dryer, the more switches needed, for the different cycles. It should be possible to filter the incoming air to the dryer blower and use that to suck the warmed air in. IDK what your line temp is on your OWB, but doubt its hotter than the coolest dryer setting.

Of course, my days with appliance repairs ended a while ago. Good for you in trying it. Are you heating the water for the house also?

My line temp is 185 and yes I am heating my domestic water with it too. But since I am forcing the air in with a fan it does pretty well, unlike the way it normally works. How hot does an electric element get?

 

[zogger]

Well we also hang to dry when we can, but with 7 people in the house and being on a farm, we can really got through some laundry. In fact the clothes dryer is rather unique to the US, and if you go to other industrialized countries they do not have dryers. Even high rises in China hang to dry, but in the house!

Oh, I think you did a fine job so far, and being a nerd I appreciate the skull sweat that went into your build. Our solar here is mostly passive, clothesline and greenhouse, but I do also have a small solar array with a charge controller and small battery bank. Thats about as sophisticated a gear as I have now, we just use an old room heater for wood heat right now, no OWB nor any other than a conventional electric water heater.

now I would like to have a kiln, solar powered and trashier wood chunks heated, that exhausted the warm moist air from the seasoning wood into the greenhouse at night during the winter. The exhaust/fan part could be solar PV powered if needs be, at least as a backup to grid powered. That would be a slick dual purpose unit. Heck, if it was large enough, put a clothesline in there!

 

[Fifelaker]

Had a furnace tech tell me it "won't work" Because it wont get hot enough. My thought was it cant get above 212* or the water will boil and the plastic fabrics will melt. So I built one been using it for 4 years now. Yes it takes a little longer but it will work. Unfortunatly he moved before I could show him how it wont work.

 

[8433jeff]

Had a furnace tech tell me it "won't work" Because it wont get hot enough. My thought was it cant get above 212* or the water will boil and the plastic fabrics will melt. So I built one been using it for 4 years now. Yes it takes a little longer but it will work. Unfortunatly he moved before I could show him how it wont work.

Yeah, does he think its gets warm enough outside for clothes to dry?

As to how hot an element gets, I don't know, but I do know they glow. An exchanger in the bottom of the dryer should work fine, as thats where the air entering the drum comes from. Forced air through the exchanger would speed the process, just like the normal way it operates.

 

[fubar2]

We use nuclear fusion here, delivered for free.

So do you, just yours works when it is raining out! Plus it took a lot of nerdish skillz!

Our electric dryer went out two years ago, hauled it to a shop, they went out of business and no dryer..hmm..had the outside line up, used it some of the time, told GF to just use that until I got another one, and...never needed the dryer. So didnt replace it. We just avoid doing laundry on rainy days, besides that, use it year round, even in the winter.

When I was growing up as a kid in the 50s, all my mom had was a wringer washer and the solar dryer, seemed to work. I remember helping quite a bit with that, being the oldest (along with every other household chore stuff). That freeze drying effect in the winter is a hoot.

I guess I dont mind the stiffer laundry, and I like the sun and air dried towels a lot.

Ah yes I remember the jeans you would carry over your shoulder like a 2x4 and break over a chair arm before you put them on.

 

[lfnh]

Hey zeek, nice solution and good writeup. Appreciate your sharing this.
If you don't mind, i'll save this offline for a rainy day.

btw, not sure this applies to all dryers, but seem to remember the heat source on was in part controlled by exhaust air temp sensor.

 

[rancher2]

Ah yes I remember the jeans you would carry over your shoulder like a 2x4 and break over a chair arm before you put them on.

When my mom died 10 years ago she still had the original electic dryier she had gotten with her first automatic washer in the late 60's. She had the money to run the drier. She just liked to hang clothes out. I remeber the freeze dryed jeans when I was a kid.

 

[Perk]

I use my OWB hot water loop to PREHEAT my electric dryer. I did a little sheet metal work on the dryer fresh air inlet to redirect the inlet air via a 4" (Same size as exhaust outlet) aluminum flex line. Used a 4" to 6" reducer and a 6" 12 X12 register boot with a 12 x 12 water to air heat exchanger. The dryer fan pulls the air through this arrangement just fine and if the stove is off, it doesn't care. I didn't want to restrict the water flow of the main hot water loop, so the dryer loop is not in series, it is a parallel flow. A small 120 V zone pump is wired to the dryers on/off switch and comes on with the dryer. I installed a swing gate check valve on the main loop between the inlet and outlet tees to avoid any crossflow. The outlet leg has a spring loaded check valve so that there is no flow in the dryer loop unless the dryer and the pump are on. I tried it with the dryer's heating element disconnected, and it dried the clothes, but it took a super long time. However, with the air being preheated into the dryer, the heating element cycle times are much reduced.

I already had the pump and the duct, so I've got about $75.00 in this. My wife refuses to use a clothesline, so maybe this will pay off some day. I don't really care, I just like the Idea of it.