efficiency gains in electric dryers?

[saichele]

Just moved to a new house in central PA, and the owner left a decent washer but an antique dryer - 1967. That said, it still runs, still dries.

So I'm wondering what real efficiency gains have been achieved in electric dryers? A resistance coil is a resistance coil, is it really worth laying out 400 bucks? There might be some nominal improvement in the motor/tumble mechanicals, but that's gotta be pretty small right?

Steve

 

[BrotherBart]

Yeah they are all about the same. The reason there aren't efficiency labels on the new ones like there are on clothes washers, dish washers and other stuff.

 

[pastera]

Newer dryer will dry faster because of better engineered air flow
HE washer helps a lot with the high speed spin cycle - clothes come out almost dry

 

[Grisu]

Still the most energy efficient dryer:

 

[BrotherBart]

Got one. It goes up in the stove room when the stove lights off for the season. It and the hanging clothes rack.

Funny part is that they were both new in the box laying in front of the box at the landfill one day when I took the trash to the dump.

 

[firefighterjake]

Newer dryer will dry faster because of better engineered air flow
HE washer helps a lot with the high speed spin cycle - clothes come out almost dry

In addition many new dryers can use sensors to control the length of drying . . . instead of just spinning around for a set period of time they can be set to turn off once they sense the clothes are dry.

 

[pastera]

Still the most energy efficient dryer:

Have a couple - one for the wood insert and a second for the pellet stove. Drying with them doesn't pump conditioned air outside and adds to the humidity.

If your clothes are stiff when air dried, you're putting too much soap in the washer (easy to do with a HE unit)

 

[mustash29]

If anything, that 1967 unit may be built better than today's stuff. I think my parents still have the same GE dryer from about the same era.

I am currently using a Wirlpool super capacity that I bought in late '94. Other than removing the back and cleaning out the blower fan a couple of times and installing a kill switch for the buzzer it has never needed anything. We use the dryer for nearly everything.

Oh yeah, the kill switch is labeled as "buzz" and "STFU"

 

[Highbeam]

The improvement is that modern dryers sense moisture and shut off when the clothes are dry. Old ones just used a timer.

 

[Swedishchef]

I agree with the engineered air flow improvement. Other than that and the moisture sensor, that's about it. I am not gonna pay $1200 for a dryer that can steam my clothes. When the warranty is up and it break, it is easier to pay for the $600 dryer to be replaced than some motherboard in the $1200. A friend of mine who is a technician said it best: "fancy washing machines: a drum holding up to 40 lbs of clothing, with water, spinning at 1000 RPM while controlled with electronic circuit boards, what can go wrong after 12 months?" I do understand that they have come a long way but I still find them pricey.

Andrew

 

[saichele]

Thanks. I'll probably just ride this out till it dies, then see if I can upgrade 20 or 30 yrs on Craigslist.

 

[drizler]

Keep the old one. You won't find anything that well built today. This guy above is a litttle trick I learned in Europe. Take your spin dried clothes for a ride in this puppy and you will wrangle out another quart or two out of it before you toss it in the dryer. I got the pic off Amazon while searching "clothes spiner". It's old school over there but pretty recent here. It will save you a lot of KWH on your electric bill and wear on your dryer.
Something to watch out for if you like to hang clothes in the basement is creating high humidity. With tight houses you can really dump a ton of moisture in the house. Not a problem if you are low to begin with but it can show up in rusted stuff in the house. We run a dehumidifier in the basement all year round and it really spikes when it's all closed up and towels are hanging.

 

[TMonter]

Thanks. I'll probably just ride this out till it dies, then see if I can upgrade 20 or 30 yrs on Craigslist.

Just a FYI, with Black Friday on the horizon in a couple months, it's a good way to pick up new appliances on the cheap. We bought a new dryer one year and a washer the next on Black Friday sales and paid half of retail. We're generally not big black friday people but if you can save 50% on major appliances that are starting to fail...

It's too bad Miele doesn't offer big discounts on Dishwashers, I had to pay damn near full price for ours earlier this year.

 

[velvetfoot]

I find it stupid to pay the same price for a dryer as for a washer. There seems to be a whole lot less that goes into a dryer, but they want identical prices for a matching set.

 

[pastera]

I buy my washers/dryers at the Sears Outlet (scratch and dent)
Less than half price and most are unused (dents/scratches from delivery)
I have septic so I wanted a HE washer to save on water output.

 

[Dune]

Old dryers were 5800 watts.
New dryers are 5000 watts.
The best thing you can do is replace the vent with 4" PVC. This will cut drying time.

 

[heat seeker]

As to sensors on older dryers:

My dryer came with the house, and I assume it's at least 15 years old or so. I have had to replace a few parts over the years, but it keeps running. A couple of months ago, one of the thermostats quit, so I had to replace it. I discovered, after studying the diagrams, that there is a "dryness" sensor of a sort. It uses a thermostat to monitor the exhaust air temperature. The timer motor does not run unless the outlet temp is above a certain temperature. As the clothes dry, the outlet temperature rises (due to less evaporation from the clothes), so the timer runs and eventually times out.

Not exactly high tech, but it seems to work.

The "time" option on the timer bypasses that thermostat, and simply times out whether the clothes are dry or not.

I suppose the newer dryers use more sophisticated methods, but this works just fine for me.

 

[TMonter]

Old dryers were 5800 watts.
New dryers are 5000 watts.
The best thing you can do is replace the vent with 4" PVC. This will cut drying time.

I wouldn't recommend that on an older dryer which can in some instances run higher temperatures than the new class of units. He'd likely be better off just using smooth aluminum or steel ducting and long radius elbows where appropriate.

Also, using PVC in many locations will violate building codes which means if you do have a fire there is a chance insurance wouldn't pay out. The additional pressure drop of steel/aluminum over PVC is going to be pretty negligible as long as you don't exceed 3 90 degree elbows which most dryer manuals call out anyways.

 

[Dune]

I wouldn't recommend that on an older dryer which can in some instances run higher temperatures than the new class of units. He'd likely be better off just using smooth aluminum or steel ducting and long radius elbows where appropriate.

Also, using PVC in many locations will violate building codes which means if you do have a fire there is a chance insurance wouldn't pay out. The additional pressure drop of steel/aluminum over PVC is going to be pretty negligible as long as you don't exceed 3 90 degree elbows which most dryer manuals call out anyways.

Steel ducting would work though not as well.
Clothing would catch fire long before PVC just so you know.

I have been using 4" PVC for 13 years. My brother is a master plumber and gas fitter, I am pretty sure he would have told me if it were illegal.

If one did choose metal duct, it would be far superior to only tape the joints together with metal tape than to screw them together since the screws will cause clogging points that will trap lint and that could cause a fire

 

[TMonter]

Steel ducting would work though not as well.
Clothing would catch fire long before PVC just so you know.

I have been using 4" PVC for 13 years. My brother is a master plumber and gas fitter, I am pretty sure he would have told me if it were illegal.

If one did choose metal duct, it would be far superior to only tape the joints together with metal tape than to screw them together since the screws will cause clogging points that will trap lint and that could cause a fire

The IBC says dryer installs require rigid metal duct.

M1502.5 Duct construction. Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

(broken link removed to http://www.iccsafe.org/iccforums/Pages/default.aspx?action=ViewPosts&fid=9&tid=4160)

Also PVC has static issues that causes the lint to stick to the surface which steel does not tend to do. (And PVC is only rated for up to 120F unless you are using CPVC which I believe is up to 230)

You are correct on the lack of screws, when assembling metal duct you should use metal tape or joint compound.

 

[Chimney Smoke]

As far as efficiency gains, a dryer is basically 0% efficient by design. It converts electricity to heat. As stated above, the most realistic differences are the humidity sensors and lower wattage of newer devices. Kind of like AC units. The old ones will turn your bedroom into a freezer but use 4x the electricity of a newer one that maintains the temperature you set. That being said, I have replaced a 30 year old dryer with a new cheap one and my electric bill dropped around $25/month.

 

[Dune]

The IBC says dryer installs require rigid metal duct.

M1502.5 Duct construction. Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

(broken link removed to http://www.iccsafe.org/iccforums/Pages/default.aspx?action=ViewPosts&fid=9&tid=4160)

Also PVC has static issues that causes the lint to stick to the surface which steel does not tend to do. (And PVC is only rated for up to 120F unless you are using CPVC which I believe is up to 230)

You are correct on the lack of screws, when assembling metal duct you should use metal tape or joint compound.

From your link (just to clarify, not being argumentative; I am an ardent supporter of building codes in general)
There is no way to properly transition to PVC, this is untrue. A 4" steel smoke pipe fits over the dryer outlet and into the PVC (as is legally required). I use 1 metal 90 then a 4 foot long piece of PVC. I routinely check the PVC and have never had any buildup (it is too smooth).

That being said however, I will change it to metal the next time I am in there, in accordance with my mantra, "leave nothing to chance". However since 1/16" is aprox. 16 gauge and smoke pipe is 26 or 30 gauge I will not be meeting that part of the code.

 

[semipro]

"Condensing" dryers may also be a more energy efficient option. Used much more in Europe, they use a heat exchanger in a closed cycle mode to dry clothes. They do heat the air in the room they are in but don't vent outside.
Some use tap tap water as the heat exchange medium, exhausting the heated water to a drain. These seem less common now though.

I've thought of using one of the air-based units in the area where my heat pump water heater is to try and recover the heat produced by the dryer for our DWH.

 

[jharkin]

"Condensing" dryers may also be a more energy efficient option. Used much more in Europe, they use a heat exchanger in a closed cycle mode to dry clothes. They do heat the air in the room they are in but don't vent outside.
Some use tap tap water as the heat exchange medium, exhausting the heated water to a drain. These seem less common now though.

I've thought of using one of the air-based units in the area where my heat pump water heater is to try and recover the heat produced by the dryer for our DWH.

This is a really cool idea. Its true that an electric dryer converts 100% of the electricity it consumes into heating the air - but a lot of that heat then just vents outside. In winter I wouldn't mind redirecting that waste heat into my cold basement... Or how about preheating the supply to the DHW tank?

 

[Chimney Smoke]

This is a really cool idea. Its true that an electric dryer converts 100% of the electricity it consumes into heating the air - but a lot of that heat then just vents outside. In winter I wouldn't mind redirecting that waste heat into my cold basement... Or how about preheating the supply to the DHW tank?

Unless you can separate the moisture out that's a bad idea. Moist air = mold.