Rewiring 240v to 120v Bosch dryer

[washingpowder]

Having moved to a new apartment I discovered it lacks of a 240v line, but there are 20A outlets available(they run separately). Bosch condenser dryer has two heaters, 700W and 2000W. According to its plate the max wattage is 2800.
It was used with a 3-prong cord (neutral to ground).
Would connecting those two hots together make it work on 120v?
Should the third wire be connected to neutral or ground?

 

[whirlcool]

Why not just rewire the outlet to give you 240V there? From what I have been told here before is it all can be done at the outlet without having to change anything in the circuit box.

 

[arbilab]

Let's assume the 2800W is both heaters plus the drum/blower motor (which may well be wrong, 100W seems skimpy for a fullsize dryer motor). On a US dryer, the motor would run from one leg to neutral, 120V. For a Bosch/Euro dryer? Or is this US Bosch? 2700W of heat also seems somewhat skimpy for a fullsize dryer. Or is it even fullsize?

However, if the 2700W of heating element is designed for 240V, resistance is fixed and half voltage equals half current, I-squared x R gives you 675W of heat. Not quite half a hair dryer. It definitely wouldn't exceed 20A, or the more conservative UL rating for single appliances at 120V on a 20A line, 1600W. But it would exceed your patience waiting for towels to dry. Roughly an hour and a half, depending upon humidity.

Running a (dedicated) 240V dryer on 120V may be possible but it's definitely not 'right'. This (government**) building runs 240V stoves on 218V*. 22V doesn't sound like that much is missing, but due to I-squared R above, it behaves as if 44V were missing, or 196V. You know how surface elements are supposed to light up on 'high'? Well they still do but you have to turn the room lights off to tell that they are 'lit up' at all.

(* 218V is a compromise between 120V to neutral in dual phase [normal household] power and 3-phase industrial power which produces 120V to neutral and 208V between 120* phases. They up the 120V to 125, and then the 208 comes out 218 (+5V on both phases). These are measured, not theoretical or imaginary values.)

(** Not only for the wonky power, but stay out of government institutional housing if at all possible. You wouldn't believe the smells. We're talking boiled pig intestines. If that doesn't sound bad enough, it smells worse.)

 

[foraloysius]

The question might be what voltage the motor is. If that's a 240V one, it's not possible.

 

[launderess]

Three Prong 220v Plug

Is what some European laundry appliances use here in the USA instead of the more common four prong American. European appliances that run on 208V-240v power use three prongs not the four we have here. Miele's washing machines and dryers required the four prong but that is also because they ran on 120v/220v, IIRC.

European dryers tend to run on lower wattages than what you'd find in the USA. My AEG is only 2735 watts, and some Miele dryers only ran on 2700 to 3000 watts.

To the OP's query you need a dedicated 220v line, not a 20amp/120v. However think your are wanting to run the power from two separate 120v outlets (that are out of sync) to get 220v. That may or may not work and could be dangerous over the long run.

If you own this apartment would probably be easier and safer to have an electrician take a look at the circuit panel box and see if a 220v outlet can be added. If so that seems a better option.

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www.diychatroom.com

 

[combo52]

240 Volt Bosch Condenser Dryer

If you have a dedicated 120 volt outlet you can have an electrician change a breaker in the panel to a two pole breaker and change the outlet, this will give you a 208 or 240 outlet to run the dryer [ there is NO 220 volt power in NY, or any where else in the US for that matter ]

If you could post a picture of the model# tag and rating plate from the dryer we can tell for sure.

Even if the dryer has a 120 volt motor and would run on 120 volts the heat output would be so low to make an already slow dryer almost useless, even if you only have 208 volts in your apartment the dryer will take 25% longer to dry than it would on 240 volts.

 

[foraloysius]

It would work out with a vented dryer perhaps, but with a condenser dryer you need a reasonable difference between the inner and the outer temperature, otherwise the condensing system will not work or work very inefficiently.

 

[launderess]

there is NO 220 volt power in NY, or any where else in the U

Really? Don't tell Bosch.

 

[washingpowder]

Thank you for your replies.
Unfortunately it's the only dryer possible to use due to lack of venting.
Long drying times don't make an issue, a separate spin dryer may also help with that.
Unfortunately I rent the apartment, and don't think rewiring anything would ever be possible.
Even if it would take 3h to dry a load of towels, it's still a much better option than laundromat(never), line drying or hanging exhaust duct out of the window.
Regarding the inner and outer temperatures, during the winter I got the marvelous idea to open the condenser chamber and let the warm, moist air into the room - and the dryer never got noticeably warmer. It seems the closed air circulation system doesn't need too much power. On the low-heat settings only the 2000W heater is used, and the glass door get painfully hot to touch after around 30 minutes.
Scan of wiring diagram attached. It seems the motor is connected to both hot wires.

 

[washingpowder]

And plate.

 

[launderess]

Can't Be Done I'm Afraid

Again unlike Miele dryers sold in the USA (120v/208v-240v), what you've got a hold of there requires pure 208v-240v power, that is nothing inside runs on 120v.

For the record have both condenser dryer and vented (older Whirlpool compact), and the latter beats the former IMHO in terms of performance. Vented dryers simply get the job done faster. With Con Edison seemingly have gone mad this winter with rates, has put me off the idea of running a dryer for two or more hours to dry a load that can be done in an hour or less.

At 2500w you are pushing slightly above the max draw of a 120v/20 amp circuit. Depending upon how touchy your circuit breakers are they may not like this.

 

[davetranter]

Transformer

Wouldn't a transformer be the best/easiest option?? No rewiring needed, and useable for any appliance!!

I have a nice 7.5kVA 110/120V - 220/240V dual primaries/secondaries.... four 30Amp windings... Transforms either way, or just provides isolation..... Built in the U.S.A. by Elgar/Onan.

Highly recommended

All best

Dave T

P.S. I just attemped to use a 'pointed' bracket (shift ',' and shift '.') at each end of the hyphen above, in order to emphasise the 'either-way' transformation capabilities, but the site would have none of it.... Is this a 'known' issue???

 

[warmsecondrinse]

Transformers?

I'd like to hear more about the transformer option. How would it work in that situation. I'm afraid I'd know very little about electricity.

Thanks,

Jim

 

[washingpowder]

I guess a transformer would work but either by limiting usage to 100W or having a 40amp line.
It's a longe shot, but since there are two separate 20amp 120v lines available, may it be split between two cords?

 

[launderess]

Transformer

Largest step-up/down transformers sold for domestic use that do not require hard wring are 5000 watts. A dryer pulling 2700watts is going to put a strain on all but the highest quality (all come from mostly Asia/China and are of varying quality). Many state up front that they aren't to be used for appliances that generate heat or cold such as dryers, ovens, etc...

Then there is the problem you cannot obtain more than 2400 watts from a 120v/20amp circuit. Drawing 2700 watts for this dryer is only slightly over that amount but depending upon how long the dryer is run (and more importantly how often and long the heaters are engaged), circuit breakers could trip or fuses blow. [this post was last edited: 3/2/2014-19:00]

 

[washingpowder]

The wattage would be limited to 2100 by using the 2000W heater only (low-temp deactivates the 700W).
In this case, should one cord be attached to ground and L1, and the other to L2?

 

[combo52]

240 Volt Bosch Condenser Dryer

Unfortunately your dryer has a 208-240 volt motor so you can not run it without using a transformer, which you may be able to do if you never use the full heater wattage.

Hi Launderess, there is NO 220 volt power in this country, other countries do have 220 volt power, you have taught me many things for which I am grateful and I know that you always strive for correctness and that is why I am making a point about voltages, when people start talking about 220 volt current it makes them look very misinformed, you quickly loose credibility among people that actually know something about home wiring systems.

 

[launderess]

@Combo

It's a cold Sunday and one is stuck indoors! Am just pulling your chain on this "220v" stuff because I *know* I can! *LOL*

 

[Chetlaham]

Are you sure the panel only has 120? Unless its a very, very old building its highly unlikely. Is there a dedicated AC outlet somewhere? Ant circuit you don't need?

 

 

Assuming the dryer is straight 240 and not slash 120/240 rated it can be done. I would say the amp draw is about 11.25 amps at those wattages, probably about 14 with the motor and everything. If its over 14 amps you will need 12 gauge wire and a 20 amp circuit.  

 

Anyways, all that would need to be done is moving the black and white wires to a double pole breaker. Your going to get 240 or more likely 208 since a lot of NY is fed from 3 phase networks.

 

Next step would be to add a NEMA 6-15 or 6-20 outlet for the dryer, and make sure no other outlets are on that circuit or there is zero chance of anything being plugged in if so. Your probably better off taking those out just in case.

 

I read that you renting so be careful, and of course before you do this run your findings by us.

 

Truth is without 208 or 240 the dryer will not work. If its slash rated it might since the heaters could just be dropped onto the 120 volt line and will run at 1/4 the power.

 

A transformer will be heavy and expensive in the hundreds of dollars range. And if your looking for 20 amps at 240 the transformer will need at least a 40 or 50amp breaker at 120 volts. Good chance you will not have wiring that thick in your apartment unless its feeding a range which would then mean you do have 208/240.  A transformer at that power will be very impractical and will cost the same of just getting a compact 120 volt whirlpool dryer.  

 

Only way to make this work would be the availability of 208 or 240 and some rewiring.