Washer/Dryer Combo

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by nrc, Nov 3, 2008.

  1. nrc

    nrc New Member

    Messages:
    4
    I just purchased a washer dryer all in one unit (see link below) for my condo unit.

    http://www.lgwasherdryer.com/pdf/3431_spec_install.pdf

    It's drain hose is about 3/4" maybe 1". I would like to connect this drain hose to my kitchen sink. The sink has a disposal and a dishwasher w/ air gap.

    What are my options? Can I connect this machine directly to the dishwasher discharge line (downstream of the air gap)? Or does it require another air gap through my counter top?

    thanks for the help
  2. kingsotall

    kingsotall Plunger/TurdPuncher

    There is a certain amount of code for washers. The drain must have a standpipe of aleast 24 inches I believe and the standpipe must have a trap six inches off the floor.
    Even if you wanted to still hook it up to the disposer there would be too much water and it would start to come up through the sink.
  3. nrc

    nrc New Member

    Messages:
    4
    hmm

    so I shouldn't go with the handyman who wants to connect it directly under the sink.

    He didnt mention any of the stand pipe issues or trap or backflow, etc etc
  4. Terry

    Terry Administrator Staff Member

    Messages:
    14,994
    Location:
    Bothell, Washington
    You would need to access the wall plumbing and cut in a tee off of the 2" kitchen sink line.
    You will need the standpipe for it too.
    If you try to drain through the disposal, it will be all over the counter.

    [​IMG]
  5. nrc

    nrc New Member

    Messages:
    4
    thanks Terry and King.

    Just cause I'm a curious guy, is it because the sink line doesnt have enough capacity? If so, does it make a difference that this is a smaller unit (2.44 Cu.Ft Capacity).

    http://www.lgwasherdryer.com/combos/wm3431hw.htm
  6. Terry

    Terry Administrator Staff Member

    Messages:
    14,994
    Location:
    Bothell, Washington
    I've seen portable dishwashers drain into the kitchen sink before.

    I haven't seen on of these in use.
    From a plumbers standpoint, I would be hesitant to recommend it.
    I can see that if they have reduced the speed of the drain enough, it could work, but I may not be the right person to ask.

    I have added washer drains to some apartments turned condo, and the inspections have been interesting when you add the required plumbing for the washers.
  7. Nate R

    Nate R New Member

    Messages:
    472
    Location:
    Milwaukee, WI
    How much water does a dishwasher hold?

    I'm looking at an under the counter washer that uses only about 4 gallons of water at a time. It has similar draining options. They even recommend the possibility of using a dishwasher drain. 4 gallons of water? I'm sure a dishwasher uses a similar amount or more? And they don't end up on the counter.

    http://www.bshextranet.com/files/techtoolbox/WFL2090 INSTALL.pdf

    I think there may be an exception to be made as far as NEEDING 2" standpipes. These front loader, tiny capacity, very low water usage units just don't have much water to drain.

    A average dishwasher in 1978 used 11-15 gallons per cycle. Did they not drain the same way they do today - through a tap in the sink tailpiece? http://www.joe.org/joe/2003february/rb3.shtml

    So if this washer runs 2 rounds of water in a cycle, we're talking ~8-9 gallons in a sink drain. That doesn't seem crazy to me.
  8. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,347
    Location:
    Yakima WA
    I have heard that there are some small washers that use a very small amount of water and do not require the large drain that a regular sized machine needs. I do not know what drain requirements they have, so unless you can get some really knowledgeable help here, you might try the factory CS. Standard washers dump their water very rapidly which is why they need a 2" standpipe and drain.
  9. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    These new washers use a very small amount of water and the manufacturer shows in their instructions it draining to a sink with a dishwasher tailpiece.
    Under present codes that is not allowed but I believe you will see it in upcoming revisions.
    Last edited: Nov 4, 2008
  10. frenchie

    frenchie Jack of all trades

    It's not how much water, it's how fast it's getting pumped.

    I know this much - when you take one of those "portable" (on wheels) subcompact washing machines, the ones that hook to the kitchen tap with the 'quick connect' fitting, and the drain line hooks on the edge of your sink... when it drains, the flow is much faster than what a normal kitchen sink drain can handle. By the the the machine's done draining, and starts spinning, the sink's 3/4 full.

    So, it seems to me, if you hooked up a washing machine to the typical dishwasher connection, your sink would backfill every time...

    Except the side-arm connection on a dishwasher sink pipe, is way smaller than than the drain. The flow would constrict, something terrible, and it's not like there's a sink, up-flow, to temporarily hold it...

    So I think when your machine tried to drain, it's either blow the drainpipe off, or the back-pressure'd kill the pump; or you'd kill the motor, trying to spin when the machine's still mostly full of water.

    Anyone know if there's data avaible on the flow rate? Wouldn't be that hard to crunch the numbers.
  11. nrc

    nrc New Member

    Messages:
    4
    I'm really appreciative of how helpful and open minded everyone on here has been.

    I'm going to contact the CS line tomorrow, but my guess is that they dont want the liability and that is why they dont give detailed instructions in the manual. But I'll let you know.
  12. Nate R

    Nate R New Member

    Messages:
    472
    Location:
    Milwaukee, WI
    But the washing machine hose on these small machines is about the same size as the dishwasher tailpiece. It's not much of a restriction at all compared to the line that hooks into it. Again, we're talking about less water than a dishwasher uses.

    I have not seen and can't seem to find data on flow rates for small washers. But when I see that Bosch recommends a dishwasher tailpiece as an option, I'd think that it would at least usually work. (IE: the pump isn't that fast.) They could very easily say that a standpipe is recommended over any other option, etc. But instead leave several options.

    I would assume also that the flow rate would be low enough for this to work as these smaller machines aren't really competing on cycle time, etc of the bigger machines. So they don't need to drain as fast as possible. (In fact, a complaint some have about the smaller machines is long cycle times.)

    Did a little research. Found that for normal to large size washing machines, the fastest pumpers have flow rates of 17-21 GPM!

    [​IMG]
    According to what I've found, a 2" trap fixture could be up to 22 GPM. Which is what I'm assuming the washer manufacturers are working off of. (They assume a perfect system for the highest flow washers, I guess.)

    So I'm assuming that chart is then correct, since I haven't heard stories around here of properly plumbed 2" washer lines overflowing.
    So, 1 1/2" drain should be able to handle 15 GPM. If that is true, then the 4.4 gallon discharge from the Bosch I'm looking at would need to take at least 18 seconds to not back up into the sink. I don't own it yet, so I don't know if that's true or not.

    Either way, clothes washers used to only need a 1.5" line for full sized units, correct? In fact, in WI (I know, we're not a good example at all) it's still code for a 1.5" standpipe for a clothes washer. And clothes washers used to hold a LOT more water than the 4.4 gallons I'm talking about draining through a 1.5" drain.

    Will be interesting to see if codes do change to reflect the increasing usage of low water usage machines like this as Redwood mentioned.
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