plumbing a steam oven

efsDecember 4, 2011

I need to design plumbing that will go behind cabinets for a plumbed steam oven, which I dot not have yet and will nto have during cabinets' installation (I hope to purchase the combi oven from Miele that is suppose to come to US market next year so I have no instructions for it yet). I looked into the instructions from UK and the ones for Gaggenau combi oven, but I have the following questions:

Do I need to have a P-trap on the waste line or may I use a waterless trap ?

Can I simply drain it into my basement laundry sink similarly as my washing machine drains into it? If so, what is the longest run such drainage arangement can have (I need ~ 20 feet to get to the sink).

I am in Connecticut.

Here is a link that might be useful: waterless trap

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The discharge line from a steam oven MAY NOT be directly connected to the DWV piping. The oven is required to have an Indirect Waste, which means the line must drain into a sink or floor drain, and the lowest portion of the drain line from the oven Must Be a minumum of 2" above the flood level rim of the recepter.

And there shall be no trap on the discharge line from the oven.

    Bookmark   December 4, 2011 at 8:57AM
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thank you- is there a limit on the length of the pipe that runs from the oven before the airgap? The waste line from the oven itself is 10 feet, but I need >20 feet to drain straight to laundry sink in the basement.

    Bookmark   December 4, 2011 at 1:36PM
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I am not aware of any limit, providing that all the horizontal run is pitched with a 1/4" per ft pitch however, you will have to use copper or iron pipe to make the line because the discharge temp of the water from the oven exceeds the maximum temperature rating for PVC or ABS

    Bookmark   December 4, 2011 at 5:52PM
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thank you so much....

    Bookmark   December 4, 2011 at 6:18PM
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"Do I need to have a P-trap on the waste line or may I use a waterless trap ? "

Items listed for use in "RV's and boats" are not typically allowed in houses under the plumbing code.

Valve type devices have a nasty habit of failing to close when debris builds up on them, even soap scum.

Use in foreign countries is not a good indicator.

    Bookmark   December 5, 2011 at 9:57AM
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Will iron be less expensive than copper?

I was told copper only, but I am guessing it may cost me a fortune to run 24 ft copper at 1.5 inch drain. Any idea what is the cost I am looking at?

    Bookmark   December 12, 2011 at 2:41PM
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I have gotten more info (once I looked up pricing for copper pipes I got desperate and called Miele in Germany).

The water will be discharged at 70 Celsius, (which is 158 F)- can this go into a plastic drain pipe? If yes, which one exactly: ABS or PVC?

The more detailed manual I finally gotten today states: Water hose data
Stainless steel inlet hose
length 1,500 mm (1.5m) (diameter sign: "crossed over O" 12.5 mm )
Connection to stopcock / connection to appliance each
33.5 mm (~ 1.5 inch)
Plastic drain hose:
length 3,000 mm (3.0 m) diameter: 12.5 mm (a bit short of 1/2 inch)
Connection to odour trap / connection to appliance 15 mm (0.6 inches)

When laying the water pipes in ducting, we recommend a
minimum inner ducting diameter of 50 mm (2 inches).

Connecting the drainage hose:
Connect the drain hose to the odour trap using the hose
connector (diameter 21 mm).
Secure the hose using a hose clip.

Am I reading this correctly that I need a 2 inch plastic drain pipe to connect to a waste hose of the appliance?

US code stipulates indirect drain for steam oven, which I can accomplish, but 24 ft of copper? Do I really need copper?

    Bookmark   December 12, 2011 at 6:21PM
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The max temp for PVC is 140 F.

The max temp for CPVC is 200 F - but CPVC isn't normally used for DWV applications.

Lazypup, what would code say about using CPVC for a drain in this application? Are there CPVC DWV fittings available?

    Bookmark   December 13, 2011 at 8:16AM
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as a side question: my cloth washing machine uses water at ~158F (70 C) when I run sanitary cycle (with the heater from the washer additionally heating the "hot" water suppplied) - would that be problematic with the black drains that I have installed in the laundry room as well?

    Bookmark   December 13, 2011 at 8:56AM
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CPVC is not approved for DWV and the maximum working temp for PVC is 73degF

    Bookmark   December 13, 2011 at 9:49AM
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I should know better than to question Lazypup... but it looks to me that the rating for PVC is at 73 deg F while the max service temp is 140. Anything above 73 deg and the pipe has to be de-rated for pressure and spans between supports.

efs, I think the answer to your question is this:
If you want to be completely to code, do the drain in copper or galv. It will be crazy expensive, but there you are.

If it's unlikely to be thoroughly inspected, do it in PVC. It's going to work fine, but if the inspector really digs into the job, he could raise a red flag.

CPVC is sometimes used in lab drains to handle corrosive chemicals. There are DWV fittings available, but are very limited in supply and are hard to get. Even so, an inspector probably wouldn't approve it.

    Bookmark   December 13, 2011 at 10:49AM
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I will agree that 2" types K,L or even M copper could prove rather expensive, but if you use thinwall DWV grade copper it should prove affordable.

I doubt that you will find thinwall DWV copper in a homesupply such as Lowes or HD, but if you contact a commercial plumbing supply or if you talk to the proprietor at your local ACE or True Value hardware stores they can get if for you, and although it is more than PVC, it is still affordable.

    Bookmark   December 13, 2011 at 11:39AM
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    Bookmark   December 13, 2011 at 3:00PM
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