Water supply for a washer
April 3, 2016 10:39 PM   Subscribe

Can you help me with some DIY questions about installing a washing machine without a hookup?

[This is anonymous because it's an apartment and I'm a renter and blah blah blah.]

I've got a small portable washing machine. It's designed to be usable by hooking to a kitchen faucet, but the process is rather tedious and I'd like to try for a more permanent connection. I think I've got a route to the shutoff valve under the kitchen sink that will involve drilling only one or two small unobtrusive holes in some cabinet walls.

I need to go from a 3/8 compression fitting to a 3/4 hose thread on the back of the machine, over a distance of roughly 10 to 12 feet. I'd really like to use 3/8 PEX tubing, since it will fit through 1/2" holes which is the largest drill bit I have. I could get a larger drill bit if it's really necessary, but I'd like to keep the holes as small as possible.

I figure I'll start with a 3/8 tee adapter (like this one) to tap into the existing supply line of the sink. Then what? I need something to connect 3/8 PEX to a 3/8 compression fitting. I haven't been able to find an adapter for that. Or can I attach it directly using a nut and one of the sloped rings/ferrules? If so, where do I get that?

On the other end, I need a 90 degree elbow with a 3/8 barb on one end (or even a push-to-fit connector) and a 3/4 hose thread on the other. I've not been able to find this. Any links?

Everything that I've found seems to be oriented towards different use cases, such as installing PEX supply from scratch, not adapting. For example, the only PEX to compression adapters I can find are shutoff valves, and they're reducing, e.g. they take a 1/2 PEX and provide a 3/8 compression fitting. I don't want that. Also, I've found icemaker supply kits that almost seem to fit my needs, but they all use 1/4 tubing which seems small. Also, they have the compression fittings molded into the ends of the plastic, so you can't take off the nuts, which means the hole has to be even bigger.

If PEX doesn't work out then it seems I can use braided stainless supply lines, possibly joining two shorter ones together to make the required length. They seem much simpler to work with as they all come with compression fittings. Should I be doing that instead of PEX?

For complicated reasons I need to mail order everything, so please don't tell me to go to a local store and ask somebody. I need links to everything. Thanks.
posted by anonymous to Home & Garden (9 answers total)
You might want to try this hose from Fluidmaster. The one from here at Amazon may do the trick, if you got two and bolted them together.

Remember to use Teflon tape on the joints.

Maybe do a flow test to see if that water line will provide the flow the dishwasher requires.
posted by Marky at 1:20 AM on April 4, 2016

I'd like to start of by saying this is a bad idea: the potential costs are a lot bigger than the potential benefits plus you seem to be underestimating the skill level of this project... but sometimes a bad a idea is a good idea, so...

I need something to connect 3/8 PEX to a 3/8 compression fitting

you should be able to find a compression fitting to connect to pex. then you can connect the two 3/8 compression fittings with 3/8 flexible copper: you will need to get a little compression "jacket" for the compression fitting on the sink end.

I need a 90 degree elbow with a 3/8 barb on one end (or even a push-to-fit connector) and a 3/4 hose thread on the other.

i doubt this exists. also, you need to be careful, not every "3/4" connector has the same threading. you might be able to find a hose that goes from your "3/4" to "3/8" with or without that kind of adapter depending on the threading. i'm not sure without looking at a bunch of little brass parts and it may just not be possible the way you want to do it. honestly, you really might find that learning how to sweat copper makes this project a whole lot easier: you could just make a washer hook-up fed by a 3/8 connection.

also, do you actually have the tools to do pex plumbing? you can't just push the pex over a barb for residential water pressure.
posted by ennui.bz at 1:25 AM on April 4, 2016 [3 favorites]

I wouldn't use PEX in this situation. I'd just stay with the 3/8 and 3/4 compression fittings. You can find some pretty long washer supply hoses. Look in the dishwasher supply hose section also for various lengths.

The more connectors you have, the more places there are to leak so try to minimize the pieces.
posted by LoveHam at 4:40 AM on April 4, 2016 [1 favorite]

I have to agree with ennui.bz that you seem to be underestimating the skill level involved here. It's not that this has to be difficult, but water supply pipes are prone to causing huge amounts of damage if you screw up an assembly and something pops loose when you're not there.

As has been noted, PEX would complicate things unnecessarily. Go with the braided dishwasher-type supply lines. A new spade-type drill bit is cheap. Assuming your washer has a male hose thread inlet, you can use a dishwasher adapter like this to connect it directly to the braided line.
posted by jon1270 at 5:01 AM on April 4, 2016

This is a rental property, and you're proposing doing some pretty serious DIY plumbing. If this springs a leak while you're out, are you prepared to pay for potentially 1000's of dollars in water damage? Just keep doing the tedious thing where you uncoil the washer supply line and screw it to the sink faucet. No good can come of messing with plumbing you don't own in a property that you're inhabiting temporarily without the owner's explicit permission. This WILL bite you in the ass, either when it leaks, or when the owner discovers your unapproved plumbing job at moveout.
posted by cosmicbandito at 7:49 AM on April 4, 2016 [1 favorite]

Some of the adapters you're calling out probably don't exist, because there is so little call for them in normal circumstances. If you really want to use PEX you'll probably have to convert to pipe thread as an intermediate step, like 3/8 compression->3/8 MPT->3/8 PEX via adapters. Also, you might already know this but 3/4MPT and 3/4 garden hose are two different things - different thread pitch and one tapers, one doesn't. You can do this, but it will take an fugly string of adaptors. It might be easier to do it all in 3/8 copper and make the transition on the washer end, but even flexible copper is a bit dodgy for a portable appliance.
posted by werkzeuger at 9:37 AM on April 4, 2016

Several people have referenced dishwasher connections, but the info in your post sounds like a clothes washing machine. Which is it? And though you discuss supply line options, what about the drain/ outflow? Why make a more permanent connection for one without the other?
If this is actually a clothes washer, the flow rate of water a 1/4" or 3/8" line can deliver at any pressure may be a factor, and the rate of discharge from a full load. Both are much more than a dishwasher needs/ outputs.
posted by TDIpod at 12:39 PM on April 4, 2016

Yes I assumed clothes washer, that's why I referred to garden hoses - I think they use that connection for their inlets, not pipe thread. The OP refers to a "3/4 hose thread." I think we're talking about a clothes washing machine.
posted by werkzeuger at 6:48 PM on April 5, 2016

The OP refers to a "3/4 hose thread." I think we're talking about a clothes washing machine.

I assume the same. Some dishwashers use 3/4" garden hose threads too, so dishwasher hookup kits with adapters suitable to the OP's needs are commonly available.
posted by jon1270 at 4:31 AM on April 6, 2016

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