Domestic Plumbing - 5/8" fittings?

I'm a bit of a plumbing neophyte. I'm trying to add a by-pass to my water heater. It has plastic tubing with some odd fittings which use barbed ends with threaded nuts. I figure I would rip it all out and replace it with those easy to use "quick connect" fittings. Well... turns out my hose is 5/8" OD and seems most all fittings don't come in that size. I did see some fittings on West Marine's site that claim to be 5/8" OD. But they are made by Seatech and oddly enough, Seatech's web site doesn't show any 5/8" fittings. Any guidance on how best to proceed would be appreciated.

Pipe and tubing is measured by its ID not OD. The fittings on your water heater are 1/2" PEX. Any hardware store has them.


David

OD is on the fitting package

Thanks for the reply David. But the Watts quick connect fittings use OD on their packaging. I bought 1/2 OD tubing at Home Depot and 1/2" OD fittings. But the OD on my tubing is definitely 5/8". Seems everyone's fittings jump to 3/4".

Irrespective of tubing size and the quick connect fittings, let me challenge the premise of putting in valves, tees, etc to make winterizing the hot water heater easier. It will take an hour or so to install the fittings and they will cost ???

I just winterized my boat's potable water system and it has what looks like the same hot water heater plumbed with PEX fittings like yours. I just unscrewed the PEX nut on both the in and out connections to the water heater, slipped a 1/2" piece of clear plastic tubing over the end of the tubing barb, clamped it down with a 3/4" hose clamp and I was done. If you unscrew the joints between the elbow and the water heater inlet, you will have a PEX barb that you can slip the tubing over.

Took about three minutes and cost a couple of bucks for the 1/2" tubing.


Next year after flushing out the antifreeze, I will pull off the tubing and reconnect. Should take a couple of minutes.

David

Greetings,
Pipe is, as far as I know measured as to ID. Tubing on the other hand is measured as to OD. Copper is done this way. Plastic may be different.

That doesn't look like Pex to me.
This is Pex:

They both could be pex.....just different fittings.....the transparent pex looks just like my salt water system pex.

There are 2 way valves for just what you are looking to do. Many RV places sell them as older RVS were not set up that way but the newer ones often are.

My RV had a 2 way valve on the water heater and one at the water pump to select the water tank or a pigtail that you put in one gallon bottles of RV antifreeze. Flip 2 valves to bypass the water heater and that issue and use the fresh water pump to winterize the system. After winterizing hundreds of boats..,I never felt anything was easier.

In some ways, the RV industry makes the marine industry look like dolts.

JackD said:

It has plastic tubing with some odd fittings which use barbed ends with threaded nuts. I figure I would rip it all out and replace it with those easy to use "quick connect" fittings. Well... turns out my hose is 5/8" OD and seems most all fittings don't come in that size.

Click to expand...

The fittings in your pics are Flair-It fittings, available on line or at many RV stores.

See FLAIR-IT by THC for details...

I understand SharkBite metal fittings -- from Home Depot, etc. -- are also equally easy to use... and there's not necessarily a reason why all your fittings have to be the same product.

-Chris

djmarchand said:

Irrespective of tubing size and the quick connect fittings, let me challenge the premise of putting in valves, tees, etc to make winterizing the hot water heater easier. It will take an hour or so to install the fittings and they will cost ???

I just winterized my boat's potable water system and it has what looks like the same hot water heater plumbed with PEX fittings like yours. I just unscrewed the PEX nut on both the in and out connections to the water heater, slipped a 1/2" piece of clear plastic tubing over the end of the tubing barb, clamped it down with a 3/4" hose clamp and I was done. If you unscrew the joints between the elbow and the water heater inlet, you will have a PEX barb that you can slip the tubing over.

Took about three minutes and cost a couple of bucks for the 1/2" tubing.

Click to expand...

I don't even bother to do that. We have the same water heater as pictured (Atwood) and I mostly just drain it... draining being augmented with the air compressor via the whole freshwater system.

After using the compressor, I usually bump a little antifreeze through the freshwater strainer/pump/accumulator and some of that AF usually gets into the water heater tank too... but that's not entirely intentional.

Anyway, the Atwood manual says any residual water left in the tank won't harm anything if it freezes. And note, the drain is lower than the inlet/outlet fittings.

I leave a length of drain hose permanently attached to the spigot, and usually connect that to a longer hose I can use to actually drain the tank overboard... which in turn saves wet-vac'ing the bilge afterwards.

-Chris

I took a different approach on mine. Not better but I will share for an added choice. I unscrewed the fittings directly off the water heater, which left me two female threaded fittings. Home Depot sells a short 1/2 inch plastic pipe with threads on both ends with the sprinkler stuff that screwed onto both pipes to join them and bypass heater

Try this.
(Camco - RV Boat Quick Turn Permanent By-Pass Kit Plumbing Heater Element Motorhome).
It should hook up to your existing set up.

Camco

jskinner30PII said:

Try this.
(Camco - RV Boat Quick Turn Permanent By-Pass Kit Plumbing Heater Element Motorhome).
It should hook up to your existing set up.

Click to expand...

Yep! Have it sitting here on my desk. I guess the issue is more about trying to eliminate those odd fittings. Thanks to all!

I hate plastic fittings, it made everyone a plumber? Are you having an issue with the fittings leaking or do you just want to change them out? I havethe 1/2 pex, red and blue. I found over the years the plastic tubing becomespretty rigid, does not want to conform to a new angle or pitch . Not sure youcan get to all your fittings? The Shark bite fittings are expansive but arereusable and will work on any same OD dimension tubing. They are great if you want tojoin dissimilar metals and plastic. Sometimes a little heat helps when changing out plastic fittings and retaining the same pipe or tubing runs. You could go to Home depot and purchase the pex fittings and tubing or use what you have above.
Jeff.

Careful!?! The PEX on my 2005 MS34T is metric 15mmID. The threaded connections are 1/2". No shopping at Lowes for these.

Several plumber friends have warned me about Pex tubing from Home Depot. They raved about Pex, just buy it from a plumbing supply house for more predictable quality.

Jack, I was trying to figure out what the reading on your caliper in post three meant.
What the heck does E290 mean? Oh wait........never mind.

Actually that's pretty close to 15mm.

LongJohn said:

Careful!?! The PEX on my 2005 MS34T is metric 15mmID. The threaded connections are 1/2". No shopping at Lowes for these.

Click to expand...

Long John,

ID or OD? I'm starting to thinkmy 5/8" is really 15mm tubing. That is OD though.

OK, I give up. What does e290 mean??

E290

I think that was a joke. "E290" was the reading on my caliper. Upside down. In other words ".0623"

JackD, I'll have to look when I go back hopefully this weekend. I might have mis-remembered cuz I'm old. I remember solving the problem by removing the push-on PEX coupling, dropping a little glycerin on the PEX, heating a piece of nylon reinforced flex tubing and slipping it over the end of the pex. Double hose clamp. A barbed nipple on the other end of the flex tubing can connect to anything. My memory is that the flex was 3/4" ID.

Here are the dimensions of inch sized PEX tube.
PEX tubing technical specifications and general installation practices
Why don't you buy a 15 mm fitting and try it. I bet 15 mm PEX measures E290 OD.
I won't be back to my store until Monday or I'd go measure a piece for you.

ranger42c said:

The fittings in your pics are Flair-It fittings, available on line or at many RV stores.

See FLAIR-IT by THC for details...

I understand SharkBite metal fittings -- from Home Depot, etc. -- are also equally easy to use... and there's not necessarily a reason why all your fittings have to be the same product.

-Chris

Click to expand...

Jack, the clear/transparent PEX tubing Luhrs-related builders used is usually marked with color coded (red for hot, blue for cold, no surprises there) sizing info printed along the tubing somewhere. The whole boat will have the same stuff, so if tubing near the WH isn't marked, it'll likely be visible somewhere else, e.g., into and out of the freshwater pump, etc. (I think Lurhs Group builders switched to opaque red and blue PEX in more recent years, before the bankruptcy.)

I have the same WH and the same fittings as yours. Just checked my picture deck, but don't happen to have one with the sizing info visible; some of the other info is, but not the sizing.

That said (and from memory of our system), I'd bet your PEX tubing is marked as 1/2" (ID) and then the Flair-It fittings are sized to match.

-Chris

ranger42c said:

Jack, the clear/transparent PEX tubing Luhrs-related builders used is usually marked with color coded (red for hot, blue for cold, no surprises there) sizing info printed along the tubing somewhere. The whole boat will have the same stuff, so if tubing near the WH isn't marked, it'll likely be visible somewhere else, e.g., into and out of the freshwater pump, etc. (I think Lurhs Group builders switched to opaque red and blue PEX in more recent years, before the bankruptcy.)

I have the same WH and the same fittings as yours. Just checked my picture deck, but don't happen to have one with the sizing info visible; some of the other info is, but not the sizing.

That said (and from memory of our system), I'd bet your PEX tubing is marked as 1/2" (ID) and then the Flair-It fittings are sized to match.

-Chris

Click to expand...

Good bet, having worked with the pex on the newer Sea Rays....best way to ID what was probably used on that model and make versus some universal number that might not have been used.

Builders an be goofy from one build to the next....but usually consistent on a particular run.

close the loop

Well, just to close up this thread... If you recall, I have tubing that is 5/8" OD. We had debates about using ID or OD for various types of pipe/tubing. I bought 1/2" OD fittings at Home Depot, which of course did not fit. But they did not have any that were 5/8". I went to a large plumbing supply nearby and the guy there was of no help. I then went to West Marine, thinking perhaps this was a "marine" thing. I bought Whale fittings that said 15MM on them, thinking perhaps my 5/8" was indeed 15MM. But the fine print on the package also said 1/2". (How can 15MM (.59") be the same fitting as 1/2"?) They didn't work. Finally, the genius brother in law looks at it and says this is 1/2", goes to Lowes and hands me Blue Hawk fittings, marked as 1/2". Says they work with PEX, CPVC or copper. Fits like a glove.

Bottom line: Yes, these "push fittings" can make anyone a plumber, but the industry is doing its best to make it confusing for us laymen.

Jack,
The blue hawk and shark bite fittings are great, re-usable. I did double check of my tubing and it is Sea-tech. It looks identical to Pex with same OD. It maybe the same stuff just a different manufacture? From your picture it looks like your blue hawk fittings are plastic. They sell a similar blue hawk 1/2" OD fitting made of brass and plastic. A little expensive I have never seen 15 MM. That doesn't mean anything, plastic changed the plumbing industry forever. Now your faucets are plastic and not chrome plated brass or bronze.
I always identified pipe by OD, can't remember anyone identifying a pipe or fittings by ID?. The old saying was you can thread pipe not tubing.
Glad to see you found the fittings at the local Lowes or Home Depot.
Jeff.

Pipe Sizing Demystified

jskinner30PII said:

I always identified pipe by OD, can't remember anyone identifying a pipe or fittings by ID?. The old saying was you can thread pipe not tubing.

Click to expand...

HISTORY OF PIPING SIZE TERMS
Pipe sizes can be confusing because the terminology may relate to historical dimensions. For example, a half-inch iron pipe does not have any dimension that is a half inch.
Initially, a half inch pipe did have an inner diameter of 0.5 inches (13 mm)—but it also had thick walls. As technology improved, thinner walls became possible, but the outside diameter stayed the same so it could mate with existing older pipe, increasing the inner diameter beyond half an inch.
The history of copper pipe is similar. In the 1930s, the pipe was designated by its internal diameter and a 1⁄16-inch (1.6 mm) wall thickness. Consequently, a 1-inch (25 mm) copper pipe had a 1 1⁄8-inch (28.58 mm) outside diameter. The outside diameter was the important dimension for mating with fittings. The wall thickness on modern copper is usually thinner than 1⁄16 inches (1.6 mm), so the internal diameter is only "nominal" rather than a controlling dimension.[6] Newer pipe technologies sometimes adopted a sizing system as its own. PVC pipe uses the Nominal Pipe Size.

Pipe sizes are specified by a number of national and international standards, including API 5L, ANSI/ASME B36.10M and B36.19M in the US, BS 1600 and BS EN 10255 in the United Kingdom and Europe.

There are two common methods for designating pipe outside diameter (OD). The North American method is called NPS ("Nominal Pipe Size") and is based on inches (also frequently referred to as NB ("Nominal Bore")). The European version is called DN ("Diametre Nominal" / "Nominal Diameter") and is based on millimetres. Designating the outside diameter allows pipes of the same size to be fit together no matter what the wall thickness.

Thanks for the education Don. Seems that using OD for everything would make sense. But I surely could not find any 5/8" fittings.

Greetings,
Mr. JD. " Seems that using OD for everything would make sense." Well, yes and no. Pipe is measured and designated by ID whereas tubing is measured and sized by OD. So your water pipe may actually be water tubing. Throw in the SAE or metric system and...