Hello all,
What steps should I take in replacing the hot water supply line? (see pictures below)

It's a gas water heater. The existing hot supply line is 1/2" and I want to replace it with 3/4".

Appreciate your feedback,
DK

Can I simply unthread the existing union and replace it with the union I am holding in the picture?
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What is that branch on the existing line....is it some sort of old hammer arrester?

 

What you are holding in your hand is not a union - it is an adapter, treaded female NPT x soldered connection. That fitting has to be unsoldered or cut and replaced.

There is a union in the photo - about eight inches below your hand. That can be loosened, and the threaded nipple above it untreaded. Then it's soldering from there on up.

 

Thanks for the clarification Mike.

Just want to make sure I understand.
I can replace the existing line by untreading the nipple that joins the union (which is almost right on top of the water heater)

If that's the case, I suppose I can just by a new nipple and solder the new adapter and 3/4" pipe ahead of time. Then I can tread the new nipple into the existing union.

(I'm new at this...can you tell)

 

Not sure I understand why you would replace the nipple? If a union ain't leaking, leave it alone!

Make sure you use TWO wrenches when you remove the existing threaded adapter... don't stress the connection at the water heater!

Just remove the 1/2" piping, thread on the new adapter and go up from there...

 

Are you intending to replace the existing threaded nipple between the union and the adapter? I guess that would be OK, but why not reuse it?

I'm wondering what you are trying to accomplish? Is pressure drop to high? Are you just wanting to replace that little 3" (or so) stub above the adapter fitting? Or something more?

If you're just wanting to replace that little 3" stub with a larger pipe, I doubt that will reduce the pressure drop noticeably. Pressure drop is proportional to the length of the pipe, so up-sizing a 3" segment won't do much if anything. In any case, you'll have to replace the tee above the 3" stub, which involves breaking additional connections.

If I were going to the trouble of ripping into the piping, I would think about replacing the two existing unions with dielectric unions (for galvanic corrosion prevention) and adding isolation ball valves in the inlet and outlet of the hot-water heater. That will allow servicing or replacing the tank without shutting off the water for the whole house.

 

I am adding a new bathroom group in the basement plus a utility sink. Most plumbers say 3/4" should be the standard.

I may have misunderstood your reply earlier. Sounds like I can just remove the existing 1/2" adapter and replace it with the 3/4" in the picture.

I bet this thing will be a bear to get off.

 

I'm still unsure what you are attempting to do. How much 1/2" pipe are you wanting to replace? If it's just that 3" stub, forget it - it's meaningless, despite what you report "most plumbers say."

No, you can't just replace the 1/2" adapter with a 3/4" adapter. What about the tee above (downstream) of that?

When you say that "this thing will be a bear to get off," are you talking about the soldered joint of the adapter? One minute with a hacksaw, or one minute with a torch.

I sense that you are inexperienced with soldered copper piping. I would advise you to think again before continuing. Either call a plumber, or just forget the whole project (my choice).

 

I'm not sure what is hard to understand about what he wants to do. I think the title of the thread says it all. He also said he is adding a bathroom in the basement and wants to increase his hot water supply to 3/4".

That adapter shouldn't be too hard to get off. Make sure you use thread sealant like pipe dope or teflon tape when you thread the new one on. Then just sweat everything together from there.

 

Right on drooplug. Thanks for your reply!

 

What Mike is asking is a worthwhile question though...

How much 1/2" are you planning to replace? If it is just a few feet, then I'm with him, don't bother... if you intend to rip out and supply all the baths including the new one, then you might gain from the larger pipe size... you certainly won't need more than 1/2" pipe feeding the individual fixtures though... running 3/4 to the new bath, then branching to the fixtures with 1/2 will be fine.

Is the cold side supply to the heater 3/4" all the way back to the main line? If not, then again, it will be a pointless endeavor, because you will have pressure drop there also.

Again, Mike's point is that there is no point unless there are long runs of 1/2" feeding the hot to all the fixtures in the home...

One other thing... Code Enforcement... you might have to do it just to make them happy.

P.S. you asked about that 'thing' on the branch... is it just hanging there? the pic cuts off the left side of it... does it go anywhere?

By the way, this post is kinda off-topic here... this is a forum for boilers and such... these questions are better asked in the general 'Plumbing' forum...

 

Hi NJ,
I will be running 3/4 to the new bath group and branching 1/2 to the fixtures. I'm not sure where the idea came that I just wanted to replace a few inches with 3/4....yes of course that would be pointless. I probably should have been more clear in my post saying something like, "help replacing ALL of the existing 1/2 to 3/4."

The cold supply is 3/4 from the main to the water heater.

The branch on the existing line does end right there. I thought it might be some sort of hammer arrester..I don't know.

Thank you NJ for pointing out that I posted this in the wrong forum. It should be in "Water Heaters" right below 'Toilet, Sinks, Showers etc....'

I appreciate everyone sharing their knowledge.

 

I would actually think that 'general plumbing' might have been a better choice, since it doesn't directly deal with the water heater itself, but it's a moot point anyhow.

That device could be some sort of hammer arrester... or possibly some weird pressure relief? Is the port on the bottom threaded? I wouldn't mind seeing a closer pic of it, for curiousity sake. Any manf name or model # on it?

 

No model #.
The mfg is Watts Regulator Company our of Lawrence, Mass.
(It ends right where you see it. It doesn't go through the wall. Sometimes the angle of pictures can be a little misleading.)

 

What's in the envelope attached to the pipe close by? Maybe it's something to do with the fixture in the picture. Is that a threaded opening pointing down? It kinda looks like a fill valve oriented the wrong way. Maybe a pressure relief valve oriented the wrong way.

 

What's on the 'top' of the bell shape? an adjustment?

I'm gonna go with it's a pressure relief valve...

 

yes, the threaded opening is down.



this is what is in the envelope




I have a few follow-up concerns/questions. (This thread should probably be moved but I don't know how to do that.)

If I replace the 1/2 line with 3/4, do I need to add some sort of pressure relief valve?

The water heater is 22 or 23 years old (It's a Reliance). I know I "should" get a new one because of the age, but we haven't had any problems with this one. I don't have the money to replace a new one...unless I put it on credit.


Maybe I should just scratch replacing the 3/4" line and do that when I get a new water heater. In the meantime, I suppose I can just use 1/2" on the new fixtures. I guess I am getting cold feet because a lot of "pros" say the life expectancy of water heaters are about 20 years.

Anybody have any thoughts on the age of this brand, as well as my dilemma?

 

Yeah, that's an antique temperature relief valve. Might also be a pressure relief too... and you can just dispose of it when you re-do the piping. For one thing, out on the end of the pipe like that, it's never going to sense the temperature properly anyhow, and (see below) you've already got a proper valve on the water heater.

No... there's a temperature/pressure relief valve on the side of the water heater itself... nothing more needed.

I'd say it's going on borrowed time... usually the failure is that the tank begins to leak... so keep your eyes open for dampness under the unit. Most of the time they won't allasudden bust open and flood the basement (they can, but it's kinda rare)... but instead will leak slowly... then more, then more, etc...

I would pipe the new bathroom properly... use the 3/4" all the way back to where it ties in. If it's a short run from there back to the water heater, might as well replace that section as well. The rest of the house you can do later if you wish, but there's no sense in not doing the 'new work' properly.

One thing that you do want to do when you re-pipe is to provide a 'heat trap', as this will prevent the hot water from migrating up the pipe by 'gravity' or 'thermo-siphon'...


photo courtesy comfort-calc.net

By going down, then up again, the hot water can't migrate.

I had a Reliance electric model here that I replaced at 25 years old, and it hadn't started leaking yet...

 

Just curious, should'nt the flu be pitched up a little, sorry if it was already mentioned, and I did not see it.
Sid

 

Sid, you reminded me that I wanted to mention something about that flue pipe arrangement! thanks...

I think the way this is set up is that the boiler flue is coming in from the right side, into that larger diameter " Y " connector, and that's what's stuck in the chimney hole... if it is what I think I see, I'm not too awful crazy about it being vented that way... in fact, I'm not even sure it's 'to code' ? but I ain't real hip on fire codes and such, so I don't know for sure... all I know is that it looks uhhhh... troublesome to me.

 

Can't speak to the codes (which can vary from place to place, including where I live which has NO building codes). But here in natural-gas country, it is very, very common, even in new construction, to vent the water heater and the furnace into the same flue. That will require some sort of wye or tee.

But, as always, a CO2 detector would be most desirable!

 

Thanks for recommending a heat trap. That makes a lot of sense. I'll be sure to keep the Reliance brand in mind when I have to replace it.

 

Take it for what it's worth, but internet search on the brand indicate that there may in fact be a problem with pilot lights staying lit... I would guess that if there were a problem, it would have been addressed by now, most of the complaints seem to be about models that were sold in 2008 or so.

The fact that we've both gotten over 20 years out of ours does speak well to the quality of the tanks on the OLDER models though, but who knows now?

By the way, most water heaters sold today have 6, 9, or 12 year warranites... Reliance does sell a model with a lifetime warranty.

Many of the water heaters sold today are actually made by the same manufacturer... and branded with different names.

 

When you do decide to replace the water heater, the biggest chore might be getting the limed-up old one out of the basement. Two men and a 2-wheeled dolly should do it. Or, you could try cutting the tank in two with a sawzall and take up half at a time.

I notice from one of the photos that you have cedar subflooring - nice.