Time for a new HWT, looking for advice to make sure I get it right

[lead11]

Hi, new here. I'm looking for advice to make sure when I do a HWT swap later this week I get it done right.

Our HWT is nearing double its life expectancy and lately we've noticed it runs just slightly cooler a little quicker, and then possibly as a warning before giving out the humidifier valve seal sprung a leak. The valve is a bit of a hack job, installed on the hot side, it is a needle valve into a mounting bracket with a rubber gasket that mounts into a hole drilled in the copper pipe. It is just a pressure fit, the valve doesn't actually seat, close or isolate anything, it's a stupid way to do things in my opinion. It was slowly leaking this morning and I noticed a puddle and some soaked insulation in the HWT. Took it off, cleaned the copper pipe surface and reinstalled it, seems good for now.

Anyways. I need to replace this HWT unit with something similar, maybe go 10 gallons more but stay with this setup to avoid upgrading things like the hi efficiency exhaust and intake piping job, along with the coring that is bound to be necessary. Home Depot has this in stock so I think it should be a near direct replacement, except the 38K to 40K BTU jump, hopefully the existing 1/2" gas line feed and the 3" exhaust flue is enough for this unit.

https://www.homedepot.ca/product/rh...uZ0ofFWMGBUkD5m4lfhoCzm4QAvD_BwE&gclsrc=aw.ds
In case the link doesn't work it is a Rheem Performance Platinum 50 Gallon (189L) 12 Year 40,000 BTU Tank Gas Powered Damper Water Heater

My reason for posting is questions on best practices and any local code (Alberta, Canada) for installing something like this. Perhaps unions and ball valves all around, hot and cold side? Changes to something to make it better, or last longer, or make it easier to service, etc. Any helpful suggestions are welcome.

First picture is the stupid humidifier feed valve and then some pictures of the rest of the setup.

Thanks in advance

 

[Twowaxhack]

You don’t need a power vent water heater .

Replace that needle valve ASAP. Cut a tee in and install a ballvalve.

The gas pipe size should be fine if it’s working now.

Connect the new water heater just like you see the old one.

 

[Twowaxhack]

Your current water heater was manufactured in October of 1999.

 

[lead11]

Thanks for the replies!

You don’t need a power vent water heater .

Replace that needle valve ASAP. Cut a tee in and install a ballvalve.

The gas pipe size should be fine if it’s working now.

Connect the new water heater just like you see the old one.

By power vent, do you mean the high efficiency types with the extra doodad piping for the intake and exhaust? If so, I agree, I don't need one of those. Just replace, like for like, with a 20 year updated unit.

Regarding the needle valve, absolutely I'm going to put a tee and proper valve in. Quick question, if this is the feed for the humidifier on the forced air furnace, should it be coming off the hot or cold side?

I'm good on gas. Great.

In terms or reinstall, any benefit to having unions or ball valves on both the hot and cold side? Or just valve on the cold, as currently is, and solder the tank in place?

Your current water heater was manufactured in October of 1999.

Yea, I did a little serial number dating around Christmas and thought this would be the year we replace it. How long do these units usually last?

 

[MicEd69]

Are you missing a dielectric fitting in the hot water line?

 

[lead11]

Are you missing a dielectric fitting in the hot water line?

Yup, just double checked, yes I am.

My guess is someone replaced that 24" chunk of pipe on the hot side for some reason, possibly when the furnace was updated. The pipe is newer compared to the rest and poorly soldered, I'm guessing it was a quick fix at the end. They missed a few things.

 

[Twowaxhack]

There are dielectric nipples in the inlets. You also have a dielectric union on the cold. A union is not typically required, I don’t use them, some people do. I believe they used a brass female adapter on the hot side.

Your link was to a power damper water heater. I originally thought it was power vent.

I do not install a ballvalve on the hot side, most people don’t. For the cost there’s not enough benefit, if any at all. The cold valve turns the hot water off.

Consult your owners manual but most equipment would use cold water.

 

[MicEd69]

Dielectric unions work very well at stopping current flow caused by dissimilar metals in plumbing systems. The electrolyte (the water) provides a small looping electrical path through the two joined dissimilar metals. This small electrical current eventually consumes the lesser noble metal, steel, when connected to a copper line. The dielectric union provides a complete isolation between the dissimilar metals thus better protecting the pipes from galvanic corrosion. However, the corrosion will still occur, but at a MUCH lower rate as the two dissimilar metals are totally insulated from each other by the union.

On the other hand, dielectric nipples are just about worthless because they do not electrically isolate the two dissimilar metals, Therefore, they do not break the electrical circuit. The only thing that they do is offer a slightly longer circuit path through the water which probably slows the galvanic corrosion a bit, but nothing like the total isolation of a dielectric union.

 

[Twowaxhack]

The water plays a huge role in the rate of corrosion. The bungs are the thickest part of the water heater so it’s usually not a factor unless the water is highly reactive. The tank craps out somewhere else.

Rheem engineers went over this extensively with data from failures all over the country. They use to give tours to professionals and teach you about every aspect of a tank water heater.

 

[MicEd69]

Yes, the bungs are the thickest part of the water heater, and the water heater does fail at a thinner/weaker point.

I was simply describing the process of galvanic corrosion. Unless the dissimilar metals are electrically isolated from each other, galvanic corrosion will be accelerated, as in the case of the dielectric nipples. Not only is this theory, but absolute fact.

Now looking at failures across the country is great, but not knowing the actual geometry of the system, the water quality, any preventative maintenance performed at a location, engineering analysis of the actual failure of each water heater in the study, etc., all you have is listing of failed water heaters. With various plumbers and DIYers performing installations, any data collected without the details above could not be considered scientific, but rather anecdotal at best. However, it could be somewhat useful, just not something any engineer would take as gospel. It would be much better to use the absolute knowledge of how galvanic corrosion works and use those facts for a proper installation.

 

[Twowaxhack]

Separation is the answer but your conducting through the fluid, which is water. How much separation is dictated by the conductivity of the fluid.

That conductivity varies as the water composition varies.

So is 2” enough ? 7” 8” ?

That’s what the engineers at Rheem said.

 

[Twowaxhack]

I’ve had good luck in my area with 3/4” x 6” brass nipples into the tank. But only a few people are willing to pay for that.

The nipples that come with water heaters are junk. They’re thin like conduit, plastic lined.

Most every dielectric union I’ve every found on a water heater is leaking or has leaked. They’re just garbage so we don’t use them.

Just like this example.
https://homeinspectiongeeks.com/why-dielectric-unions-are-common-failure-points-in-water-heaters/

 

[MicEd69]

From the article:

"A dielectric union is a plumbing fitting that is meant to join two dissimilar metal pipes so they don’t experience a galvanic reaction and begin to rust."

"We find many dielectric unions that have started to rust which will eventually lead to a water leak if not remedied. So why does this happen...?"

"If the union is not installed correctly, then it won’t protect against galvanic corrosion. ... Often the issue is that these fittings are not perfectly installed and some small contact is made. Additionally, if you use a union with a short sleeve, then that can be an issue as well."

Again, engineering wise, a properly installed Dielectric Union is way superior over a Dielectric Nipple.

And as I said in my first post, "However, the corrosion will still occur, but at a MUCH lower rate as the two dissimilar metals are totally insulated from each other by the union." So, it is not at all surprising that most every dielectric union you’ve every found on a water heater is leaking or has leaked.

 

[Twowaxhack]

I’d rather use a brass, bronze or even a stainless nipple. 6” or longer. The longer the more protection you’ll have. If it’s an electric heater IMO the best connection method is pex with bronze fittings, brass or stainless fittings. Some codes will disagree.

Those plastic lined nipples are the weak link and so are the typical dielectric union. It’s a cheaper solution compared to mine but it’s also inferior. What I’ve seen in the field backs it up. The dielectric unions leak before the heater and are sacrificed……that’s why they turn into a ball of rust. The inside also fills with corrosion, that’s not from improper install.

 

[hdtvkeith]

I had a GE (made by Rheem) unit from Home Depot that leaked bad 7 years ago. I had always used AO Smith before and immediately went back to AO Smith, never had an issue with AO Smith, even though I know they are not the same as they were years ago. HD Pro rated the warranty and gave me refund for that amount since I di not buy the replacement from them. Brandford White is an excellent brand, but I hear they tent to have burner issues occasionally.

Also not sur what cd is up there, but check your expansion tank if you have one or maybe you need one.

 

[Twowaxhack]

If you look inside the fitting there’s only the thickness of the sealing gasket of separation between the copper pipe that’s inserted into the brass half of the union.

That’s not far enough to stop the corrosion with some if not most water chemistries.

Any dummy can see how to install it.

 

[MicEd69]

A dielectric union reduces the rate of galvanic corrosion by electrically insulating two dissimilar metals from each other. Water quality and eventual mineral deposits will determine the rate at which the corrosion ultimately occurs.

Dielectric nipples do not insulate the dissimilar metals at all. As they provide an electrical connection between the dissimilar metals, their method of reducing the rate of galvanic corrosion is simply by increasing the distance between the two dissimilar metals by lining a nipple with plastic.

Note that both devices will still result in galvanic corrosion.

While it is a great idea to perform routine maintenance on your water heater, like draining it yearly and replacing the anode at some interval, most people do not do that. Several posts on this site even perform a vinegar flush of their water heater. So, if one does go through all that, adding another step of unscrewing the dielectric unions, cleaning any mineral deposits from the internal of the line, replacing the internal gasket, and lubricating the threads of the union, would pretty much eliminate any problems with the dielectric union. And that effort would not really add that much time and could be performed during the tank draining time. Such a preventative maintenance would be harder to perform on a dielectric nipple and would have limited if any benefit.

 

[Twowaxhack]

I’ve taken apart dissimilar metals ( galvanize and copper ). That have been in service for 60 yrs that had no corrosion.

Everyone starts crab walking when real life parts and pieces get thrown on the table to inspect. They either don’t believe it or talk about why for 4 hrs…..

 

[arctic bill]

I find the price high , Your old tank lasted 20 years , why not just replace it. instead of some expensive 12 year tank i saw price of $1000 for a gas 50 gal tank plus plus , I do live in canada . just compare prices google search 50 gal hot water tank natural gas.

 

[Twowaxhack]

Here the Home Depot has a 50 gal gas with 6 yr warranty for 689.00.

9 yr is $809.00

The 12 yr is $889.00