Forum Title: Valve replacement at main supply
The handle has stripped off the main shutoff valve inside my house. I'm looking to replace it but there are a couple issues I'm considering.
First is the fact that the supply line here is copper, while most of the house is plumbed with galvanized. Currently installed is a stop and waste valve with copper sweat connections on each side, and above the valve is a sweat to MIP adapter that is connected directly to the galvanized pipe that leads to the rest of the house. I do not want to reinstall copper on galvanized like this as I wish to avoid galvanic corrosion.
Second, this valve is located in a subfloor crawlspace which requires a minute to access and it gets rather cold in the winter. Also right above this valve is a tee, one side which leads to a stop a waste valve and then an exterior hose bib. This location froze and broke over the winter, but there is an electric heat tape installed now to avoid this in the future.
First question. Initially I was going to install a dielectric union to transition from the copper to the galvanized. Now I'm thinking it would be better, both in terms of ease of installation and in reducing the chance for a leaking dielectric union in a somewhat difficult to access space, to use CPVC to transition between the metals. I'll screw (with thread seal) CPVC fittings onto a galvanized nipple on one end and a copper sweat to MIP adapter on the other end, with CPVC pipe between. Are there any disadvantages to this approach? Is CPVC okay with the electric heat tape? Any code issues that could be involved here?
Second question, what kind of valve should I put here? Should I use a CPVC valve, or should I put a brass valve on the copper end and then transition? I like ball valves due to their ease of operation, do they have any disadvantage in this application?
Any other issues I haven't thought of or explored yet? Thanks for the help!
Post By: Abcool Ac& Heat (Johnston, RI), 09/15/2017
A good quality brass ball valve is definitely recommended in this application. As far as the transition goes I would go with the dielectric union. CPVC is not a material that I would ever recommend installing.
I think it's fair to call people's opinions of dielectric unions (at least as far as I have seen) mixed. Lots of people claim it's a leak waiting to happen, your thoughts on this? Also, out of curiosity, why are you down on CPVC?
First the dielectrics. Nearly every water heater I have serviced or replaced has utilized dielectric unions. Rarely has the source of the call been from a leaking dielectric union. On to the CPVC. This material is prone to cracks and splits. Also if it requires repair you are forced to use a glue joint. Almost all of the glues on the market recommend a 24 hour cure time. I hate to tell my customer they have to wait 24 hours before I can even leak check my work. That said I have had to make such repairs and I am reminded of an instance about a year ago. I was changing out angle stops in a condo that utilized CPVC. After completing the swap my helper and I went to lunch. We also went to the supply house. We killed about an hour and a half before returning to the job to turn on the water. Any plumber will tell you that this is a nerve racking moment. Water on, and no gushers. Phew, dodged a bullet there. Now on to repairing the drain below the kitchen faucet. As I completed my repair on the drain I turned the faucet on and off a few times. THE NEW STOP CAME OFF!!!! Half inch hot water line flowing full on in a hardwood kitchen owned by an older woman who never had kids (immaculate home). I quickly put my hand over the open pipe and screamed to my apprentice to shut the house down. The palm of my hand blistered form the burn in the shape of the Olympic rings. Did I mention its prone to cracks and splits?