Trying to turn the cold water feed to the water heater today and it wouldn't do it.

I don't mean it shuts it off 99% with a slow drip, I mean it will not turn off any at all, the hot water remains in full blast.

Doesn't seem the stem is broken either, it does not spin, I can turn it counterclockwise and it will meet resistance and stop at some point. If I then turn it clockwise to close it will turn a few revolutions and meet resistance and stop. It is almost as if the stem and the gate has separated but in that case the stem would spin right?

Is there any solution? Besides replacing with a new valve?

You can disassemble it and see what's going on, maybe replace the gate/bonnet assembly from a new Mueller valve. I wouldn't waste my time doing tha. I would replace with a ball valve instead.

I can't loosen the bonnet, it is a tight angle and I can't get a very large wrench in there. I actually have two other new valves just like that in my garage so I could replace the parts if necessary but I just can't get it open.

If I unsolder this valve and solder on a new ball valve it can be done but I need to turn water off to the building which affects 3 other units so I need to schedule and notice 48 hours prior to doing it to have it turned off for may be an hour for me to swap this out.

On the other hand, if it's stuck 100% open, I could thread on a new ball valve to the male adapter after the 90 and be in action in about 1 minute, but it's a hack to leave a bad valve in line like this.

Definitely a hack, and to be avoided is possible. There could be a future bonnet leak.

george yes it's a hack, I will make a new sweat valve and report back.

well due to tenants in other apartments being home I only had 2 hours of window to get this working, and to change out a valve I was thinking 1 hour the most even with things going sideways...not so fast LOL.

First of all, when I removed the old gate valve, it seems what was causing the problem was the valve not closing completely from debris buildup. I did open and close the valve multiple times, and turning it on and off hoping to dislodge any debris but didn't work. Here is a picture of the old valve you can see a lot of debris.



I do have two of the same gate valves, brand new, but I decided to use a full port ball valve instead.



after unsoldering the old valve, the heat somehow set of the smoke/fire alarm, and since all the alarms in each apartment are all daisy chained, all the smoke alarms went off, oh boy I ended up having to chase down the alarms and reset them all, wasted half ah hour doing that.

I soldered on a new 3/4" ball valve, good news is there is no leak, bad news is it does not shut off the hot side completely.





When I turned the valve off, a hot side faucet would slow and slow but still a steady small stream. I thought may be the faucet has an issue with cross over, so I turned off the cold faucet shutoff and the stream continues. I left it running like this for 20 minutes and still going, so definitely a problem.



My conclusion is this ball valve is not shutting off water to the water heater 100%. Either it is defective, or when I soldered I damaged the seat or some other guts. I did remove the lever while soldering and when I put it back I tried to rotate the stem past the stop to make sure it's not the stop that's off a bit.

So I am thinking unsoldering this ball valve and put on yet another ball valve tomorrow? Anything else worth trying?



Edited 2 times.

Personally I prefer using/installing threaded ball valves instead of soldered valves.

So in your situation installing a male adapter, then a quality 3/4" fip ball valve and then a brass nipple.

Then no 90 degree and instead just taking an all stainless flex and attaching it to the nipple (even if it might take a longer flex).

I prefer to solder ball valves on my work table, held in a vice. Everything is controlled - no residual water, no restricted access, no trying to wick solder up on a vertical joint. All these take extra heat, risking damage to the valve. I cool the valve down immediately after soldering. I also back off the packing nut a bit before soldering and tighten it back up after soldering. There is a couple of extra couplers involved but they don't cost much and do not introduce restriction.
I head to a job with the ball valves already soldered. Of course, occasionally, there is not enough space for rxtra couplers and I cannot pre-solder the valves.

Also helps to use quality ball valves. Vic has previously referred to the quality of Kitz valves. Same valves I use, they are branded M.A.Stewart in Canada.

vic, I agree sometimes I use a threaded valve to avoid soldering too close to the middle of the valve.

However the issue I have there is if I were to solder on a male adapter to the copper, and thread one on, I don't have control when the threaded joint is tight the ball valve may not be facing where I need it for the handle to open out.

What I have done sometimes is to first solder a male adapter onto a short piece of copper pipe and thread the male adapter end onto the valve on a vice, and after that connect to the copper by sweating a coupling which is further away from the valve itself.

OK here is a mystery.

Today I took another 3/4" ball valve to the property planning to replace the bad one I soldered on yesterday.

Before I turned water off to the building, I decided just to test one more time. I shutoff the valve feeding the water heater yesterday (the bad one that wouldn't stop 100%). I opened the hot side of a lav sink and 20 seconds later the flow stopped completely.

THIS MAKES NO SENSE. I tested it yesterday and it kept a slow flow!

The only difference was, when I left last night, I turned off the breakers to the water heater. Does this make a difference?

So I got curious, I turned this valve back on and let everything pressurize. Turned the WH breakers back on. Turned the valve off again, and turn on the lav valve hot side. Water slows but kept coming in a very slow stream. Hmmm...flipped the breakers off, and the flow slows and stopped completely.

My theory is with the breakers on, and the lav faucet hot side opened, when I shutoff the cold side inlet valve, no water feeding the tank, but the water inside the tank is being heated and thus expands and pushes water in the pipes to flow...but eventually it has to find an equilibrium and stop right? I had it flowing slow for 30 minutes yesterday and never stopped so I assumed I either had a defective ball valve or I damaged it when I soldered.

But if I turned WH breakers off, and shut inlet valve off, water stops.

This is not making sense to me, and I never had to do this before. Thoughts?

Depending on how hot the water in the tank is at start, it can take hours for a electric water heater to fully heat up a tank. So it is possible for the water to flow for thirty minutes just from expansion due to heating.