Calling all Plumbers Recirculating Pump
A client of mine that I have done a lot of work for, small and large projects called me yesterday telling me they have water in a bedroom. On the phone and knowing the house well we quickly narrowed the source. Fire sprinkler was not leaking, adjoining bath all the pluming was on the other wall and it was dry, laundry washer on other wall and it too was dry.
I thought water heater, which would be odd the house is ten ears old and heaters here tend to last 16 or a bit more. Told him I would be up in an hour, got there, stepped on the carpet it was wet. gas water heater bone dry on bottom but there was a bit of water by the wall. The mechanical closet is in the garage, heater ajoins the bedroom and laundry walls. Go in crawl space water is running down 2 of the pipes. He calls me “find it yet” I explain I am close, it is in the wall but which pipe I am not sure, I just hope it is not one right behind the heater.
I cut the wall open at the bottom thinking a nail may of gone into the pipe from the base board on the other side rusted out, and started leaking, nope. So further up the wall another hole and there it is; ( this is in flow order starting down stream) plex – stub out copper supply ell – sweat 1/2 ball valve – 12″ pipe – sweat reculating pump – 9″ pipe – 90 degree ell horz – 18″ pipe – 90 degree ell from horizontal to vertical – 3′ pipe to bronze check valve – galv nipple to tee from there one side of tee has a drain valve other has nipple to water heater.
The leak was right where the plex was crimped, taking it off it was pitted on the inside. Then the pipe at the outlet of the pump breaks, it was just about paper thin. So I replaced all the pipe to the horiz tee.
Question of the day what caused the failure?
I have gotten several answers:
The pump (I am going to get the model # today) it has no timer runs 24 hours. One person
at a supply house thought the fact that it is always on caused the pipe to fail.
The few galvanized fittings with the heater tank caused the pipe to fail due to electrolysis, was another thought.
I just don’t want this to happen again to them. lucky they were home, they both travel quite a bit.
Any thoughts all of this is 1/2 pipe. I will take some photos and post them.
Thanks Wallyo
Edited 9/15/2009 12:09 pm by wallyo
Replies
The gym where I go to, which opened in 1993, has had significant problems with the (soft) hot water eroding copper pipes. It happens most often in the showers, where a stub was installed in the faucet port of the shower valve and iron (present in the water here) accumulates in the stub. About half of the 20 or so showers in the men's locker room have succumbed to this problem, and a week ago they had to shut down the whole place for a day to replace other pipes.
I'm guessing you have a sort of "all of the above" situation -- the iron nipples, perhaps in combo with iron in the (soft?) hot water has created a situation where the constantly running pump (reproducing the heavy use scenario seen at my gym) promotes electrolytic erosion of the copper.
I would think if the iron nipples are to blame the problem would be closer to the water heater? Am I wrong on that Idea. Remember the flow is into the nipples not away from them and wear is closer to the pump.Wallyo
The iron nipples (and other iron in the water) "activate" the water in a way to make the water more reactive with the copper. In still water you'd see the reaction near the nipples, but in moving water it'll tend to be where there's the most turbulence.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Thanks Dan I alway thought it was the pipe to pipe contact not the water flow, makes sense though the wear as I said was the plex to copper and right after the pump the area wit hhe most turbulence.Here are two photos or the two fittings.
Trust me, it has nothing to do with the iron.
Velocity erosion. Slow down the water.
Rich what you lay out is more of a three part solution.Smaller pump, timer and valve. If it were your house would you change out the pump or go with a timer and valve.I already picked up a cool plug in digital time, with a large read out and battery back up, that can more then handle the 85 watts this pump uses. So that is done, but if a new pump is needed I would suggest a pump with timer.That leaves the valve what type gate, ball, or compression? If I go this route on which side intake or out flow? I would think out flow. But with a smaller pump the valve may not be needed.Also any thoughts on a thermo shut off?http://www.plumbingsupply.com/circpump.html#timerBut it does seem like the current pump is way over sized.Thanks again Wallyo
Edited 9/16/2009 6:58 pm by wallyo
Smaller pump is always first choice. A globe or needle valve is best, but a ball valve will work. But remember, you just have to barely open the valve to get some flow.
Wouldn't worry too much about the thermo shut off, flow is the issue.
Here are some photos probably too many but you know what they say about pictures.
Edited 9/16/2009 11:25 am by wallyo
You have erosion caused by velocity of the water. Most common at elbows.
Curious as to the pump model #.
Two part solution. Get a smaller pump and add a valve to restrict the flow. Normal flow rate for most pumps is about 4 feet per second. 4 feet per minute would probably work. Needs to be a separate valve cause over time it won't shut off due to wire stripping. ( the flow of water can cause grooves in the valve).
Second is a timer, available for most pumps, has on/off trippers every 15 minutes. Set the timer for 15min on/off when water is required and off the rest of the time.
Rich I have some photos of the set up will put them up tomorrow the pump itself is a Grundfos UP15-18B5 Using the link then clicking on Product Descriptions,
it is the second pump from the top on the chart.http://www.grundfos.com/Web/HomeUs.nsf/Webopslag/PAVA-53SLGKA bit more info this is a one story house almost, there is a bonus room one story up but no plumbing at all up there. The return back to the pump is fifty feet away at most in the master bath.If you click on Sizing guide it gives some more info if you can take a look let me know what you think.By the way 3/4 supply and 1/2 return.Hey thanks a bunch.Wallyo
Edited 9/16/2009 1:14 am by wallyo