Hot water circulation pump causing leaks

[kcroyalsfan]

I built a new house 3 years ago and my wife talked me into a hot water recirculating pump. All plumbing is pex, but has copper connections. It was professionally installed. The loop is 3/4 pex and then at each hot water outlet, there is a tee and a short run of smaller line comes from the loop to feed it. The pump has a thermostat on the return end of the line, but it runs 24/7. Water is hot within 3 seconds, which is nice.

Yesterday, one of the copper elbows in the loop got a pinhole leak. When I replaced it, I noticed that it was very thin. I thought maybe the pump was causing electrolysis. But now I have researched and discovered that this is a common thing. I'm not at home now, so I don't know what size pump we have, but I'm guessing it's too big. I already don't like how much money we are spending by running the pump and hot water heater almost constantly.

This house is on a family farm, not in a subdivision, so there is no doubt I will live in it for decades. So I'm looking for a long term solution. Is a smaller pump the answer? Or should I bite the bullet and do away with the loop and pump and put in a manifold now? The quick hot water is nice, but not at the expense of leaks after only 3 years.

Also, the leak occurred at one of only two 90 degree elbows in the loop. When the plumber first put in the loop, he didn't get it anywhere close to the kitchen sink. So I asked him to extend it, and to do that, he cut the loop and put in two 90 degree elbows, and extended the loop over to the kitchen. I could easily take those two elbows out, add some more line, and make these connections straight if that would help. But again, don't want to have another issue in 5 or 10 years with the straight connections or tees.

Thanks

 

[hj]

The length of the line is NOT the problem. The problem is that you are not throttling the pump flow down so you getting a high velocity and "eroding" the elbows, and maybe some tees.

 

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[Jadnashua]

I know you have pex, but with the fittings, this may prove useful...the Copper Institute calls for a maximum velocity of hot water in copper piping of 5fps, which is only about 4gpm in 1/2" and 8gpm in 3/4" copper pipe. Pex generally allows a higher velocity, but the fittings are a restriction, and the flow goes even higher there momentarily (Venturi effect). The stated problems with exceeding that are eroding of the pipe, greater frictional losses, and noise.

My recirculation pump is like a 1/28th HP thing...you do not need much velocity. If it were on a timer (mine is), the first time it turns on in the morning, mine can take over 2-minutes to get hot at the furthest sink (the tub takes about 30-seconds, but has over 3x the volume of a sink valve), but is nearly instant for the rest of the day.

If you don't have one, add a valve after the pump to slow it down, or change the pump.

 

[Jadziedzic]

Consider the Bell & Gossett ecocirc e3 recirculating pump: maximum flow of 3 GPM, available with timer and/or thermostatic control and/or variable speed, consumes very little power, it would be an excellent replacement.