Plumbers here??? Got circulating pump problem.

I'm hoping that I can figure out what's going on w/ my circulating system before opening it up. I'd like to keep experimenting to a minimum...

That said:

We've got a circulating pump on the hot water (duh!) for our faucets/etc. There are 3 return lines, all which 't' and feed into a circulating pump. This feeds back into the hot water heater. There is an electronic timer on the pump. It's worked perfectly since installation/construction about 8 years ago.

Yesterday, 2 of the 3 areas served had a HUGE drop in temp. One is lukewarm at best, one is medium warm, the final one is unaffected.

The 2 problem areas will get hot if you turn the hot water on and wait a minute or two. They appear to steadily increase in temp during this time.

The easy answer is that the pump is failing. Or is it? I'm afraid that there is a blockage in 't' where 2 of the return lines come together.

All other parts of the system are fine and nothing environmental has changed.

I do not have isolation valves for any of the return circuits, but plan to install them asap. As a result, troubleshooting is almost impossible.

Ideas?

I have a recirculating system also, I was told to check for sediment build up where tees are located due to no flow to keep sediment moving along. We opened the water heater drain valve to let sediment flush out. You might try this and see if your issue is resolved.

I don't think your problem is what mine was. I don't have pumps. Not sure if this helps, but, I have 2 hot water heaters in my house. And one started doing the same thing. Only in winter when it was cold. It too FOREVER for hot water to come out of the shower. It was 2 things. Rats had chewed large section of foam wrap off pipes. And the single knob that you twist for warm or cold had come out of adjustment in the back. Not allowing enough hot water to pass. I took it apart and cleaned off the build up and lubed it. Still working like charm now. I also rewrapped the pipes with thicker foam and tons of silver tape. So, that problem solved for now too.

I think these systems are supposed to feed back into the heater at the drain valve or popoff valve but ours does not. It goes into a 't' where the cold water enters the heater. So, correct or not, there's no chance tank sediment is clogging up the works. In addition, the HWH is only 6 mo old so it should be spick and span in there.

Just got back from home depot with 3 'shark bite' pex cutoff valves. Am gonna get in attic, install them, and close them off one at a time to see what I can find out. Not a bad idea to have them in place anyway.

turbodog said:

There are 3 return lines, all which 't' and feed into a circulating pump. This feeds back into the hot water heater. There is an electronic timer on the pump. It's worked perfectly since installation/construction about 8 years ago.

Yesterday, 2 of the 3 areas served had a HUGE drop in temp. One is lukewarm at best, one is medium warm, the final one is unaffected.

The 2 problem areas will get hot if you turn the hot water on and wait a minute or two. They appear to steadily increase in temp during this time.

The easy answer is that the pump is failing. Or is it? I'm afraid that there is a blockage in 't' where 2 of the return lines come together.

Click to expand...

turbodog,

If it was pump failure wouldn't all the zones be equally problematic? Since you're only having issues with two of them it's probably, as you've written, a blockage somewhere in the return system of the two affected zones. The most likely area is the T. However, since the two zones have varying degrees of temperature perhaps the blockage is at the return manifolds under the sinks. Nevertheless, I'd start at the T. Since I don't know how your system is plumbed, I'm referencing the one in my mother's home. I think you understand the problem. You just need to dive-n n-fix it. I hope it goes smoothly.

One more thing, if you go to the hardware store for parts, don't refer to it as a hot water heater. I did that once and the two guys behind the counter laughed. Then one said, "We don't have parts for a hot water heater. We only have parts for cold water heaters." Last time I made that mistake. Although, with your pump, you do have a warm water reheater.

~ Chance

Chauncey Gardiner said:

turbodog,

If it was pump failure wouldn't all the zones be equally problematic? Since you're only having issues with two of them it's probably, as you've written, a blockage somewhere in the return system of the two affected zones. The most likely area is the T. However, since the two zones have varying degrees of temperature perhaps the blockage is at the return manifolds under the sinks. Nevertheless, I'd start at the T. Since I don't know how your system is plumbed, I'm referencing the one in my mother's home. I think you understand the problem. You just need to dive-n n-fix it. I hope it goes smoothly.

One more thing, if you go to the hardware store for parts, don't refer to it as a hot water heater. I did that once and the two guys behind the counter laughed. Then one said, "We don't have parts for a hot water heater. We only have parts for cold water heaters." Last time I made that mistake. Although, with your pump, you do have a warm water reheater.

~ Chance

Click to expand...

Yup. I have heard that joke before!

Headed to the attic in 15 mins. Will see how it goes.

I am a mechanical contractor - do you have check valves on the recirculating line

sounds more like the cold water is feeding into the recirculating line

turbodog said:

Yup. I have heard that joke before!

Headed to the attic in 15 mins. Will see how it goes.

Click to expand...

Pictures please.

~ Chance

Matrix 100 said:

I am a mechanical contractor - do you have check valves on the recirculating line

sounds more like the cold water is feeding into the recirculating line

Click to expand...

Yup. They were not there originally. We had plumber add one about a week after we moved in. Took care of that problem.

Chauncey Gardiner said:

Pictures please.

~ Chance

Click to expand...

Ok.

Cut water off to house. Drained pressure.

Went up, snipped 3 return lines, installed 3 'shark bite' cutoff valves.

Turned water & pump back on.

Opened return lines one at a time. Have HOT water on any single line, but all 3 at once yields same problem.

Time to get a new pump.

check the size of the pump and type - some pumps have a speed controller (grunfos), also some pumps have a check valve built in

My question now is this...

Existing pump is inline with the return lines. So when it's not running, no water passes through the pump.

New one has wrong sex (on both ends) so I need two adapters to replace pump. However, it will bolt right up directly to the heater. I could just leave old pump in place (unplugged) and be done with it. But ALL hot water will flow through new pump. I think that might result in unacceptable flow reduction...

But much easier to pop into place directly on top of the heater...

Matrix 100 said:

check the size of the pump and type - some pumps have a speed controller (grunfos), also some pumps have a check valve built in

Click to expand...

Both are like 1/250 hp with no check valves.

two pumps ? - the circ pump, I think it needs to be bigger 1/10 hp

my new thinking on your problem - the pump is pulling water from the line with the least resistance ( shortest line)

you also need to put the check valve on the discharge of the line - so you need to remove old pump and replace

you won't have room to your recommendation

Matrix 100 said:

two pumps ? - the circ pump, I think it needs to be bigger 1/10 hp

my new thinking on your problem - the pump is pulling water from the line with the least resistance ( shortest line)

Click to expand...

See original post. Has been fine for years. Recently started acting up.

it's very odd - worked before but not working now

did you try to balance the system - since each loop works - the shortest loop shut valve off 50 %

another note - pumps are mechanical and they do fail - but I would recommend a bigger pump

Matrix 100 said:

it's very odd - worked before but not working now

did you try to balance the system - since each loop works - the shortest loop shut valve off 50 %

another note - pumps are mechanical and they do fail - but I would recommend a bigger pump

Click to expand...

Once the shutoff valves were installed I though about using them to force a balance, but once just 2 valves were open the temp would not hold acceptable levels.

I've got the new pump in and all is good now. Water temp is HOT at all locations and the temps are pretty close to one another, close enough to not worry about it.

The old pump is still inline with the return lines. I've got the electrical unplugged from it. I put the new pump on the hot output from the heater itself. Flow does not appear to be affected much.

Will drop by home depot and get straight pipe needed to bypass and remove old pump.

nice to hear all is working

bad ascii art

The general consensus is - the pump impellors must have experience some cavitation - which cause the impellors to stop pumping watering at the rated amount

typically I won't buy a recir pump at home depot - try a plumbing wholesaler


all the best