Problem with Hot Water Circulator Pump

[polldav]

I have a Grundfos pump (link below) installed right next to my water heater. I am fairly sure it was a retrofit pump but I am not 100% positive about that. I connected it to a zwave outlet which integrates with my home automation stuff, so basically the pump always stays in "on" mode and the outlet it is plugged into turns on either at certain times or when we hit a button (I'm just including this in case the power cycling is likely to have caused some damage).

The pump is about 4 years old. Everything had been working fine, but the last couple days I've noticed hot water is instantly available even when the pump hasn't run for hours and it would normally take a couple minutes to get to the hot water. At first I was worried there was a leak somewhere in the house, but I've searched all over multiple times for any signs and can't find anything wrong.

My new theory is that the pump isn't closing correctly when powered off, which allows water to kind of passively flow throughout the house so hot water is always available. I believe this is true because:

1. The pump was hot even after being unplugged for hours
2. The mystical instant hot water goes away if I close the valves on either side of the pump
3. The pump is kind of at a low point in the house. I don't know where the guy that installed it pulled the "input" from, but there could certainly be a kind of slow downward flow that allows this to happen.

I'm not a plumber and don't really know anything about pumps, but my main questions are:

1. Is this what likely happened, or does it seem crazy?
2. Is there anything I can do to try and "fix" it (e.g. clean out some gunk inside the pump or something).
3. If I end up replacing the pump, can anyone suggest a better option? All I need is a durable, VERY low power/flow pump with no frills at all (no timer, no sensing etc). This pump is like $300 to replace and seems excessive.

Link to specific pump: http://www.amazon.com/dp/B000JGA0S2/?tag=skimlinks_replacement-20

Edit to include better link: https://us.grundfos.com/products/find-product/comfort-pumps-up-10.html

Edit #2: Best link I've found with the most information: http://www.pexuniverse.com/grundfos-up15-10b5-tlc-circulator-pump-59896215

 

[frodo]

a pump is nothing more than a impeller spinning.

it does not "close off" , when the pump is off water can pass thru it.

to top you need a motorised valve to open when the pump kicks on and close when pump turns off


your model, requires it to be reprogramed if you have a power failure.

also, it needs to be installed /oriented correctly no more than on a 45 degree .

have you lost power? has it been reprogramed?

 

[polldav]

to top you need a motorised valve to open when the pump kicks on and close when pump turns off

your model, requires it to be reprogramed if you have a power failure.

also, it needs to be installed /oriented correctly no more than on a 45 degree .

have you lost power? has it been reprogramed?

It has lost power, but it has lost power hundreds of times before without any problems like it is having now. There is really nothing to "program" on the thing except the timer dial, which is not used because I only leave the pump in "on" mode (not timer mode).

The pump is installed horizontally so I'm sure the installation angle is fine.

To clarify the pump I listed, I actually have something that looks more like this:

https://us.grundfos.com/products/find-product/comfort-pumps-up-10.html

The model number on the pump matches that other link I had posted, but maybe the "comfort system" includes a motorized valve inside that I can't really see? Maybe it's just that part that failed?

 

[polldav]

Here are a few pictures in case you can tell if it has a motorized valve inside the casing by seeing anything here:

 

[johnjh2o]

The fitting that makes the cross connection between the hot and cold has failed allowing the water to circulate on gravity. (hot rises cold falls) Replace the fitting and your problem will be solved.

 

[gladiatormaniac7]

Sounds like you don even need a pump, because you have enough gravity to let it circulate by itself

 

[johnjh2o]

That was how the old systems were set up but they required a designated return line. If conditions are right it will gravity with his set up but he will also get hot water out of the cold water lines.

 

[polldav]

The fitting that makes the cross connection between the hot and cold has failed allowing the water to circulate on gravity. (hot rises cold falls) Replace the fitting and your problem will be solved.

I'm not sure, but I was under the impression that this whole setup was completely separate from the cold setup. I've never gotten hot water out of a cold faucet.

Basically, I visualize it like this in my head: http://www.plumbinghelp.ca/old/images4/Forced hot water recirculation.jpg

I know I have seen some diagrams with a cross connect, but I've never gotten hot water out of a cold faucet and it doesn't make sense to me so I never really think about it that way.

The first photo I posted shows basically everything I see of the input pipe that comes from the wall (left side of the pump). Is one of those pieces between the shutoff and the pump what you are referring to as the failed piece?

Edit: Now I see there should be a crossover connection under a random sink in the house. I'll go search for one and see if that's how my system is set up.

Sounds like you don even need a pump, because you have enough gravity to let it circulate by itself

The main reason I want to fix it is because I don't want to waste the money to heat the water when I don't need it - that's why I set it up with the zwave outlet so I can push a button, but it doesn't just automatically do it all day long. I read some stats when I first came across the pump that estimated $300-$600 a year in extra natural gas costs by running one of these things 24 hours a day. Based on how fast the water gets cold sitting in the PVC, I don't have a hard time believing that.

 

[johnjh2o]

The drawing that you posted has a designated return line. This set up you posted has the fitting that is used for the cold water line becoming the return line. Which one do you have?

https://us.grundfos.com/products/find-product/comfort-pumps-up-10.html

 

[polldav]

The drawing that you posted has a designated return line. This set up you posted has the fitting that is used for the cold water line becoming the return line. Which one do you have?

https://us.grundfos.com/products/find-product/comfort-pumps-up-10.html

I definitely have that pump/timer combo. I can't find any kind of crossover connection under any sinks or at the laundry or by the water heater though.

I didn't own the house whenever this thing was installed, so I don't know what's inside the walls, but I don't think I am missing anything that would be visible to me. We have all Wirsbo pipe in the house, so that metal crossover pipe would stand out pretty well.

 

[gladiatormaniac7]

I'm not sure, but I was under the impression that this whole setup was completely separate from the cold setup. I've never gotten hot water out of a cold faucet.

Basically, I visualize it like this in my head: http://www.plumbinghelp.ca/old/images4/Forced hot water recirculation.jpg

I know I have seen some diagrams with a cross connect, but I've never gotten hot water out of a cold faucet and it doesn't make sense to me so I never really think about it that way.

The first photo I posted shows basically everything I see of the input pipe that comes from the wall (left side of the pump). Is one of those pieces between the shutoff and the pump what you are referring to as the failed piece?

Edit: Now I see there should be a crossover connection under a random sink in the house. I'll go search for one and see if that's how my system is set up.



The main reason I want to fix it is because I don't want to waste the money to heat the water when I don't need it - that's why I set it up with the zwave outlet so I can push a button, but it doesn't just automatically do it all day long. I read some stats when I first came across the pump that estimated $300-$600 a year in extra natural gas costs by running one of these things 24 hours a day. Based on how fast the water gets cold sitting in the PVC, I don't have a hard time believing that.

Maybe just Installing a power operated control valve to open and close at certain times of the day?

 

[KULTULZ]

a pump is nothing more than a impeller spinning.

it does not "close off" , when the pump is off water can pass thru it.

to top you need a motorised valve to open when the pump kicks on and close when pump turns off

Question frodo...

Is the style of valve you are describing is as shown below?

I believe this is intended for a boiler system and is expensive. Are there other model(s) available cheaper as it is only a recirc system? I am asking for myself and this does not pertain to the present thread subject.

Valve (Electric Motor Shut-Off)- Series LFEMVII-6400SS

 

[KULTULZ]

The OP has the pump mounted on a dedicated return line connected @ the WH drain line.

While using the same pump as shown (Grundfos - also makes the WATTS branded system) that setup (being discussed) with mixing valve is used on the hot water outlet of the WH (pressure system).

His is a suction system with dedicated return line with no mixing valve used.

If there is no check valve (anti-backflow device installed @ the pump), hot water will circulate (backflow) within the return circuit.

 

[gladiatormaniac7]

Or better yet, instead of Installing a motorized valve, install a heat trap on the hot water supply out of the water heater. Basically a upside down p-trap made of the water piping that you have. I would pipe back down and then back up to the fixtures

 

[gladiatormaniac7]

Or better yet, instead of Installing a motorized valve, install a heat trap on the hot water supply out of the water heater. Basically a upside down p-trap made of the water piping that you have. I would pipe back down and then back up to the fixtures

I would say at least a 12" hot water p-trap. That should stop circulation when the pump is not running

 

[gladiatormaniac7]

About a 12" drop and then back up to your fixtures. It would stop gravity circulation when the pump is not runnung

 

[Mr_David]

To clarify the pump I listed, I actually have something that looks more like this:

https://us.grundfos.com/products/find-product/comfort-pumps-up-10.html

The model number on the pump matches that other link I had posted, but maybe the "comfort system" includes a motorized valve inside that I can't really see?
Maybe it's just that part that failed?

There are no motorized valves in the pumps. Frodo already told you that.
You don't have a comfort system. That is used (retrofitted ) when you do not have a designated 3rd return line back to the heater.
I have seen some systems with a designated line that stay hot after the pump has failed.
Gravity back flow like mentioned previously. It is an unusual occurrence. the density of the water changes with temperature.
Hot water rises because it is less dense than cold water. Cold water sinks because it is more dense than hot.
If the system is piped just right the there is a hot flow up and a cold flow down that becomes a continuous current cycle.

That could be one cause.

If your lines are running through a concrete slab that is not likely to happen.
You might have what you originally thought you had. A leak. On a line under the slab.
Check for a leak on hot system. You have to test it not just look for a visible leak.

Do you have a check valve on the return line?
If so , it may have failed and water is flowing backwards through the return line taking a path of least resistance to the farthest fixture.

 

[gladiatormaniac7]

There are no motorized valves in the pumps. Frodo already told you that.
You don't have a comfort system. That is used (retrofitted ) when you do not have a designated 3rd return line back to the heater.
I have seen some systems with a designated line that stay hot after the pump has failed.
Gravity back flow like mentioned previously. It is an unusual occurrence. the density of the water changes with temperature.
Hot water rises because it is less dense than cold water. Cold water sinks because it is more dense than hot.
If the system is piped just right the there is a hot flow up and a cold flow down that becomes a continuous current cycle.

That could be one cause.

If your lines are running through a concrete slab that is not likely to happen.
You might have what you originally thought you had. A leak. On a line under the slab.
Check for a leak on hot system. You have to test it not just look for a visible leak.

Do you have a check valve on the return line?
If so , it may have failed and water is flowing backwards through the return line taking a path of least resistance to the farthest fixture.

Sounded like he said that the pump was the lowest part of the system and I didn't see any part that said he has a slab

 

[Mr_David]

Sounded like he said that the pump was the lowest part of the system and I didn't see any part that said he has a slab

True. but if I was looking at the heater in a finished room with drywall the pump is lower than the supplies on top. That's all you see
You can't see the if the system is turning down into the slab. So that is an unknown and I'm just tossing in a few what if's.

 

[gladiatormaniac7]

True. but if I was looking at the heater in a finished room with drywall the pump is lower than the supplies on top. That's all you see
You can't see the if the system is turning down into the slab. So that is an unknown and I'm just tossing in a few what if's.

Ya your right. What do you think of the heat trap idea?