Certain Faucets Never get Hot

[chackett]

Hi All-

We live in a relatively new home (~5 ish years old). It was plumbed with a hot water recirculating system and a pump in the garage near (or on) the water heater. We are the second owner of the home, so I wasn't involved with the setup or installation of the system, and as far as I can tell, it mostly seems to work fine. Water is very quickly hot at most faucets. Definitely quicker than it could have traveled there from the water heater.

There's a pretty strange scenario where if one of the kids is taking a shower upstairs, hot water will absolutely never arrive at the kitchen sink. No matter how long you let the hot water run at the kitchen sink, it'll just never get hot.

One of our neighbors said they had a similar issue. They called a plumber, and according to the neighbor "they immediately knew what was wrong and fixed it." They made it sound like it wasn't a big deal. I called a local plumber - in fact the plumbing company the local inspector said was likely the company that did the work when the house was built, but that plumber didn't seem familiar at all with the recirculating system. So I'm not really very confident in calling them back to get more assistance.

Any ideas? Where can I even start investigating? I'm very handy and capable, I just don't have any knowledge or familiarity with this type of recirculating system.

Thanks all!
Chris

 

[Twowaxhack]

Check valve may have failed at the pump ir in the pump on the recirc system.

This would possibly allow cold water to back feed through the recirc line to the kitchen or other fixtures.

 

[Geofd]

When the shower isn't being used is the water hot in the k.s faucet??????
Is it a single handle shower valve ?????
Is it a single handle faucet in the kitchen????

 

[chackett]

Thanks for the replies.

Twowax: I will definitely see if I can check that. Thanks for the suggestion,

Geofd - Thanks - When an upstairs shower is not being used, the hot water behaves normally at the kitchen sink. Basically gets hot instantly. It's a single handle valve in both the kitchen and in the shower. I haven't tested it, but I think the lack of hot water at the kitchen sink happens when anything else is running (like the washing machine is filling upstairs) I guess I could test to see if the lack of hot water at the kitchen sink happens when ANYTHING is drawing hot water upstairs.

 

[Twowaxhack]

Yeah, I think I’d make sure I had a good check valve in the return line. Sounds like it’s failed or it’s nonexistent. Some recirc pumps have the check valve built in.

Do this test.

Turn the shower on upstairs. Turn the kitchen sink hot water on.

Now go to the water heater and feel the piping of the hot water return. It’ll probably be cold when it should be hot.

If you keep your hand on the hot water return while other people turn the faucets on you might be able to feel the backflow happen as the pipe goes from hot to cold.

The hot water return should be hot or really warm, never cold unless you’re completely out of hot water.

 

[chackett]

Awesome .. thanks Twowax - I'll check it out now!

 

[chackett]

I don't mean to be dense, but for some reason, my poor brain is having a hard time visualizing how this thing works. Here is a photo of the plumbing at the water heater.

 

[Twowaxhack]

Do the test I asked and feel this pipe I have circled in red with the insulation removed. It should be hot or warm and stay that way. If it goes cold then it’s backfeeding. That would mean the check valve is bad. I’ll circle the check valve in yellow.

 

[Twowaxhack]

The return line is the pipe that’s far left. It enters the pump on the left and exits the pump on the right. It goes through the check valve ( one way valve ) and connects to a tee below the stop valve on the COLD side of the heater.

As the pump runs the water circulated down the cold water inlet through the dip tube and hot water is pumped out of the hot water side, the left side through the loop of hot water piping and is returned back to the water heaters cold inlet.

The pumps direction of flow is from the wall, through the pump, through the check valve and into the cold water inlet, out of the water heater. Repeat.

You have the cold and hot marked backwards in your pic.

Do you know what your water pressure is ? Is the kitchen close to the water heater ? Just curious on those two questions…..

 

[Twowaxhack]

Your check valve is in the wrong place unless you have another one in the cold line.

I like this piping diagram for top fed recirculating systems.
https://ohmefficient.com/instant-hot-water-recirculating-pump/

But to be honest, I prefer to pipe the recirc line to the bottom of the heater. Most of our systems are open and do not require expansion tanks. If you pipe the return to the top of the heater then it requires check valves that close the system and it requires thermal expansion control.

I’m surprised the complaint isn’t “ I’m getting hot water out of cold faucets “

 

[chackett]

Your check valve is in the wrong place unless you have another one in the cold line.

I like this piping diagram for top fed recirculating systems.
https://ohmefficient.com/instant-hot-water-recirculating-pump/View attachment 35751

But to be honest, I prefer to pipe the recirc line to the bottom of the heater. Most of our systems are open and do not require expansion tanks. If you pipe the return to the top of the heater then it requires check valves that close the system and it requires thermal expansion control.

I’m surprised the complaint isn’t “ I’m getting hot water out of cold faucets “

You are 100% correct that I mislabeled the hot and cold side. Pressure is 70PSI at the tank and the kitchen sink is probably the closest water fixture to the water tank minus the exterior bib.

 

[Twowaxhack]

Before we get too far off in the weeds let me tell you what I’d do if it was my house.

I’d remove that check valve and cap that 1/2” stub that’s left near the tee at the top of the water heater.

Then I’d pipe that return line to the bottom drain opening of the water heater and install a new check valve.

So instead of a top fed return, you’d have a bottom fed return.

There are pros and cons to a bottom fed return but for most homes it works well.

I believe this would solve all your problems. With the hot water anyway

 

[Twowaxhack]

@breplum maybe he will read over the thread.

 

[MicEd69]

Before we get too far off in the weeds let me tell you what I’d do if it was my house.

I’d remove that check valve and cap that 1/2” stub that’s left near the tee at the top of the water heater.

Then I’d pipe that return line to the bottom drain opening of the water heater and install a new check valve.

So instead of a top fed return, you’d have a bottom fed return.

There are pros and cons to a bottom fed return but for most homes it works well.

I believe this would solve all your problems. With the hot water anyway

I'm a little confused?

In February 2022, you posted:
With the return piped to the bottom there has been reports of problems for some systems, depending on the temp drop of the return water.

This can cause the burner to fire too often and the lag between on and off can over heat the tank. It’s basically stacking caused by the return water being well below the set point of the thermostat

So the manufacturers started recommending a top fed return that uses the dip tube. Manufacturers started making the dip tubes shorter to prevent stacking by the user, this was done years ago.

 

[chackett]

Before we get too far off in the weeds let me tell you what I’d do if it was my house.

I’d remove that check valve and cap that 1/2” stub that’s left near the tee at the top of the water heater.

Then I’d pipe that return line to the bottom drain opening of the water heater and install a new check valve.

So instead of a top fed return, you’d have a bottom fed return.

There are pros and cons to a bottom fed return but for most homes it works well.

I believe this would solve all your problems. With the hot water anyway

Awesome. Thanks, I can definitely do that. To just to restate what you suggested, so I know I understand it Cut and cap the line from the right side of the check valve (between the check valve and the verticle section of the cold line). Then basically re-plumb from the right side of the recirc pump and feed it into the lower threaded port (where my pressure gauge is currently attached)? Oh .. and installing a new check valve between the recirc pump and the threaded connector toward the bottom of the tank. Does that sound right?

Thanks!!
Chris

 

[chackett]

@breplum maybe he will read over the thread.

Did this response get edited or deleted? I don't see a message from @breplum in this thread. If there is another thread I should read over, I'd like to..

 

[Twowaxhack]

I'm a little confused?

In February 2022, you posted:
With the return piped to the bottom there has been reports of problems for some systems, depending on the temp drop of the return water.

This can cause the burner to fire too often and the lag between on and off can over heat the tank. It’s basically stacking caused by the return water being well below the set point of the thermostat

So the manufacturers started recommending a top fed return that uses the dip tube. Manufacturers started making the dip tubes shorter to prevent stacking by the user, this was done years ago.

Yes, I’d still pipe to the bottom. It’s rarely a problem. It’s my preferred method because we have open systems in my area. The original poster appears to have an open system right now. If he pipes it correctly through the top it will close his system.

That’s why I said there are pros and cons of a bottom fed.

IMO simple is best if it works most of the time.

 

[Twowaxhack]

Did this response get edited or deleted? I don't see a message from @breplum in this thread. If there is another thread I should read over, I'd like to..

He’s another plumber on the forum. I’ve summoned him to this thread.

 

[MicEd69]

Yes, I’d still pipe to the bottom. It’s rarely a problem. It’s my preferred method because we have open systems in my area. The original poster appears to have an open system right now. If he pipes it correctly through the top it will close his system.

That’s why I said there are pros and cons of a bottom fed.

IMO simple is best if it works most of the time.

I understand the pros and cons better after your post last February. But my confusion was that I had agreed with the person back in February that his current return piping to the drain valve connection was good. But then your post implied that piping to the drain valve wasn't the best way to pipe a recirculating line because the manufacturers started advising the returns to be piped to the cold-water inlet and that the water heater manufacturers have modified their dip tube lengths years ago to keep from "stacking" to occur in the water heater,

And now I find out that your "preferred" method it to pipe them to the drain connection of the water heater which is what I though was good until you responded with your February post implying otherwise. So, I guess I'll go back and do what I first thought was good last February, which is your preferred piping method anyway.

Thanks for providing your experience, insight, and best practice methodology on this forum.

 

[Twowaxhack]

I understand the pros and cons better after your post last February. But my confusion was that I had agreed with the person back in February that his current return piping to the drain valve connection was good. But then your post implied that piping to the drain valve wasn't the best way to pipe a recirculating line because the manufacturers started advising the returns to be piped to the cold-water inlet and that the water heater manufacturers have modified their dip tube lengths years ago to keep from "stacking" to occur in the water heater,

And now I find out that your "preferred" method it to pipe them to the drain connection of the water heater which is what I though was good until you responded with your February post implying otherwise. So, I guess I'll go back and do what I first thought was good last February, which is your preferred piping method anyway.

Thanks for providing your experience, insight, and best practice methodology on this forum.

If the system is open and you want to keep it open then bottom return piping.

If there is a stacking problem then you can adjust speed of pump, temp of water or pipe it through the top.

If you pipe it through the top then you’ll need to add thermal expansion control.

Personally if the system is open, I keep it that way unless there are issues with stacking. That means bottom piping.

Pipe it the way it works for the particular situation.

If the OP pipes his return line to the bottom and then he starts complaining of stacking…….I’ll tell him to adjust pump speed, temp OR pipe it through the top.

I believe the OP’s system to be Open, so I advised bottom piping as my first option.

Here’s what I posted in February for others that may be clueless and confused.


As I said, there are Pros and cons.