No hot water, is it the pump, or did I do something wrong?

steam-rookie

So, as I mentioned in my last post, my hot water storage tank blew a leak. Its ridiculously old, and rusted out on the bottom. We had about a 1/2 inch of water on the basement floor. It took a few hours, but all of that has been cleaned up.

I purchased a new tank, and a whole **** load of copper fittings. Yesterday I removed the old tank, and installed the new one. I spent about 8 hours dry fitting, cleaning, fluxing, and soldering. Then came the moment of truth. I turned the water on, I opened the hot water faucet that was closest to the tank. I listened while the new 40 gallon tank filled up, and to my complete amazement. No leaks. Every soldered joint that I did was good. Water was now flowing through all the pipes, the new tank, the pump, and all the faucets in the house. Not a drop of water was leaking. I felt like I was now on the home stretch.

Next, the new tank had to be wired up. Not as a hot water heater, but just as a storage tank. I have 110 going in the top of the tank, it bypasses the top thermostat, and top heating element. It only attaches to the bottom thermostat, and also the pump.
It was now time to turn on the boiler.
So, I hit the red switch. The boiler fires right up, and I can hear the pump go on.

My wife and I are now doing the happy dance.
The happy dance did not last very long. About 5 minutes. That's about how long it took for us to realize something was wrong. The pipe on the top on the new tank was getting unbelievably hot. The pipe at the bottom of the new tank, where the pump is, was ice cold.

So that's why I am starting this thread. We still Have NO HOT WATER.
I have attached before and after photos. Absolutely nothing is different, other than the new tank. Everything was plumbed exactly like it was. It's been working with this configuration perfectly fine for 30 years. We very rarely ever run out of hot water.

What could possibly be wrong. The water flowed freely through the pipes, the pump, the coil, the new tank, and all the faucets.
Is it possible that I can hear the pump running, yet it's not pumping the water. Could my luck be that bad. Could the pump have broken at the same time I had the leak.
The leak was catastrophic.
The entire tank emptied out.
I did cut the power to the pump, but it ran for a few hours with the empty tank.
I can hear the pump motor running, but it's not circulating any water.

I would hate to change out the pump for a new one, without knowing for sure that is the problem.
I'm guessing that it's my only option. It’s a,
Little Giant circulating pump model # CMD-100-3B
It appears that this model is no longer made, or available.
I would also welcome any suggestions as to what an equivalent model pump I could use.
Any input on this whole mess would be welcome.
Thanks,
Steam Rookie

HVACNUT

You removed the swing check.
It needs to be there.

Larry Weingarten

Hello, I'd like to see a ball valve right at the base of the tank, so you could close it and open the drain valve. This would force water and importantly, any air out of the plumbing and through the drain valve. It could be that the pump is air-locked.

Yours, Larry

SuperTech

I think it being air bound like Larry mentioned is the most likely scenario.

It's strange that your setup uses an electric water heater for a storage tank. If it were mine I would wire in 240 volts to the elements as well so I could use them if the boiler isn't working for some reason.

HVACNUT

> @SuperTech said:
> I think it being air bound like Larry mentioned is the most likely scenario.
>
> It's strange that your setup uses an electric water heater for a storage tank.


Booster tanks are very common by me. Not so much now, as people are realizing it's not much more efficient than a tankless coil. So when it's time to replace the heating system, a boiler with a tankless option isn't even offered. And rightly so.

The OP removed the check valve (seen between the boiler and tank on the circ line in the first pic) and needs to be there to prevent cold mix.

steam-rookie

Thank you for the reply's. The original set up, long ago, did have a check valve. We replaced the old washing machine, with a new, front loader. The water hammer was unbearable. Many things were tried to get rid of the banging. The only thing that worked was getting rid of the check valve. The banging stopped, and all was nice and quiet.
I know its not ideal, but it has been working fine, without the check valve, for many years now.
Larry W, and all,
"It could be that the pump is air-locked."
That's it !!
I connected a hose to the drain valve at the bottom of the water tank. I then opened a hot water faucet upstairs.
As soon as I turned on the hose, the pump began to rattle, rock, and roll, very loud.
So, I put my hand on that bottom pipe, and low and behold, it was starting to warm up.
However, there was still a little bit of a rattle, in the pump.
I did manage to take a pretty long shower, before the hot died out.
All day the pump is on. It is not overheating, just running all day.
The rattle noise is still there. The hot water in the house is just not good, or there at all.
What I think I need is :
The correct way to get the air out of that pump.
Any suggestions would be very welcome
Thanks,
Steam Rookie

Larry Weingarten

Hi, Glad the system is giving you some good clues! How difficult would it be to add a ball valve right at the tank drain, between piping and tank? With that valve closed, you could flush any air from the system.

Yours, Larry

HVACNUT

Glad it got fixed by the advice from @Larry Weingarten .

That being said, I've never come across that issue, and can only assume it's because the check valve is not there so the circulator was dead heading due to water flowing in both directions.

In addition to the valve Larry recommends, I would install the check valve. You didn't get rid of the water hammer issue, just one of the symptoms. Seems like you also need a domestic extrol.

steam-rookie

Its still not working. The pump is still making the rattle noise.
I am getting so frustrated. I have tried everything to get the air out of that pump. I have even emptied the tank, and refilled. Still, no change. You can probably tell from the tone of this message how aggravated I am getting.
The system has worked perfectly fine for years, without the check valve. It has also been fine all those years with the tank drain in the current location.
Everything was put back exactly the way it has been for 30 years. The only change was the new tank. What the f__k.
The only thing left would be that maybe the pump is broken.
There is no way to know this. There is no way to test it.
Also, the pump is no longer available. They don't make it anymore.
If I go to all the trouble, to cut that pump off, I would at least like to have a new one to put back on.
I can cut the pump off, take it apart, and see if anything is broken in side. But if it is, I do not have a repair kit, and I do not have another pump. So what then??
Does anyone know what the replacement/equivalent, pump might be.
Sorry this post sounds so angry.
Steam Rookie

HVACNUT

Check the manual I posted.
Install the check valve.
If that doesn't work I'll eat your hat.

steam-rookie

Thank you Hvacnut.
I took a good look at the diagram. It would mean I take the whole thing apart, and completely re pipe it with the pump on top.
In regard to the check valve.
I have had the check valve on and off several times over the years. I have tried both kinds. The spring type, and the other kind. Both had the same effect. a loud bang, every time the washing machine would fill. this was many times per load, and we could just not bear the banging. So what I did is remove it altogether. That reduced refused the banging, and made laundry bearable. It has been without the check valve altogether now for years. I have noticed the back flow that you are describing. I have felt the tug of war in the pipe, between the hot and the cold. Despite this, the hot always wins, and we have plenty of hot water in the house. So, nothing has changed, except the tank.
I am not looking to change everything around that has been working, more than adequate, for so many years.
I just want it to work, like it used to, with the old tank
Steam Rookie

HVACNUT

You dont need to re pipe. Just install it on the discharge side of the circulator.

And installing a domestic extrol will eliminate or at least quiet down the bang from the solenoid on the washer.

steam-rookie

Thanks for the reply,
I will look to see if I still have the check valve. Its not a big job to cut that in.
Like I said, I have had check valves in that location in the past.

Whether or not the check valve was there did not have any effect on my hot water system.

In other words, the hot water loop, WORKED WITH or WORKED WITHOUT, the check valve.

WHY WOULD THAT BE A DIFFERENT NOW?

I suspect something is wrong with that pump.
I should not have to disconnect the power from the pump, every night, before I go to bed. (it never turns off, i don't like the idea of it running all night).

I am going to try to post this tread in the hot water section of this forum. Maybe I can find out more about what might be wrong with the pump, or find out what pump I should buy to replace it.

I was convinced the rattle noise was air in the pump. Things did get a lot better when I bled/burped the system.
However:
The pump still has a slight rattle sound.
The discharge pipe still has a vibration sound
The pump runs 24 hours a day. (unless I disconnect it)
The discharge pipe is ice Luke warm-to-ice cold.
The pipe never heats up the way its supposed to.
The pump is not pumping.
Its a circulating pump, and it is clearly not circulating.
Steam Rookie

BobC

If there is air in the pump it won't work. If you burp the system does tit seem to work right for a little bit and then fade? That would mean air is getting into the system.

The impeller on that pump could be worn, nothing lasts forever. The fact it's running nonstop is doing a number on your electric bill. If it were mine I would install a check valve and a new pump because the cost of running it 24/7 is going to add up fast.

The more you dither, the higher your electric bill will be.

Bob

JUGHNE

One thing that may be different from the old tank to the new tank are the nipples on the top of the new tank.
IIRC, they have check valves build into the SS nipples.
IDK if this matters in this case but someone here may know.

JUGHNE

With the end of the heating season here, you could connect 240 to your WH and shut down the boiler.
Then you could clean your sight glass fittings.
Add air chambers near the washer.

Perhaps your insert coil is limed up causing problems for flow.

SuperTech

> @JUGHNE said:
> One thing that may be different from the old tank to the new tank are the nipples on the top of the new tank.
> IIRC, they have check valves build into the SS nipples.
> IDK if this matters in this case but someone here may know.

This is correct. Many new tanks have "heat trap" nipples in them. They are supposed to serve the same purpose as the inverted trap on the hot water outlet that many guys neglect to pipe in. They are supposed to prevent unwanted convection.

@Steam_Rookie if you are going to replace the circulator I would check the amperage draw before removing it. If it does need replacement look into a circulator with an integral flow check built in. The flow check can be removed and re-installed very easily.

Tim_D

You need a check valve between the pump and the coil, an expansion tank and a way to purge. The purge has to be between the pump and the coil as well so that it pushes water through the pump and check valve.

steam-rookie

Hi Larry, and everyone that has tried to help,
I am finally starting to calm down now. Plumbing is a lot more than just water in a pipe. For a rookie like me, it can be very frustrating.
I am still having air trapped in that pump. It is still not working the way it should be. (or at all)
Larry said,
"I'd like to see a ball valve right at the base of the tank, so you could close it and open the drain valve. This would force water and importantly, any air out of the plumbing and through the drain valve."
HVACNUT said,
"In addition to the valve Larry recommends, I would install the check valve".
Also, Tim D Says:
"You need a check valve between the pump and the coil, an expansion tank and a way to purge. The purge has to be between the pump and the coil as well so that it pushes water through the pump and check valve."
So. What should I do?
I attached two photos with both plans.
Steam Rookie

Larry Weingarten

Hello, I'm not sure it's an either-or. But why not try installing the ball valve as I suggested, flush things and see what happens? From there, if it isn't working, there is more to do.

Yours, Larry

Jamie Hall

I honestly haven't been following this whole thing that closely, however I have become curious.

As I look at the photos, here's what I think I see: the cold feed for the hot water system comes down from somewhere to a T on the line connecting the boiler to the little pump, and has a shutoff valve on it. The other boiler connection goes into what I assume (can't see on the photos) the cold inlet to the new hot water tank. There's a valve on that line, too. Th hot water to the house comes out of what I presume is the hot water outlet. Then at the bottom of the tank instead of the usual drain you are hooked up to a line which goes to the inlet of the little pump and I presume there is a valve on that, too.

Correct?

Now. If we are all on the same page, have your tried this? Close the domestic cold feed line and open a hot water tap somewhere. You should get no flow. Now turn on the boiler and the little pump. The line from the boiler to the tank should get hot. Probably very hot. If it does get all the way over to the tank at very close to the same temperature fairly quickly, you have flow in that pipe. To confirm, patience. Eventually the outlet drain from the tank should at least get warm, confirming that there is not only flow, but that the contents of the tank are being warmed up.

If you are getting no flow, either the pump is air bound, which is unlikely, or the pump was damaged by running dry -- which is quite possible.

A check valve at the outlet of the pump, to prevent cold water from getting into the tank bypassing the boiler, would be a good idea, but I can see that it might well have worked without it, provided the pump has enough shutoff head to overcome the tendency to backflow.

dopey27177

Dumb question. Did you tie the supply to the tank in the right inlet tap. There supposed to be a dip tube in the inlet where the incoming hot water goes to the bottom of the tank and rises to the top and out the inlet port.


Jake