Boiler Taco Circulator Pump hot

Jbraun3043

Just replaced my old oil boiler with a new nateal gas boiler. Had to move the moutin too. Now the circulator pumps are heating up. Thw pippes to both sides of the pump are cold, but the pumps are hoy to the touch. I dont want to blow the pumps, and I blead the lines of air. Does anyone know what i am doing wrong?

Jamie Hall

Looks like you have a drain and purge valve just above each pump. Do you get any water out of the drain if you open it? Chances are good the system is air bound, and needs a good purge.

SteveSan

What is the model numbers of the Taco pumps? On the black disc on the back of the motor, you will see the normal amp draw. If you take an amp reading and are at nameplate amps the pump is fine. If around 1.5 times that rating, the cartridge could be locked or as Jamie said, you need to bleed the system.

Under normal conditions our pumps usually run about 140-160 degrees.

If you have any questions, please give Taco Technical Services a call during normal business hours Mon-Fri 8am-5pm EST 401-942-8000 and just ask for Technical Services

HVACNUT

You need purge stations on the returns, not the supply's. And I only see one return.

EdTheHeaterMan

There is a 3/4 x 3/4 x 3/4 tee on top of the boiler with blue PEX going to that return. That may be a different problem for a colder day. @HVACNUT

If your pipes are cold to the touch and the motor is hot, then you are not moving water. There may be water at the pump location but if there is air in the loop that the differential pressure can not overcome, that water ain't movin'

This is what my mind's eye sees inside the pipes

In the top system, the radiators need to be bled (the air let out), but the pump is off so the water in the supply and the return are the same level.

In the Lower system where the pump is operating, the pump's differential pressure (or head) is lifting the supply water a little, and pulling the return water down a little. But the pump is not powerful enough to make the water climb over to a radiator and waterfall into the return.

If it were powerful enough to do that, you would get some circulation, and if properly designed, it may even start to relocate some of the air in the radiator to the air purger (not shown) and correct itself over time. But not all systems are properly designed. That is another story. You can read about it in a book called Pumping Away, sold here in the store.

Jbraun3043

Thank you guys. I checked the system for air, and the radiators for air, and no air came out and only water. I have not checked the amps. I will do that. The system had power, but was not running, and it still was hot

HVACNUT

Ok, you're purging in reverse.

The circulators are pumping away? Arrows up?

Closing the ball valves below the circulators, and purging from above the circulators. Are you watching the pressure as you're purging? Don't let it get too low. If the fill can't keep up with the purge, squeeze the hose and let it catch up.

The emitters are all piped series loop? No branches?

HVACNUT

You have bleeders on your radiators? Everything has been re-piped, not just piping near the boiler?

Jbraun3043

THe arows are up.

Jbraun3043

When i replaced the boiler, i also replaced the old steal basement pipes, wirh PEX. The steal used to connect to copper, that ran thrpugh the zones. Now it is PEX run to the copper

mattmia2

Does that boiler have a built in circulator?

Jbraun3043

Only the round side is warm. The section that is connected to the pipes the same temp as the rest of the pipes. Both pumps feel this way

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1812023#Comment_1812023

This^

The primary circuit is lacking the circulator. I do not believe this boiler has an internal circulator.

Without it, you get nothing to the pumps.

EdTheHeaterMan

Removing all the Iron pipes and replacing those pipes with PEX!?! that is your problem. Did you follow the original piping design with a main PEX and Tee fittings to each radiator? OR did you make home runs from each radiator back to the boiler room?

Some pictures or a line diagram of how the new piping is configured will help.

If i were going to remove all the big iron pipe in the basement, this is how I might run the PEX pipes to a manifold near the boiler. Many of the Pre-built manifolds are equipped with flow meters to help in balancing the system.

Jbraun3043

I ran everything in a similar manet to how it was formerly done. Each pump to a zone (1st floor, and second floor). Both floors join back at the return.

Jbraun3043

I know this is odd. And anoying. Thank you all for looking at this

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1812126#Comment_1812126

Did you originally have a primary/secondary setup on the old boiler? I tend to doubt it. This new setup needs a primary pump to circulate fluid through the boiler. Your two pumps are isolated from the boiler and cannot do anything to circulate fluid THROUGH the boiler because it is on a completely different circuit. We refer to what you have is "hydraulically separated". The two circuits (the boiler and the system) are isolated from each other. Each needs a pump (or more than one pump in the case of a zoned system……..two in your case).

LRCCBJ

Refer to page 21. You can see the primary pump.

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Triangle-Tube-INS199S-User-Guide.pdf

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1812126#Comment_1812126

I am seeing this in my minds eye:

And looking at this, I can see that is is very hard to get all the air out of the system if it is piped this way. With PEX tubing there will be lots of high and low spots that will trap air. using the radiator vents will fill the radiators and still leave air pockets. Trying to purge the PEX with high velocity water (like a series loop system) will not work, because the water has too many paths the follow. You will need more valves and purge stations if you are connected this way.

I dont know if you will ever get all the air out. Here is one thing to try. After you have all the air that you can possibly remove by venting and purging, try to fill the system with 28 PSI pressure. this will compress the remaining air into its smallest bubble. Then run the pump and see if the water will start moving past the air separator. (You do not need to operate the boiler to run that pump. You just need to wire nut an extension cord to the pump leeds and plug it into a wall outlet. You are doing a test, this is not a permanent solution.)

If you get the water to move , then continue to run the pump for an hour or more to see if any air gets removed. with the circulator pump still operating, turn on the boiler and introduce heat into the system to accelerate the air removal process.

If that does not work then you will need to do some repiping add purge valves at each radiator and remove the air individually from one loop to the next.

EdTheHeaterMan

I would have used this design where each radiator has a home run to the boiler room where ther is a manifold for purging each radiator separately.

And the return would have a separate line to the copper piping below the boiler. and depending on the total BTU output of all the radiators combined, your "shared piping" may need to be larger that the PEX you have.

I would recommend one of the prebuilt manifolds like this one. it has individual valves for purging and balancing each radiator, a purge valve and individual flow meters built in to the manifold.

Or you can build your own manifold with copper or PEX fittings and tees and valves if you have the time.

And since I am basically telling you that your design needs to be completely redone, did you use Oxygen barrier PEX tubing? If not all those steel and iron pipes that are connected to the radiators and the radiators themselves will start to rust internally and in a year or two you will be there flushing out all kinds of rusty mud from your system.

Jbraun3043

I love that design. I a looking to pull everthing andre running it via the manifolds, like you show. I would have no more T connectors. I am looking at the boiler. The boiler has its own internal boiler pump, on the return side. I have the other two circulator pumps set to chanel 1 and Chanel 2.

EdTheHeaterMan

Your boiler has an internal pump that is strong enough to move the return water thru the boiler and back to the primary loop. It is not strong enough to operate the entire system. that is why the manufacturer recommends on Primary/Secondary piping with a separate system circulator. (two system circulators in your case). How many radiators are on zone 1? How many radiators are on Zone 2? I would get a manifold with at least one additional opening for future use. That one can stay capped off. I remember using Wirsbo/Upinor manifolds that are 2, 3, 4, or 5 branch circuits. If you needed 6 you just put two of the 3 port manifolds together. There are many more options available.

You will need to know a little about pipe sizing, a 1/2" pipe can handle 15000 BTUh and a 3/4" pipe can handle 40,000 BTUh. If uoir m=boiler NET rating is over 40,000 BTUh, you may need to feed the mainfolds with 1" shared piping. I see that all of your return piping is sharing one 3/4" PEX tube. That will be a problem if you need to move 50,000 or 75,000 BTUh on those cold nights in mud winter.

Look at this book on Zoning Made Easy to better understanding why you may need to use 1" or even 1-1/4" pipes in your system design.

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/108119-Reference%20Guide.pdf

And here is one of the handy Rule of Thumb charts on pipe size selection.

hot_rod

I think wet rotor, water lubricated circulators get as hot as the water flowing through them. If you run 180f boiler temperatures, the pump may run that hot or hotter