Pump friction heat

Jim_46

Hi, I was testing out the new radiant floor set up yesterday and I had the pump going for quite awhile. The Temp gauge after the pump showed the supply line to be pumping 95 degree water (temporarily while the crete cures)The supply pex felt warm but the return pex even after a long while still felt cold. The pump was getting hot I presume from friction from the motor spinning and unable to circulate fluid. Now I will obviously repurge the pex and try to get any air out and yes I am sure that the pump and check valves are all facing the right way but I have another suspicion. There is a swing valve in the horizontal return pipe just before the Tee that goes back to the 3-way mix valve. But also after the tee the final return pipe turns vertical and goes down into the main return pipe to the boiler. Here in this vertical pipe is a spring check valve to stop returning MAIN water from going up the pipe. Before I installed it I felt the spring and it felt fairly strong. The zone 2 pump is on the supply line aprox. 17 ft. from the boiler. It has to pump through two 200 ft. pex loops and then return another 17 ft. to the boiler through this spring valve. Could this spring valve possibly be to strong for the pump or do you figure its just air in the system? Its an Astro 30B.

Jim_46

Hi, I was testing out the new radiant floor set up yesterday and I had the pump going for quite awhile. The Temp gauge after the pump showed the supply line to be pumping 95 degree water (temporarily while the crete cures)The supply pex felt warm but the return pex even after a long while still felt cold. The pump was getting hot I presume from friction from the motor spinning and unable to circulate fluid. Now I will obviously repurge the pex and try to get any air out and yes I am sure that the pump and check valves are all facing the right way but I have another suspicion. There is a swing valve in the horizontal return pipe just before the Tee that goes back to the 3-way mix valve. But also after the tee the final return pipe turns vertical and goes down into the main return pipe to the boiler. Here in this vertical pipe is a spring check valve to stop returning MAIN water from going up the pipe. Before I installed it I felt the spring and it felt fairly strong. The zone 2 pump is on the supply line aprox. 17 ft. from the boiler. It has to pump through two 200 ft. pex loops and then return another 17 ft. to the boiler through this spring valve. Could this spring valve possibly be to strong for the pump or do you figure its just air in the system? Its an Astro 30B. Thanks JE

hr

Are you sure

the pump is spinning? If they get hot to the touch in a low temperature system, this often indicates they are stuck!

Most wet rotor pumps will take a lot of abuse. I'd isolate the pump, remove the motor from the volute with the four allen screws and check for solder or other debris.

Be sure to cool the thing down first. It may flash to steam when you open it it it is that hot.

They can also overheat if they cavitate, or are air locked. Noise is usually one indicator of this. A properly installed, sized, and purged system should be noise free, even at the circ itself.

If this is a concrete slab installation it can take hours or even a day to feel much return temperature, depending how many btus and gpms you are throwing at it.

Keep looking, if you haven't found something wrong, somethings not right

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Jim_46

Thanks Hotrod, no I don't know if it was spinning or not. It is completely quiet although you can feel it running. All I know is that the motor part is way more hot than the actual water going through it and I'm concerned that it may be trying to pump air. You don't think the spring check is too strong of a spring to open eh? Anyways I will check for more air in the loops. I may take the pump off and check for solder etc. as you suggested. Thanks JE

hr

It could be dead heading

pumping against a closed valve. I've seen Grundfos Brutes circ run for days against closed valves! I'm not familiar with that brand or model.

Generally higher head (larger hp and sometimes higher rpm) pumps won't last as long deadheaded.

The manufacture of the check will have a pop pressure rating. Rare to find a small check with a spring that strong, on the plumbing shelves. Guess you could always remove it to eliminate it from the equasion.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

DanHolohan

Here's the formula

for figuring heat rise inside a dead-headed pump.

Why you should never dead-head a pump

It pays to wander off the Wall.

Jim_46

Hi Guys
I never said there was a closed valve etc. I just mentioned the spring because I was looking for reasons for the pump to be hot. I looked at the brand new spring check valve and it is a 3/4" sweat that seems to have a brand name of Nisbo or something and reads 250 wog. So that shouldn't be too strong of a spring, correct? The pump itself is an Armstrong Astro 30B and it reads: Amps .80, Watts 80, RPM 3000 and Working Pressure 140 PSIG Max. It is pumping into 2 loops of 200' of 1/2" Pex. I will check for air in the loops in the morning as well as any solder etc. that may be in the pump. JE

hr

By closed valve

we mean any obstruction to flow such as a stuck check.

I have seen swing checks with brass flappers get soldered shut by over fluxing and adding too much solder. Could this have happened?

The check itself probably is not the problem, unless it is soldered shut

Sounds like a lot of pump for two loops. How did you come up with that size? What is the load (gpm) requirement of that zone?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Jim_46

Well I can check the two swing checks because they have cleanout access but not the spring valve I'll just presume it is okay. By the way when the pump is running the Flow gauges on the manifold does show that there is supposedly between a 1/4 and 1/2 GPM going through it. As for the pump sizing I should explain for any of the pros that think the home owners are trying to take their business. I had tried to go about it the right way and had gone to a Radiant floor supplier to find an installer. I was set up with both a heating contractor and a parts list. That pump was recommended after they did a heat analysis I don't know what the GPMs etc. were myself. I already had that very pump that I had used for only about a month or so on a Domestic water tank setup. Anyways the installer put the pex tube in the floor and went on to much bigger jobs and two months later he still couldn't find the time to finish what he had started and after a failed attempt at getting another contractor to finish the job I was forced to finish it myself. I have quite a lot of experience in soldering, wiring, carpentry etc. and I did my homework and thanks to the wonderful help we get from this website the job is just at the fine tuning stage ( I will add a picture of the Manifold board) except of course for this hot pump. If you think the pump is too big can I adjust it back a bit? There is a turn knob at the end of the motor with a screw driver slot. I could definitly feel the flow in the supply pex going into the floor and I did put a pressure gauge in the return line and it reads that there is pressure I just hard to tell how much flow is comming back out of the floor back to the boiler. Maybe the pump motor temperature is normal, I don't know.

Jim_46

Well I can check the two swing checks because they have cleanout access but not the spring valve I'll just presume it is okay. By the way when the pump is running the Flow gauges on the manifold does show that there is supposedly between a 1/4 and 1/2 GPM going through it. As for the pump sizing I should explain for any of the pros that think the home owners are trying to take their business. I had tried to go about it the right way and had gone to a Radiant floor supplier to find an installer. I was set up with both a heating contractor and a parts list. That pump was recommended after they did a heat analysis I don't know what the GPMs etc. were myself. I already had that very pump that I had used for only about a month or so on a Domestic water tank setup. Anyways the installer put the pex tube in the floor and went on to much bigger jobs and two months later he still couldn't find the time to finish what he had started and after a failed attempt at getting another contractor to finish the job I was forced to finish it myself. I have quite a lot of experience in soldering, wiring, carpentry etc. and I did my homework and thanks to the wonderful help we get from this website the job is just at the fine tuning stage ( I will add a picture of the Manifold board) except of course for this hot pump. If you think the pump is too big can I adjust it back a bit? There is a turn knob at the end of the motor with a screw driver slot. I could definitly feel the flow in the supply pex going into the floor and I did put a pressure gauge in the return line and it reads that there is pressure its just hard to tell how much flow is coming back out of the floor back to the boiler. Maybe the pump motor temperature is normal, I don't know. P.S. in the picture you will notice that I had to put small sections of copper and brass connectors to extend the Pex, the installer didn't leave me enough hanging in the basement. He didn't send down enough thermostst wire to reach the relay box either. Also the 3-way mix valve and Air eliminator etc. are over in the boiler room if you don't see them.

hr

Maybe it's OK

looks like a pressure gauge on the return. what does it read with all the pumps turned off? Now what does it read with the pump running. If you get a pressure increase, and the flow meters show flow, I'd say you have flow

Measure the pump temperature and see how hot it is actually getting. Still a lot of pump for 2 short loops. I'd guess a Grundfoss 15-58 Super Brute on speed 1 would be a better choice. They are not very expensive

Sounds like that Astro may be a high head pump? If so you may be exceeding the maximun velocity of 4 FPS through your system.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

hr

Here is your pump curve

http://www.armstrongpumps.com/Data/pdfbrochures/Links/01_05_002/10.12 Astro.pdf

If you only need to move 1 gpm you would best be served with a much smaller pump.

HREF="http://www.heatinghelp.com/getListed.cfm?id=144&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Jim_46

Thats good info Hotrod. The pressure gauge reads about 15 psi. when idle and anywhere from 18 to 20 psi. when flowing depending if the boiler is on or not. So there seems to be flow. I have to check into more on the specs of that pump such as the High Head part that you mention and the max. fps. etc. If it is too big I wonder why it was recommended for the job? Anyways I'm going to get it all running again and check the temp. of the motor and go from there. If I burn it out, I will look into the Grundfos 15-58 Super Brute. Thanks

Jim_46

Here's a thought. Here's a picture of the boiler supply connection. Where it shows a Tee after the Flow control valve on top of the boiler there used to be an elbow because it only went to the main Zone 1 radiator system. I have added the Tee to now also go to Zone 2 the radiant floor system. The pump for the new zone is 17' away under the heated floor. After the pump is a swing check. Also there is a check just where the return from the radiant floor connects to a tee at the boiler return. But what I have always wondered is should there be a one way swing check right after that tee in the picture. One for the direction of the new zone 2 and one for the direction of the main zone? Would the new zones' pump be working over time trying to pull water from the opposite direction of the main line after the tee. Or is this irrevelent?

Jim_46

For what its worth, I have a little digital thermometer with a long wire with a sensor on the end of it for also monitoring outside temperature, anyways, I taped this sensor on the pump motor. While the pump is pumping water which is 106 F the sensor is showing that the motor climbs to about 110 F it shuts off after awhile, I don't think the slab sensor is satisfied yet, it may be just shutting down from over heating. Does 110 F seem hot for the motor?

Ron Schroeder_2

Hi JE,

The Astro 30 is a wet rotor pump so the motor is in contact with the pumped fluid so the motor will be as hot as or a few degrees hotter than the fluid. I wouldn't worry about the motor overheating until you are over 210 degrees with 190 degree water or 20 degrees over water temperature with cooler water.

Ron

Jim_46

Thats very interesting to hear. Thanks Ron