# How to tell if a circulator is working?



## 907plumber

Whats the best way to make sure a circulator is working? I had a call the other day where I could have sworn the circulator was working, There was vibration in the pipe and a faint humming noise. Anyway, I left and the lady emailed me and said her circulator was replaced by another guy and it works fine now.


It seems like everytime I watch a tech check a circulator they dont have a clue really if its spinning or not either. I have seen them feel them, put a screwdriver on the body and listen and I did see a tool once that spinned in a clear glass, but the guy that had it didnt have much faith in it if I recall.


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## OldSchool

This is for direct drive motor only

There is a tool. It is a magnet in a little site glass. It only tells you if the motor is spinning. 

There could be a problem with the impeller. The motor has to be pulled from the body of the pump in order to verify the impeller is not damaged. At the same time you can check if it is spinning with power on

Sent from my portable office....yes I am at work


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## RealLivePlumber

Amp draw.


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## OldSchool

RealLivePlumber said:


> Amp draw.


Again this only tell you if the motor is spinning. Not if the impeler is intact

Sent from my portable office....yes I am at work


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## futz

RealLivePlumber said:


> Amp draw.


I've seen that fool so-called "experts". Motor still draws amps and hums when it's seized. :laughing:

I usually use the stethoscope (screwdriver against the ear and touching the pump body) method. Occasionally I'll get a pump that you can't be sure about. Usually those are the ones that aren't spinning full speed (sticky old bearings) and need replacing anyway. Worst case I'll pull the motor and power it up to see.


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## Widdershins

I put my paw on it -- If the pump is considerably hotter than the surrounding pipe, then it's shot.


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## eddiecalder

Amount of amps drawn compared to FLA of the pump will give you a better idea. Also check to see any shaving on the ground which could indicate a worn coupling. Depending on flow rates you can some time feel the water running in the pipe. You can usually hear the water as futs said as well.


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## Hydronictech1

The easiest way is to slowly close a valve in the line and listen for flow noise, if that isn't conclusive, then measure current draw relative to specs, and/or look inside.


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## Greenguy

If in doubt...replace it

I normally do Amp draw, listen to it, feel the vibration, pulling pump is last resort because at that time the gasket may not reseat properly, now you have two issues.


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## trick1

Amp draw hasn't failed me yet.

If the amp draw is less than 10% of rating on the pump , than usually means the improper is sheared.

If its more than 10% of its rating, that usually means a failing or locked rotor.

Iny experience a locked rotor means an amp draw of 1.3 amps or higher on a 007.

You could also perform a capacitance test on the start capacitor if your so inclined but I just replace the pump.


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## wundumguy

Amp draw.

1. Stick ammeter on circulator.
2. Note the Amps.
3. Gradually restrict the outlet side of the circulator.*
4. Note the Amps.
-- The current will drop off as the circulator outlet becomes increasingly restricted.**
5. Open the outlet side of the circulator.
-- The current will climb back to normal (for the system) as the outlet is fully opened.

* Depending on the system design (often the case for older residential systems), there may not be isolation valves for the circulator - apply a little creativity. In some commercial systems, either the return or supply header isolation valve may also serve as a circulator outlet isolation valve, etc.

** Some non throttling valves (eg., not a globe valve) may need to be almost closed before they begin to measurably restrict flow.
Restricting the outlet is similar to reducing pipe size. If the current draw reacts as expected, then the motor must be working and the impeller must be intact and coupled. If there is no change to the current draw despite the restriction/destriction, then something is wrong. For example, the motor could be on life support, the impeller could have fallen down and can't get up, the spring coupler doesn't want to hold hands with the impeller shaft, or maybe the valve is permanently open/closed regardless of the handle position.

I'd normally use this method with wet rotor circulators and small air-cooled pumps. Although, with air cooled pumps, you can already see if the motor shaft is spinning. The bigger air-cooled pumps with, eg., Armstrong No 5 seal bearing assemblies and up or the base mounted pumps, are normally installed with inlet and outlet pressure gauges, so we could just use the gauges to determine what's going on inside the volute.


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## ]3ones

temperature difference will tell you if the pumps working.

Or Boiler will hit hi limit if there's no flow. If the limit fails the relief valve will open. If that's plugged your boiler will go boom......all because you didn't know if the pump was working......lol:jester:


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## OldSchool

]3ones said:


> temperature difference will tell you if the pumps working.
> 
> Or Boiler will hit hi limit if there's no flow. If the limit fails the relief valve will open. If that's plugged your boiler will go boom......all because you didn't know if the pump was working......lol:jester:


Now the systems have way more than one pump....

If you are doing injection type of system or infloor there is many pumps..... the system area or zone the pump is doing could be air locked... 

Is it the pump or is it air locked


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## ]3ones

OldSchool said:


> Now the systems have way more than one pump....
> 
> If you are doing injection type of system or infloor there is many pumps..... the system area or zone the pump is doing could be air locked...
> 
> Is it the pump or is it air locked


When you get into multi zone systems yes it gets a little more complicated but not rocket science to tell if a pump is not working or the system is air locked. Most properly piped zoned systems will have T&P gauges installed If your using a Rahau/wirsbro manifold for a zone loop (e.g in-floor heating) they all got visual flow meters on them. I guess you can say there is no 1 step fool proof way to know the pumps not working if you don't understand the system short of taking the pump out.


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## OldSchool

]3ones said:


> When you get into multi zone systems yes it gets a little more complicated but not rocket science to tell if a pump is not working or the system is air locked. Most properly piped zoned systems will have T&P gauges installed If your using a Rahau/wirsbro manifold for a zone loop (e.g in-floor heating) they all got visual flow meters on them. I guess you can say there is no 1 step fool proof way to know the pumps not working if you don't understand the system short of taking the pump out.


That would be true for a header for infloor with flow gauges... Injection is not the case..... and now with the direct drive circ pumps... some guys are finding it difficult to trouble shoot.... especially if they are not the one that designed and installed the system....

A couple of years ago I was called out to an apartment building because there was no heat in the lower floor apartments..

The first contractor that went in told the landlord that his pipes were blocked and they had to do a total repipe of all the lower apartments for the heating system..

I was called out for a second opinion and quote...

I had to laugh that the first company had him sold on riping everything out....

I checked the main circ pump a # 3 armstrong,,,, motor was working and the spring coupler was spinning away still attached to the bearing assembly.....

So what was wrong????

I took the pump apart and the impeler ate right into the body of the pump housing...

Of coarse there would be no flow....

Changed the complete pump out and he had all the heat he wanted...

So yes some times you have to take it apart...


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## ]3ones

OldSchool said:


> That would be true for a header for infloor with flow gauges... Injection is not the case..... and now with the direct drive circ pumps... some guys are finding it difficult to trouble shoot.... especially if they are not the one that designed and installed the system....
> 
> A couple of years ago I was called out to an apartment building because there was no heat in the lower floor apartments..
> 
> The first contractor that went in told the landlord that his pipes were blocked and they had to do a total repipe of all the lower apartments for the heating system..
> 
> I was called out for a second opinion and quote...
> 
> I had to laugh that the first company had him sold on riping everything out....
> 
> I checked the main circ pump a # 3 armstrong,,,, motor was working and the spring coupler was spinning away still attached to the bearing assembly.....
> 
> So what was wrong????
> 
> I took the pump apart and the impeler ate right into the body of the pump housing...
> 
> Of coarse there would be no flow....
> 
> Changed the complete pump out and he had all the heat he wanted...
> 
> So yes some times you have to take it apart...


I ran into a very similar situation with an armstrong S 57 pump in a low rise apartment building the impeller was completely shattered in into pieces. Damn thing cost $300 to replace and 30 mins to figure it out lol


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## Miguel

Just clamp your amprobe over L1. It'll tell you lots. Nothing conclusive but it'll give you a huge insight over what's going on and save you mucho time troubleshooting.
Too high a draw and it's deadheading/airlocked somewhere (prolly not a pump problem); too low and it's likely a clogged or worn impeller. Change the pump. No draw but voltage present? Pump is pooched. Change the pump.

I learned from a guy that was completely unfamiliar with the wet rotor cartridge pumps. He'd first listen. then shine a light at the coupler, then put his hand on the motor and deduce from that whether it was the pump or some other problem. He even used to use a technique that I'd call dangerous but seemed to work for him. If all looked good but the "hand on the motor" made him go, "hmmm" he'd hold a screwdriver in the spring coupler opening and gingerley hold it and move it so that the rotation of the motor (the coupler) was hitting on the screwdriver shaft. He'd feel the vibration of the pump from that and be able to say if the motor was "weak", or if the pump (impeller, whatever, was shot). I could never master this process and just went with my meter.

Nowadays with DDC and other "smart" circulators it gets more difficult to troubleshoot but your best friend is still a good multimeter with an amp clamp. At least with that you can tell what your circulator is TRYING to do.

Btw, if it's a B&G and it goes "clackity-clack-clackity-clack" it's supposed to do that.


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## rjbphd

Or you can use a magnet tester that spin when holding at end of motor while pump is 'running' . Won't work on Taco pump.


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## vinpadalino

I read Amps. But if the circ dosent work you wont have hot water going to that zone or the house. Rule out what works first. Check tstat, aquastat has power, power at C1, power at circ. 
The temp at the boiler will be 180 boiler will be hot but zones wont, not that hard when you slow down and think about it. It's the only control that moves the water around the house..


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## jnohs

If the feeder is placed after the boiler but before the circulator then you can fill the line with some water with the boiler off and then when you turn it on you should fell a rapid change in tempature in the pipe, also you can shut off the boiler heat up a section of pipe and when you turn on the boiler feel to see if it is cooled rapidly. I do not think these ideas are the best way to check but in certain situations where the idea meets the application they do work.


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## rjbphd

Who let this wannabe 'master' jnohs in here?


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## 907plumber

So what is the amp draw supposed to be?


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## Miguel

907plumber said:


> So what is the amp draw supposed to be?


Usually sez it right on the rating plate of the pump. Good idea to measure the voltage first just to be sure it isn't running over/under rated voltage. You can adjust the current draw from that (ie: if pump is 120v but you only read 109v then curent draw can be expected to be slightly higher and visa versa).
Don't get confused with a FLR (full locked rotor) rating on the pump either. If you read that reading then the pump is siezed and is not turning! That rating is for the electricians to safely size the supply line and breaker size for given pump.
If you do this on a day-to-day basis then the numbers that you get will either make sense or non at all. That's when you start investigating the pump as the source of the problem (or suspect that someone has shut off a valvel, or there may be an airlock situation, etc.


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## Miguel

Wot the heck is a "valvel"???
Did I say that? Fat-finger typing. Sry. lol


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## highpoint

Today I was at a customers house who piped his own system! Worst crap I had ever seen. He had a pressure gauge, pump, pressure gauge. I asked him a about and he told me it was so u can dial in the flow In your system -like duh. I've never heard of this sort or math that turns psi into Gpm but apparently he can do it. It did however work well to close a valve and see which pumps were working or not as the pressure would go up.


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## rjbphd

highpoint said:


> Today I was at a customers house who piped his own system! Worst crap I had ever seen. He had a pressure gauge, pump, pressure gauge. I asked him a about and he told me it was so u can dial in the flow In your system -like duh. I've never heard of this sort or math that turns psi into Gpm but apparently he can do it. It did however work well to close a valve and see which pumps were working or not as the pressure would go up.


 So you'll need a heating guy for this job?


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## pilot light

Always pull the pump!:yes:


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## eddiecalder

highpoint said:


> Today I was at a customers house who piped his own system! Worst crap I had ever seen. He had a pressure gauge, pump, pressure gauge. I asked him a about and he told me it was so u can dial in the flow In your system -like duh. I've never heard of this sort or math that turns psi into Gpm but apparently he can do it. It did however work well to close a valve and see which pumps were working or not as the pressure would go up.


All you need is the BTU/H and the Temp rise.
BTUH = GPM x Delta T x 500


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