Circulator function verification?


  #1  
Old 10-31-05, 07:36 PM
BobW
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Circulator function verification?

I bought a 5 year old house with Weil-McLain CG 12 propane radiant heating system several months ago. I thought the radiant heat was working but never really tried to use it to warm things up because it was 70 outside. This weekend I tried to use it for real and discovered the system would not heat the floors in any reasonable manner. So some tests:

1) 24 VAC controls from thermostats and to 4 zone valves all have good signals and act as expected. On demand 24 VAC goes to the valves, otherwise blocked by thermostats.

2) Boiler lights off rising to around 170 and around 20 PSI as expected.

3) TACO 007 F5 circulator has 120 VAC to its coil and starting cap when a thermostat is demanding heat.

All sounds fine but until this weekend when we tried to heat floors as a test, with only the pilot on as I discovered during the real investigation, the system had a fairly loud hum to it. I wrote that off until this weekend when I got the main burners on and running as required, but without resultant floor heating. The hum has now disappeared and the output to the house is very hot as expected but the return is tepid regardless of the zone or zones demanding heat. And the circulator is very hot to the touch and makes no noise at all anymore. At one point I thought it might be jammed and not knowing anything about the circulator I started to remove what I assumed was it's back can to see if I could make the rotor rotate. After loosening the 4 bolts a bit it began to spit out the antifreeze (it's a closed system with expansion tank, and as I now know the TACO 007 F5 is a wet rotor with replaceable cartidge) so I immediately screwed it back down tight. After that the first time I asked for heat the two zones actually began to heat. Then I turned them off, fiddled some some more, tried a few other sanity checks, and from that point on, despite good boiler pressure and temperature and high temperature output no heat came from the floors, the return pipe was cold, and no noise from the circulator. Same symptoms as before the momentary apparent succesfull function of the system.

So I think the circulator is frozen, working against it's coils, and thus running hot when it tries to move and can not rotate.

1) Is there any way to tell if the TACO 007 F5 is actually spinning when powered on, other than by heating up the return pipe?

2) How does one replace the cartridge (no instructions on any website including TACO).

3) If you replace the cartridge by simply removing the back and replacing the cartridge, that will result in coolant all over the floor, so how do you refill with antifreeze given that the cold water source is just water and there is no obvious input for an antifreeze load? (I do not know at the moment if the system has valves above and below the circulator, which TACO does make, which could limit coolant loss. But any loss will put air in the system requiring bleeding, I assume, which I will also need to learn how to do.)

Many questions, few answers. Any comments welcome. Never had one of these before and I can use the help.
 
  #2  
Old 11-01-05, 05:27 PM
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Circulator

You can check the circulator with a clamp on amp meter. A reading of zero would indicate the pump is either not getting power or is off on overlaod. If memory serves me right, normal current load is about 0.7 amps. A reading over that would indicate some kind of problem leading to a possible overload.
 
  #3  
Old 11-01-05, 05:50 PM
BobW
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good suggestion

Grady,

Good idea. Quoted current is 0.71 A. Now I wonder
if I have a clip on amp probe for my DVM. Have to look.
 
  #4  
Old 11-02-05, 05:03 AM
G
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The current draw test is a good idea to verify if the pump is working. Its not like the old B&G 100 pumps which are so easy to tell if they are running.

Cant you just also wire your DVM in series and check for current draw that way if you dont have a clamp-on ammeter probe handy?
 
  #5  
Old 11-02-05, 05:22 PM
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Dmm

Yes you can use the DMM if it has an amp function. I don't know what locked rotor amps on a 007 would be. Most DMM's have a max of 10 amps. I doubt the 007 would draw 10 amps even with a locked rotor. If the meter has a capacitor test function, you might want to check the cap.
 
 

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