Circulating pump not starting …


  #1  
Old 10-26-19, 08:14 AM
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Circulating pump not starting …

DIY Community:

I have a 3-zone hot water baseboard heating system that consists of a Utica MGB1002 boiler, a Taco 007-F5 circulator, three Honeywell zone valves, and a Honeywell L8148E aqua stat.

While I was out of town last week, I could tell that something had failed because all three thermostats were calling for heat, but temperature was dropping.

The gas pilot is on and tank trmperature based on the analog gauge is 190 F. I can hear the zone valves opening and closing and believe that the three end switches are closing when heat is required. There is no water leak near the circulator and I don’t hear it try to start, nor do I hear the circulator relay in the aqua stat click on.

At this point, my best guess is that the circulator relay in the aqua stat has failed. Have I missed something? Are there other diagnostic tests that I can perform?

If I am confident that the zone valves are open, can I temporarily hard wire the circulator pump to an AC source to confirm that the pump starts and runs when it has power?

Thanks for your consideration.

John
 

Last edited by shott; 10-26-19 at 08:24 AM. Reason: Addin aquastat model
  #2  
Old 10-26-19, 11:45 AM
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There is something wrong with the controls for the pump. If you have a multimeter and know how to use it, and have an electrical schematic for the system, you need to systematically troubleshoot the problem. If this is outside your experience and skill level, then call a pro whose references you've checked.

Hay-wiring 120V directly to the pump is potentially unsafe and won't substitute for methodical troubleshooting.
 
  #3  
Old 10-27-19, 02:07 PM
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Note: I have done some further, more careful testing.
I can now measure 120 VAC across C1 and C2 when one (or more than one) of the zones is calling for heat. The circulator relay IS kicking in ... I was wrong on that part in my original post.

Also, I have confirmed that once the boiler has cooled to something closer to 160 F, that the main burner does come on for a minute or two when there is a call for heat. While I do not have the high-limit circuit, it must be working because it cuts off the main burner when the boiler tank reaches about 190 F.

So, at this point, everything that I can easily test electrically is working ... and it seems more likely that my Taco 007-F5 has failed..I'm about to turn off the system completely to let it cool and shut off voltages in preparation of a pump replacement.

I do have two followup questions:

1. The Taco is a cartrige pump so I can (if I can find one locally) replace only the cartridge rather than the entire pump. However, this is likely a 30 year old pump, Would I be smarter to simply replace the entire pump rather than only the cartridge.

2. While I don''t have valves directly on either side of the pump, I do have valves to shut off both the supply side and return side for each zone. Should I shut them before removing the pump so that I only drain the boiler and main manifolds rather than draining the zones as well? I do have a valve with hose bib directly under the pump for easy draining.

Thanks for your consideration.

John
 
  #4  
Old 10-27-19, 04:53 PM
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A Taco wet-rotor pump does have a replacement cartridge. The cartridge is a somewhat passive device - replacing it is unlikely to solve your problem.

When there is a call for heat, are you getting 120-V at the motor's terminals? If not, then you need to forget replacing parts on the pump, and systematically troubleshoot with a multimeter to find out where the voltage is being lost. Or else, call in a qualified pro.

Good luck.
 
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Old 10-27-19, 06:50 PM
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Thank you for your response. Thus far, my measurements were in the aqua stat on the two terminals that run to the pump. In the morning, I will make sure that voltage gets all the way to the pump terminals at the other end of the armored cable.

However, thus far it is looking more like a problem in the pump than what I originally thought was an upstream electronics problem.

Thank you for helping me better understand what the Taco cartridge. Although I won't know until I visit my local plumbing/HVAC supply house, I expect that I'm more likely to find a full pump than a cartridge anyhow.

Thanks again. I appreciate your having taking the time to respond to my questions.

John
 
  #6  
Old 10-27-19, 08:45 PM
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Yes, you can temporarily run the Taco to verify it is running. That is a basic diagnostic test.

Taco 007 frequently go, so best move is to by a new $98 Homedepot replacement. Replacement cartridges cost $90, so new pump is better, can use it a cartridge. It is always good to have a spare.

If the motor is bad and replacing entire pump is an issue, a quick fix is use new motor as cartridge.

Installing isolation valves, typically 3/4 ", on either side of pump can make future replacement and service easier, especially on a cold winter day.

On of the problems with Taco is the inlet port gets blocked with material buildup so removing them for inspection is worthwhile.

https://www.homedepot.com/p/Taco-Com...07F5/205741246

https://www.supplyhouse.com/sh/contr...+007+cartrodge
 
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Old 10-28-19, 02:52 PM
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Thank you so much for your detailed response.

I was able to find a Taco 007-F5 at a local plumbing supplier this morning (they had 58 on the shelf ...) and had the heat running by noon.

It took me longer to drain the system than to replace the pump, so I appreciate your suggestion to add isolation valves on either side of the pump. As it will get down to 25F tonight and 14F tomorrow night, I didn't think that today was a good time to add those valves ... particularly because my main input line to the pump is 1" copper and I didn't want to run the risk of badly soldering a threaded fitting on a one inch line.. However, this summer, when the heat is off, I think that I will add those valves and have a spare pump on hand.

What did I find when I took apart the pump? It was initially frozen and would not move. There was a lot of reddish brown grit in the area and I expect that grit had worked its way into the bearings or rotor and jammed things up. I was able to free it up so that it would turn but you could still tell that there was enough grit to impede smooth operation.

Thanks again for all of your valuable suggestions and insights. I greatly appreciate your help.

John
 
  #8  
Old 10-28-19, 04:27 PM
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That's good news. I wonder about the source of the grit that jammed the pump? Maybe you need a whole-house filter on your incoming water. They do help - you need to replace the filter elements every six months or every year.
 
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Old 10-28-19, 05:39 PM
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Thank you for that thought. I don't see too much grit in the aerators of my sinks and had thought, maybe incorrectly, that the grit that I was seeing was rust particles from the cast iron boiler and pump even though my house plumbing is copper. We DO have hard water, but I would have thought that acidic conditions or introduced oxygen would be more likely to cause rust formation. I fear that the boiler may be original to the house which makes it 30 years old. It may be nearing the end of it's service life. I will certainly keep an eye on things.

Thanks again for your input and comments.

John
 
  #10  
Old 10-28-19, 07:35 PM
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One of the best whole house filters is a Watt WH-WLD. The top rotates 3 position valve to filter, shut off or bypass. Clear plastic body shows filter status.

I installed mine on fresh water feed to boiler and hot water tank, rather than at meter for whole house. Changed filter after two years when it looked rusty. There was not pressure drop.

https://www.ebay.com/i/323887094339?...BoCuaUQAvD_BwE

https://www.amazon.com/Watts-Premier...32W/ref=sr_1_7
 
  #11  
Old 11-02-19, 08:53 PM
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As a DIYer set up my system so on cold winter day can deal quickly with issues.

Put 1/2" shut off ball valve on expansion tank.

Water pressure regulator / safety valve assembly has unions on either side and shut off valve to facilitate service and removal.

All zones can be isolated and opened with rest of system still heating house.

Have two circulator system, so some zones can be operated when other is out of service.

Oil lines have 24” hoses and Ό “ ball valves so burner, filters and pump can be easily serviced with minimum mess. To change nozzle remove 3 nuts, pull burner then replace it. Fifteen minute job.

Boiler is 60 year old, cast iron 86% efficiency, fired at 50% of rating due to reduced heat load from insulation and new windows, doors, etc. Would replace boiler only if irreparable leaks developed.
 

Last edited by doughess; 11-02-19 at 09:11 PM.
 

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