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[ronh]

Hello

I have a Central boiler 6048 model. It was installed last year and since then I have replaced the pump at least 10 times. The parameters are as follows: Boiler is open system that is connected into the existing boiler. Physically, its 100 foot from this connection and consists of 50' of 1 1/4 pex and 50' of 1" copper. The total distance around to the registers is around 250' of 3/4" copper and 3 different zones.  Water temp in the boiler was at 190F and 400 foot above sea level with the pump 3' below water level.  I started out with an 009 pump and it went out in 3 weeks. Tried the 008, same thing. Spoke with Taco and suggested 007 in series feeding 009. The 007 burned up in 5 days. After going thru the calculations, I believe the 009 is running at 9 GPM and requiring more NPSHR than my boiler setup can provide so I turned down the temp to 175F to see if that lowers the NPSHR and fixes the problem. And yes, the voltages were checked out already. Taco suggested going to the 200-20WB series pump.

Any help would be appeciated as I have had several local "experts" look at this with little help.

[yoderheating]

 I'm sure you have already thought of this but the pumps must be installed in a certain way. Certain positions will cause them to fail.

[ronh]

Yes, the pump is mounted vertically pushing down. It was installed by the Central Boiler dealer and from what I read in the TACO docs, it's right.

Thanks
Ron

[countryguy]

Is it possible there is a check valve in the system and the pump is working against it? Sometimes the circ pumps come with plugs in the flanges to keep debris out, just suggestions. I know your probably at trial and error trying not to pull your hair out.

[1grnlwn]

Is it possible you are getting air in the system somewhere? 

[Bull]

Not sure what the ID of the 2 pipes are (1 1/4 pex to 1 copper) but could the drop in size be causing back pressure on the pump?

[RSI]

How are the pumps failing? freezing up, windings burning out, etc?

[jackel440]

I know the pump shaft has to be in the horizontal plane and not the vertical plane on my Grundfos pumps.I would imagine the Taco pumps are the same.You said you already verified that but I am just thrown what I know out there.

[ronh]

Thanks for all the suggestions. What I have done is flush out the boiler and replace the water (10ph) with softened water (6ph). Also installed a 1" bypass with a valve half open. Also installed a TACO 2200-200-WB at TACO's suggestion. There was also a 5' piece of 3/4" in the line that was replaced with 1". So far it appears to be working fine. Ran it up to 190 degree and the pump wasnt cavitating. Dropped it back to 180.

Also, one question was how the pumps were failing. All the rotors siezed up and sometimes burnt the windings. I'll keep this forum posted on the progress, as someone may have this problem.

[RSI]

That new pump you got is not water lubricated so shouldn't have any more problems. Did it cost much over $300?
Do you happen to have a watt meter? (ie kill-a-watt) from what I have seen that type pump is quite a bit more efficient but never had one yet to test. A regular circulator seems to draw the full rated power at any load. From what I have seen these don't. I am thinking about trying an Armstrong E9 pump which is the same design as that Taco but cheaper. If it only uses half the electricity it would pay for itself in a few years.