seals going out 6 months in heating system

Steamhead (in transit)

The comment above on pH is noteworthy I recall someone adding(batch method)high pH boiler treatment to the the Boiler Feed Tank and the ceramic/carbon seals went south on a regular basis (about a 2 month cycle) carbon side was gone, down to the plastic. This was a light duty applacation. Switched them to metering pump after the feed pump and no more calls on seals. I would think it is worth a quick check.

[Deleted User]

about seals in pumps

this is a commercial issue. we have about 8 hot water pumps that circulate water throughout the building to different fan coil units. We treat the loop with nitrate chemical and keep it in the 500-800 range PPM. For the past 6 years we replace bearing assemblies/seals every 6 months or less. this time I tried a new style pump, B&G 60 series, instead of Armstrong. We put the new pump in yesterday, and in about 5 minutes the seal blew. the pipes look clear with no trash in them, the water temp is set at 180F and the seals are rated for 220F. We have had the manufacture in and our Engineers look at it with no solution, but everyone suspects the nitrate in the syatem. what do you guys think???????

Steamhead (in transit)

More info

Realy need more info like head (static and diff) inlet piping, any vibration or deflection the model, and size for anyone to take a shot at it. It is probably Nitrite based and what do the chem people say.

[Deleted User]

They are branch related, some 8GPM, some 15 GPM, 15ft and 25ft head. Piping is black iron and varies from 1" to 2", we installed a 6" main line Spirovent last year to get rid of entrained air and dirt.

[Deleted User]

Chem people say its probly not Chem realated.

tim smith

Did you just replace bearing assembly or entire pump?

Just wondering. It is necessary to replace motor mounts at same time or you will eat up bearing assemblies. Just wondering.

[Deleted User]

Tim,

we do not replace mounts, no need to, they are suspended from the ceiling and mounted horizontally, others were dropped down to the floor on stands and mounted vertically, they have the same issue. It don't matter if we do a bearing assembly, whole new pump or just the seal, no longer than 6 months do they last

tim smith

I would have to say must be water quality. Maybe to much grit

or sand in water. Have you had a tds test done on water? Man , 6 mos really bites on lifespan. I have been working on B&Gs for 26yrs and never ran into ongoing problem like that. Will be interested with what you come up with. I wonder if its a chemical eating the rubber holder of ceramic seal or as I said above, grit etc in water eating away ceramic seal. Good luck

[Deleted User]

Have you

tried Viton seals?

MikeyB

B&G pumps

Mike does the system have a bladder/expansion tank? is it set at the proper air side pressure? we had a similar problem on start up of a new bldg,(this system was pretty big) the bladder tank was never pressurized w/air,it was set up w/water right from start up, every time we started up the HW system the pressure would get do high the seals on the pumps would leak at anyplace they could and we had ethlylene glycol in the system. We got in touch w/ the tanks manufacture and we started from scratch w/filling the tank to the proper air side pressure then introduced the tank to system water pressure and everything worked like it should. It might be a pressure problem

Mark Hunt_6

I agree with Tim


I saw a job last year where bearing assemblies and seals were blowing out in 2 months. Wet rotor pumps burning up in 4.

Water quality tests showed over 1200ppm TDS. Constant make up water being added to the system along with red dye. The dye was to help locate the leaks and the ENTIRE system leaked unless the system maintained 120 degree water in it. Easy in the winter, not so economical during non-heating months.

Mark H

Paul Pollets

Question??

Why are 3 piece pumps being used for such low flow rates? A water lubricated pump (i.e. Grunfos 15-58)would handle the flows with much lower electrical consumption, and cost.

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Matt_67

We saw a system that had ongoing seal problems - it turned out the pH in the system was very high. When that was fixed the seal problem went away.

[Deleted User]

this is a steam to water system, the boilers aren't in my building they come from a plant across the street, PH is in normal levels.

We are picking up a grundfus pump today to put in and try since they have no seals, we'll see how they go

tim smith

If it eats B&G seals it will eat the wet rotor pump bearings

also. You will just have to replace entire pump then. Tim

Unknown

You say hot water converter?

Interesting this is. Of what pressure is the steam in relationship to the hot water pressure I might ask?

[Deleted User]

Steam pressure is around 15 pounds into the heat xchanger, through the coil on the water side its around 40PSI

Unknown

How Well

Are the converters controlled? In the past I have seen a lot of converters running wild because of poor control strategies making 240*F during periods of light load. My gut would still tell me it was a pH issue with oxygen aggravating it also.

tim smith

What temp on the water side are you running.

Big Will

Grundfoss wet roter

I wish they would make them bigger. I am sure their are situations wear they will die but so far every time I run into a situation where a B+G is loosing seals alot a wet rotor versa-flo from Grundfoss runs long term just fine.

[Deleted User]

temp is based on outside air, this time of year when it cold the set point is at max 180F, it is very well controlled pneumatically.

We installed the grundfus I'll let ya'll know how that one works