Colorado replacing old circ pump - need input

The single speed flo center circ pump failed. It is on a 31 year old "loop pump kit" LPK from Command Aire Geo HP 2 ton closed loop pressurized system. While give great info on variable speed pumps - am opting to not temp fate and use OEM replacement. The local HVAC guy will install, but no Geo experience. So some back up advice helpful.

The loop has no manifolds - headers on system outside. One income pipe/one outgoing. Flo center - incoming into an air expansion that goes into the circ pump and from pump directly to Geo unit. The circ pump has an isolation valve on each side of pump. I know that the two isolation valves are shut off and only pump motor and impeller installed - not entire pump.
Q: How do you get pump filled and air out without pushing air into loop?

I would think opening one isolation valve with screw open until fluid comes through - but it appears that Grundflos is saying NOT to use pump to bleed system.

Q: LPK says to use one of the opened isolation valves to adjust loop pressure back to 40 psi. What and where would the HVAC guy do that? Would it be done on Petes of both incoming AND outgoing loop pipe connections at HP?

Anyone have experience with these really old geo systems?

 

Add-on: the pump issue may be related to a failed electrostatic filter unit that wires through a shared 6 amp Bus fuse. Took filter off line and pump working again. Had huge lightening strike and think power surge wounded/killed a bunch of electrical components including the farm's well pump. Good thing I wasn't outside in my tin foil hat.
QUESTION: Should the circ pump on the geo flo center be hot to the touch? I don't remember it being hot before, but may be getting flinchy due to the number of items damaged. One would think geo's loop temp in would keep the pump cool.

 

Hi and welcome!
A flow center pump that lasted 31 years should win an award. Grundfos pumps have wet rotors now, meaning that the fluid cools the rotor/motor. If it is hot to the touch it may be nearing the end of its life. What model pump is it? As to your first question a variable speed pump prolly will not give you the roi of a single speed unit. Are you able to replace the pump only or are you having to replace the entire flow center? The reason I ask is that anon pressurized flow center would eliminate the techs purging issues.
hope this helps
Eric

 

Eric - I was thinking the same thing on the pumps life - but the entire geo system has managed to run that long. Pump = UP26-99 F and is a fluid cooled single speed. The pump ID stamped on the label has only 5 numbers! The pump is within the original Command Aire Loop Pump Kit (LPK) that has loop coming into a air expansion chamber that goes to the pump, which has an isolation valve on each side. The LPK has two purge connections (regular old faucet looking units) that have caps over the inlets. This a really simple looking system that has only one poly pipe in - one out each have a shut off valve to the loop. Looking at the specs, the 1" loop poly pipe connects to 1 -/2" poly connected by the exterior headers.

I hope to replace pump only as there are isolation valves each side of the volute. BUT the unknown is if each valve will close completely. The LPK instructs to replace only the pump and impeller leaving the volute end intact. It also states to regulate HP pressure by adjusting one of the isolation valves to the provided table specs for the LPK installed. Purchased an OEM Grundflos to replace it out of sheer fear of screwing with a system design that clearly works. That old trouper died yesterday but HVAC has not shown up to replace it yet. Called over 3 weeks ago hoping to change before pump failure.

Q: If the isolation valves function - can pump be replaced than air purged from pump body through the center "bleed" start up screw of the pump by opening isolation valve on the air expansion/incoming loop side and replacing pump screw when fluid only escapes? Local HVAC not geo and have no purge cart.
Q: HP was running with no loop circulation - before I caught it and shut down. What harm to compressor may have occurred? Would any of the system have kicked in to save the compressor ?- the blower was running but didn't check for compressor before shutting down. Likely wouldn't know what I was looking at other than on vs off.

 

Q? Is your unit equipped with PT ports?
If it is, it is quite possible to shut valves leading to your loops and change the pump only in existing cabinet. Then insert needle adapter connected to a garden hose bled of all air first and loosen the center bleed screw, let it run until only water escapes and tighten the screw. Then use the hose to boost pressure to like 30 psi and let it ride.

It is also possible to isolate the loops and install PT ports to facilitate this maneuver. It is also possible to install a air escape valve like the ones used on hydronic boilers with a isolation valve to help bleed any residual air out of the system after surgery. After like a week of operation check your pressure, adjust and isolate your air escape valve via the isolation valve you installed.

hope this helps!
Eric

 

Eric, I can't begin to tell you how your help matters. I'm good with hiring these jobs done - just can't get locals to show up. Been waiting over 3 weeks for the HVAC to come out here - a passive solar home in 100 degree weather pretty much sucks without the HP working. It's DYI or croak in the heat. I wouldn't hire me - but I can get it done. It was easier to manage when little jobs in my 60s - but I know enough to not electrocute myself....probably.

There is a Petes port at the HP incoming hose from flo center and another at the outgoing to loop from the HP. The pressurized flo center has a hose bib on its top each side to flush/purge. My plan is to close the isolation valves on each side of pump; remove pump and impeller from the volute and replace with new one then open incoming side pump isolation valve with the Grundflo bleed screw loosened then tighten - which you have confirmed as a working option. Would that push air out and flood the pump body? Would it push any air to the outgoing side of the volute or is the point to simply flood the pump body so it will operate?

I hit a wall at the part about trying to pressure the loop and I'll have to research about hydronic isolation bleed type valve. I'm not sure I quite get that. My generation, time wasn't wasted on showing women/girls how things work. I can get there, though....probably.

The basement doesn't have any hose connections and while I could add one - the farm's water is alkaline and has bacterial rust in it, so using it to pressure the loop may introduce problems. Although, the well was likely the original source of the fill/purge and its held its own for over 3 decades. I was thinking that after replacing pump it might work ok until I could get the Geo HVAC from Kansas to come out. Have them do a fill/purge, tune and clean the coil. Hate that they want 5 bills just to make the trip plus time and costs for any work - but once per 31 years is pretty much a bargain if the repairs hold for another 31.

Do you think half-ass and call the experts to come and finish will get it done?

 

Search ebay for [geothermal fill tool].

Here is an example: https://www.ebay.com/itm/Geothermal...765179?hash=item26209aadbb:g:~t8AAOSwKoFa0RCb

Use that or something similar connected to a garden hose with the needle plugged into one of the PT ports to fill and pressurize the system. Crack open one of the hose bibs at a system high point to vent air from the flow center as water is being pushed into the PT port. Once the air is purged, close the hose bib and pressurize system to desired pressure. To insure clean water is injected into the system, connect your garden hose to the fill tool with the fill tool valve closed. Now go to the other end of the hose where you intend to connect it to the water supply and take a funnel and several gallons of distilled water from the grocery store and pre-fill the hose with distilled water. This way you are just using your water supply as a pressure supply to push clean water into the system.

 

^^^^^
What a work around idea that is!
Completely agree
Eric

 

Arkie6 and Eric - THANK YOU. Clearly, age has slowed my uptake - but with the visual aid of the fill tool and all sets of descriptions - the bulb lit. Maybe only 15w but I'm able to put all your instructions together and should be able install the pump easily.

That said, I'm mindful of the fact that the pump isolation valves and the flo center fill hose bibs very likely have not been operated since the system was put on line in 1988. Absolutely not in the 18 years I've owned the place. Simple projects aren't always.

Can the pump be replaced while I wait for the fill tool? That way the project can be done in parts - the HP is down anyway. To clarify, as geo systems have evolved over the decades, the only PTs are at the loop in and loop out at the heat pump. The shut off valves, on the system, are at the loop in to the flo center and the loop out after the HP. So I will be filling at the PT either to or from the HP as my system doesn't have manifolds rather only headers as a component of the loop.

Does it matter: use in or out PT? Can the loop fill tool be used to get an start pressure or do I need a loop gage? Given the age of the loop, a start point for reference seems like a good idea. Is there a difference between off pressure and running pressure? System specs = 15-40 PSI. No less than 10 not more than 40 PSI. Any idea of volume of water to pressurize (i.e. 50' x 3/4")?

The water here eats metal - can hear it chewing on the water heater anode rod as I type. So I need to be sure no well water enters the system. Can I assume that the volume of added water will be slight enough that I don't need to consider antifreeze? Specs are 15-20% max by volume. Sorry about this question - but does antifreeze wear out over time? Have a tester I use on my tractor - ??

Will use the adjacent water heater as a pressure option and a new 50' garden hose fill with distilled water and purge air/debri into the basement sump then hook to tool.

The flo center instructions state to use a pressure gage in running HP in and out PT and subtract from each other. Flo rate, in GPM related to pressure difference of the two #s, is given per the flo center model. A difference of 3 PSI = 30 GPM. It instructs to use one of the pump isolation valves to adjust water flow to desired rate. WTF? Is balancing the flo/gpm rate an important detail? If the isolation valves are functional - pretty simple detail.

Have I added or left off anything that scares either of you? Life would be so much easier if the professionals would take these little jobs in order of call request. My thanks - you two Geo Heros

 

An option I use to pressurize my loop and add make up fluid is a basic garden pump sprayer. I just cut the hose end and added an adapter that would connect to my hose bib. I let loop pressure push into the sprayer to ensure no air in the line, then I pump up to desired pressure.

 

Thanks for the alternative. Since I have to buy a PT port pressure gage anyway - going to combine filler/gage. But I can see a number of uses for this "portable" pressure solution around the farm on small projects.

EVERYONE..... there seems to be a bunch of geo people doing DYI loop pressure adjustments - I assume with positive results. Anyone have goofy adventures with PT ports - valves - or hose bibs in the process and your quick solution? Knowing this system's components have gone decades untouched, I have waking terrors of things not opening or not closing.

Typically, things tend to crap out in the same way - so ANY great "oh my moments" you guys can share that may prep me in advance while I wait for the tool/gage? Those *hit happens events?

 

Ok Guys - have a problem. Grundflo and my flo center state to leave the volute and only replace motor/impeller. Isolation valves are a large brass screw head on each side of volute - out valve frozen and in valve moves as both directions not seeming to open or close. Entire motor lodged against volute end. Had to whack to get it loose.
Removed old motor and found that the impeller shaft had snapped AND IMPELLER end STUCK and firmly lodged in the volute. Could be whacking caused that - but how do I get the remaining impeller end out? Can't see any place to insert anything to remove - maybe can put a wrench on small protrusion where impeller breached the cylinder and try to turn/free it. Is another whack an option?

The orig. volute end has bolt holes not the open slot like the new part and the bolts are located where it may be a problem for me to reach/remove. The air expansion on one side and hose bib for flush on the other side as well as the cabinet frame are in the way - likely attached after the pump. Anyone have experience with this? How much pressure can be applied without risk of cracking the volute ?

 

I did not chime in on your request for " what if's " because all this crap is normal for a system of your age. I will tell you what I tell all my new mechanics. It is already broke. Any attempt to salvage old parts short of stupidity is encouraged. If the salvage attempt is not working, we no that we tried, and move on to new parts.

The short answer is do what you can to make it work. If it does not we are here to help and get you resolution.
hope this helps ease your mind.
Eric

 

I have the replacement ready - the end portion broke off and is so tight in the volute opening its almost like its part of that flange body. If there aren't any magic fixes to remove the stuck portion - Plan A= channel locks; Plan B = whack it and hope it breaks loose. The HP already not working so if I have to do a major disassemble to get to the volute bolts - that's life.

Worst case, I'll replace with a non pressurized flo center and call the geo guys from Kansas to fill/ purge. As built, this set up has functioned for over 3 decades and hate to mess with a design that works. Time to go whack stuff. Eric - thanks.

 

Let us know how you get on.
Eric

 

After the impeller end snapped off and stuck in the volute, I pondered then took my plumber' wrench to grasp the smooth nub..then whacked the wrench - the part eventually came loose. Good thing as it gave loop info- see pictures. The orig impeller/housing was made of stainless steel and still excellent condition - cast iron body not so much. Not slime there - solid rock/shale type build up. Question about the pump isolation valves answered - brass screws to open/close the valves were completely eaten away flush with the valve body. Answers whether or not the original fill used my metal eating well water.

I had shut the loop in/out, but thought there would be pressure to the pump. None - very little fluid drained although maybe due to the pump loop being the high point. Can I assume an amount of scale chunks are circulating in the loop? What kind of damage would chunky fluid do to the HP itself?

As I'm going to need to have the Kansas Geo techs take the 4 hour round trip with their flush cart - I can either go with the orig pressurized pump center or go with one of the non-pressurized flo centers being used in systems. Input - ??

It's not about saving $ - local companies just won't come out for small repairs. I'm scary - but I show up.

 

The orig flow center is a pump - isolation valves on each side - air expansion tank - hose bib/valve 1 - hose bib/valve 2. Entire pump and both iso valves failed and condition of fill/purge hose bibs: change to non-pressurized Geo-flo - NP Plus flow center seems to be the best option using same UP26-99F but hope stainless steel can be substituted. Install FC then have Kansas geo guys come out to purge. The Geo-flo Plus adds an additional 3-way valve after the HP that isolates HP from the loop for flushing the HP alone.

When called to get on schedule for the geo HVAC - they asked why - on an installed loop - I thought the system needed purged when installing NP flow center. ?? I'm confused. Isn't that good practice/required?

Given the scale encrusted on/in the volute - won't the loop fluid/HP likely have debri? Probably from dissipated antifreeze. Will NP FC filter out/improve loop quality? On a NP flow center - how is loop pressure or flow rate from pump adjusted. Or is it no longer an issue?

Anyone have experience with Geo-flo NP or on going from an older pressurized Flo to a new NP flo center? Haven't purchased the Non-P center yet - any better ideas on how to get the circ pump up and running?

 

No worries, that is some crusty crap. In your position I would definitely go with a non pressurized system. If you do you will gain 2 things.
1. the ability to service your own system
2. the ability to shut down the system, clean and monitor anything collected in the np tank.
While flushing and purging a system of your age is good practice, many installers simply set up the np and let it go, relying on the flow center to flush the air from the system, you simply monitor and add fluid when needed. In my experience corrosion is only present in the flow centers and sometimes the units, not really the loop itself.
I am a flow center products fan, so no experience with geo flo. I have worked on all of them and both companies are reliable and produce good products. I have installed np units on several older systems with good results for the homeowner being able to self heal so to speak. The np's I have installed have been on vertical as well as horizontal loops with the same good results.
Hope this helps
Eric

 

Perfect - thank you. The NP Plus has an add-on that puts an extra 3-way valve between HP and return loop that isolates HP for flushing. My concern, on loop debri, was the 2 missing isolation valve screws. 1-1/2" to 2" long and 1/2" diameter eaten/broken maybe loose in fluid = loop abrasion leading to early pipe failure. Loop is polypropylene pipe. But totally missed that fluid enters heat exchanger and R-valve before loop return.
Eric - were early exchangers baffled construction like today? 1988 = Stainless steel vs todays alloys? Had to add freon to HP in July to gain performance - local HVAC didn't find any leaks. Is it possible for pinhole leaks at exchanger to be cause of freon loss? If possible, make sense to have Geo guys replace exchanger at NP flow center install as I'll require a flush cart be used? Each Kansas geo service call has a $500 base charge to cover the 4 hour RT for the techs. So if the exchanger age/ damage = trip plus maybe another flush cart - better to put into 1 trip if needed.
While the NP tank fluid above circ pump provides head pressure for pump to run - how is flow rate and loop pressure adjusted to system specs on a non-pressurized flo-center? Old center used pump isolation valves for flow rate and fluid injection for pressure and PT ports to check.

 

Hey - as isolation valves to adjust flow completely gone - what impact on HP or loop of unrestricted flow - for years? GF UP-26-99 115v. It is registering in my head as lost efficiency for heat/cooling transfer to/from loop. That's $ lost, but is there actual damage done to system running full out?
For forum folks asking about high bills from an otherwise functioning Geo system, would this be a starting point to an answer?