Need Grundfos submersible pump help

[Jason Carney]

I have an odd situation. The original owners of my house installed a geotherm hvac system in the 90's and used a guy who had an odd way of installing pumps. The loop has a submersible pump in a well casing in my backyard. 20+ hvac people have never seen such a setup. Apparently he had pumps custom built in Denmark for these installs.

Long story short, the leads on the wire harness are short and the splices are in glycol all the time. My unit goes out once every 1-2 years and I pull the pump and resplice with the best waterproof splice I can find.

This last time, the wire where it enters the harness rubbed through and the current actually cut some of the metal. I'm basically stuck with a wire too short to splice.

The question is, can I get a new wire harness like this (see pic). I can't imagine this just pushes on there, but I'm afraid to yank on it. The motor is an MS402, which is still made, but I can't find anywhere in the parts diagram where a harness is available.

In addition, I want to explore getting a new pump. Any recommendations in the Indianapolis area who can fix these/size another pump for me? Only other option is to dig a new $8,000 loop in my backyard.

 

[VAWellDriller]

Looks like regular 4" well pump to me...shouldn't be a problem....get new unit since it's so small...or motor or motor lead...I doubt your hvac guy was getting pumps and submersible motors custom made.

 

[Sponsor]

 

[VAWellDriller]

Or go back with a grundfos 3" unit and have a lit more wiggle room.

 

[Jason Carney]

Thanks. I thought I could get a replacement too but I was told this is an oddball combination. The motor is a .5 HP and the pump is .33 HP @ 10 GPM. I can't seem to find anything comparable online. Apparently geotherms are picky on pressure.

 

[VAWellDriller]

A new 1/2 hp with 1/2 hp 10 gpm pump end will only you slightly more flow and pressure....but if you're worried 1/2 hp motors are still readily available and will bolt right on you pump. There is a wire guard missing in you picture that would keep that from happening.

 

[Jason Carney]

Thanks VA, I appreciate it. Looks like I can find that exact motor for $500, which is probably reasonable given that I would spend quite a bit to have this rewired. I assume there isn't anything tricky about swapping motors?

 

[Valveman]

They still make the 1/3HP pump, but only 1/2HP motors. So you can still get a 10S05-6, which is a 1/3HP pump, and attach a 1/2HP motor. This should not be a very expensive pump, but your heat pump can't save any money if you have to purchase a new pump every year or two. Those pumps should last decades. What is causing the wire problem? Is the pump cycling on and off, or just ties directly to the eat pump with no pressure tank?

 

[Jason Carney]

Thanks valveman. That pump looks good, but if I do the math right the cubic meters/hr translates to just over 8 gpm, and my current unit is 10gpm, so I worry about flow rate. The leads on this motor have deteriorated after being in glycol for so long (closed loop). Ive cut and spliced probably 8 times over 13 years and can't seem to keep the insulation on the wires. I had to remove the wireguard due to splicing, so vibration killed me this time - right next to the motor. This is a relay-driven unit that acts as the flow center. When I got a new waterfurnace they assumed it was open loop and were shocked when they cut the lines and glycol came out. We found the well casing in the backyard.

 

[TKB4]

Is the pump in a flow center or did the installer put some 4 inch pipe in the closed loop ? I believe people may be missing that the wiring is in glycol not water. I know grundfus make the closed loop circulation motors used in most climate master geothermal systems even the newer variable speed ones but do not think wiring is exposed to the glycol but I don't believe so the closed loop piping is probably connected directly to in and outflow side of pump . It seems to me like you should change to this type setup. Pics might help. It could be setup with something like a recirculation hot water pump that keeps instant hot water available in whole house but not sure how they would work with glycol either and doubt their flow rate high enough.

I believe Ingrams Water and Air sells closed loop pumps separate from their geothermal units they are pretty helpful with info so you might want to give them a call doesn't cost anything to get another opinion from them.

 

[Valveman]

I don't think you can use the circulator type pumps if there is any suction lift. Glycol will melt the rubber on the wires. You maybe able to find some tape that would not be effected by Glycol and just wrap the wires from top to bottom. I use to do this when pumping crude oil, but that special tape is expensive.