Solar Pump Failure ? Help

garyh3

Ok Yesterday I notice that our solar system was very hot 140 degrees and that the pump on the display was turning but the water in the tank was not getting any hotter.

Went up into the attic and the pump was very hot it was making a noise like it was turning. The pressure gauge was at 1.6 bar and the temp gauge was really high.

On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol.

Any ideas? should I run off the solar system?

I also notices that the installers didn't put any stop valves between the pump so it looks like the system will have to be drained to replace the pump if needed ? Any help appreciated?

The pump is a grundfos ups 25-60 180

garyh3

Here is a pic of the pump

spose

If it’s reading over 60 at the pump then to me that says it was moving the glycol around the system. If you have a bypass circuit was it circulating through that instead of to the tank. My guess is something within your settings to not allow temperature that high to sent to the water tank. Should be running ok today if nothing mechanically wrong

garyh3

spose wrote: »

If it’s reading over 60 at the pump then to me that says it was moving the glycol around the system. If you have a bypass circuit was it circulating through that instead of to the tank. My guess is something within your settings to not allow temperature that high to sent to the water tank. Should be running ok today if nothing mechanically wrong

Sorry when i took the pic it was early morning but the temp gauge was upto 140

spose

If the pump wasn’t moving the glycol I would expect the gauge near the pump to stay cold so my guess fault is elsewhere. Even with terrible weather today should still be putting some heat in the tank. Your display should give you temperature at the panel and bottom of tank.

garyh3

spose wrote: »

If the pump wasn’t moving the glycol I would expect the gauge near the pump to stay cold so my guess fault is elsewhere. Even with terrible weather today should still be putting some heat in the tank. Your display should give you temperature at the panel and bottom of tank.

The hot water tanks display S1 panel’s were 140 but S3 didnt change which is top of the tank so i presume the water from the panel's didnt get circulated around the system?

freddyuk

Possibly pump Capacitor has failed. Easy to replace without draining down. You can run the pump and remove big screw (bucket underneath) and check if the rotor is actually spinning - gently touch rotor with screwdriver as it can hum but not actually pump. If the capacitor has failed pump will get hot. Don't mess with capacitor until you know what you are doing as they hold a high charge. You could swop the capacitor from your central heating pump just to check once it has been discharged.

garyh3

freddyuk wrote: »

Possibly pump Capacitor has failed. Easy to replace without draining down. You can run the pump and remove big screw (bucket underneath) and check if the rotor is actually spinning - gently touch rotor with screwdriver as it can hum but not actually pump. If the capacitor has failed pump will get hot. Don't mess with capacitor until you know what you are doing as they hold a high charge. You could swop the capacitor from your central heating pump just to check once it has been discharged.

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

mordeith

garyh3 wrote: »

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

We had a similar issue where the tank wasn't getting hotter. I don't know much about it but there is a gauge attached to the pressure vessel and it was lower than the it should have been so water wasn't circulating properly. Plumber sorted it by adding glycol. Not sure if he drained old stuff first or not (as I say I'm too familiar with the workings?

garyh3

mordeith wrote: »

We had a similar issue where the tank wasn't getting hotter. I don't know much about it but there is a gauge attached to the pressure vessel and it was lower than the it should have been so water wasn't circulating properly. Plumber sorted it by adding glycol. Not sure if he drained old stuff first or not (as I say I'm too familiar with the workings?

Pressure is just below 2 so would expect to some heat to get into the tank

garyh3

garyh3 wrote: »

Ok thanks will get my multimeter out and check capacitor. Will check carefully if it has any charge currently. Ive already tested the pump and it does turn with a screwdriver

Ok unit seem to be a complete power unit so I dont see a way to remove and replace just the capacitor. There was 0 V on the capacitor which I would expect as its not been on for a while. Can you buy just the power assemble of the Pump ?

Thanks for your help

garyh3

ok pulled capacitor out 0 on the multi meter not taking a charge

does anyone know where to get one of these capacitors

has 2 wires coming out from a resin top

MD MKP
2.5/400
mkp 2,5 uf +- 5%
400v ac 30000h/KIA
460 ac 10000/KIB
25/85/21
400v ac 10000h/KIB
25/100/21
50/60Hz

en 60252
04.02

Size is about 2.5Wide x 4.8High cm

freddyuk

Digikey....

garyh3

put in a new capacitor docent make any difference I think the pressure is low ? below 1 bar when cold

freddyuk

Pressure will not affect flow if the pump is actually pumping. It may be an airlock between collector and pump. Is there a valve on the collector or high up in the system where you can bleed it? (there should be).

garyh3

hi freddyuk let me take a few photos, docent seem to much to the system. Would love to know what i can do to resolve this.

The only think i do not see is any isolation valves between the pump.

Pump is a 25-60 180 what can i use to replace this Grundfos pump if it is gone?
is it possible to use a 130 and put isolation valves between the pump ?

thanks

Gary

garyh3

Photos of System

John.G

That pressure of < 1.0 bar when cold is certainly too low as it probably can't overcome the static head, it should be 1.5/2 bar when cold, mine is 2.6 cold and ~2.8/2.9 hot.
Just get it topped up, I would be surprised if it is the pump, it will also require venting while topping up.

freddyuk

If the pump station is in the attic?? - there wont be much static head? ... so first thing is to vent the system from the roof vent (if there is one) or simply crack the joint at the collector when its cold. If you get air leaking but no fluid then that's your problem.

homewardbound11

It sounds like it’s air locked

John.G

Also check the pressure (tyre pressure gauge) at the air end with system cold, should be ~ 2 bar.

garyh3

the Expansion Vessel is at .8 bar ? should I increase to 2.5?

When you say "crack the joint at the collector when its cold" can you explain.

thanks

Gary

John.G

Increase it to until it reaches 2/2.25 bar, if the "water" end pressure is the same then you will not have lost any water/glycol mix and it should be OK without venting.

garyh3

thanks John Ill get me bike pump out !

John.G

As you are pumping it up, stop pumping if the (water end) pressure stops rising before you have reached 2 bar, that will give a fair indication of whether you have lost any liquid.

garyh3

pumped the expansion vessel to 1.6 bar and nothing moved !

John.G

You said in first post "On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol." I take it you just turned the motor shaft with a screwdriver?, you also said that during the day it seemed to be getting a call to run (controller display) so I think the only other thing to do is either check with a m.meter at the pump terminals for voltage when it is being called to run from the controller and/or run a separate supply to the pump and see if will it run, can't think of anything else. If you do decide to run it off a separate supply just give it a few seconds as you don't want to thermally shock the system if the collector temperature is still very high.

For interest what is your controller make/model and do you have E,Tubes or F.Plates?

Also, have you any error codes displayed on the controller?.

garyh3

John.G wrote: »

You said in first post "On the Night when it was cool I took out the screw on the pump and turned the motor seems to run fine? is the pump busted?. was only replaced about 3 years ago with the glycol." I take it you just turned the motor shaft with a screwdriver?, you also said that during the day it seemed to be getting a call to run (controller display) so I think the only other thing to do is either check with a m.meter at the pump terminals for voltage when it is being called to run from the controller and/or run a separate supply to the pump and see if will it run, can't think of anything else. If you do decide to run it off a separate supply just give it a few seconds as you don't want to thermally shock the system if the collector temperature is still very high.

For interest what is your controller make/model and do you have E,Tubes or F.Plates?

Also, have you any error codes displayed on the controller?.

No error codes
Grundfos 25-60 180
Solar evac tubes
Now if i unplug the cables from the pump and turn on call the wires are live with multimeter
When i connect them to pump and call there dead? Is there a short maybe?

Gary

John.G

Hi Gary,
Some controllers output a variable speed signal to the pump so could be a fault at that end despite your readings, I would just supply a external power supply to the pump and see if it drives it.

Controller make/model??.

garyh3

think is Sorel TDC3 controller been in about 15+ years now

garyh3

John.G wrote: »

Hi Gary,
Some controllers output a variable speed signal to the pump so could be a fault at that end despite your readings, I would just supply a external power supply to the pump and see if it drives it.

Controller make/model??.

Ok Ill get some extension lead and plug I have some flex cable somewhere and connect direct to power. See if that works

CHeers