Which replacement Pump ?

[letmedoit]

I suspect the pump on our combi-boiler may have had it (cold rads. downstairs - system flushed OK recently). I will be removing the pump to check it out per other posts on the forum, but have a couple of questions should it need replaced.

It is a Grundfoss UPS 15-60 AO (fitted with auto-vent) which retail at £120 - £140 (e-bay) There are other brands that retail at 1/3 the price that meet the spec. but don't have a fitting for the auto-vent.

1. Are the cheaper pumps good value or false economy ?

2. Would not having the auto-vent creat problems (the boiler is at the highest point in the system).

Thanks

 

[spraggo]

Yes it is false economy, you get what you pay for and the Automatic air vent is essential.

 

[bengasman]

Combi pumps can be specific for the boiler, and must be replaced with the exact same model unless the manufacturer approve of another model.

 

[letmedoit]

Pump passed the "Finger Test" at setting 3 on workbench. But after re-installing I checked the shaft under the bleed screw; It stopped on setting 1, struggled to get going on 2, and was definately not running as fast as I think it should have on 3.

Before I part with the cash price for a new one are there any other checks/repairs that can be done e.g the capacitor ?
Thanks

 

[Groovejet]

I dont see any problem in replacing the pump head only, onto the existing body. Basicly keeping the body incorparating the AAV.

I've done it many times and so have other Gas fitters i know.
I,ve even fitted budget pump heads onto boilers which are still running to this day, with no problems. (Wilo Pump) Approx £30 screwfix)
Ok cheaper pumps arnt as energy efficient (Well thats what they say?) but they do the job just as well.

As long as the boiler is'nt in warranty then whats to lose? Nothing?
You want the boiler fixed at a reasonable price, so why pay over £120 just for a pump.

-Purchase 15/60 pump of your choice, remove the 4 allen headed screws, pull head off body, fit pump head onto existing body, tighten allen screws, fill boiler & vent the air out. BOBS UNCLE, FANNYS AUNT!.......SAVED A FEW SQUID!!
If you want a decent pump, go for a 15/60 Grunfoss Pump, it's still gonna save you £££

 

[letmedoit]

I dont see any problem in replacing the pump head only, onto the existing body. Basicly keeping the body incorparating the AAV.

-Purchase 15/60 pump of your choice, remove the 4 allen headed screws, pull head off body, fit pump head onto existing body,

I take it any Grundfos 15-60 pump head can be swapped. However, (as money is very tight !) you have said ^^^^^ any make. Are there brands out there that will definately fit the Grundfos body and any that definately won't (also any to definately avoid) ?

When we talk about quality this Grundfos pump is only 6 years old !
Thanks

 

[nickso]

the AO should take a normal 15-60. the only difference is the body.

grundfos are good, what colour is the system water?

 

[letmedoit]

grundfos are good, what colour is the system water?

To be honest the water is always full of black particles. This combi was fitted to an existing system on which the rads are almost 40 years old !

The system has been flushed a few times each time the DHW-heat exchanger clogged up (not surprised I hear you say !). We even added x-400 sludge remover for a month once and inhibitor has always been added afterwards. A friend who recently had his conventional boiler replaced has offered me to try his old pump. It is a Grundfos 15-50 with which I intend to swap the head across. Maybe the money I save on the pump can go toward a Magnaclean filter as I definately can't afford to replace all the rads !

However, the impeller on the existing pump does not show any wear (probably because the sytem has been flushed so often). Would the particles in the water affect the pump motor in any way ?

 

[letmedoit]

However, the impeller on the existing pump does not show any wear (probably because the sytem has been flushed so often).

I forgot to add; when I took it apart the pump housing was clean inside without any sludge or deposit build-up (probably because the sytem has been flushed so often !).

 

[letmedoit]

OK, friends pump was just the same as mine on "Finger Test". Either they are both good or they are both broke, so no point swapping !

(Wilo Pump) Approx £30 screwfix)

Checked Screwfix website and Wilo pump is £65, only £10 cheaper than Grundfos 15-50. Decided to bite the bullet and went to B&Q as it's nearest and sell both. Guess what - all sold out ! Did notice on the models on the display board that the Wilo rotates in the opposite direction to the Grundfos anyway.

Will now have to wait until Monday to find a Plumbers merchant

 

[JohnD]

To be honest the water is always full of black particles. This combi was fitted to an existing system on which the rads are almost 40 years old !

hurry up and fit that Magnaclean. You can add X400 as well, the Magnaclean will trap the loosened black sludge before the X400 loses its power and the sludge settles out again. I guarantee you will be amazed and delighted when you see how much sludghe it traps.

Top up the X100 inhibitor on final fill.

 

[spraggo]

You need a 15-60 pump.

 

[letmedoit]

You need a 15-60 pump.

I recognise that the pump fitted in the boiler is a 15-60. But, reading other posts on here indicate that the 60 is a rating for "6m Head" which is not important on a sealed sytem (especialy as my boiler is in the attic anyway).

Other than being rated for 5m head, doesn't the 50 pump have the same flow rates etc ?

I only ask as if the merchants don't have a 60 because of the winter CH-repair rush (like B&Q), it will keep my options open if I can just buy a 15-50.

 

[spraggo]

You need a 15-60 pump.

I recognise that the pump fitted in the boiler is a 15-60. But, reading other posts on here indicate that the 60 is a rating for "6m Head" which is not important on a sealed sytem (especialy as my boiler is in the attic anyway).

Other than being rated for 5m head, doesn't the 50 pump have the same flow rates etc ?

I only ask as if the merchants don't have a 60 because of the winter CH-repair rush (like B&Q), it will keep my options open if I can just buy a 15-50.

The 15-60 is used to overcome the resistance of the combi boiler heat exchangers as they have a higher flow rate and head.

 

[letmedoit]

Just had a trawl through some plumber supply websites. Screwfix also do a Pegler TC6 pump which has some good user write-ups at 1/2 the Grundfos price.

Don't know if it will fit the Grundfos body, anyone help ?