HELP! Central heating pump knackered!

[Avocet]

Hi All, The boiler circuit breaker keeps tripping. However, it's fine if I disconnect the pump, so I'm assuming the pump has had it (As far as I'm aware, it's the original one, so it's been there since 1995).

The pump is a Grundfos UPS 15-60

Our local Screwfix is open until 1600. Can anyone give me some suggestions as to what I could replace it with, please?

 

[Johntheo5]

A 6M DAB Evosta 3 or (like mine) a 6M Wilo Yonos Pico, just check that your old selectric is 130mm between the f;langes.
Maybe also buy a pair of pump isolating valves as the 1/4 turn type you havr usually start leaking around the spindle o rings if you isolate them.

 

[Avocet]

A 6M DAB Evosta 3 or (like mine) a 6M Wilo Yonos Pico, just check that your old selectric is 130mm between the f;langes.

Thanks for getting back. So that's 130mm between the mounting faces like this? (Which, without removing it, it does look roughly like that's what it's going to be).

 

[Avocet]

The boiler is an old Worcester Heatslave 20/25 oil boiler from 1995 if that makes a difference?

 

[Johntheo5]

Thats it, either of the above 2 pumps will be fine, sometimes theres a reduction on one or the other.

 

[Avocet]

And the valves either side of it. They look like 2" across flats on the unions that screw on to the pump. Does that mean the pump inlet and outlet are G 1 1/2" ?

 

[Avocet]

The copper pipes at the other end of the valves are 21.56mm outside diameter.

 

[Johntheo5]

They are all fairly standard, just try the new valves on the new pump, the pipework is 22mm.

 

[Avocet]

They've got a Wilo Yonos Pico 25/1-6-130 in stock. Is that the one you were thinking of?

Wilo Yonos PICO 25/1-6-130 Glandless Circulating Pump 230V - Screwfix

Order online at Screwfix.com. Easy installation and set-up, accessible through 'Green Button Technology'. High energy performance is achieved through the proven EC motor technology and precise setting in 0.1m steps. Longer de-blocking routine can be activated manually. Error code indication for...

www.screwfix.com

 

[Johntheo5]

That's the one, a very nice, silent pump.

 

[fixitflav]

They've got a Wilo Yonos Pico 25/1-6-130 in stock. Is that the one you were thinking of?

That says the pump connections are 1" BSPM. I think they're more likely, 1½" BSPM (as you say in #6), like the Grundfos and everybody else. Just so you get the right valves if you replace them.

 

[Johntheo5]

25mm refers to the pump port(s) diameter, the connections are definitely OK, 1 1/2 ins, 2ins across the flats. When I installed mine 5 years ago, it replaced a old Salmson and I used the original isolating valves.

 

[Avocet]

Thanks gents. Sorted now and we're nice and warm again! Heaven knows what would have happened if we'd had to call someone out at this time of year!

I went for a Grundfos UPS 3 in the end. That has 1 1/2" ports and and works against a higher static head and has a slightly higher flow rate. I was going to try and change the two ball valves as they looked like they'd been weeping, but the ones I got, ended up leaving me only 128 mm between the mounting faces (with no washers!) and the pipework is so tight there. I'd have had to try and re-make two really tight bends (see bottom photo in Post#1) in 22mm pipe, and try to get both faces parallel and exactly the right distance apart, which I didn't fancy my chances of doing! I ended up re-using the old ones (which, miraculpously, don't seem to be leaking right now).

 

[Johntheo5]

The UPS3 is a giant of a "6M" (6.4M) pump with ~ 50% more power than the normal 6M pump, even the lowest constant speed (CC) mode at 4.2M will provide plenty of head for 10 rads or more, unfortunately it doesn`t display the flowrate or the power.

 

[Avocet]

The UPS3 is a giant of a "6M" (6.4M) pump with ~ 50% more power than the normal 6M pump, even the lowest constant speed (CC) mode at 4.2M will provide plenty of head for 10 rads or more, unfortunately it doesn`t display the flowrate or the power.

Something I probably should have mentioned in the original post, is that we've quite a few radiators. I don't know if you could a double radiator as one or two radiators but we've got 14 if you count them as one radiator (obviously more if you don't). I found this online for it:

So around 3 cubic metres of flow per hour at 3m of head, on its fastest speed. The old one was always set to its fastest speed, and if the table on it is to be believed, it'll manage 0.44 litres per second on that - which is about 1.6 cubic metres per hour, but it doesn't say at what pressure. Certainly this one should shift a lot more water! I found this graph on another thread and if that's for my old pump, then it was doing about 2 cubic metres per hour (0.6 litres per second) on its highest speed at 3 metres of head.

I guess I should be able to put the pump into its variable flow rate mode and maybe save a tiny bit of energy? Are there any downsides to having a pump with a high flow rate?

The other thing I should have mentioned, is that the piping is all microbore.