replacing pumps on boilermate 2000

Hi some advice please. Can I replace my three pumps on the boilermate 2000 currently grundfos ups 15-50x18 with grundfos ups2 15-50 heads? If I go for the Alpha's im informed they are too big for the depth of the cabinet and the casing will not fit. Has anyone replaced their pump heads without difficulty or any subsequent running issues? If so which pumps do you recommend would the ups2 be ok. On all pumps or just the heating one's. Tia

The boiler & heating pumps (left & middle) fit what you like.
On most units they are 15/50. BUT on the larger units they are 15/60 so check the numbers.
The right hand pump must be the Gledhill XB004.
You will see a post on here ref; Warning 15/50 pumps.
I would always use Grundfos pumps as they are the best.
The new pump heads should fit although you may have to set the position if needed.
Mike

Thought I would put my experience with new pumps down for others.
My DHW pump (the RHS pump) began making a noise when the bath tap was turned on full so I thought I would replace the pump. Incidentally our water is not hard so I did not think there would be any problems with scale and the system is well dosed with inhibitor and the sensors are fine. I looked on Grundfos website and saw the replacement pump for the xb004 could be an Alpha 2 or 2L --- big mistake. As has been noted already you must replace like for like on the DHW pump. Anyway I fitted the new Alpha and two replacement pump valves as well (after using bungs in the F and E tank and Air Vent pipes in the loft). I switched the electric back on and turned on a hot tap to test. The pump powered on ( the Alphas have leds on the front which illuminate when powered on). The ACB worked fine for about two cycles of turning on and off the hot tap and then stopped modulating the power, providing 240 volts to the DHW pump ALL the time instead of just when the hot taps were in use. This is not how the system is designed to work but I should say that if I turned the Alpha pump down to its lowest power setting it did provide a workable hot water solution and did not appear to use a great deal more gas either! Anyway what I ended up doing was swapping the new Alpha pump with the one in the middle (the CH pump). All the pumps were originally the same part number. Has as been noted the Alpha pumps are much longer than the original and if placed facing straight out it is true the Boilermate cover will not fit, however the Alpha's can be angled to the left or right and then they will fit. I also saw somewhere ( maybe on one of Mike's posts) that it may be a good idea to use a relay to isolate the pump from the ACB. I have done this with the new Alpha pump on the CH circuit and so far so good. I rang CET Ltd at Watford about a replacement ACB and this was delivered within 24 hours at a cost of £81 plus post. The moral is if you are replacing the DHW pump you must, as Mike has said, pay the extra for a XB004.

Thanks so sorry you had such a trial. I have decided  replace all three as they are 13 years old so I've bought grundfos ups2's fro the heating ones and will purchase a new 15/50 x 18 from gledhill next pay day. Then I will iff possible replace all three heads together.  If not I will do whole pump replacement.  I was advised it would probably be best to replace all the gate valves as they mis function but I'm going to see how I go on that o e as can turn the water off and nip to screwfix or plumb centre if needed. Luckily at the mo we're not needing the heating so much ( thats the main pump culprit). So I'm hoping once its a lovely day n kids at school I'll get dad round and we'll crack on giving it a face lift.  I'm hoping that this will suffice for a nother few years. All your tips and experience from this group is greatly appreciated.  Thanks guys yr stars ☆★☆★☆