Grundfos pump

[chunks99]

I am looking to replace a faulty Grundfos central heating pump being a TOTAL novice would really appreciate some advice. Pump is a 15/50 pump but is a class F showing various pumping rates 1800rpm, 1150rpm,etc. I can find 15/50 pumps on line but class H with varying pump rates and also class F's with again varying pump rates. Is this such a big deal or can I buy any class F or class H? Any help/advice would be appreciated.

 

[Ermintrude]

You shouldn't be installing a non a rated pump nowadays! Fit a wilo as they are much better - indicated by the 5 year warranty opposed to grunny 15mins. Any second hand pump may not last 30s but some last 5 years