Can I replace a Grundfos 15/60 with a 25/80 - Hlep Please

[mikeh71]

Hi
We have moved last year to an older house which has 25 rads and there is a Grundfos 15/60 pump in CH system. Basically not all radiators get hot when system running, there are two honeywell controllers and if downstairs is off then upstairs gets hot and vice versa, however when full system on then upstairs doesnt get that hot.

I have tried to balance the system from furthest radiator but still not helping so my question is can I replace the 15/60 with a UPS2 25/80?

Are there any complications with doing this ? I know the 25/80 is around 50mm longer but is there anything else?

Thanks for any help in advance.

 

[ShaunCorbs]

open vent or sealed system?

 

[lame plumber]

you probably need to flush and clean out your system before swapping pumps, more likely to be clogged up, a bigger pump may just move the muck to another position

 

[SimonG]

Can you not zone the radiators and a pump on each zone?

 

[mikeh71]

Hi
Thanks for the replies, its a sealed system.
If both upstairs and downstairs get hot when the other system is not on/calling could that still be a clogged radiator?
Thanks

 

[ShaunCorbs]

could be or maybe slightly blocked flow pipe

you could try turning a few rads off down stairs and see if if a few upstarts start to get hot

and it would help / better if you put some cleaner in the system for a week or two