Leaking isolation valve above central heating pump
Hi
I wanted to ask some advice, to avoid me having to call a plumber round as I believe what I think I can do will help me.
So, I have an old British Gas Grundfos UPS3 pump and the motor is giving up. It's noisy and only runs on setting 3 which is not efficient at all. I bought a new Grundfos UPS3 15-50/65 which is a direct swap. Now, I am very competent with all types of DIY, and having watched YouTube videos, it's pretty easy to change. The issues I came across was that when I went to turn off the top isolation valve, it started to leak (funnily though I had to turn it anti-clockwise to close). Anyway, I only turned it a little and then reopened it so it didn't leak.
I believe that even if turn the valve fully to close, it will still leak as the bearings have worn being very old pipework, so the only way I can do the swap is to drain the system. I've seen videos on how to do it, as I don't have a drain valve but there are multiple ways (tail pipe and hose with jubilee clip will probably be my method). Would this be the best way to enable me to change the pump, but also to change the isolation valve at the same time?
I also saw that draining would give me the opportunity to put inhibitor in to clean the system so it's kind of a win win. I have a normal boiler and hot water tank, not combi so don't have to worry about the pressure on the boiler.
Any advice and confirmation would be much appreciated.
Thank you