CH with Microbore bypass loops and proper bypass valve

[John.g]

What make of ABV is installed now?.

 

[Rob1234]

Not sure what make it is...
But - stop ends fitted and I now have 20-25C drop on the return - It was 10-12C before BUT the boiler is sitting at 26% modulation with 72C flow, 51C return and still not getting much flow it seems...

Thanks for help and advice everyone and kudos for screwfix being open today - I think I need to start a new appropriate topic for the boiler!

 

[Rob1234]

Screwfix

Worst comes to the worst 10mm push fit cap ends and inserts

Thanks Shaun - Screwfix were open today, it was not apparent from their web site - and yes, push fit caps and inserts was the way to go, I figured not messing with the 19 year old manifold connections was preferable...

 

[John.g]

Not sure what make it is...
But - stop ends fitted and I now have 20-25C drop on the return - It was 10-12C before BUT the boiler is sitting at 26% modulation with 72C flow, 51C return and still not getting much flow it seems...

Thanks for help and advice everyone and kudos for screwfix being open today - I think I need to start a new appropriate topic for the boiler!

If the boiler is at 26% output then only running at 4.94kw and a flowrate of 3.37LPM!! If that is correct then something seriously amiss. Is the DHW cylinder heat up time OK.

 

[ShaunCorbs]

10mm gets blocked very easily sounds like you need to start looking at maybe a blockage at the inserts

 

[Rob1234]

If the boiler is at 26% output then only running at 4.94kw and a flowrate of 3.37LPM!! If that is correct then something seriously amiss. Is the DHW cylinder heat up time OK.

Yes - Cyl seems to heat up fine - all 22mm between boiler and cyl, predictably...

It's got sludge removing stuff in the system at the moment, which is still building up on the filter magnet to maybe 2 - 3 mm thick bumps in a day or 2, - I'm hoping this starts to clear more out now the flow is going round the rads instead of the bypass loop stupidity...

Before the boiler change, I had a grundfos pump set at maximum rate and that did heat up the rads OK (old glowworm 18HXi, looked ready to die at any moment)

Th new Vitodens has a more powerful pump internally - but the boiler never seems to set it above 65% speed, making it less powerful than my old one - and there's no minimum speed setting option, only a max speed setting for the pump, which I had already set to 100% before I found the bypass loops... The boiler pump is a fancy PWM controlled version, so no switch or buttons to play with, unfortunately.

I was wondering about getting the old pump put back in place...

 

[Rob1234]

10mm gets blocked very easily sounds like you need to start looking at maybe a blockage at the inserts

Hi Shaun, yes, the plumbers who fitted the boiler really don't like the push-fit and I can see why, having seen the little holes in the inserts... Unfortunately cheapskate Persimmons pay installers by the number of houses they complete, so quick and dirty is very much what you get. I was really hopeful that blanking off the loops was going to fix it all, but still some work required it seems... I'll keep the system pumping through the worst rad in the daytime for another couple of days and see how much more gritty gunk comes out I think..

Thanks for your help and suggestions - Screwfix today was a real bonus

 

[ShaunCorbs]

The boiler controls the pump to manage a difference of 20dc flow and return

 

[ShaunCorbs]

Hi Shaun, yes, the plumbers who fitted the boiler really don't like the push-fit and I can see why, having seen the little holes in the inserts... Unfortunately cheapskate Persimmons pay installers by the number of houses they complete, so quick and dirty is very much what you get. I was really hopeful that blanking off the loops was going to fix it all, but still some work required it seems... I'll keep the system pumping through the worst rad in the daytime for another couple of days and see how much more gritty gunk comes out I think..

Thanks for your help and suggestions - Screwfix today was a real bonus

They will be straight runs so worse comes to worst remove from the manifold clean the inserts if blocked and do the same at the rads and all should be good

Easy way to spot them if any rad is very slow to heat / doesn’t

 

[Rob1234]

They will be straight runs so worse comes to worst remove from the manifold clean the inserts if blocked and do the same at the rads and all should be good

Easy way to spot them if any rad is very slow to heat / doesn’t

The boiler only goes to 60% even with 30C drop when I put more rads on - I feels like it's trying to be too efficient and if there was more flow, the boiler could ramp up more, like the old one did.

The pipe run to the worst rad is far from straight or sensible, the rads all have a pair of elbows on each pipe at the hole in the plasterboard and swap to copper microbore from the hole to the rad itself, so loads of opportunities for blockages, but the flow at the valves when the rads were off for hosing through seemed pretty strong.