I have Underfloor Heating and a thermal store, to make sure mains pressure DHW still functions correctly need to install a shunt pump across the boiler primaries.
So with a lot of pre-thought, assembled pump, isolation valves, non-return valve, and a whole bundle of end feed Tees & elbows.
Drained system down .. store has a baffle so there is upper & lower drain cock .. unscrewed the bypass valves & pressure gauges.
With trepidation cut into 28mm primaries, and commenced to dry fit the new pieces. The 28mm electrical zone valve on primaries was weeping from actuator shaft when 'open' .... so had to replace that as well during drain down. Also the store has a automatic air bleed valve that looked sorry for its self so replacing that as well.
To fit zone valve, simplest way was to cut off pipe above olive, and fit a new piece of pipe below direct to new T piece (shunt connection).... Easy enough reduced number of joints.
All joints done, reassembly .... and found that I could not now reinstall pressure gauge as it fouled the new pipe run ... could nut turn it to screw it into male bsp fitting.
The fitting was a Kuterlite cast bronze fitting 28x 28 x1/2" bsp
As time was after 6pm ... thought best approach heat up fitting and rotate by 30 degrees - gauge will then fit .......... bad choice. Heated up OK and rotated ... but try as I might I could not get the joint to remake ... even good quality flux ... just looking black & cruddy ... no nice ring of solder.
OK .. plan B .. remove fitting clean it all up and remake joint. Top piece popped out easily, but bottom would not come out ... after much effort pipe collapsed.
So small thing No.1 was screwing in gauge failed !
No DHW that night ... OK next day decided to get new fitting - nobody has one in stock .... so will have to use a 28 x 28 x 22 Tee, reduce 22 to 15 put in a small piece of 15mm pipe and then fit a 15mm to 1/2" BSP union.
Annoying things is, I could have added an extension to exiting Kuterlite fitting and avoided replacing it .... trying to finish in one day caused me a lot of extra work.
Put it all back together ... including remaking all the tank connectors, bypass valve ... 22 individual joints.
Started to fill .. and load noise of escaping air ... found that the lower of the drain cocks was not sealing. Found the rubber washers had disintegrated on both drain cocks ... cost pennies - but didn't have any ... So small thing No.2 was drain cock washers failed !
It was after 6pm ... but took a chance phoned my mate (Manager at local PTS) he was just leaving and would take a pack with him .. and meet me at a half way point.
Replaced washers, filled, pressurised ... one slight weep at tank primary connection ... 1/4 turn of nut fixed that .... drained flushed, refilled & added inhibitor.
Job done ...... overall very pleased no leaks no bad joints ..... just caught out by 2 unexpected events.
Need to make changes to the Underfloor heating take off next, going to install a 28mm temp mixing valve, currently direct connect to heat exchanger - it can wait a week I think .