C
Click4
Hi,
just a a quick background, hot water used to take a long time to come through.
while doing bathroom, found this to be because boiler 15mm hot water outlet was T'd into original 22mm pipe from when it was a gravity system.
all 22mm pipe replaced for 15mm and piped directly back to boiler... This improved times it took for hot water to come through and gave improved pressure also.
then thermostatic mixer shower was installed, and hot water went back to being slow to come through.
identified the problem, when hot water tap is turned on, the pressure drop in hot water pipe is far greater than the cold so it starts back feeding. Going to fit a pressure equalising valve with inbuilt non return valve to fix this... However I want to fix the root cause of the hot water pressure drop. Also removed a further additional isolator valve from boiler cold feed which improved pressure slightly further.
static pressure was 4 bar, dynamic pressure on cold with shower on full is 2.8-3.0 bar.
however dynamic pressure on hot is 1.8-2.0 bar! 2 bar drop from static and 1 bar less than cold. Which is why the back feeding is occurring... It's also a lot lower because I suspect that a venturi effect is occurring and the hot water is being sucked through the pipe.
so would seem there is still some kind of restriction on the hot water side of things on the boiler.
couldnt find an inline filter, so would I be correct in assuming it's a possibility that the secondary heat exchanger is scaled up? And that the limescale is causing an internal restriction?
i know it has a heat exchanger problem being sludged up as it's going hot and cold also, but that wouldn cause a restriction on cold water side, only heating side... So it maybe scaled up as well.
but either way there must be a restriction somewhere for dynamic pressure to drop 2 bar! At most I would of expected same drop as cold water.
Thanks in advance.
just a a quick background, hot water used to take a long time to come through.
while doing bathroom, found this to be because boiler 15mm hot water outlet was T'd into original 22mm pipe from when it was a gravity system.
all 22mm pipe replaced for 15mm and piped directly back to boiler... This improved times it took for hot water to come through and gave improved pressure also.
then thermostatic mixer shower was installed, and hot water went back to being slow to come through.
identified the problem, when hot water tap is turned on, the pressure drop in hot water pipe is far greater than the cold so it starts back feeding. Going to fit a pressure equalising valve with inbuilt non return valve to fix this... However I want to fix the root cause of the hot water pressure drop. Also removed a further additional isolator valve from boiler cold feed which improved pressure slightly further.
static pressure was 4 bar, dynamic pressure on cold with shower on full is 2.8-3.0 bar.
however dynamic pressure on hot is 1.8-2.0 bar! 2 bar drop from static and 1 bar less than cold. Which is why the back feeding is occurring... It's also a lot lower because I suspect that a venturi effect is occurring and the hot water is being sucked through the pipe.
so would seem there is still some kind of restriction on the hot water side of things on the boiler.
couldnt find an inline filter, so would I be correct in assuming it's a possibility that the secondary heat exchanger is scaled up? And that the limescale is causing an internal restriction?
i know it has a heat exchanger problem being sludged up as it's going hot and cold also, but that wouldn cause a restriction on cold water side, only heating side... So it maybe scaled up as well.
but either way there must be a restriction somewhere for dynamic pressure to drop 2 bar! At most I would of expected same drop as cold water.
Thanks in advance.
