mate not happy with me what a day

[vern]

what diffrence will it make cos you took combi out and fitted combi in ???? and when you get balanced pressure you would have not had cross over mate ,simples

It's to do with resistance simples, if the shower valve or any mixer tap offers the cold an easier route than through the combi it will crossover, remember the hot pipes will be under slightly less pressure when an outlet is open (depression)

For cold to go through the combi, inlet valve, filter, flow restrictor, flow turbine/ switch, internal pipework, plate heat exchanger, more internal pipework......lots of resistance.......you get the idea, every boiler will be different also!

 

[SafeGasInstall]

check your understanding of flow and pressure !!!
restriction from valves heat exchangers ect will not affect PRESSURE , but amount of water (volume)
going to op , if all was good with old combi and taking into account that no one will down size when doing combi swap then will there be any chance that this will affect your shower performance .....just thinking it will cos you fitted a NRV to the hot to the boiler wrong way around as if it was correct way around will let the water came out of the hot water pipe traveling from your shower mixer to boiler position where you fitted it !
any way its sunday and dont have time for this

 

[SafeGasInstall]

btw was vern your mate that was working with you ?

 

[buckley plumb]

btw was vern your mate that was working with you ?

no mate

 

[dancinplumba]

static pressure is not affected but dynamic is

 

[vern]

check your understanding of flow and pressure !!!
restriction from valves heat exchangers ect will not affect PRESSURE , but amount of water (volume)
going to op , if all was good with old combi and taking into account that no one will down size when doing combi swap then will there be any chance that this will affect your shower performance .....just thinking it will cos you fitted a NRV to the hot to the boiler wrong way around as if it was correct way around will let the water came out of the hot water pipe traveling from your shower mixer to boiler position where you fitted it !
any way its sunday and dont have time for this

Zzzzz check your understanding, resistance has a huge effect, like electric water will take an easier route if there! Like dacinplumba has said it's dynamic not static once the tap is open!

once you have been to to combi that cross flows through a mixer tap or shower you will know, as swapping the boiler won't solve the problem, I wonder why Gloworm and Worcester train their engineers to look for this for under warranty reports of water not hot enough, when all else is good with the boiler, do a search on here and wind your neck in or maybe you don't have time as it's Sunday???

 

[SafeGasInstall]

static pressure + dynamic pressure = total pressure.

 

[dancinplumba]

static pressure + dynamic pressure = total pressure.

really ? well i never

 

[vern]

static pressure + dynamic pressure = total pressure.

Great.....do you now understand how cold can cross flow and dilute the DHW temp at all outlets? I will recap its about resistance whether at 1 bar or 5 bar the outcomes the same....

 

[Leo21]

Now without anyone getting bent out of shape this might help. I've got a shower fitted on a job that I know is passing. Because before I fitted a combi a so called plumber piped the shower, cold main to cold and tank fed to hot. The cold main was pushing through the shower and pouring through the vent into the tank. Anyway fitting a combi has cured this. All the big words on here are a bit confusing for me, and I'm only reporting what I found and what the cure was.

 

[buckley plumb]

Now without anyone getting bent out of shape this might help. I've got a shower fitted on a job that I know is passing. Because before I fitted a combi a so called plumber piped the shower, cold main to cold and tank fed to hot. The cold main was pushing through the shower and pouring through the vent into the tank. Anyway fitting a combi has cured this. All the big words on here are a bit confusing for me, and I'm only reporting what I found and what the cure was.

i dont know the calculations but had it a few times now . next time your on a job with a combi connect a washing machine hose accross the hot and cold wmc taps and open both the same amount then turn any hot tap on and you will see - its the same principle.dont know why but 3 times i have had it happen. wether it be due to different restrictors in shower valve etc i dont know just know glowworm engineer made me look 2 inch tall when he showed me.

 

[SafeGasInstall]

Point I was on about is it would be ok if it was on on the first place before boiler was change. Many combi swaps I have done when you turn the mains back on it does cross over but only cos you got nothing pushing on the hot side so when get equal push shower will work OK
Good night every one 🙂

 

[SafeGasInstall]

i dont know the calculations but had it a few times now . next time your on a job with a combi connect a washing machine hose accross the hot and cold wmc taps and open both the same amount then turn any hot tap on and you will see - its the same principle.dont know why but 3 times i have had it happen. wether it be due to different restrictors in shower valve etc i dont know just know glowworm engineer made me look 2 inch tall when he showed me.

mate pressure and volume are diffrent things !!!!
next time do the washing machine houses and take fading of standing pressure and flow and you will understand !
good nigh pal sleep well

 

[buckley plumb]

Point I was on about is it would be ok if it was on on the first place before boiler was change. Many combi swaps I have done when you turn the mains back on it does cross over but only cos you got nothing pushing on the hot side so when get equal push shower will work OK
Good night every one 🙂

shower worked ok mate just some of the other taps were luke warm - was not sure about before as boiler had totaly packed up customer did say after the water has never been so hot .good night

 

[SafeGasInstall]

And last thing don't fit glow worm boilers

 

[dancinplumba]

its volume now ??

 

[SimonG]

It's like an episode of the Waltons 🙂

 

[buckley plumb]

It's like an episode of the Waltons 🙂

good night simon lol

 

[vern]

its volume now ??

Lol yes.......not!

if I tee'd in the cold to the hot under a combi, with a ballofix valve just cracked open.....wonder what would happen? Yep you guessed it some would bypass the boiler and dilute the hot outlet temperature, regardless of pressure or volume!

In short all we are trying to say is the shower may not be effected as much,as say any tap in the house which will have reduced temperature, depending on how bad the crossflow is......

 

[vern]

It's like an episode of the Waltons 🙂

Good morning John boy!