Calculating Vent Pipe heights?

[wild nomad]

Hi there,

When calculating the height of the vent pipe for a CWSC, do you take the 'head' from the water level of the CWSC to the bottom of the hot water storage tank or to the lowest draw off point. I think it's the later but I'm doubting myself.

Thanks in advance

 

[chris watkins]

Hi there,

When calculating the height of the vent pipe for a CWSC, do you take the 'head' from the water level of the CWSC to the bottom of the hot water storage tank or to the lowest draw off point. I think it's the later but I'm doubting myself.

Thanks in advance

Base of the cylinder to the water level in the storage cistern in Metres x 40mm + 150mm = height of open vent measured from the water level to the crown of the bend over the cistern, is normally high enough.

 

[kirkgas]

Never ever calculated one, not saying I shouldn't have, but always just took it up past the water lever by about 2' then back down haha, oh the good old days when we just done stuff

 

[Billy Bob Bob]

Never ever calculated one, not saying I shouldn't have, but always just took it up past the water lever by about 2' then back down haha, oh the good old days when we just done stuff

Wot he said +1

 

[chris watkins]

Never ever calculated one, not saying I shouldn't have, but always just took it up past the water lever by about 2' then back down haha, oh the good old days when we just done stuff

I know what you mean, I was taught, take it up as high as poss (within reason). It wasn't until I went into teaching that it became necessary to calculate the B… thing.

 

[kirkgas]

I know what you mean, I was taught, take it up as high as poss (within reason). It wasn't until I went into teaching that it became necessary to calculate the B… thing.

Yes that's when you realise how much you did poorly over the years, haha what is they say? "Those who do, do and those who can't, teach"

 

[Twizz]

On this subject at work there is a vent pipe that goes out side and above the roof and discharges on to the tiles,why?

 

[kirkgas]

An external vent was the way we all used to do it, I'm not sure why but was told it was to remove the risk of hot water contaminating the cold water, and/or remove the risk of someone being scalded, this was changed when the water regs changed to stop wasting water, as an external discharge went into the gutter, and now the internal one goes back into the tank, it also probably has something to do with the fact that it's less work therefore cheaper to return it inside

 

[wild nomad]

An external vent was the way we all used to do it, I'm not sure why but was told it was to remove the risk of hot water contaminating the cold water, and/or remove the risk of someone being scalded, this was changed when the water regs changed to stop wasting water, as an external discharge went into the gutter, and now the internal one goes back into the tank, it also probably has something to do with the fact that it's less work therefore cheaper to return it inside

Probably also has something to do with the pipes freezing in winter.

 

[kirkgas]

The pipe wouldn't freeze in winter as there's either no water in it above tank water level or under fault conditions you would have near boiling water in it

 

[Ermintrude]

An external vent was the way we all used to do it, I'm not sure why but was told it was to remove the risk of hot water contaminating the cold water, and/or remove the risk of someone being scalded, this was changed when the water regs changed to stop wasting water, as an external discharge went into the gutter, and now the internal one goes back into the tank, it also probably has something to do with the fact that it's less work therefore cheaper to return it inside

NHBC probably wanted this but was before then was it not?