Pipe size to indirect vented DHW cylinder.

[Steve001]

Is there a rule for this? I'm asking because I'm upgrading a mate's hot water cylinder, he's got a tiny one there at the moment, guessing 8-900 high and only 350 diameter, it's all 22mm from the boiler then goes down to 15mm for the last metre or so after the zone valve.

Happy that the previous is 15mm due to small size of tank, i'll be replacing it for a bigger standard size jobby, my reckoning is to upsize it to 22mm, but that got me thinking, any calcs you can do for this to make sure it's right, MIs? What do you fellows do?

Cheers for your help.

 

[kirkgas]

if it is fully pumped it would be "better" in 22mm pipe right up to the cylinder, as this will assist recovery rate, new cylinders should be looking at 20min recovery if done in 22mm, we used to run the whole hot water circuit in 15mm from the zone valve (prob to save us time/money TBH) there will be pipework calculations in a BS doc somewhere but not really worth a big calculation

 

[Steve001]

I do love this forum, the one thing with working on your todd, no one there to bounce things off or looking over your shoulder saying "what you doing muppet? when your doing something wrong.

22 it is then. I'm putting in a normal cylinder, he's having mine as I'm getting a combi slotted in, as long as I can prize it from the grasp of the contractors for a few quid. Oh the beauty of renting when you dont have to worry about your own plumbing.

not that the mrs isn't on my back for a new bathroom.


Thankyou Kirkgas. And If i get off this site I will try and find the BS stuff when I'm really bored.

Steve

 

[kirkgas]

I do love this forum, the one thing with working on your todd, no one there to bounce things off or looking over your shoulder saying "what you doing muppet? when your doing something wrong.

22 it is then. I'm putting in a normal cylinder, he's having mine as I'm getting a combi slotted in, as long as I can prize it from the grasp of the contractors for a few quid. Oh the beauty of renting when you dont have to worry about your own plumbing.

not that the mrs isn't on my back for a new bathroom.


Thankyou Kirkgas. And If i get off this site I will try and find the BS stuff when I'm really bored.

Steve

Thankyou Kirkgas. And If i get off this site I will try and find the BS stuff when I'm really bored.

BS6700 might have something (cant remember if this is only for domestic pipework rather than heating)