pipe size supply loft tanks

[Dave30]

I am upgrading my loft tanks on a lead main gravity system to the new poly tanks. Cold water tank and F&E

My current supply for both tanks is a single 15mm pipe from the airing cupboard up to the loft with 2 Tee offs for each tank, is this size enough? or will it cause water hammering as I do hear a rattling sound when I use the hot water?

I was thinking of keeping the 15mm for the F&E tank and tee off 15mm to 22mm at the airing cupboard and running and running a separate 22mm for the cold water tank and 15mm for the F&E tank?

would this help . Thank you

 

[Burnerman]

15mm supplies are fine - its the capacity of the large tank that ensures you have enough hot water at your disposal.
If you include isolators in the supply, do use full bore ones.
John

 

[Agile]

The F&E tanks only take a small flow of water every few months so they can be teed off the supply to the cold tanks anywhere in 15mm.

If you are concerned by the refill time consider fitting a larger ball valve as the orifice in the valve is much smaller than the supply pipe.

 

[Dave30]

The F&E tanks only take a small flow of water every few months so they can be teed off the supply to the cold tanks anywhere in 15mm.

If you are concerned by the refill time consider fitting a larger ball valve as the orifice in the valve is much smaller than the supply pipe.

thanks

The old tanks used to sound like a waterfall filling up but there was two 25 gallon tanks for both cold and hotwater and it also used to create some water hammering.


I will also only have one cold water for the hotwater cylinder rest is coming the mains.I was planning on using the fluidmaster side entry Valves on the new cold tanks to reduce filling noise and hammering would this be ok?