On Wed, 1 Aug 2018 00:53:22 +0100, John Rumm
wrote:

On 31/07/2018 21:38, wrote:
The flow to my bath has dwindled over the years, it's a conventional
vented cylinder and 3/4" copper pipes, is there likely to be any
benefit in dosing the cold water tank with sulphamic acid and then
recirculating through the bath tap connection with a pump?

A tub of fernox DS3 will make enough gallons to fill the tank and the
cistern, so yup recirculating with a pump for a few hours should do the
trick. Keep the immersion on for better performance (but don't let the
cistern get too hot if its plastic - they can go droopy if not well
supported)

Thanks, to clarify I intend to first empty the galvanised steel cold
water tank and wet vacuum any scale in the bottom. I was only going
to part fill it and would add the fernox DS3 as you advise. I was then
intending to attach a spare central heating pump to the 15mm shower
connection which is TEEd off the bath hot water tap and return the
water to the cold water tank via a length of HEP20 dumping back into
the cold water tank.

AJH