assuming you wish to do this because you want it to be on permanently to dry towels even when heating is off - i don't think it is usually done by connecting to the hot water supply, but runs instead from the primary. pretty involved, not a job for a diyer if unsure of what to do. get in a pro.
[quote="nitro23456"]Why would you want to do this? are you planning on using it as a shower as well?[/quote]
Obviously not but for most of the year my house is not heated or heated solely through a muti fuel stove. The central heating is rarely used. However, the water is heated twice a day throughout the year so it seems to me sensible that the towell rail is heated by the hot water and not the central heating.
to get the water from your hot water storage cylinder to the towel rail you would need to open a hot tap further down the line until the rail fills with hot water. not only will this be wasteful but as soon as you run a bath and deplete the hot water in the cylinder the rad will run cold. so no hot towel on exit from the bath. additionally the water in the rail will then just sit there static so will quickly cool, giving up its heat without warming the room hardly at all.
baffled as to how you think this will work.
as i said before this type of arrangement where a bathroom rad is heated independently of other rads on the heating circuit is normally set up so it gets its feed from just after the primary circuit when the water is pumped to the heating coil in the cylinder, NOT from the domestic supply.