Heated towel rail cold

[Dave H]

Hi - I have recently installed a heated towel rail to replace a traditional radiator on my single pipe system. The rail is approx 1.5 metres from the old radiator and is tee'd into the hot water storage cylinder. The rail does not get hot ! I have drained the system and bled the rail - just get water venting (ie no air). I also vented the rail with the return valve shut off until it filled with hot water and then opened up the return valve - it got hotter and remained hot with the system set to water only - got a bit cooler when the heating was switched on. This morning when the system started up(water only to start and then water and heating together), the rail remained cold . There is traditional rad also tee'd into the storage cylinder - working fine ! The valves (simple on/off not TRV) are working OK !

Could it be something to do with the level of the pipe run or height of the new rail, or is the new rail competing with the traditional rad also tee'd into the cylinder ?

Any help much appreciated !

Dave H

 

[WHPES]

Let us know how you get on.

 

[migoplumber]

just to check, youve said single pipe system.
do you have a one pipe system, ie the flow and return of said towel radiator are fed from the same pipe. if they are your towel rad could be cold locked, but better you define your single pipe system first !

 

[Dave H]

The rads are fed by a sigle pipe system (ie flow and return at bottom of rad) - the towel rail is actually tee'd into the 28mm flow and return to the hot water cylinder coil - the way I have extended the pipes to the towel rail (to keep them under the floor) has built in a rise (3-4 inches) on the return part of the loop so think this is stopping the gravity fed flow ?

 

[Dave H]

Hi - the levels of the return from the rail (which is tee'd into the return on the water cylinder coil circuit) are the problem (the circuit is gravity fed and the return from the rail has a 3-4inch rise built into it).
I am going to make the hot water cylinder circuit pumped with a couple of motorised valves to switch between the water and water/heating settings on the programmer - should also sort the problem of the upstairs rads getting hot when only water slected at the moment.
Thanks a lot for all your suggestions - especially payney1974 (pinpointing the levels problem)and oldplumber,WHPES and UKPITA !