Towel Rail takes ages to heat up if at all

[BarrySingh]

Hi,

My towel rail will only partially heat up. However, if I switch off a couple of rads it fully heats up quite quickly.

The pressure on the boiler is 1 bar resting and no more than 2 bars running.

I've recently had the expansion tank recharged as it was running a little in the red.

My Bolier is a Grennstar Junior 28i.

Any thoughts?

 

[just pumps]

Is the inlet pipe hot to touch? Thinking it may need bleeding or the system needs balancing.

 

[BarrySingh]

Is the inlet pipe hot to touch? Thinking it may need bleeding or the system needs balancing.

Yes it's hot. Top gets hot but bottom only gets hot when I turn a few rads off. I've noticed resting pressure is down to 0.5 bar after say 10 days of running.

 

[JohnD]

Turn off the hot radiators.

I expect the cool one will warm up

If so, you need to balance the system.

 

[BarrySingh]

Turn off the hot radiators.

I expect the cool one will warm up

If so, you need to balance the system.

Thanks, yes it does when I just turn the other upstairs one's off and leave downstairs hot and on.

 

[just pumps]

Now you need to read about balancing the radiators.

 

[JohnD]

Balance the radiators. It is done by closing the hot ones, not by trying to open the cold ones more.

For a quick start, identify the lockshield valve on each one (not the manual or thermostatic valve). Close it fully and open half a turn only. Fully open the thermostatic or manual valve at the other end. . Run the heating for at least half an hour without touching them. Are they all approximately equal in heat? A rough guide is that the inlet pipe should be "too hot to hold" and the outlet pipe should be "too hot to hold for long." If not, close down the hottest ones by one quarter of a turn and run for another half hour.

Do not open any of them fully.

Do not adjust any of them by more than a quarter turn in half an hour

During fine tuning, do not adjust more than one rad in half an hour.

All the adjustment is within the first turn from fully closed.

You can do more precise adjustment using thermometers.

Rooms where the radiator is too small need to be adjusted hotter than rooms where it is too big.

 

[BarrySingh]

Thanks. It makes sense to regulate the flow so enough juice makes it all the way round the system before the boiler cycles off.

Don't know why it just seems to have happened though. (Or I've just noticed it!)

 

[BarrySingh]

Does it matter which way round the inlet/outlet pipes are? A while ago I marked them all up and sometimes the inlet is lockshield-side and sometimes TRV- side.

 

[JohnD]

Don't know why it just seems to have happened though. (Or I've just noticed it!)

Perhaps you have some TRVs that have opened in the recent cold weather, changing the flow routes.

Or perhaps sediment is disrupting flow

 

[JohnD]

Does it matter which way round the inlet/outlet pipes are?

No.

Though some TRVs are directional.