Living Room Radiator Not Getting Hot

[WSB]

When you start turning on the others, do it via the lockshields. Makes sure they're all closed and then crack them open 1/2 turn each time until you feel the flow pipe start to heat up, then move onto the next until you can just get heat flowing through them all.

Will do.
Shouldn't the lockshields eventually be fully open though?

 

[DP]

Some further checking......
Boiler heated water goes to each radiator. Some runs are long, others medium and some short
The pump will favour the short runs

Check system balance by going down on your knee and grasping both connecting pipes at each radiator to check the difference of temperature between the two pipes. If there is no or little difference, close the lock shield valve a turn or so. Where the difference is large, open the lock shield further. Do this check with pipes going to cylinder as well

If you have clamp thermometers, set the difference between the pipes to 11 degree C or close to that. Any alteration will need system to stabilise before further adjustments are made

Check temperature difference between flow and return at the boiler too- should be about 11 degree C

 

[Madrab]

Shouldn't the lockshields eventually be fully open though

Nope, certainly not, that was probably the issue, the system wasn't balanced so no flow was getting to that rad. This is just the start of the balancing process to obtain flow to all the rads.

Once that's done then it's fine tuning to get the temp differentials correct but the first step is to get them all to heat up properly

 

[terryplumb]

What he said ^^^^

 

[WSB]

I see.
That makes sense. Learned something new today.
So presumably the one furthest away will typically want the lockshield open more than those closer.

 

[terryplumb]

Very likely.

 

[Madrab]

Are all the pipe feeds to the rads the same size for them all too?

 

[WSB]

All 15mm piping yes

 

[WSB]

Thanks all for your help
Been tinkering with balancing the rads as suggested.
Got all running now. The worst ones are at least warm.
Will continue with some fine tuning though.
Thanks again all

 

[Madrab]

If you are still struggling then the pump may be getting lazy and in effect dropping in output, especially if it all worked fine before.

 

[DP]

If you are still struggling then the pump may be getting lazy and in effect dropping in output, especially if it all worked fine before.

Or the pump speed is too low

 

[WSB]

Can the pump speed be adjusted?
It's a Grunfoss selectric UPS 15-50 130.
Has what looks like an adjustable disc in the middle. Will turning that do anything?
Been the same pump since the 17 years we've been living here so at least that old.

 

[WSB]

Just had a look at the pump which has a 1,2 or 3 settings and currently set to 3,so guess its already on its highest setting.
Maybe just on its last legs.
Have Baxi cover for the boiler which covered the diverter valve.
May cover the pump too.

 

[BlueLoo]

I'd be removing all the rads, flushing them out, then dumping cleaner in the system for a few weeks because it sounds like your system is bunged up.
Then again, i ain't a plumber.

Pump on speed 3 is odd.

 

[WSB]

I'm guessing that maybe pump was set to 3 as either it needed a bit more oomph due to being old and worn or that the distance to rads warrants it.
House is a large ish 4 bedroom which has also been extended on top of that a couple of times.