Designer radiator problem

[terryplumb]

If the problem rad heated fully ,all over ,then there is nothing wrong with that rad. Your problem is the system is not balanced.

 

[johnny2007]

If the problem rad heated fully ,all over ,then there is nothing wrong with that rad. Your problem is the system is not balanced.

I've followed all balancing instructions from internet and the plumber went around with a thermometer checking entry and exit points.
Made some slight adjustments but overall he said it was fine.

 

[terryplumb]

You should ask him why it heats fully when other rads are turned off.

Plumber has been and said the diffuser in the radiator creates this problem and there's nothing we can do.

He reckons that either the internal diffuser is same as many others and makes things worse.

Also ask him how the magic diffuser changes its mind when other rads are turned off.

 

[johnny2007]

You should ask him why it heats fully when other rads are turned off.

Also ask him how the magic diffuser changes its mind when other rads are turned off.

He said more flow/pressure gets water to pass through small holes of the diffuser when all other rads are closed.
He also said there are lots of these designer radiators giving similar problems, especially the vertical ones.

 

[terryplumb]

He is quite right ,it does need more flow. And how do you achieve that ?
By restricting the flow through all the other radiators.....called balancing.
The fact is the radiator works perfectly well , if it gets what it needs . If it doesnt ,that's a system problem ,not a faulty radiator. Balancing problem is the most likely, pump inadequate ,or basic piping problem are possibilities,but given the fact that a previous radiator was in that position and worked fine , I would be surprised if it's anything other than a balancing issue.

 

[johnny2007]

Ok, thanks.
I will try rebalancing from scratch.
I had used my notes from last year when i did it last, but we changed a downstairs towel radiator and this one, so that's probably the problem.
I'll report when done.

 

[terryplumb]

Why hasn't the plumber balanced the system ,he should have done it when installing the rads??
Why are you doing it ?

 

[johnny2007]

Why hasn't the plumber balanced the system ,he should have done it when installing the rads??
Why are you doing it ?

He did.
But we went from a starting point that I had made myself, so lockshield valves opened to a certain amount as i had written down last time.
He then adjusted a few valves using a thermometer

 

[johnny2007]

Ok, will do full balance in the next few days, but closing the lockshield by half turn of the radiator before the problem one makes a difference already.
So, thank you, it's most likely a balancing problem.
Thanks.
One question: the last radiator in the system, which is the one in the bathroom, does it need balancing or stays fully open?

 

[terryplumb]

Starting with your system cold ,no radiators on ,start up central heating and go around all rads making a note of those that heat up first / quicker than others. Then each rad that gets hot quickly ,turn down their lockshields half a turn. And see what the problem rad heats like.

 

[johnny2007]

Starting with your system cold ,no radiators on ,start up central heating and go around all rads making a note of those that heat up first / quicker than others. Then each rad that gets hot quickly ,turn down their lockshields half a turn. And see what the problem rad heats like.

Will do.
Question about the last one of the system:
Does it need balancing or just open both valves fully?

 

[terryplumb]

Leave it alone ,for now .Follow the advice in my last post ,making a few adjustments to the rads that heat up first ( which may or may not include the last one on the system) may be enough to get your problem rad working fully.

 

[johnny2007]

Ok.
Do i leave all valves as they are now and then shut half a turn the ones that warm up first?
Or i open trv fully and close lockshield fully, then open the lockshield half a turn and check that temperature is 12 degree difference as I've always done? (Possibly wrong)

 

[terryplumb]

Open fully all TRV's. Leave lockshields as they are . Then turn on c/heating , assessing which heat first etc.