Replaced Radiator Valves, 2 radiators not heating up as quick

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I replaced 9 radiator valves today (gone from TRV to manual cos the TRVs were not working out).

2 of the radiators are taking forever to heat up. They are not the first or last rads on the circuit.

The flow pipe to the rads is searing hot, but the radiator lukewarm and the return pipe colder still. I therefore don't think it's a balancing issue.

I've had a look inside the valve and when fully open the close-stop seems to only be half way up I would have expected a bigger gap for water to flow through..

Is this enough or is this causing reduced flow into the radiators and therefore the delay?

I've attached a pic of the valve.

IMG_0384.JPG


Cheers!
 
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Sounds like a balancing issue to me

Thanks

Even though the flow pipe is burning hot and the rads are not the first or last on the circuit?

The lockshields haven't been changed.
 
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The flow pattern geometries of the new valves have probably been enough to upset the balancing.
Try re-balancing.
 
I replaced 9 radiator valves today (gone from TRV to manual cos the TRVs were not working out).

The flow pipe to the rads is searing hot, but the radiator lukewarm and the return pipe colder still. I therefore don't think it's a balancing issue.
So you decided to ditch the TRVs without bothering to find out why they were not working correctly. The answer is, in most cases an incorrectly balanced system.

I've had a look inside the valve and when fully open the close-stop seems to only be half way up I would have expected a bigger gap for water to flow through.

Is this enough or is this causing reduced flow into the radiators and therefore the delay?
How much water do you think flows through a 1kW rad every minute? It's not very much.

For a 10C temperature difference it is 1.44 litres; half that for a 20C difference. A two kilowatt rad will be twice as much - it's proportional.

Just to give you an indication of how little a valve needs to be opened, a good starting point, when balancing a system, is to open all lockshield valves by half a turn. Then make minor adjustments (1/12th turn or less at a time) to fine-tune the system. The most any lockshield valve needs to be open would be about one turn.
 
I replaced 9 radiator valves today (gone from TRV to manual cos the TRVs were not working out).

The flow pipe to the rads is searing hot, but the radiator lukewarm and the return pipe colder still. I therefore don't think it's a balancing issue.
So you decided to ditch the TRVs without bothering to find out why they were not working correctly. The answer is, in most cases an incorrectly balanced system.

I've had a look inside the valve and when fully open the close-stop seems to only be half way up I would have expected a bigger gap for water to flow through.

Is this enough or is this causing reduced flow into the radiators and therefore the delay?
How much water do you think flows through a 1kW rad every minute? It's not very much.

For a 10C temperature difference it is 1.44 litres; half that for a 20C difference. A two kilowatt rad will be twice as much - it's proportional.

Just to give you an indication of how little a valve needs to be opened, a good starting point, when balancing a system, is to open all lockshield valves by half a turn. Then make minor adjustments (1/12th turn or less at a time) to fine-tune the system. The most any lockshield valve needs to be open would be about one turn.
What are you talking about mate.

I ditched the TRVs because they were closing and staying closed for hours at a time even though the room and radiator was freezing. As soon as I took the cap off hot water flowed into the radiator, so I've had no TRV caps for a few weeks. They were crap.

I'll work on rebalancing. Cheers.
 
I ditched the TRVs because they were closing and staying closed for hours at a time even though the room and radiator was freezing. As soon as I took the cap off hot water flowed into the radiator, so I've had no TRV caps for a few weeks. They were crap.
OK, they could have been cheap TRVs - you don't say which make/model they were. But your problem might have been caused by poor balancing, which could have meant that the pressure differential across the TRV exceeded manufacturer's specification. When this happens a TRV will behave like an on/off switch, rather than a proportional controller.
 
But your problem might have been caused by poor balancing, which could have meant that the pressure differential across the TRV exceeded manufacturer's specification. When this happens a TRV will behave like an on/off switch, rather than a proportional controller.
Exceed the pressure differential on a domestic system?????...
 
I ditched the TRVs because they were closing and staying closed for hours at a time even though the room and radiator was freezing. As soon as I took the cap off hot water flowed into the radiator, so I've had no TRV caps for a few weeks. They were crap.
OK, they could have been cheap TRVs - you don't say which make/model they were. But your problem might have been caused by poor balancing, which could have meant that the pressure differential across the TRV exceeded manufacturer's specification. When this happens a TRV will behave like an on/off switch, rather than a proportional controller.
Where did you read that, yeehaw plumbing school?
 
Not difficult to do if the pump is set to max to "force the water through the pipe", as I've seen suggested by a 'professional'.
I can honestly say that I've never encountered a domestic central heating system that utilised a 10 metre head pump (circulator)...:censored:....although I must confess I've installed a few circulators in series over the years..;)
 
In my current property I spent 450 quid on 9 Arroll TRVs. They are beautiful to look at but perform poorly as TRVs.
WJF84

They are fitted with yesterdays technology. Wax sensors!
And the sensor looks as though its encapsulated inside the valve body. Perhaps the functional design was compromised in order to keep them looking er.. beautiful?
 
In my current property I spent 450 quid on 9 Arroll TRVs. They are beautiful to look at but perform poorly as TRVs.
WJF84

They are fitted with yesterdays technology. Wax sensors!
And the sensor looks as though its encapsulated inside the valve body. Perhaps the functional design was compromised in order to keep them looking er.. beautiful?
So I should have said they were expensive rubbish, not cheap!
 
Why did you not fit new TRVs with liquid sensors?

Instead of fitting lockshield valves you might as well have just set your old TRVs to maximum or even taken the heads off. You don't seem to understand what they are meant to do or how they work.

Try balancing. You don't seem to accept that balancing is ever necessary!

See FAQ

Tony
 

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