Furthest radiators not getting hot

[Harry Bloomfield]

It reads as if the system may need balancing, to reduce the flow through the radiators which get hot first and hog the flow.

 

[windsortg]

Thanks. Excuse my ignorance but if nothing has been changed on the heating system and all radiators used to heat up efficiently before summer, what would cause the system to now need balancing?

If I need to balance the system, is it the case of turning down the TRVs on the rads that get hot the quickest? From my limited knowledge on balancing a heating system, I was under the impression it is the lockshield valve (opposite side to the TRV) that is adjusted to push the flow of hot water to the other rads?

 

[terryplumb]

It is the lockshields that are used to balance. Have any rads been removed for decorating / plastering etc ?
If none have been altered since system previously all worked well,then it's unlikely that balancing is your issue.
When the problem rads heated fully today ,were all other rads on the system fully heating as well ?

 

[windsortg]

Thanks @terryplumb and everyone else for your advice. No rads have been removed/altered since system previously all worked well. To be honest, I did not check all the other rads to see if they were fully heated. I will check though later today when the heating comes on to see if all the rads fully heat up. At the moment, we only have the heating to come on for a couple of hours in the morning.

My gut feel is that once the heating has turned off via the room stat, and then the room thermostat later triggers the heating to come on when the temperature drops below the set temperature on the room thermostat, the 3 furthest rads from the boiler struggle to heat up.

I will hopefully be able to confirm this later this evening.

 

[Harry Bloomfield]

Thanks. Excuse my ignorance but if nothing has been changed on the heating system and all radiators used to heat up efficiently before summer, what would cause the system to now need balancing?

If I need to balance the system, is it the case of turning down the TRVs on the rads that get hot the quickest? From my limited knowledge on balancing a heating system, I was under the impression it is the lockshield valve (opposite side to the TRV) that is adjusted to push the flow of hot water to the other rads?

Correct, you need to turn down the lock shield valves, on the opposite end to the TRV - but as a permanent fix. Turning down the TRV's was suggested as a temporary test, just to see if the supply to the remote ones might improve. Be aware that a fraction of a turn on the lock shields makes a lot of difference to the flow through the rad, when they are nearly closed.

What might have changed, is simply your house temperatures, so the local rads are hogging more flow.

 

[Bouy]

Thanks @terryplumb and everyone else for your advice. No rads have been removed/altered since system previously all worked well. To be honest, I did not check all the other rads to see if they were fully heated. I will check though later today when the heating comes on to see if all the rads fully heat up. At the moment, we only have the heating to come on for a couple of hours in the morning.

My gut feel is that once the heating has turned off via the room stat, and then the room thermostat later triggers the heating to come on when the temperature drops below the set temperature on the room thermostat, the 3 furthest rads from the boiler struggle to heat up.

I will hopefully be able to confirm this later this evening.

You are allowed to switch the heating on now so you don't have to wait till the evening to report back