Cold Radiator

Belenus

Albermarle said:

housebuyer143 said:

Belenus said:

housebuyer143 said:

Albermarle said:

nofoollikeold said:

I suspect you need to balance the heating system.  Endless "how to's" on youtube.  Balance it on the lock shield valves (the ones at the opposite end to the TRV end).  Its a pretty boring, time consuming, job, but you should only have to do it once.

That was my first thought, but why would this one radiator suddenly start being a problem, when it was all OK before?

Yes, this is what I don't understand. It's been working fine for a month or more as that's when the heating has been back on again - why would it suddenly stop being okay? 

It's gas central heating, system boiler. I switched over the TRV with one that I know works and the one from this cold rad works fine on the other, so it must be okay and it works when the rads are off. 

It's not just the rad that is cold either, it's all the pipes to it. 

The TRV actuator may be fine but have you checked that the pin in the valve is ok?

Remove the TRV and, using a coin or the back of a spoon or similar to protect your thumb, press down on the pin. It should go down and spring back up again when you remove the pressure.

If not, gently use pliers or grippers (use paper or cloth to protect the pin from scratches or marks) to move it up and down and see if that gets it working again. It shouldn't leak but have an old towel or something under it to protect the floor or carpet.

Thank you so much for this detailed reply, I'll try that shortly and see if that gets it going.

For  sure this is worth trying as it is a common problem, but if the pin was stuck down ( as often happens) then the radiator would stay cold, even when you switched the other radiators off. 

Good point but it may just intermittently stick down so worth checking.

It will only take the OP a few minutes to eliminate or confirm the pin as the problem.

OP have you tried bleeding that radiator to eliminate trapped air or gases.

Also, if you do get it hot again by turning off the other radiators, check to see if it is hot all over and not cool at the bottom (sludge) or top (air). A build up of sludge in the bottom could be the problem.

housebuyer143

Belenus said:

Albermarle said:

housebuyer143 said:

Belenus said:

housebuyer143 said:

Albermarle said:

nofoollikeold said:

I suspect you need to balance the heating system.  Endless "how to's" on youtube.  Balance it on the lock shield valves (the ones at the opposite end to the TRV end).  Its a pretty boring, time consuming, job, but you should only have to do it once.

That was my first thought, but why would this one radiator suddenly start being a problem, when it was all OK before?

Yes, this is what I don't understand. It's been working fine for a month or more as that's when the heating has been back on again - why would it suddenly stop being okay? 

It's gas central heating, system boiler. I switched over the TRV with one that I know works and the one from this cold rad works fine on the other, so it must be okay and it works when the rads are off. 

It's not just the rad that is cold either, it's all the pipes to it. 

The TRV actuator may be fine but have you checked that the pin in the valve is ok?

Remove the TRV and, using a coin or the back of a spoon or similar to protect your thumb, press down on the pin. It should go down and spring back up again when you remove the pressure.

If not, gently use pliers or grippers (use paper or cloth to protect the pin from scratches or marks) to move it up and down and see if that gets it working again. It shouldn't leak but have an old towel or something under it to protect the floor or carpet.

Thank you so much for this detailed reply, I'll try that shortly and see if that gets it going.

For  sure this is worth trying as it is a common problem, but if the pin was stuck down ( as often happens) then the radiator would stay cold, even when you switched the other radiators off. 

Good point but it may just intermittently stick down so worth checking.

It will only take the OP a few minutes to eliminate or confirm the pin as the problem.

OP have you tried bleeding that radiator to eliminate trapped air or gases.

Also, if you do get it hot again by turning off the other radiators, check to see if it is hot all over and not cool at the bottom (sludge) or top (air). A build up of sludge in the bottom could be the problem.

I've just done the pin thing and it doesn't seem like it's stuck, comes on fine again when other rads off and goes off again when they are on 😭. Although I feel like it took longer to heat up this time.l (I didn't think it was going to) The pipe was burning but the radiator was cold so I hit the valve and pushed it up and down and maybe that encouraged the water in. 🤔
The pipe goes cold when the radiator is cold  and hot when it's hot. 

I bled it but only water came out. The radiator was power flushed in May so I would be surprised if it's sludged up, but even so it's hot all over. 

ThisIsWeird

Hi hb143.
Could you confirm which end of the rad heats up first - the TRV or the l/s end?
Do you have the cap removed from the l/s? Have you adjusted it at all?
Always worth labelling a l/s spindle with a paper flag so you can note how open it is before you begin tweaking. Tape a wee paper flag to it, and then screw it down clockwise until it stops - count how many turns and parts turns this takes, and then return it.
It's unusual that it's so distinctly on and off. If your system was imbalanced, then I'd still expect it to heat to some degree. So it suggests perhaps an issue with one of the valves, that the rubber washer is loose or something.
Possibly, tho', it is an imbalance, and the cooler weather means the other rads remain TRV-open for longer as these other rooms still need heating. Perhaps, before, the other rooms would warm up quickly and begin to close their TRVs, and that then sent the required flow to this rad without you noticing there was a delay?
With the other rads closed, and this kitchen rad now working, you should be able to hear the flow through it? So, ear to the pipe whilst you steadily turn the TRV down from 5 to 1. If the kitchen temp is around 19oC, the TRV should begin to become firm to turn at 3 or 2, loose above this - is it? The quiet hiss at 5 should become more pronounced at 3 as the flow is being shut off, and pretty much disappear at 2 and beyond.
Compare that with another rad - do they sound similar?
And please report how 'open' the l/s on that rad is.
Finally, with the TRV fully open, and the rad getting flow (other rads off), try turning the l/s on it open and closed smoothly, as you did the TRV - tho' it'll take more turns. See if you can get a nice fitting spanner or socket on it so you have good control. Open it a good 4 turns from the closed position, and then steadily close it clockwise whilst listening to the hiss. How does the noise compare with the TRV end?
Is it, for example, a gentle (no 5) hiss at 4 turns open, ditto at 3, getting more hissy at 2, and the hiss going steadily away at 1 turn and beyond?
And then open it again slowly - does the hiss quietly begin at a fraction (1/4) turn open and steadily and smoothly increase until you are 2 or more open? Or is there a delay, possible a wee clunk, a sudden change?
(I had a strange experience with my bathroom towel rail a few days ago, when I wanted to tweak the l/s open a touch more - it's used as a by-pass. I gave it a fraction turn and the hiss increased - and then 'clunk', shut off. A touch more, and hiss-clunk. Once more, before it didn't clunk off and worked ok. Turns out the TRV and l/s were on the wrong ends, so the l/s' washer was seemingly being blown closed by the wrong direction flow each time, until it was finally open enough to cope - these washers tend to be a bit loose on the spindles. If I find the idiot who installed them, I'll beat myself up.)
On that note, HB, can you see a direction arrow on the chrome body if the TRV or l/s?

housebuyer143

ThisIsWeird said:

Hi hb143.
Could you confirm which end of the rad heats up first - the TRV or the l/s end?
Do you have the cap removed from the l/s? Have you adjusted it at all?
Always worth labelling a l/s spindle with a paper flag so you can note how open it is before you begin tweaking. Tape a wee paper flag to it, and then screw it down clockwise until it stops - count how many turns and parts turns this takes, and then return it.
It's unusual that it's so distinctly on and off. If your system was imbalanced, then I'd still expect it to heat to some degree. So it suggests perhaps an issue with one of the valves, that the rubber washer is loose or something.
Possibly, tho', it is an imbalance, and the cooler weather means the other rads remain TRV-open for longer as these other rooms still need heating. Perhaps, before, the other rooms would warm up quickly and begin to close their TRVs, and that then sent the required flow to this rad without you noticing there was a delay?
With the other rads closed, and this kitchen rad now working, you should be able to hear the flow through it? So, ear to the pipe whilst you steadily turn the TRV down from 5 to 1. If the kitchen temp is around 19oC, the TRV should begin to become firm to turn at 3 or 2, loose above this - is it? The quiet hiss at 5 should become more pronounced at 3 as the flow is being shut off, and pretty much disappear at 2 and beyond.
Compare that with another rad - do they sound similar?
And please report how 'open' the l/s on that rad is.
Finally, with the TRV fully open, and the rad getting flow (other rads off), try turning the l/s on it open and closed smoothly, as you did the TRV - tho' it'll take more turns. See if you can get a nice fitting spanner or socket on it so you have good control. Open it a good 4 turns from the closed position, and then steadily close it clockwise whilst listening to the hiss. How does the noise compare with the TRV end?
Is it, for example, a gentle (no 5) hiss at 4 turns open, ditto at 3, getting more hissy at 2, and the hiss going steadily away at 1 turn and beyond?
And then open it again slowly - does the hiss quietly begin at a fraction (1/4) turn open and steadily and smoothly increase until you are 2 or more open? Or is there a delay, possible a wee clunk, a sudden change?
(I had a strange experience with my bathroom towel rail a few days ago, when I wanted to tweak the l/s open a touch more - it's used as a by-pass. I gave it a fraction turn and the hiss increased - and then 'clunk', shut off. A touch more, and hiss-clunk. Once more, before it didn't clunk off and worked ok. Turns out the TRV and l/s were on the wrong ends, so the l/s' washer was seemingly being blown closed by the wrong direction flow each time, until it was finally open enough to cope - these washers tend to be a bit loose on the spindles. If I find the idiot who installed them, I'll beat myself up.)
On that note, HB, can you see a direction arrow on the chrome body if the TRV or l/s?

Thank you for such a detailed reply, I'll try this later and report back. Now you mention it though... The TRV on this radiator is the only one in the whole house that's on the right while all the rest are on the left - not sure if that's significant, but could be like you mentioned. 

Albermarle

housebuyer143 said:

ThisIsWeird said:

Hi hb143.
Could you confirm which end of the rad heats up first - the TRV or the l/s end?
Do you have the cap removed from the l/s? Have you adjusted it at all?
Always worth labelling a l/s spindle with a paper flag so you can note how open it is before you begin tweaking. Tape a wee paper flag to it, and then screw it down clockwise until it stops - count how many turns and parts turns this takes, and then return it.
It's unusual that it's so distinctly on and off. If your system was imbalanced, then I'd still expect it to heat to some degree. So it suggests perhaps an issue with one of the valves, that the rubber washer is loose or something.
Possibly, tho', it is an imbalance, and the cooler weather means the other rads remain TRV-open for longer as these other rooms still need heating. Perhaps, before, the other rooms would warm up quickly and begin to close their TRVs, and that then sent the required flow to this rad without you noticing there was a delay?
With the other rads closed, and this kitchen rad now working, you should be able to hear the flow through it? So, ear to the pipe whilst you steadily turn the TRV down from 5 to 1. If the kitchen temp is around 19oC, the TRV should begin to become firm to turn at 3 or 2, loose above this - is it? The quiet hiss at 5 should become more pronounced at 3 as the flow is being shut off, and pretty much disappear at 2 and beyond.
Compare that with another rad - do they sound similar?
And please report how 'open' the l/s on that rad is.
Finally, with the TRV fully open, and the rad getting flow (other rads off), try turning the l/s on it open and closed smoothly, as you did the TRV - tho' it'll take more turns. See if you can get a nice fitting spanner or socket on it so you have good control. Open it a good 4 turns from the closed position, and then steadily close it clockwise whilst listening to the hiss. How does the noise compare with the TRV end?
Is it, for example, a gentle (no 5) hiss at 4 turns open, ditto at 3, getting more hissy at 2, and the hiss going steadily away at 1 turn and beyond?
And then open it again slowly - does the hiss quietly begin at a fraction (1/4) turn open and steadily and smoothly increase until you are 2 or more open? Or is there a delay, possible a wee clunk, a sudden change?
(I had a strange experience with my bathroom towel rail a few days ago, when I wanted to tweak the l/s open a touch more - it's used as a by-pass. I gave it a fraction turn and the hiss increased - and then 'clunk', shut off. A touch more, and hiss-clunk. Once more, before it didn't clunk off and worked ok. Turns out the TRV and l/s were on the wrong ends, so the l/s' washer was seemingly being blown closed by the wrong direction flow each time, until it was finally open enough to cope - these washers tend to be a bit loose on the spindles. If I find the idiot who installed them, I'll beat myself up.)
On that note, HB, can you see a direction arrow on the chrome body if the TRV or l/s?

Thank you for such a detailed reply, I'll try this later and report back. Now you mention it though... The TRV on this radiator is the only one in the whole house that's on the right while all the rest are on the left - not sure if that's significant, but could be like you mentioned. 

If it is the right sort of TRV , it can still be OK even if installed on the return flow . However it is normal to have them on the flow side.
To check when the radiator does start to heat up, the flow pipe into the radiator will get hot first.

FreeBear

ThisIsWeird said: Always worth labelling a l/s spindle with a paper flag so you can note how open it is before you begin tweaking. Tape a wee paper flag to it, and then screw it down clockwise until it stops - count how many turns and parts turns this takes, and then return it.

Use a marker pen (Sharpie type) and put a line on the spindle & body. Gives you a permanent mark to line back up.