No heat from 1 Radiator

Lex Luthor

One of the radiators in a bedroom is just not heating up tonight. All the rest of the house if fine and it just was noticeable this evening when the heating came on at 5.

It was one of 2 rads that was put in a few years ago when we got an extension of 2 bedrooms, but the rad in the other new bedroom is nice & hot. Both new rads as far as I know get their water from the same source.

I opened the bleed screw and water came out and there is no heat on the pipe in to the rad which you'd normally expect.

Any ideas?

311

Sometimes when builders put in radiators ,the qualpex they use gets kinked and the radiator will take ages to finally heat.
Other than that ,it could be dirt or system needs balancing.

Lex Luthor

the system is balanced. I just checked my press gauge and its reading 0.5 bar so I need to get the pressure up.
Out with me bike pump for the next half hour

suitseir

I had a problem like that and I was told by a plumber to leave the system going and turn off every other rad except maybe one in bathroom or utility room and see if it heats up. If it does, it is just a matter of dirt in the system as opposed to air. You might want to try this during the day.

311

Lex Luthor wrote:

the system is balanced. I just checked my press gauge and its reading 0.5 bar so I need to get the pressure up.
Out with me bike pump for the next half hour

Pressure wont heat radiators

Lex Luthor

ok update....got the pressure back up to 1bar and the heating is on now about half an hour and its still not heating.

I have a funny feeling that the TRV on that rad is busted. Coincidentally, the wife was in that room today painting and it looks like she knocked off it as it is not steady at all in its position. Its rocking at the top so I'm thinking its in a closed state.

Am I getting warm?

JamesM

Lex Luthor wrote:

the system is balanced. I just checked my press gauge and its reading 0.5 bar so I need to get the pressure up.
Out with me bike pump for the next half hour

I presume that you are not serious :eek:
I remember someone told someone else on this forum some time ago that they should use a pump to pump up the expansion vessel

Is the valve thermostatic ? Could anyone have turned off the valve (some people do not check this). Did you turn on another rad, which may take the flow from the cold one ?
As suggested, try turning off the other rads and see if the cold rad heats - if it does then there is not a blockage - you need to balance again.
Jim.

JamesM

Lex Luthor wrote:

ok update....got the pressure back up to 1bar and the heating is on now about half an hour and its still not heating.

I have a funny feeling that the TRV on that rad is busted. Coincidentally, the wife was in that room today painting and it looks like she knocked off it as it is not steady at all in its position. Its rocking at the top so I'm thinking its in a closed state.

Am I getting warm?

Take the TVR off completely and make sure that the pin is up. If you push it down, it should pop up again on a spring.
Jim

Lex Luthor

JamesM wrote:

Take the TVR off completely and make sure that the pin is up. If you push it down, it should pop up again on a spring.
Jim

do I need to drain the system down to remove the TRV?

Lex Luthor

JamesM wrote:

I presume that you are not serious :eek:
I remember someone told someone else on this forum some time ago that they should use a pump to pump up the expansion vessel

Is the valve thermostatic ? Could anyone have turned off the valve (some people do not check this). Did you turn on another rad, which may take the flow from the cold one ?
As suggested, try turning off the other rads and see if the cold rad heats - if it does then there is not a blockage - you need to balance again.
Jim.

Jim, ya, thats what I did...I used the bike pump. Pressure was down at 0.5 bar and now its up at 0.9bar. Is that a problem? :eek:

There is a thermostatic valve on this rad. It definitely feels different to the other one I have on the other rad. Its rocking back and forth if you grab it. I'd say she gave it a knock today.

No other rads have been switched on recently.

JamesM

Lex Luthor wrote:

do I need to drain the system down to remove the TRV?

No, just take off the top, (plastic ?) part. The solid body has a pin in the centre. You should be able to push the pin down and it should spring up again. Maybe the pin is stuck down - try and grip it with a pliers, pull it up and loosen it off.
Jim.

JamesM

Lex Luthor wrote:

Jim, ya, thats what I did...I used the bike pump. Pressure was down at 0.5 bar and now its up at 0.9bar. Is that a problem? :eek:

As far as I know, the only to way to raise the pressure in the system is to open the fill valve in the hotpress, or wherever it is.
The expansion vessel has a diaphragm across the centre of it. There is air on one side and water on the other side. It is pressurised from the beginning. When the water in the system heats, it expands and compresses the air. I would think that if you pump it up too much, you will burst the diaphragm. You will increase the pressure in the system, but that is not necessary. 0.5 is fine.
Jim.

Lex Luthor

JamesM wrote:

As far as I know, the only to way to raise the pressure in the system is to open the fill valve in the hotpress, or wherever it is.
The expansion vessel has a diaphragm across the centre of it. There is air on one side and water on the other side. It is pressurised from the beginning. When the water in the system heats, it expands and compresses the air. I would think that if you pump it up too much, you will burst the diaphragm. You will increase the pressure in the system, but that is not necessary. 0.5 is fine.
Jim.

Thanks Jim, I had to drain down the system a few months ago to fix a leak so maybe I didn't pressurize it up enough when I filled it. I had already opened up the fill valave in the hot press prior to this and it only came up to 0.5 bar, which is why I thought about pumping it up after speaking to someone on the phone who told me to do that. Up until then, I hadn't a clue what that orange vessel in the hot press did.

Lex Luthor

JamesM wrote:

No, just take off the top, (plastic ?) part. The solid body has a pin in the centre. You should be able to push the pin down and it should spring up again. Maybe the pin is stuck down - try and grip it with a pliers, pull it up and loosen it off.
Jim.

Does the plastic part just pop off or is it secured on by a knurled nut? I can see one just below it.

JamesM

Lex Luthor wrote:

Does the plastic part just pop off or is it secured on by a knurled nut? I can see one just below it.

Different makes have different methods of removing. Some just twist off. But I have seen the type with a big knurled nut just under the head, so that's probably it. If it seems loose - there may actually be something broken in the head. Loosen the knurled nut, lift off the head and you should see a pin sticking up in the centre of the body. It should be proud of the body, and spring up when you push it down. If it is stuck down, that is your problem - it is shutting off the flow. Sometimes a gentle tap on the top of the pin with a light hammer or pliers will make it spring up. Otherwise try to pull it up with a pliers or vicegrips to loosen it off. It should be free, and spring up when you push it down.
Maybe the bang it got is jamming the pin down.
Jim.

Lex Luthor

JamesM wrote:

Different makes have different methods of removing. Some just twist off. But I have seen the type with a big knurled nut just under the head, so that's probably it. If it seems loose - there may actually be something broken in the head. Loosen the knurled nut, lift off the head and you should see a pin sticking up in the centre of the body. It should be proud of the body, and spring up when you push it down. If it is stuck down, that is your problem - it is shutting off the flow. Sometimes a gentle tap on the top of the pin with a light hammer or pliers will make it spring up. Otherwise try to pull it up with a pliers or vicegrips to loosen it off. It should be free, and spring up when you push it down.
Maybe the bang it got is jamming the pin down.
Jim.

Thanks Jim, I'll give it a go tomorrow morning. Weather is good today so the bedroom is warm enough so no harm done.
It feels like it got a knock alright as its definitely rocking side to side when you grab the plastic body of the TRV and the other rad I have with a TRV is steady.

Lex Luthor

Jim,
I took off the plastoc top section of the TRV (Myson) but the pin was in the up position. It definitely springs up and down like you said and always returns to the up position.
But when I turned the heating on with the top section off, heat started to flow through the rad.
I haven't put the top part back on but it seems to be working ok. The spring mechanism in it, gets stiffer, the more you switch it to the closed position.
I'll leave it off till tomorrow and put it back on then and see if there is a fault in it, but I'm guessing it got a knock while her indoors was painting
Thanks for your help

p.s. System pressure is running about 1.4bar and rests at 1bar when off. Sound ok with you?

JamesM

Lex Luthor wrote:

p.s. System pressure is running about 1.4bar and rests at 1bar when off. Sound ok with you?

That should be OK. (Hopefully you have not stretched the diaphragm too much - I am not sure how you would find out though) Remember to always fill the system when it is cold, so that it takes in the maximum amount of water.
Jim.