Cool Radiator

meadowcat

Could anyone help me with this - maybe moneysaving plumber or somebody equally knowledgeable and lovely.

The radiator in my kitchen is not as hot as the rest of the radiators. There is no air in it. The house is less than 2 years old. Could it be the thermostatic valve that is faulty?

moneysavingplumber

Flattery doesn't make me any cheaper .

The system probably just needs balancing, the radiator in question is probably the part of the circuit with the greatest resistance, so the problem is probably with the valves at the other end of the radiators in the system rather than the thermostatic ones. As the system is quite new then you shouldn't have any problem with leaky rad valves if you try to balance it yourself.

At the opposite end of the radiator to the TRV there should be what we call a lockshield valve, you will usually have to remove the plastic cap to adjust it (they usually just pull off or may have a securing screw in the top).

I would suggest turning all of these valves completely to the off position (clockwise, gently with pliers until you feel it come to a stop). Make sure the TRVs are set to maximum. Turn the heating on and make sure any room thermostat is set to maximum. Begin with the problem radiator and start by opening the lockshield valve by half of one turn to begin with. If it fails to get hot open another half of one turn and continue like this until there is only a slight difference in temperatures between the pipe going into the radiator (flow) and the one coming out (return), and the radiator is hot. Once this is set move on the closest radiator, gradually working back (usually start on the ground floor and then do upstairs, starting usually furthest from the pump) carrying out the same procedure for each radiator. For a condensing boiler the optimum temperature difference between flow and return is 20 degrees.

meadowcat

Luv ya MSP. You're not cheap at all, you're very dear to us all. What would we do without you. :A

I'll try that tomorrow. :beer:

Jolaaled

moneysavingplumber wrote:

Flattery doesn't make me any cheaper .



At the opposite end of the radiator to the TRV there should be what we call a lockshield valve, you will usually have to remove the plastic cap to adjust it (they usually just pull off or may have a securing screw in the top).

.

Please can you help...i can't turn the lockshield nut at all...it's so tight that it won't budge. any tips very gratefully received...it's my daughters bedroom rad and she's freezing on the cold school mornings. thanks very much.

caveat_emptor

Jolaaled wrote:

Please can you help...i can't turn the lockshield nut at all...it's so tight that it won't budge. any tips very gratefully received...it's my daughters bedroom rad and she's freezing on the cold school mornings. thanks very much.

I take it you've bled the rad. If the lockshield has a gland nut try unscrewing this until you can turn the valve shaft.

moneysavingplumber

Don't force it. With older valves and ones without a gland nut you run the risk of causing them to leak if you disturb them. I assume it is the centre spindle that you are attempting to turn. If it won't move, leave it be.

As caveat_emptor says, try bleeding it with the heating off to ensure it is full. If you have a combi or sealed system then you will need to top the system pressure back to 1 bar afterwards.

Jolaaled

thanks for you suggestions.
yes..i have bled the rad. The raditator isn't that old, as the system was installed in 1999. I'm not sure what you mean by a gland nut.
There is just a rectangular shaped brass post that has a screw thread at the bottom end, that screws into the housing. i can turn this on all my other rads, but this is stuck fast and i just can't budge it.
i'd be eternally grateful for any ideas ( apart from calling out the plumber!).
thanks again

caveat_emptor

If you can bleed the rad then one of the valves must be open. Close the main valve and the try to bleed the rad again. If you can, it would indicate that the lockshield is open. If not, when you take the lockshield cover off you can see the valve spindle with a square at top. Below this some valves have a hexagonal/square gland nut that compresses the spindle seal around spindle. As MSP says not all valves have this gland nut so replacement would be the only solution.
But if the rad has been ok in the past it's unlikely that the lockshield is the problem

Jolaaled

I"m pretty sure that there isn't a gland nut. I think it's just that the lockshield nut has been done up so tight ( by previous plumber), that i just cannot turn it with pliers. Is there anyway to loosen it..i've tried WD40, but no luck
thanks

meadowcat

MSP, it's me again :rolleyes: I haven't tried this balancing thing yet. There was something I wanted to ask you before I do it.

This radiator that I was asking you about, when I initially turn on the heating it does get really hot - just like all the other rads, but then it cools down as if the thermostat had kicked in. That's why I was wondering if it is the thermostatic valve.

Don't know if I need to tell you all this, but here goes.

The heating is pressurised. I have a solar panel which is also pressurised (?) I think.

Before the solar panel was installed, the pressure dial was always at about 1 whether the heating was on or off. After the panel went in, I found that when I turned the heating on the pressure rose significantly, so in order to keep it below the red danger line when the heating is on, I need to keep the pressure way down when the heating is off. Don't know if you need to know any of this. Don't even know if I've made myself clear.

moneysavingplumber

Well the TRV may be kicking in because of residual heat from appliances with it being in the kitchen, or the rad may be oversized for the room. The system pressurisation issue isn't likely to affect this issue.