Stuck Domestic Thermostatic Radiator Valves.

[macabethiel]

When the warmer weather comes I will drain down the central heating system and replace a couple of my older thermostatic radiator valves as they tend to stick after a rest during the summer.

In the meantime any tips on how to persuade them to open again ?
Usually I can give the body a tap as I unscrew them and they start to open but one seems rather stubborn and will not submit to my gentle treatment.

Any plumbers or experienced central heating engineers amongs our members with a tip for a short term fix until spring?

[solarman216]

Originally Posted by macabethiel

When the warmer weather comes I will drain down the central heating system and replace a couple of my older thermostatic radiator valves as they tend to stick after a rest during the summer.

In the meantime any tips on how to persuade them to open again ?
Usually I can give the body a tap as I unscrew them and they start to open but one seems rather stubborn and will not submit to my gentle treatment.

Any plumbers or experienced central heating engineers amongs our members with a tip for a short term fix until spring?

what is the make and model of the valve? Rick

[macabethiel]

I have attached a photo as I can't tell if its a MA or a WWV ?

Cant work out how to take the knob bit off either my other one has a simple screw collar this one is all plastic looking !

[Ianinessex]

I had some a bit like this, the plastic top which houses the thermostat was held onto the valve by a collet style fitting. the collar had to be pushed or twisted back towards the main plastic part and this released the grips of the collet enabling the plastic part to be removed.
Once the plastic bit is off, the valve body has a small brass pin that goes into the valve. If it is working, you can push the pin in to close the valve. You need to use something like the flat of a bit screwdriver to spread the load as it has a strong spring, or a pair of pliers to grip the top end of the pin, but be careful not to bend or damage the pin. When you stop pushing, the pin should come back out with the force of the spring. If the valve has stuck shut, the usual problem, I grip the pin with the pliers and move it in and out briskly a few times. This normally frees the valve and the pin will stay out in the "valve fully open" position.

Hope this helps

[rustic]

When I have bought and fitted similar valves, they came with a manual over ride knob. Which often gets discarded... except in my house lol...
You removed the top part, leaving the pin, then screwed on a plastic knurled knob, that pressed down on the pin as you screwed down on the plastic knob.

So the information in previous posts is correct.

What I would do, is remove the top, and make a bund out of plastercine and fill with WD 40, so some soaks down the pin hole.
Then work the pin with vertical pressure, without bending the pin, or pening over the end.

As with any radiator valve, they prefer to be seized up than free running, so it's worth working both valves at the ends of each radiator every year or so... but this doesn't happen in real life, and when you do try them....they leak...
Mind you... the lock shield valves are around a £1 or so...

[Mobieus_uk]

Welcome to my world, this is what i do for living, they can normally always be freed up by tapping down on the pin when you remove the thermostatic head, if that doesn't work then a few sharp taps from the side can help, the reason they are sticking in the first place if that you probably have contaminated water in your heating system so its worth probably flushing the system

If your any good at plumbing try and cut in one of those magnetic cleaners on the return pipe back to the boiler http://www.adey.com/installers/filte...n-professional
they work really well and you can use them do add inhibitor to your heating system.

Dont underestimate the importance of a decent inhibitor like http://www.sentinelprotects.com/uk/p...x100-inhibitor as this will slow down the corrosion thats going on on the system, i say slow down because you can never stop it, this is why chemist refer to water as the universal solvent but you can slow it down to get a good life expectancy out of the system

If you system is on the old type that is you have a tank in the loft look for signs of it getting warm (pumping over)as this could be a indication that the cold feed is partially blocked and will cause all sorts of issues with water quality

[rustic]

Interesting points there...
How often should the inhibitor be changed, and what about using descaler prior to flushing, that's what I have done in the past.?

I tend to do it if I here the boiler kettling, making noises when heating up.

But I will also check circulation in my header tank... thanks for the tip.

[Mobieus_uk]

Inhibitor doesn't need changing as such but the levels do need to be maintained, it depends how much water is going into the system over the course of a year, its hard to tell if its fed from a tank but with the modern sealed system you have to manually keep the pressure topped up so you get a feeling of how much water has gone in. with a tank I would throw a bottle of inhibitor in at least once a year

You can buy kits to check the levels but they are manufactuer specific so sentinal will test only for sentinal and fernox will only test for fernox

a system that sealed and with very little topping up say 4 times a year would probably go a few years before re-dosing is required

you can run cleaners in the system, leave them in for a few weeks then flush out

Tips

1.. If all your radiators all get hot from top to bottom then there not much to worry about, if you have cold spots on the middle then you may have sludge deposits in the radiator, if forms in the middle and builds a sort of hump, it does this because the water is at its lowest velocity at this point so debris will drop

2.. take a sample of the water into a clear bottle, you can do this from the air vents on the radiator but let the water run a little otherwise you will get all the crap that has parked behind the vent and you wont get a true reading

3.. a good well dosed system should look like tea without milk or a light cider, opaque

4.. if it looks dirty then it probably is, first rule of testing the water is what does it look like, often after a few minutes a dirty sample will all settle in the bottom of your container, gives you a good idea of whats floating about, if it doesn't sink all to the bottom and stays in suspension you may have a cleaner in the system preventing the debris from settling, makes flushing out easier

5..if you have a problem with a radiator, turn off all the other rads, if it gets hot from top to bottom you have eliminated sludge as the cause and its more of a balancing issue or maybe a airlock, I've done this on plenty of systems and you get a load of gurgling in the pipework then the radiator goes toasty hot

1mm of scale reduces the heat transfer by something stupid like 30%, scale is a great insulator

[solarman216]

I can add a little bit to Mobieus details all of which are spot on, the sample of water taken you can put a couple of steel nails in itand check after a couple of days any sign of rust and inhibitor is needed, when bleeding rads hold a lighter or match close to the bleeder, if it burns it is not air but Hydrogen a by product of corrosion, Rick

[Mobieus_uk]

Originally Posted by solarman216

I can add a little bit to Mobieus details all of which are spot on, the sample of water taken you can put a couple of steel nails in itand check after a couple of days any sign of rust and inhibitor is needed, when bleeding rads hold a lighter or match close to the bleeder, if it burns it is not air but Hydrogen a by product of corrosion, Rick

I did that test once and the customer complained, lol, just go by smell I think it has a cabbage type smell if its hydrogen

[Ogri]

I'll just add a word of caution when trying to free the stuck pin: If, like me, you are not a plumber but a ham fisted oaf, it is possible to pull the pin completely out of the valve

This leaves you with a broken valve and a leak that in my case couldn't be fixed without draining the system down

So, just go carefully with those pliers/grips...

[rustic]

Originally Posted by Ogri

...This leaves you with a broken valve and a leak that in my case couldn't be fixed without draining the system down ...

If you have a a storage tank, ie ball cock, then you can buy a kit from Screwfix, basically it comprises two variable size bungs, one fits in the water outlet of the header tank and the other in the overflow pipe. Remove when completed...
I was very sceptical of course it claims you can remove a rad valve completley without draining down...

Anyhow, my task was more demanding... I wanted to cut into two 15mm central heating lines that went to a radiator and fit a "T" with stopcock for plumbing into our new conservatory... All whilst still wet. I closed down both valves on the radiator.
I sheeted up the area, buckets and containers everywhere, I had some 15mm push on blank ends just in case... Now these are worth their weight in gold...
Well to my surprise, there was minimal water leakage, not enough to half fill an ice cream tub, so these devices do work.

So changing a rad valve.... simples.

Just make sure you close the other valve on the radiator down before cutting.

I heard about these devices when my brother in law had a valve replaced by a plumber... he said he went into the loft and did something.... then just removed the valve... So I looked into it.. brilliant.

[Ogri]

Mine is a pressurised system I think with no header tank, so maybe not the same but like I said, I'm no plumber

[solarman216]

Originally Posted by Mobieus_uk

I did that test once and the customer complained, lol, just go by smell I think it has a cabbage type smell if its hydrogen

That is OK if you have a sense of smell, lost mine a long time ago, too much time in drains and sewers, also all my customers were impressed when I demonstrated, they were not so happy when I told them it was not good news, Rick

[macabethiel]

Originally Posted by Ianinessex

I had some a bit like this, the plastic top which houses the thermostat was held onto the valve by a collet style fitting. the collar had to be pushed or twisted back towards the main plastic part and this released the grips of the collet enabling the plastic part to be removed.
Once the plastic bit is off, the valve body has a small brass pin that goes into the valve. If it is working, you can push the pin in to close the valve. You need to use something like the flat of a bit screwdriver to spread the load as it has a strong spring, or a pair of pliers to grip the top end of the pin, but be careful not to bend or damage the pin. When you stop pushing, the pin should come back out with the force of the spring. If the valve has stuck shut, the usual problem, I grip the pin with the pliers and move it in and out briskly a few times. This normally frees the valve and the pin will stay out in the "valve fully open" position.

Hope this helps

So do I need a small screwdriver inserting between black plasic bit and the bottom of the white knob to prize it upwards with the valve in the open position then ?