MYSON TRV stuck in high temperature mode

nairb999 · 23 Jan 2008

Can the TRV be maintained and if so without removing from radiator

Sorry to D Hailsham - pressed ignore rather than edir

Yes the radiator is staying hot . Tried to turn knurled nut but it won't budge - been there for 10 years. Would WD40 help

D_Hailsham · 23 Jan 2008

nairb999 said:
Can the TRV be maintained and if so without removing from radiator

Do you mean that the radiator stays hot all the time even when you turn the TRV down to nothing?

If so, the pin is probably stuck. Remove the adjustable top by unscrewing the large knurled nut underneath. THis will expose the valve with a pin sticking out of the top. The pin should push down easily (use a coin or something similar not a hammer!) and spring back up. If it does not more easily apply a bit more force but be careful not to bend the pin. If the pin sticks down, use a pair of pliers to pull the pin up. It is best to have the pliers vertical above the pin to prevent bending. You may have to repeat the operation until the pin is free and springs up again when you release pressure.

If the pin is free when you first check it, it means that the fault is in the thermostatic part (the bit you took off to get at the pin). You can buy these from any decent Plumbers Merchants, though I am unsure if the DIY superstores stock them.

D_Hailsham · 23 Jan 2008

nairb999 said:
Yes the radiator is staying hot . Tried to turn knurled nut but it won't budge - been there for 10 years. Would WD40 help

No problem using WD40 on the knurled nut, but do not use it on the pin.

A pair of mole grips or similar, used gently, may persuade the nut to come undone.

The nut turns anticlockwise, looking from above; but I expect you have tried both ways

nairb999 · 25 Jan 2008

success - managed to get the head off eventually

The pin released very easily as it turned out. Valve performing correctly now

Many thanks

Softus · 25 Jan 2008

D_Hailsham said:
The pin should push down easily (use a coin or something similar not a hammer!) and spring back up. If it does not more easily apply a bit more force but be careful not to bend the pin. If the pin sticks down, use a pair of pliers to pull the pin up.

As usual, this is very bad advice.

Do NOT use pliers on a TRV pin - you risk (a) marking the surface and causing the pin to stick, and (b) pulling the pin out.

A small hammer is a perfectly acceptable, and commonplace, way of both testing and movement of and freeing off a TRV pin. To prevent damage the impact should be very light, unless you can get a swing at D_Hailsham.

nairb999 · 25 Jan 2008

Softus said:
D_Hailsham said:

The pin should push down easily (use a coin or something similar not a hammer!) and spring back up. If it does not more easily apply a bit more force but be careful not to bend the pin. If the pin sticks down, use a pair of pliers to pull the pin up.

Click to expand...

As usual, this is very bad advice.

Do NOT use pliers on a TRV pin - you risk (a) marking the surface and causing the pin to stick, and (b) pulling the pin out.

A small hammer is a perfectly acceptable, and commonplace, way of both testing and movement of and freeing off a TRV pin. To prevent damage the impact should be very light, unless you can get a swing at D_Hailsham.

Do I sense a bot of rivalry here !!!!! no need for pliers the coin approach worked very well

Softus · 25 Jan 2008

nairb999 said:
Do I sense a bot of rivalry here

No. But some people give very odd (i.e. sh*te) advice and need pulling up on it.

nairb999 · 25 Jan 2008

Softus said:
nairb999 said:

Do I sense a bot of rivalry here

Click to expand...

No. But some people give very odd (i.e. sh*te) advice and need pulling up on it.

Good shout Softus - noted

Can I share another c/h issue with you I have and that is one reported earlier and that is air in the system which is a vented system. I have had Sentinel X400 in the system now for 2 weeks and the kettling noises I was hearing in the airing cupboard have gone almost completely. When the boiler is on and the cold feed pipe gets very hot I can hear a small gurgilg noise that lasts second - normally after the heating has been on for a couple of hours. Also I have n't managed to get any air coming out of the system when I have bled the previous offending upstairs radiators.

Do you think I could get away with flushing the system although deposits still exist in pipework between overflow and pump as a magnet still is attracted to the pipe albeit slightly.

Softus · 25 Jan 2008

There's no easy answer to that question, but if all other conditions are right, you can get away with a fair bit of debris and sludge left in the system.

One of those conditions is that the pump is in the correct position relative to vent and cold feed, and I'm a bit concerned at your description because it implies that this could be wrong on your system.

If you've had corrosion then it's been for a reason, which is commonly either:

1. System needed inhibitor but didn't have any in;
and/or
2. Inhibitor was added but air was being dragged in, which negated its effect.

As long as you have flow, and as long as there is no pumping over, then I'd drain the system to clear out what you can, and refill with a dose of inhibitor.

In the spring you could start the process of removing each radiator and flushing it out with a hose in the garden. Or, you spend a small fortune on powerflushing. But that carries the risk of exposing latent leaks.

In the meantime, if you do drain down, while the system is empty you could fit a Magnaclean and be gradually pulling more debris out of the system.

nairb999 · 25 Jan 2008

Great input - other input integrated in your rsponse

Softus said:
There's no easy answer to that question, but if all other conditions are right, you can get away with a fair bit of debris and sludge left in the system.

One of those conditions is that the pump is in the correct position relative to vent and cold feed, and I'm a bit concerned at your description because it implies that this could be wrong on your system

I am fairly confident about pump position - sequence is boiler , vent , cold feed then pump

If you've had corrosion then it's been for a reason, which is commonly either:

1. System needed inhibitor but didn't have any in;
and/or
2. Inhibitor was added but air was being dragged in, which negated its effect.

Inhibitor was added by a plumber - but how much unknown - this was as a result of air in the system.

As long as you have flow, and as long as there is no pumping over, then I'd drain the system to clear out what you can, and refill with a dose of inhibitor.

All radiators at full temp - no radiator issues. I have read in a Myson Aerjec product sheet that if the feed pipe does not have a large enough capacity ie 2% then air can get into the system. My feed pipe is 15mm and 5 foot to F/E tank. System comprises 15 radiators - installation 10 years old

In the spring you could start the process of removing each radiator and flushing it out with a hose in the garden. Or, you spend a small fortune on powerflushing. But that carries the risk of exposing latent leaks.

In the meantime, if you do drain down, while the system is empty you could fit a Magnaclean and be gradually pulling more debris out of the system.

Softus · 25 Jan 2008

nairb999 said:
I am fairly confident about pump position - sequence is boiler , vent , cold feed then pump

Good!

Inhibitor was added by a plumber - but how much unknown - this was as a result of air in the system.

Yebbut, the effect of inhibitor can be eliminated if there's a lot of muck already in the system.

I have read in a Myson Aerjec product sheet that if the feed pipe does not have a large enough capacity ie 2% then air can get into the system.

Eh? Is that document accessible online?

My feed pipe is 15mm and 5 foot to F/E tank. System comprises 15 radiators - installation 10 years old

15mm is completely normal.

nairb999 · 25 Jan 2008

Eh? Is that document accessible online?

http://www.circulatingpumps.net/UpDocs/files/Aerjec.pdf

Actually it states 3% on page 2 of this pdf file

Softus · 25 Jan 2008

AERJEC said:
To prevent air re-entering the system through the cold feed
and expansion tanduring normal heating and cooling cycles
the cold feed pipe should contain volume of water equal to
at least 3% of the total system volume.

I believe this is badly worded (note the mistake in bold above).

The goal is to have enough water in the F&E such that, upon cooling, it isn't all drawn into the system with air behind it.

The cold feed pipe can be considered part of the F&E cistern, so, in theory, the bigger the better, but in practise you just adjust the height of the float on the fill valve so that the level never drops to the position of the outlet.

nairb999 · 25 Jan 2008

Softus - great commentary. I feel confidant that my installation is OK and will now follow out your suggestions.

Many thanks - look out for you again if I need further help god forbid

Softus · 25 Jan 2008

Footnote: the F&E level is a compromise - the level must not be so high that, when fully expanded (i.e. when the system is hot) it overflows.

The reason is that it will draw in fresh water when the level drops again, and this cycle of overflowing/replenishing will eventually dilute the inhibitor.

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MYSON TRV stuck in high temperature mode

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