I need to replace a TRV and don't want to drain more of my system than I need. Boiler - WB Combi in Loft Radiator - upstairs bedroom. TRV - same for same so should only take seconds to do. Bedroom - carpeted - don't want mess.
What do you suggest? Thinking turn off all upstairs rads.
Release pressure from drain valve.
Then what?
Pull carpet back, turn lockshield off, undo nut on radiator to TRV body and catch any water in a container.
Get new valve body within reach, undo nut on pipe and allow to fall down.
Very quickly remove old valve, ready with thumb over the pipe to seal.
With new body in hand, remove thumb and place TRV on the pipe.
Screw up nuts, simples!
Getting the carpet back is the only issue.
Freezer spray is one way.
But if you've not changed the inhibitor recently, now's the time to do it.
"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:
Inhibitor changed 6 months ago.
Will the water in the boiler be held back - or will it want to come flooding out - it is in the loft.
2 years ago I replaced the TRV on the bathroom radiator using a pipe freezing kit from screwfix:
Turn off the TRV completely and the lockshield valve at the other end of the radiator to isolate it. Making sure that you have something to catch the water loosen the connection between TRV and radiator (and the air drain screw on the top of the rad) and run off the water in the rad. If water continues to flow from the rad after it is empty the lockshield may be leaking.
Open the windows as the freezer usually contains ether which is an anaesthetic. Attach the sleeve for the freezing kit to the pipe below the TRV and follow the instructions to empty the spray can of freezer into it (you could do this first as you hve to leave it for 30 minutes (look at the instructions) for the ice plug to form. Check it has formed by opening the TRV if no water comes through then remove the TRV and replace with the new one.
At that point you may find as I did that the new TRV was slightly different to the 40 year old one or as on another one that the old pipe has a slightly smaller diameter than the olive so you cannot get a water tight joint so have PTFE tape available to wrap around it.
You can then either connect the new TRV to the radiator or keep it closed until the ice plug melts then open it slightly to see if the water is coming through before closing it and again attaching to the rad. The reason why I say this is that I found that the pipe to one rad had debris in it and it was that not the old TRV that was causing the cold rad.
Alan
There will be isolating valves on the boiler for the "heating" circuit (probably 22 mm), turn them both off.
You can get a sort of rubber cone to plug the outlet pipe in the header/expansion tank on indirect systems. A plumber once assured me that hardly any water would escape from the rad system if the feed pipe is blocked - but I've not tried it.
Whilst changing the TRV use the opportunity to change the lock shield valve for one with a drain off point on the radiator side of the valve, makes draining down individual radiators a whole lot easier.
Richard
Never seen that before. The boiler water content is pretty minimal compared to the rest of the system so I can't see much benefit to fitting them.
Tim
Sounds like the ideal route to an exploding boiler.
Reentrant wrote in news:d snipped-for-privacy@brightview.co.uk:
No tank - it is a combi.
Unless it's a sealed system and assuming the expansion vessel is integral with the boiler :)
Never seen any.
There might be some either side of the pump, assuming they still turn and are functional!
Yes I was making that assumption, OP said it was a Worcester Bosch combi. And yes, it wouldn't be particularly sensible to close the valves while the boiler was running, but the overtemperature trip should cut off the gas and the vent valve would prevent damage from overpressurisation. The reason for closing the valves, as Tim says, is to prevent the expansion vessel from trying to dump its contents on the carpet when the radiator is disconnected. Other water may or may not drain spontaneously depending on the geometry of the system.
Well my last three boilers over the past 25 years have had them. Two Vaillants and a Wickes. They are small "service" valves, operated by screwdriver, and on gas, DHW, and cold feed as well as radiator supply and return.
They are for isolating the pump. On a pressurised system, both the radiator "supply" and "return" are pressurised so closing only the pump side will still leave the radiator circuit pressurised.
Pipe freezers are very effective and might give you peace of mind as well as convenience. Provided the lock-shield valve closes properly you only need to freeze the pipe to the TRV. You will still, as other posters have pointed out, have to catch the water from the radiator.
newshound wrote in news: snipped-for-privacy@brightview.co.uk:
Might as well drain down and add more inhibitor!
Tricky Dicky wrote in news:9ea219b5-0909-4678-91b5- snipped-for-privacy@googlegroups.com:
I have these on the downstairs rads. Not sure if it is deliberate - or if the plumber was clearing his van out. Pipe centres need to be adjusted a bit.
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