I've been struggling trying to balance my radiators.
I noticed in SEVERAL unimportant rooms (utilty, toilet, etc) that the
rads get very hot even with the LSV down to 0.5 turn open AND the TRV
set to snowflake.
Seems like bad TRVs, so I bought one new one as a trial and confirmed
this (now fixed in that room).
A bit of Googling revealed someone stating TRVs have a limited life,
eg 5-7 years. These might be 15 years !
So that appears to be true.
If I'm going to swap ~10 of these, then it's not cheap, as I just paid
£15 for one LT117E
Also they don't sell the head only.
Out of interest, what is the fail mechanism ?
I guess no chance of fixing ?
Thanks in advance.
Mine are Myson. Currently 15 years service. Two have given trouble due
to lime scale jamming the valve plunger. Judicious scraping (bit of
brass plate) and jiggling with round nose pliers has got them working
Mine always fail closed.
I have considered asking in here if there is a suitable lubricant but
you can if you like:-)
Pins usually get stuck closed not open: tapping the pin with a small hammer
or anything similar usually pops them up again.
But it sounds like you need to do some balancing. Most of the on/off action
of the lock shield valve is in the first half turn, so you are probably
being over generous with your half turn, and a nudge of an eighth of a turn
can make the difference between hot and cold. I would start by shutting the
lock shields of the rads that get too hot right down, and then cracking them
open an eighth of a turn at a time until you get the temp you want. I find
I have to make small adjustments most years, and don't put the lockshield
screws back in, to make it easier to just tweak any a bit when you notice
them starting to run cool.
You can also experiment with the pump speeds. Set the pump to the lowest
speed that will keep the rads warm, and it will last longer and run more
quietly. If the rads won't balance at the slowest speed, move up a notch
and try again.
The pin inside the valve in the rad coupling seems fine.
I can push it in ~ 1/10" and it springs right back.
It really looks like TRV heads shot. A new TRV head fixed the utility
I agree most of the "action" on the LSVs is near fully closed.
I would start by shutting the
This is a big, old house with an extension.
The pump is, and always has been (even before we moved here) at max.
Even so, the the last rad struggles to get hot enough with both LSV
and TRV fully open. Hence I want to cool down some of the less
important rads - toilet and utility room.
The thermostat heads "fail" because the spring becomes weak. This
means the pin in the coupling valve can push it back as it has a very
It's a damned shame to have to pay ~ £13 for a complete VT117e when
all that's wrong is the spring.
I may be a bit daft - but I use stethoscope to establish the point where the
valves stop the flow. Handy when setting a thermostatic valve. When the room
is comfortable - turn the temp control slowly down until you hear the flow
start to choke. Lock the valve to stop SWMBO fiddling.
Also handy with lockshields.
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