Here's another daft question for your amusement

[Best]

Def grips have been used on that bottom nut & either grips or a badly adjusted spanner on the tail nut. Maybe the installer did it initially. Chrome can be poor & flake easily on nuts if abused a bit.

 

[Best]

Thanks for that - I know not to use ptfe on these threads now but didn't then

As for failed trv's - what happens when they fail - I'm guessing they just stop regulating ? (just being curious)

The pins in the body can start to stick - often caused by the seal around them weeping slightly & seizing them. That's usually what happens most of TRVs unless they get the heads damaged by a knock. Some heads can fail to work properly also. Myson TRV heads fail inside & close off completely. With heat the Myson heads also become brittle & snap off near base.
I feel that TRVs are a throw away thing, so a half decent looking inexpensive TRV that does maybe 15 years & then swap for new valves is exceptable.

 

[dm65]

Def grips have been used on that bottom nut & either grips or a badly adjusted spanner on the tail nut. Maybe the installer did it initially. Chrome can be poor & flake easily on nuts if abused a bit.

Agreed but not by me, honest guv

As usual for diyers, I have all the tools needed for almost any job, just lack the knowledge to use them properly and i like quality when i do buy, hence the Bahcos

 

[dm65]

The pins in the body can start to stick - often caused by the seal around them weeping slightly & seizing them. That's usually what happens most of TRVs unless they get the heads damaged by a knock. Some heads can fail to work properly also. Myson TRV heads fail inside & close off completely. With heat the Myson heads also become brittle & snap off near base.
I feel that TRVs are a throw away thing, so a half decent looking inexpensive TRV that does maybe 15 years & then swap for new valves is exceptable.

Thanks for the explanation - it explains why a test is to try and push the pin down

You see, you learn something new every day

 

[Best]

Bahcos are good, but any decent adjustable spanner would do. Just make sure to adjust the spanner extra & fully tight once you have it on the nut & you can do no better.
I have 2 of 8" Bahcos, but also have a same size okay quality & a couple of 15" very good quality Chinese adjustables & they do the job just the same.

 

[dm65]

Agreed again, it's not what you've got, but how you use it that matters

I might not know much about plumbing but I do know tools and used to do a lot of spannering - anyone remember fixing their own car or bike ?

I used to do both, don't have a bike any more and I haven't lifted a bonnet in quite a few years except to have a nosey