Here's another daft question for your amusement

[dm65]

I know this is basic knowledge but my trvs are confusing me

Started searching as I didn't want to appear to be an idiot but this seems to be impossible

Found this on the Drayton faq
What range of TRV bodies are Bi- directional?
The 15, 10 or 8mm angled body is bi directional as denoted by the double headed arrow on the valve body. ALL other bodies are flow directional as indicated by the single headed arrow head on the valve body.

All makes sense to me so went and had a look at mine and whilst they appear to bidirectional, should I have a double headed arrow or do two arrows in opposite directions mean the same thing ?

In case I've managed to confuse you as well, here's a link to a rubbish picture taken on my phone - if you zoom in, you should able to see the arrows I'm talking about

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I'll just sit back now and wait for the name calling to end

 

[AWheating]

do they work? if yes then doh worry.

 

[Rickster123]

Ptfe on the thread agggghhhhhhh!

oh sorry, they are bi directional cheap end trvs.

 

[dm65]

They work fine though if they're not bidirectional, they're on the wrong pipe

I want to know that's all - I like to know how things work

 

[dm65]

Ptfe on the thread agggghhhhhhh!

oh sorry, they are bi directional cheap end trvs.

Cheers APP

What defines it as being cheap ? (I agree, whole house has been bodged, but what gives it away ?)

I put that ptfe on btw - sorry, won't do it again as I now know it offends on this site but this was the first time I'd ever touched a radiator

 

[Best]

Def bi directional. Arrows are different directions, - simple!
I agree, - what's that ptfe there for?

 

[Rickster123]

I can smell a cheap trv a mile away Denis. And the ptfe isn't the worst bit, you've used grips instead on a spanner on the nuts.

 

[dm65]

I can smell a cheap trv a mile away Denis. And the ptfe isn't the worst bit, you've used grips instead on a spanner on the nuts.

How very dare you - I've got a pair of Bahcos that are older than my kids and they were used

TRV is what was fitted - I replaced the rad as it started leaking but kept the valves as I didn't know then how to drain the system etc

I do now so I may put my hand in my pocket later and replace them

 

[Best]

It's a cheap TRV, but I wouldn't worry about that. Some cheap TRVs last years. As long as they look decent & not damaged or painted over. That one in the photo has the chrome a bit scuffed with a spanner or grips, that can be avoided. The ptfe offends plumbers when it is put on threads that are not sealing threads, as on compression fittings like above. If that ptfe tape was supposed to stop a leak, then the water would simply pass between the nut & tail/pipe & that's if the olive wasn't sealing right in the first place!

 

[dm65]

It's a cheap TRV, but I wouldn't worry about that. Some cheap TRVs last years. As long as they look decent & not damaged or painted over. That one in the photo has the chrome a bit scuffed with a spanner or grips, that can be avoided. The ptfe offends plumbers when it is put on threads that are not sealing threads, as on compression fittings like above. If that ptfe tape was supposed to stop a leak, then the water would simply pass between the nut & tail/pipe & that's if the olive wasn't sealing right in the first place!

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)

 

[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