Thermostatic Radiator Valve

[lestergit]

My thermostatic radiator vallve has finally given up the ghost, but I am having a real problem getting a replacement. It looks to me as if the pipe connection is 22mm and the radiator connection is 27mm. I have only been able to find valves with 10 or 15mm connectors.

Any help greatly appreciated

 

[kevplumb]

you can get valves with 22mm connections 27mm dream on dont exist
buy a valve and change the tail

 

[lestergit]

Kevplumb, you'll have to excuse my ignorance (many do). I measured the old valve across the external diameter of the threads, that is where I got the 22/27mm figures from. Is this wrong?

When you say 'change the tail' do you mean the part going into the radiator?

 

[kevplumb]

yes chance to be 3/4 bsp fairly standard
plumbcentre do a decent range are you sure the incoming pipe is 22

yes the tail is the bit that goes into the rad
i appologise for being short but we have a pr**k floating about the forum taking the p**s

 

[lestergit]

Kerching!! The light's just come on. You are quite right, the pipe diameters ( as opposed to the thread diameters) are 15mm and 22mm. I presume that I need to get a tail (I'm getting all technical now!) that steps the radiator inlet from 22m to 15mm.

Funnily enough, I have changed all the radiator valves in the house over the lat 5 years, and two of the radiators, but never had this problem.

As for being a p***ck, many say I am...but not necessarily on this occasion

 

[kevplumb]

rad will be 1/2 "" bsp (standard) you get a new tail with the valve
if you dont know you aint a pr**k only if you think you know and dont
not a diff job to change valve if you get stuck SHOUT

 

[BruisedThumb]

Once upon a time, the British engineering industry decided to standardise pipe sizes. They settled on the bore as the parameter of the pipe by which each size would be known.

However, the manufacturing know-how of the day could only manufacture pipe with fairly thick walls. So, when Fred (later 'Sir Fred') Whitworth came to standardise his system of screw threads for pipe, 'British Standard Pipe' or BSP (He'd already done 'British Standard Whitworth' & 'British Standard Fred') he had to make the maximum diameter of the thread correspond with the O.D. of the relevant pipe size.

For example, the O.D. of nominal 1_1/2" pipe is actually 1_27/32". I can't remember the corresponding dimensions of the smaller pipe sizes so I'll stick with 1_1/2" as an example to make the point.

So far, so good; If you wanted to check the size of the pipe, you just had to measure the bore.

But then some clever bloke thought to himself 'This pipe is much too heavy and we're using too much steel. I reckon I could improve the drawing process and make pipe with thinner wall that's just as strong.' But he didn't want to produce a totally new system of pipe threads; everyone had tooled up with taps and dies to Sir Fred's BSP system, so he had to produce his pipe with the standard O.D. which, with the new thinner wall, made the I.D. bigger than nominal.

That's why, on a bit of nominal 1_1/2" pipe, there's nothing that measures 1_1/2". And why nothing on a 1_1/2" BSP thread measures 1_1/2" either.

The same history applies to the 1/2" BSP, 3/4" BSP and 1" BSP sizes too.

The interesting thing is that while while the UK has abandoned Sir Fred's BSW and BSF threads for structural fixings in favour of metric standards, I understand that the Continentals are still happily using BSP for pipework!

I was going to add a foot-note on why water- or gas-pipe is often termed 'barrel' but I expect you know that.

 

[breezer]

(He'd already done 'British Standard Whitworth' & 'British Standard Fred')

British Standard Fred thats a good one, but its actually British Standard Fine

 

[BruisedThumb]

Breezer:

I know that you knew that I knew that you knew that I know.

But what about the 'barrel'?

 

[BruisedThumb]

Breezer:

Thanks for the link to that wrenches/spanners site; I just had a quick look, very interesting.

Immediately below his reference to BSF he mentions BA but only in sizes down to 11. I was taught that the BA threads are, in fact, a metric system which was used in the clocks/watches business so there are sizes smaller than 11. The O.D. of 0 BA is 6 mm.

He doesn't mention flare nut spanners. Earlier this year I was looking for some flare nut spanners to tighten some MICC glands (no room for an open-ended). Halfords didn't stock the right sizes and time was too pressing for me to shop around. I eventually bought a couple of ring spanners and carefully ground gaps in them with the angle grinder. Didn't like doing that but I had no choice and the modified spanners did the job well.

One of the treasured books on my shelf is the Machinery's Handbook. Actually, I have two, a recent edition and a quite old one. My interests range across a variety of branches of engineering including some restoration work. I regularly need to look up thread sizes. The recent Machinery's doesn't give much more than Unified and Metric thread sizes but the older one lists the whole gamut, BSP (taper as well as parallel structural), Cycle threads, Brass threads and so on and so on.

Another treasured book is the last hard-back edition of the Buck & Hickman Catalogue, nearly 4" thick and nearly every item illustrated. What an education that book can be.

There's sometimes a bit of friction between Engineers and Tradesmen on this forum; what we do have in common is that there is no excuse to ever stop learning. However, I'm way off-topic so I'll stop waffling on now.

 

[kevplumb]

barrel ?

 

[blahblah]

With the utmost respect Mr Thumb you must be up for 'Anorak of the month'. Barrell, no doubt, is for blowing ones brains out!
Seriously though- I'd love to know?

 

[kevplumb]

showing your age now bla

 

[PTH]

I think I've got the same type of anorak as Thumb! I've got catalogues and text books going back more than a century.

I'm still looking out for a screw with an Armstrongs Patent Improved Machine Thread in 17/32" with a square head and a reduced shank. Anyone got a link to the appropriate Screwfix page?