newshound wrote:

On 1/10/2017 9:46 PM, Roger Hayter wrote:
newshound wrote:

On 1/10/2017 8:23 PM, Roger Hayter wrote:
I have a Myson fan assisted radiator with 3/4" female brass connections
to the heat exchanger. Would it be better to use 3/4" taper fittings
with PTFE or Loctite stuff or 3/4" parallel ones with a fibre washer?
The taper ones make better sense to me, but is there any risk of
splitting the connections if they are as cheap and nasty as most things
are these days?



(By the way, I am seeing 19mm brass threads in the catalogues now - are
they some evil EU standard instead of BSP?)


Are the Myson fittings terminated with a machined flange, or are they as
forged (not likely)? The presence of a flange implies they should be
fitted with parallel fittings and a fibre washer.

Female taper fittings are shown on this page

https://www.bes.co.uk/products/160.asp#8238


Thanks for the answer, but I'm not totally sure I understand it. The
fittings on the radiator are female, and have no obvious face on them,
although they are fairly flat. In fact, the flats of the hexagon are
within about 1.5mm of the root of the thread, so I doubt a washer would
seal well. I presumably want a male 3/4" fitting, and I am leaning
towards a taper thread one.

OK if there is no obvious face, then they almost certainly need a taper
fitting. I'm never really happy with PTFE on these, I always use the
Loctite "string" (which replaced the traditional hemp plus boss white).
No other sealant required.

I had a Myson under-unit fan assisted rad years ago but I'm not quite
sure what fittings they had. I "suspect" they had flexible hoses with
push fit at the "copper" end, and male tapers at the "radiator" end.

I am slightly surprised they don't have instructions specifying the
requirements. These days you can usually find the "manual" on the web.

The instructions say that they have femal 3/4" fittings and a straight
fitting is preferred (to an elbow presumably, but this is not stated) to
facilitate the routing of the pipes. Nothing about whether the fitting
should be a taper thread. I agree about the Loctite, by the way, it
seems to be very successful. I might have used hemp on 3/4" years ago,
it's about on the borderline. I think PTFE tape works ok on 1/2".


What is this 19mm thread, do you know?




--

Roger Hayter