Leaky MDPE Wall Plate Elbow

[JohnDean]

I recently installed some MDPE piping to create a stand pipe at the bottom of the garden. It terminates with a wall plate elbow (plastic), a 3/4" to 1/2" bush and outdoor tap. The problem is that the thread is too long on the wall plate (http://www.screwfix.com/p/floplast-mdpe-plastic-wall-plate-elbow-25mm-x/77864) or the bush/tap thread is too short if you like and it's just not possible to get a good seal. No amount of PFTE tap or packing with 3/4" washers helps.

I'm considering dumping the plastic wall plate for a brass one, although I can't find anywhere that sells them individually, as they seem to have a shorter thread and would probably produce a better seal against the brass bush anyway.

Is this my only option? Is there a cheaper, albeit hacky alternative?

 

[Terry7556]

ive recently put some of this together on a farm to a new barn and the work included 4 bib taps, all of which were brass. used mdpe to 15mm reducer and didnt have any leaks with the taps, although a few in other joints.
i noticed in a local merchants after that the mdpe all plastic bibs were £10.50 each retail, not cheap eh

 

[JohnDean]

I hadn't considered that option. If I can find a cheap 25mm to 15mm copper reducer (Screwfix only do 20mm to 15mm) then it's a definitely one way to go, I have a length of 15mm copper going spare and 15mm wall plate elbows are only a couple of quid.

 

[digdilem]

I'm normally a supporter of Screwfix, but they've dropped a ball with stocking these things. I've had a lot of failures with this type of fittings from new. Utter rubbish.

Screwfix do do the blue pushfit which are marginally better, but still have poor reliability.

The black Philmac fittings are the only ones I've found that I have any confidence in using, but my only local source is not so convenient so I stock up. They /do/ do adapters for 25mm to 15 copper, but imo, get a philmac wallplate for 25mm. External copper is split-city in the freeze.

 

[Terry7556]

i got most of my fittings from toolstation and some others from screwfix

 

[JohnDean]

With apologies for answering my own question, I tried out the Loctite sealing cord that seems to be very popular with a lot of people here. I really didn't expect it to work given my earlier attempts with PTFE and the big difference in thread length between the nylon? elbow and the brass bush but it was worth a punt at just £3. It's worked very well, almost too well as I had trouble tightening up. Much cheaper and less hassle than buying new parts.

Hopefully it will stay leak free throughout the summer. I plan on turning off the water supply during winter to avoid ice damage and I won't need to water the garden then anyway.