Best plastic fittings

[wcavanagh]

I am running in my new central heating pipes under the floor in my cottage. I have opted for plastic as I can do the two flow and return long runs in one go. 25m each, it is a very long cottage, I plan to tee off at each room in 15mm from these main 22mm pipe.

Now having not worked with plastic before. There seems to be a massive choice of types and makes of connectors, I don't want to be able to discount again, as I see some of them let you do this. For me I want want reliable connections as they will be under floor.

Ant suggestions?

A friend said I should use compression standard tee's with the inserts.

Cheers

 

[oldbuffer]

a. I'd opt for either HEP2O or JG Speedfit, the latter probably being easier to work with.

b. Don't forget you need barrier pipe for central heating to stop oxygen getting in.

c. Whatever make you go with:

i. Use all the same makers fittings and inserts. Don't mix with other makes or you may get guarantee issues
ii. Read the manufacturers instructions carefully, particularly as they relate to pressure testing. Be prepared to hire a pressure testing pump. From memory they expect the whole system (with boiler disconnected!) to be taken up to about 10 bar. It not only tests the system, but makes the grab rings in the fittings dig in.

d. I don't see any advantage to using compression fittings under the floor. If properly installed and tested push fit fittings are as reliable as compression.

e. If there is any suggestion of rodent activity under the floor, I'd rethink using plastic and go with copper. Properly soldered joints, again pressure tested (to 1.5 times normal operating pressure, say 4.5 bar for a combi) its reliable.

Good luck with the installation.

 

[Dan Robinson]

Tectite Classic is the best.

JG is crap.

Compression fittings stooopid.

Barrier pipe and pressure testing essential.

Rodents eat through copper as easily plastic.

 

[wcavanagh]

Thanks guys,

Always worked in copper in the past, so this is all slightly new to me. The pipe I have pulled in is

QPL Polybutylene Barrier Pipe Grey 25m x 22mm. Screwfix par no. 79215

I will hire a pressure tester no issues.

Just about to order all the rads, loving Christmas, lol

I have bought a plastic pipe cutter

 

[wcavanagh]

Should I insulate the plastic pipe under the floor? There is only about 3in from bottom of the joists to the ground.

The cottage is rural so mice are a possibility I guess, I was told to lay the pipe into speedfit conduit so bought several rolls of that.

 

[Dan Robinson]

Depends how drafty the floor void is I suppose, but insulation is never a vad thing.

 

[Norcon]

I am running in my new central heating pipes under the floor in my cottage. I have opted for plastic as I can do the two flow and return long runs in one go. 25m each, it is a very long cottage, I plan to tee off at each room in 15mm from these main 22mm pipe.

Now having not worked with plastic before. There seems to be a massive choice of types and makes of connectors, I don't want to be able to discount again, as I see some of them let you do this. For me I want want reliable connections as they will be under floor.

Ant suggestions?

A friend said I should use compression standard tee's with the inserts.

Cheers

Yes definitely use compression under the floors.
Most plastic fittings depend on an O ring which will fail eventually and you'll then have a leak under the floors.

The only exception is the Rehau Everloc system. Better still run continuous lengths and no joints under floors.

 

[holty]

+1 for tectite. grant oil boilers supply these to pipe up to there boiler.

 

[denso13]

Insulate as you would for copper.

 

[wcavanagh]

Thanks All,

I have to have joints under the floor to "Tee" of to each rad from the main 22mm flow and return lines, so no joints are not an option. Using plastic I can do the very long runs without joints hence the reason I have opted this time.

Still not decided on joint type for the reducing Tee's. I like the idea of compression with copper olive just from a mechanical point of view sinking that into plastic with an insert seems better than an single small rubber O ring. Will keep looking at this.

Will insulate as i normally would with copper also, thanks.

If I am running the Plastic in Speedfit Conduit Guess I will need 28mm + insulation ?

Thanks again all for advice, it all helps.

 

[Madrab]

Assume this is from a combi/system boiler and not a range, solid fuel boiler? Don't forget that you need at least a 1m feed from the boiler in copper before it runs into plastic due to the possible latent heat leak from the heat exchanger.

 

[wcavanagh]

Hi,

I will be getting someone in to install an Oil combi Boiler, as there is no heating at all on site at the moment. I plan to bring the 22mm pipes up into utility room, ready for plumber (when I find one)

Cheers

 

[CHarr]

I have very recently completed a CH installation with PolyPlumb fittings & barrier pipe. I used push-fit reducing tees 22mm/15mm for the branches to individual radiators, and used 15mm copper pipe for the above-floor visible sections connected to the rad. valves.

No problems: no leaks.

 

[wcavanagh]

Hi,

I will be getting someone in to install an Oil combi Boiler, as there is no heating at all on site at the moment. I plan to bring the 22mm pipes up into utility room, ready for plumber (when I find one)

Cheers

 

[newbuildinstaller]

people like to make things difficult.

Buy push fit tees and use them, I regularly go to houses that have 15 year plus pushfit in them.

Also if you over tighten a olive it will cut into the plastic, also compression has a much greater chance of leaking after getting hot/cold/hot/cold. THE FITTINGS ARE DESIGNED FOR THE PIPE.

You could have if you really wanted to go over board placed a manifold in the middle of the house (either accessible or above the floor) ran 22mm to that direct from the boiler. Then ran continuous lengths of 15mm from the manifold to each rad. Of course that would be pointless and expensive... but some people like this as it makes them feel their system is special (as special as rads and pipe can be anyhoo)