Fitting TRV's To Plastic Pipes ?

[Aletank]

My house was built about year 2000, i have 9 radiators which use plastic pipes rather than copper, I'm guessing 10mm definatly not 15mm.
It is a traditional system - not a combi ,I'm thinking of fitting TRV's to the rads.
Would I need a different kind of TRV because of the plastic pipes ? I was thinking of these ones http://www.toolstation.com/shop/Hea...tic+Radiator+Valve+10+15mm/d230/sd2762/p80954
I've heard I'll need some inserts Is this the kinda thing I need http://www.toolstation.com/shop/Plumbing/Pushfit/Pipe+Inserts+10mm/d20/sd3143/p96609
Wouldn't the pipe already have inserts in for the current fitting ?
Are the Speedfit inserts different to what I require ?

I've felt both pipes to determine which is the flow/return - Is it normal for the flow to be on different sides on different rads ? ( I know that with most TRV's now it doesn't matter which side they go on) I am right in thinking that aren't I ? I will try and fit on the flow side though.

I tried to balance my system a while back which i feel was a success so I have some return sides not fully open - Would it be OK to open these fully once the TRV's are fitted ?

Sorry for all the questions and i hope they not too confusing - Thanks for any replies

 

[seco services]

your pipes should already have the inserts in.

flow and return can be on opersite ends yes.
most trv's are bi-directional.

even with trv's the system still needs to be balanced.

 

[Aletank]

your pipes should already have the inserts in.

flow and return can be on opersite ends yes.
most trv's are bi-directional.

even with trv's the system still needs to be balanced.

So if i've balanced the system, i'm goin to have to fit the TRV's on the fully open Flow side anyway ?

Thanks

 

[Aletank]

Sorry but another question

What advantages do the more expensive TRV's have over the cheaper ones like i have put a link to in my 1st post ?

 

[glasgowgas]

Sorry but another question

What advantages do the more expensive TRV's have over the cheaper ones like i have put a link to in my 1st post ?

more reliable, trv heads usually a bit more robust

i always use danfoss

draytons are also good

 

[Aletank]

Just to update/finalise this thread - I've fitted my TRV's, I went for Siemens TRV's from Screwfix http://www.screwfix.com/prods/71015...emens-MTN51GB-White-Chrome-TRV-10-15mm-Angled Bi-Directional and Liquid Sensor.
I fitted 8 TRV's and also fitted a Salus Digital Room Thermostat in the hallway and left the hallway rad without a TRV.
My plastic pipes had inserts in which i left, they looked like metal inserts.
All seems good now after I sorted a boiler airlock with the help of forum members here on another thread
I've got a litre of Sentinel to go in later this week when I know for sure everything is working as it should.
Thanks again for everyones help/input !