How to bend a short length of 8mm microbore to fit a TRV

[rwd16]

I have a gas central heating system. The original radiators are connected by 8mm microbore pipe. The radiator in the extension (which already has a Drayton TRV4) is on 15mm pipe.

I wish to put thermostatic radiator valves on the rest of the upstairs radiators.

I was hoping to fit TRVs that would directly replace the existing manual valves without having to change any of the pipework, but the 8mm microbore pipes come out of the walls at an angle of about 45deg, so any TRV fitted would stick out a long way. I would like to fit Drayton TRV4 valves. However these are made only with a 15mm connection, although I understand that I can fit a 15 to 8mm converter.

It seems to me that I need to try to bend down the v short length of pipe that sticks out from the wall (approx 4 cm) to be horizontal. Then I can fit a right angle 8mm fitting, then a short length of vertical 8mm pipe and then connect the TRV to this. This would result in the TRV being vertical, although I may need to lift the radiator up the wall a bit.

I read somewhere else on the forum that there are tools for bending 8mm pipe. Will they work with such a short length of pipe? Can it be done with a bending spring and some pliers / grips? If not, can you please suggest another arrangement of pipework and fittings that will work?

 

[hi-spec plumbing heating]

8mm / 10mm pipe bender
you don't get an 8mm pipe spring, you can bend 8mm by hand if you do a sweeping bend.
and not by using grips you'll crush it

 

[namsag]

You do get 8mm pipe springs and don`t use grips just gentle pressure from your thumbs will bend it , it can also be bent carefully without a spring or benders providing you dont put too tight a bend in it.

 

[rwd16]

Thank you for the v quick and helpful replies.

My experience of bending 15mm pipe is to put a pipe-bending spring into a pipe that has to be approx 1m long so that it can be bent round a knee. This relatively long length is needed to be able to apply enough force to bend the pipe. Then the bit with the bend in it can be cut out and used.

Obviously the 8mm pipe will take less force to bend it - you said that it can be done with thumbs. But, there is only a v short section of pipe sticking out of the wall - about 4cm. It will be hard to get much of a grip to apply the bending force, so is it really possible to bend such a short length next to the wall using my thumbs? Would a pipe-bending tool do the job, or would there be no room to use such a tool here?

 

[namsag]

with only that amount of pipe you will struggle to get a bender in And a spring will struggle 2 but will be your better option .. WWW.bes.co.uk 8mm extrenal bending spring code 3738 cost 81p... Your other alternative is fit the valve on its side so valve head is horizontal...

Now those where the days bending 22mm over the knee...ouch

 

[John M]

Your other alternative is fit the valve on its side so valve head is horizontal.

Poland ?

 

[namsag]

No in the drayton instructions if you read them. not sure if they come in polish.

Checked for you johnm instructions only come in English, German, Spanish, Italian and French.. So you will have to work it out for yourself,

 

[Space cat]

In your position I would ask myself two questions: What's the wall made of and where does the pipe go once it's in the wall?

 

[TicklyT]

Good point Namsag, if the valve is bidirectional, reverse the inlet and outlet so the head is horizontal, and lays against the wall
If it's unidirectional, then maybe consider fitting it on the other end of the rad.

Never did get on bending 22mm over my knee...... Perhaps I have the wrong radius kneecaps....

 

[rwd16]

Thanks again for the helpful replies.

It seems to me that I now have 2 options:

1. Try to bend the 8mm pipe, and see what happens...
The reply from namsag suggested using an external bending spring. I've of using an internal bending spring before, I didn't know external ones existed - what's the pros and cons of each?

or
2. If that doesn't work, cut a hole in the floorboards and fit a length of 15mm pipe between the radiator and the 8mm microbore under the floor. I can run that pipe straight up the wall so I can then fit the TRV4 vertically, which was what I really wanted to do in the first place! Apart from looks, does it matter if the radiator has a 15mm feed and an 8mm outlet?

 

[kevplumb]

with only that amount of pipe you will struggle to get a bender in And a spring will struggle 2 but will be your better option .. WWW.bes.co.uk 8mm extrenal bending spring code 3738 cost 81p... Your other alternative is fit the valve on its side so valve head is horizontal...

Now those where the days bending 22mm over the knee...ouch

28 bonny lad

why i can't walk far

 

[John M]

Heres a option ....... Raise the radiators a couple O' inch extend the exsisting pipe & bend it to suit

Ok Not a brill suggestion but a option

 

[namsag]

Kev i take it your middle names are king kong. Tried some daft things in my time, not that though but yeah can see that crippling ya.