Threading plastic pipes through under a suspended floor

[tickletoe]

I wanted to try and get some advice on the best way to pass 15mm plastic pipes through under floorboards.

I have plumbed in two manifolds - upstairs & downstairs and need to connect 5 rads to each one. The manifolds are central in the house and most pipe runs will be about 3m upstairs and about 4m downstairs, although there are a couple of longer runs to small rads. Pipe to the manifolds is 22mm and to the rads will be 15mm plastic.

Upstairs I have 9inch joists so plan to drill 30mm holes in the centre of the joists and feed the pipe through. This sounds simple but on my first one I had some trouble I think because of misaligned holes. Any other tips - vaseline perhaps?

Downstairs I have a suspended floor with a foot and half cavity under floorboards. The joists are only 4 inches. I was planning to insulate the pipes and then try and pass them under the floor and clip them to the underside of the joists using builders band. I have two problems though. One is that perpendicular to the joists there are lattice brick wall supports which I need to thread the pipe through. Also there is an area of parquet flooring I hope not to have to lift up. I was thinking of perhaps trying to get a wire through and pull the pipe through, or using a hook on the end of a broom handle to help. I was wondering if there are some easier ways of doing this.

I planned to use 25mm wall pipe lagging for the downstairs but am worried that the size of this will make it more difficult to pass through. Would 19mm or 13mm be easier?

I did try and get a couple of quotes from plumbers to hang and connect up the 10 rads but both refused to take on the work and only wanted to fit the boiler. They said they had never used manifolds for anything other than under floor heating – made me worried I was doing something wrong. From discussions with the plumber’s merchant and searching online it seemed that this kind of thing was standard practice now.

Does anyone who’s done this kind of thing before have an idea of how long it will take to hang and connect 10 rads? And given the fact that I have done all the other work do you think this is why a plumber doesn't want anything to do with piping in the rads?

Many thanks for any info you can let me have - its much appreciated.

 

[Galoka]

1.Threading through the joists. What are you threading through the 30 mm hole? a bunch of 15mm pipes? Might be better off drilling a hole for each pipe, or less pipes through the hole.? The cumulative friction from each hole does add up so you want it as easy run as possible Though when I have ended up with a stiff bit a quick squirt of Silicone spray has helped things along.

I drill an 18mm hole for 15mm pipe, as well as the holes lining up, you need to take care they are horizontal, otherwise that also makes it hard to cable through. It is easy to not have the drill horizontal.

There aren't any easy ways of getting pipes through awkward situations - sometimes you just need to be creative or use a bit of lateral thinking. I made a hook from an old bit of copper pipe, fixed to the end of a straight length of PEX pipe to pull through another bit of pipe with a loop from elec cable taped to the end Can you get under the floor space? 18 inches is just about enough, though not very pleasant.

I would probably slide the insulation on - you might need to use a smaller diameter bit for the section through the wall. Again I found that a little squirt of silicone spray helps it along, then you can push multiple lengths along.

It's not uncommon for trades people to not want to take on part done job, probably because it often turns into harder work, and then things aren't done in the way they would - there are probably easier ways of making money I think if you want to split the work like that you really need to have found and agreed it with a trades person first.

Hanging rads, and connecting them up to the pipes is easy enough ( as a a rule, unless you have awkward walls etc.). Getting the pipes to the rad is the fun part

 

[SandyLyon]

You don't say which brand of plastic pipe you are using, there are two main types (not including MLC) PB and PEX.

PB is by far the most flexible and therefore easier to thread through joists etc.

PEX is far more rigid, and 22mm on coils can be a nightmare to handle in difficult situations

The vast majority of New Build houses have PB plastic pipe for that reason.

Edit: Forgot to mention, when threading pipe through joists / walls etc, protect the pipe end with either a plastic cap or some tape.
This will stop crap getting into the pipe and also prevent the pipe from being scored this could then "weep" if the "O" ring sits on it.

 

[tickletoe]

Thanks for both replies. A lot of useful information and its much appreciated. I am pleased to know I am not completely barking up the wrong tree which I started to think when the plumber turned down the work.

The pipe I have bought - and I didn't buy all I need as I wanted to test it out - is a 12mm MLC pipe - external diameter 16mm. The reason for this is that I thought for downstairs it would be better to have a pipe which you could bend and it keep its shape and its rgigidty would stop it from sagging under the joists if I don't manage to clip it as much as I should. I also thought the MLC pipe would be more durable and less likely to be damaged. It is nice pipe but I am willing to switch to another type if it is neccessary to get the job done. Has anyone used this type of pipe in this way and found it good or bad?

Upstairs though this pipe does not seem such a good idea as its rigidity makes it hard to thread through the joists. So as I didn't buy the whole lot for the job I might use it for downstairs only and get a PB pipe for upstairs. The manifold has various connectors you can buy so it shouldn't be a problem there.

I will take a look at my diagrams and see how many joists I have to go through, maybe I can re-position the rads such as to minimise the cross joist distances. Also I could put a few joins in or if that fails change pipe.

Due to some unforseen family stuff I have been unable to finish this off as planned and was hoping to get someone in to at least help. But so far I have been unable to find someone - I guess its completey the wrong time of year to be looking so looks like I'll have to find the time to complete it. My thinking is that, I have about 4 hours a day that I should at least be able to connect 2 rads in a day. Does this sound possible?

Thanks again.

 

[tickletoe]

Sorry, forgot to say the reason I was planning to use 30mm holes was I already had the auger drill bit and with 9inch joists the holes would not be a problem if spaced out every 3 x diamter, i.e. 90mm. Also the wide hole I assumed would help with the threading through. Maybe 30mm is too much and I should buy a smaller bit.
Thanks