I need to plumb in a sink, and I don't much like plumbing! So I have a few qs...
There's an existing run of 40mm sovl weld waste that I need to tap into, but I dont want to use more solv weld, and I gather compressions arent compatible with solv weld pipe due to a slight size difference. The present pipe is 42.5mm. Is pushfit compatible with this?
I plan to use microbore, since all the conditions seem favourable for it. Any reason to choose between 8mm and 10mm? What min bending radius should I stick to?
What do I use to connect the microbore to the taps?
Can I use sand instead of a bending spring?
Any recommended supplier for all the bits? Screwfix doesnt do microbore bending springs.
You say you want to tap into an existing waste pipe? What other appliances are on this pipe?
You want to use Microbore pipework to the faucets? Where is the water supplied from for the new appliance?
Microbore pipe is easily manipulated by hand, but if you want to make tight bends, you will need an external bender handle. The pipe actually sits inside a shaped form to hold the outside of the pipe wall and reduce any creasing.
More info' on the whole layout for this type project, please. Ta.
Compression (aka "universal") is compatible with both pushfit and solvent weld. However the pushfit and solvent weld are not interchangeable. Slight size difference, and the wrong sort of plastic in the case of pushfit.
Main pressure water I take it? Can't see it makes much difference, although I personally would use 10mm for something like this. I would expect 50 - 60mm to be the min radius.
What sort of taps? Traditional ones will take a BSP tap connector. You could either use ones that are terminated in 10mm or use a step down adaptor of some sort. Monoblock taps tend to have 8 or 10mm inlets anyway and come with flexi tails. These usually fit onto an ordinary service valve with the top nut and olive removed.
Never tried it, so don't know. A external spring is probably quite cheap and works well though.
Theres 2 or 3 sinks on it so far, and kitchen appliances. An antivac trap will be used to avoid gurgling.
15mm pipes are nearby, its only a short run in microbore to add, and the pressure's high.
Right - I will need a fairly tight bend at one place.
OK, the new sink is first floor, all the existing plumbing & appliances are on ground floor, almost directly underneath. I'm sure microbore will give plenty of flow for the use it'll get. Not sure what else I can tell you about layout - I'm a bit short on clues in the plumbing dept. The sink will use 2 taps, no mixer.
Sorry. That won't work. You'll need to create a loop vent from the waste stack for that amount of appliances. A fresh air inlet won't cope with three of these appliances emtpying at the same time. You'll need to upgrade the pipe itself to 50 mm to take all the appliances if they decide to all emtpy at the same time. The top of the loop can be made in 32 mm pipe to allow the air to suck in from the top branch on the stack.
But your BCO won't pass it if it's not done correctly.
The pressure is high on both hot and cold? You'll be amazed at how much flow rate will be restricted by dropping the pipe diameter that much. I think it's best if you keep the 15 mm pipe through out, because a drop in size will only allow a dribble at the taps.
You also have to reduce and increase the diameter again to fit the faucets at the sink.
Microbore bender is what to search for.
How high up is the first floor? Can you take a branch directly through the wall from the waste stack? Dropping water from a height into the pipework below won't just suck on the top most point at the new sink. As it rushes passed the other appliances, it will suck the water out the traps on them as well. Yes, even with a FAI at the high point.
Your water supply drops to the floor below, then rises to the room you want the new sink to be? And you think microbore or minibore pipework will be sufficient? Sorry, personally I don't think so. Microbore is OK for higher pressures in pumped systems or as a reducer to flow on high pressure mains supply. Small diameter pipes are not the best to supply faucets on a sink, especially if it's from a lower pressure system or low level tank fed.
Yep.My bathroom w/h basin is fed by microbore tapped off the bath feeds and when I turn the w/h taps on it almost hits you in the face when it bounces off the basin .
The cross sectional area of a 10mm pipe is less than half that of 15mm, 8mm is two thirds less. As BW said, you'd be amazed how much flow will be lost.
Right, cheers. One last question I've got. The routing of the waste pipe is to say the least tight, and what would be ideal would be to remove an existing solv weld elbow and replace it with a compression tee. I'm well aware of how solv weld works, so assume this is impossible - is it? Or is the bond patchy enough to make it doable?
Now I'm starting to see what other input you wanted. The set up is quite different to what you say there, and thankfully this bit of the puzzle is now solved.
Just thought, you might, just possibly, find flexible waste useful. In some cases, it makes life very easy compared with trying to get rigid pipe working well.
I know that it was invaluable for a couple of places here. I got the HepFlex pipe with solvent weld bits and it worked (and several years later still works) a treat.
Does that coupler comes apart to hold the 10 mm compression ring? If it doesn't, how does it work? A 15 to 10 mm reducer just tightens on the ends of the two pipes without problem. Isn't that simpler? I honestly don't know how that coupler works. I've seen two part reducer rings that allow 15 mm tube to fit in a 22 mm compression fitting. So does that coupler do the same? It doesn't look as though it comes apart, as far as I see in the photo'.
One piece reducing sets are now sold. These have a very thin part between the two more solid ends of the "reducing set", the thin part acts like and olive on the smaller pipe whilst the 'end' work like a larger olive for the fitting.
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