Y-piece or swept T?

[D4dog]

I am trying to fit a single wall mounbted spout to a bathroom. This spout has a single 3/4" inlet, designed I assume to come from a mixer tap. However, I would rather use seperate taps, which means I need to connect the outputs form hot and cold into a single pipe.

If I use a standard T, then the pressures must be balanced for it to work - which may not be the case, especially of HW is gravity fed - I could end up pumping mains cold back into the HW tank!. Yes I could use a non-return valve on each supply, but this reduces the flow rate and introduces flow noise.

Can ayone advise me of whether I can actually get a proper Y piece in copper? I could use a swept T, but this still has the two flows in contention to some extent. I do not understand why these are not available generally?

 

[Charnwood]

What size pipe will you be running from the taps?

Yes, it's push-fit!

www.Speedfit 2 way divider.

What you could do with is an injector tee. Delcop used to make them, but discontinued them a few years ago. They work on the venturi principle.
See here.

 

[Agile]

You will never get it to work well if you try to use mains cold and gravity hot!

You can buy a pressure equalising valve or a cheaper pressure reducing valve will have a similar effect. Ideally two is series with the second designed for low out pressures.

Charnwood can list each of these three! Be aware the balancing valves have a limited range and would need the specs to be compared with your mains pressure. I would use the pressure reducing valves as they are cheaper and will work well.

Its NO advantage using a swept tee. They are also very expensive.

Ideally if they were balanced you would use a tee with the output from the branch.

Tony

 

[Space cat]

It's against regulations to combine mains water and tank-fed water in the same pipe. The reason: In the event of a pressure loss on the mains side, your potentially dirty tank water could be sucked into the mains supply and contaminate the whole street!

You might get away with it if those pressure reducing/equalising valves that Agile mentions also prevent back flow into the mains supply but it's still a bodge job. To do it properly, take your cold supply from the same header tank that feeds your hot water system.

 

[Charnwood]

It's against regulations to combine mains water and tank-fed water in the same pipe. The reason: In the event of a pressure loss on the mains side, your potentially dirty tank water could be sucked into the mains supply and contaminate the whole street!

Is it against regs to fit Trevo Boost showers? Someone ought to tell Ideal.

 

[D4dog]

In that case all those gucci overflow filler systems must be illegal - they tak direct input form wall mounted taps, which are effectviely extending hot and cold water to the filler.

And of course any mixer tap does exactly the same - so how do I connect a wall spout to my hot and cold taps exactly? does thismean I MUST have a none-return valve on the hot flow?

 

[Space cat]

And of course any mixer tap does exactly the same

If you look closely at a kitchen mixer tap you'll see that it's not really a mixer at all. The spout has two separate outlets so the hot and cold water only mix after they leave the tap.

does thismean I MUST have a none-return valve on the hot flow?

You need a non-return valve on the cold flow to stop water from your tank getting into the mains supply. I expect that's how those various devices that have been mentioned get around the problem.

 

[D4dog]

The mixer on a combined bath overflow and filler are very simple - the output from the hot tap and the output from the cold tap go into the same pipe - indeed, they go into a t-piece at the base of hte spout, so are in direct opposition.

This is also true of many wall-mounted spouts.

My error - I did mean the cold supply for legal reasons. The hot supply non-return valve would be required to prevent the high pressure cold water preventing the flow of the lower pressure hot water. and potentially forcing hot water back up into the tank by either the expansion pipe or the supply to the tank.

i suppose the only way to fill the bath is then to use hot only or cold only, and not mix the two together - or to balance the pressures accordingly.

Just out of interest - how does a temperature regulator valve work, if not by connecting the hot and cold water together in one device? Does this fall into the same "illegal" bracket?

 

[Agile]

All of those things either contain or should be fitted with a NRV.

Few are fitted with an external NRV even when required.

The Water Regs probably mostly need a double NRV on the cold feed when being mixed with tank derived hot water.

Tony

 

[D4dog]

Thanks Agile - my plan is to fit NRVs, and probably boost the hot water pressure - otherwise it will take for ever to fill the bath anyway!

It is interesting that these overflow fillers and bath wall spouts all seem to contravene the regs, however - and this never gets mentioned when you buy them! That said, they are all positioned after the supply taps - if the taps themselves had NRVs in, then this would solve the problem.

Thanks all.