Buteline vs hep20 pipes

[Adsibob]

My plumber wants to use a combination of copper and plastic pipes. He says he prefers copper for the ends of runs where he connects to a cylinder, taps, shower etc., but that he prefers to use plastic for the long runs. I asked if he would be using hep20 (because I had heard good reviews of it on this forum) and he said he prefers to use Buteline. He says it's much stronger and has no rubber parts.

Googling around I found this https://community.screwfix.com/threads/well-done-wavin.186552/ which reviews the Buteline system highly (see second post and video contained therein). The test in the video is a bit irrelevant as we are struggling to get above 3 bar let alone 30! 

Any experience on this forum of using buteline?

 

If I go with buteline, which pipe diameters do I want to use for

 

1. HW secondary loop? (22mm?)
2. HW run from secondary loop to showers? (16mm?)
3. HW run from secondary loop to basins (10mm?)
4. Cold water run to basins (10mm?)
5. cold water run to shiowers (16mm?)

 

I was surprised that the plumber recommended "15mm" for basins, because I thought the advice here was always to use 10mm to reduce build up of cold water in dead legs. From the info below (taken from Buteline's website), the 10mm seems to have a tiny ID and even smaller ID of fittings, so maybe that's why he prefers 16mm (not "15mm" which doesn't seem to exist). But he also said that all taps these days have narrower hoses so it doesn't matter if we use 10mm or 15mm, but I think he's not thinking about dead legs.

 

 

[Dudda]

It's not demount-able. Once you crimpt the Buteline you can't take them apart unlike Hep20. The other thing is Buteline claim they don't have separate inserts but they are built into their fittings so they do have them it's just they're not separate like Hep20 or JG speedfit, etc. The Hep20 inserts are very thin metal and therefore  don't reduce the internal diameter much. The JG Speedfit are plastic and therefore thicker and reduce the internal diameter a bit more. Similarly the Buteline inserts which are fixed to the pipe connections are also plastic which reduce the internal diameter.

I don't think it matters which system the plumber goes for. It's if you're doing it yourself the Hep20 is probably easier as you can take them apart which will need to happen at some point somewhere.

If you've a hot water circulation loop you can use 15mm to basins. It's where you don't have a circulation loop and instead have something like a central manifold then having a 10mm pipe reduces the amount of water that has to run before it gets hot.

 

 

[Adsibob]

On 16/09/2021 at 15:02, Dudda said:

If you've a hot water circulation loop you can use 15mm to basins. It's where you don't have a circulation loop and instead have something like a central manifold then having a 10mm pipe reduces the amount of water that has to run before it gets hot.

 

 

But doesn't this assume that the hot water circulation loop goes very close to each outlet? I think his plan is to just take the hot water loop to the nearest point in each room where hot water is needed, and from there run a separate pipe for each outlet. It's this pipe that he suggested could be done with 10mm or 16mm buteline (so that's an internal diameter of 6.9 or 12.1). Working out the internal area, tells me that the 16mm buteline will hold slightly more than 3 x the volume of water than the 10mm buteline. So it will probably take 3x longer to clear the deadleg (ignoring any variation in flow rate that might come from broader pipes). Is there any downside of using 10mm buteline for a basin? Is a 6.9mm internal diameter sufficient for the supply of water to all basins (whether it's the kitchen sink or the WC)?

 

Edited November 1, 2021 by Adsibob

[Nickfromwales]

10 hours ago, Adsibob said:

But doesn't this assume that the hot water circulation loop goes very close to each outlet? I think his plan is to just take the hot water loop to the nearest point in each room where hot water is needed, and from there run a separate pipe for each outlet. It's this pipe that he suggested could be done with 10mm or 16mm buteline (so that's an internal diameter of 6.9 or 12.1). Working out the internal area, tells me that the 16mm buteline will hold slightly more than 3 x the volume of water than the 10mm buteline. So it will probably take 3x longer to clear the deadleg (ignoring any variation in flow rate that might come from broader pipes). Is there any downside of using 10mm buteline for a basin? Is a 6.9mm internal diameter sufficient for the supply of water to all basins (whether it's the kitchen sink or the WC)?

 

I've just installed and commissioned a full house system for a client, with UVC in upstairs plant room, and I fitted 10mm runs to the downstairs en-suite and cloak WC plus upstairs master are all 10mm hot and cold runs where the water pressure is 'not excellent', and the flow is more than adequate ( given modern basin taps are restricted / air blended for low flow rates anyhoo ). 

I ran a HRC to the utility and kitchen ( 15mm flow and 10mm return ) for instant premium hot water to both of those outlets. I don't ever do the above series HRC as it just doesn't rid you of every drop of the dead legs, the whole point of installing one in the first place! Also, if you do a manifold / radial setup then you need individual HRC returns back to a third manifold so you can isolate every hot outlet individually ( hot and HRC both need to be shut off to isolate a HRC serviced hot outlet  ). 

Also series HRC means several outlets can be pulling down one run of pipe, so the flow rates will suffer quite a bit too, especially with Buteline as the fittings have a lot of resistance. 

My preferred installation methods see just one fitting at the end of each continuous pipe run so flow rates are very very good indeed, even more so when preserving what flow you have where the cold mains is not as good as you'd have liked.

Any multi-occupant dwelling would deffo benefit from a 200-300L cold mains accumulator too, which are cheap enough these days, which will stave off pressure drops when things like WC's are flushed or an appliance is filling whilst someone is showering. Makes a huge difference.

[Adsibob]

12 hours ago, Nickfromwales said:

I've just installed and commissioned a full house system for a client, with UVC in upstairs plant room, and I fitted 10mm runs to the downstairs en-suite and cloak WC plus upstairs master are all 10mm hot and cold runs where the water pressure is 'not excellent', and the flow is more than adequate ( given modern basin taps are restricted / air blended for low flow rates anyhoo ). 

I ran a HRC to the utility and kitchen ( 15mm flow and 10mm return ) for instant premium hot water to both of those outlets. I don't ever do the above series HRC as it just doesn't rid you of every drop of the dead legs, the whole point of installing one in the first place! Also, if you do a manifold / radial setup then you need individual HRC returns back to a third manifold so you can isolate every hot outlet individually ( hot and HRC both need to be shut off to isolate a HRC serviced hot outlet  ). 

Also series HRC means several outlets can be pulling down one run of pipe, so the flow rates will suffer quite a bit too, especially with Buteline as the fittings have a lot of resistance. 

My preferred installation methods see just one fitting at the end of each continuous pipe run so flow rates are very very good indeed, even more so when preserving what flow you have where the cold mains is not as good as you'd have liked.

Any multi-occupant dwelling would deffo benefit from a 200-300L cold mains accumulator too, which are cheap enough these days, which will stave off pressure drops when things like WC's are flushed or an appliance is filling whilst someone is showering. Makes a huge difference.

So are you suggesting that the secondary loop should ideally go to every hot water outlet, rather than just near to it?

I have the UVC in a pump room on the second floor (loft conversion). One bathroom is directly next to that pump room. The other two bathrooms are on the first floor, directly underneath the pump room and the first bathroom i mentioned. The laundry/utility room is then under one of those bathrooms. So all of those outlets are effectively in the same area of the house, all vertically aligned, keeping distances from the UVC to a minimum. The only outlets that are a bit further out are:

• the kitchen sink which is about 5.5m or 7m from the utility room in one direction; and
• the WC sink which is about 6m from the utility room in the other direction.

Nervous that my spec simply states "secondary loop with pump on a timer to provide near instantaneous hot water to all outlets", which I now realise is really vague.

I don't really have space for an accumulator, but am paying Thames Water a fortune to upgrade my connection.

[Nickfromwales]

13 hours ago, Adsibob said:

So are you suggesting that the secondary loop should ideally go to every hot water outlet, rather than just near to it?

All the way to each outlet that you wish to have serviced by the HRC circuit  .

Not to every outlet afaic as I never really bother with baths / showers ( unless the shower is the far side of the building ) or any outlets in the immediate vicinity of the hot water device. Baths and showers typically get opened up immediately to 100% flow rate, so discharge the dead leg quick enough to not waste the heat / energy from running the HRC to such an infrequently used outlet. Bottom line…..just wait, as it’ll be 10 seconds or so max, typically, before premium temp DHW gets to that outlet so not life or death imho. 
 

Typically a basin with a 10mm feed, which runs for no longer than ~10m, will not attract the HRC. Reason being is that most HRC set-ups will have a recently used outlet or an HRC pump on for the daytime / periods of occupancy ( which will ‘pre-heat’ the larger bore pipework and the hot manifold, by design ) so the non-HRC outlets will therefore not have any discernible dead leg to shift, other than the tiny volume of cool / cold water in the 10mm delivery pipe. Works a charm.