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windycol

I am converting a stone barn with 4 washrooms to fit and a remote boiler ( 3 Ph electric due to an abundance of solar power) I intended to fit a hot water loop system, however on aquiring the required PB barrier pipe (polyplumb) i find that the application notes for this product say under no circumstances should this be used for this type of installation.:thumbs_down: So not being one to take this lying down I started digging a hole! first i spoke to polypipe to ask why? they said it was due to the oxygen content of the hot water being constantly circulated would over time strip away the barrier layer??? This sounded a little off so decided to speak to WRAS and ask if this also applied to Pex? they couldn't comment however in the course of the conversation it became apparent that WRAS approval for polypipe was originally for cold water use and that the approval for hot water had been achieved by a work around using Bs 7291 part 1 2 or 3. The WRAS approval expired in august and to date, no application has been made for re-approval, for either cold water use or for hot water use which would require a lengthy testing.
Apart from this though, My question/concern is that my understanding is that Pex is also approved under BS7291 part 1,2 or 3 and also would not be suitable under this for use in hot water loop circuits yet many suppliers of Pex and PB are saying Pex is o/k
WHAT IS GOING ON HERE?
 
Rural barn? Plastic pipes and mice dont mix.

Secondary returns not to be done in plastic. Manufacturers say no, so do at your own risk.
 
yet many suppliers of Pex and PB are saying Pex is o/k
WHAT IS GOING ON HERE?

Manufacturers test to their own standards and industry standards.
Their own may exceed Industry.

If a manufacturer says it's OK for recirculating, then it must be.
Who have you found that say it can be used.?

Speedfit
Polypipe
Marley
Uponor
Pipelife
Wavin

All the above are part of the Plastic Pipes Group, say not suitable.
 
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No pex or PB will allow circulated hot water. Only Uponor q&e is suitable.
As above though, mice love pex and PB. Why not use copper?
 
From here;
https://www.google.co.uk/url?sa=t&r...NpZTMKDEQ&sig2=x_uWnYCnHv4egl90x36DDQ&cad=rja

Uponor MLC & Secondary circulation.

Secondary circulation is classified as a system that:

 Provides potable hot water
 Maintains a temperature in excess of 65°C
 Replenishes water used in outlet with fresh water (oxygenated water) .
 Is a pumped circulation system.

If all four of the points are covered your system is classified as a secondary circulation system (or recirculation system). Plastic pipeworks manufactured under BS-7291-1/3 2010 cannot be used in secondary circulation applications. Uponor MLC pipe can be used in secondary circulation because it is manufactured under a different standard (BS EN ISO 21003-1 2008) also because of the aluminum layer within the pipework it has a higher tolerance than a standard PEX pipe system. Although there still should be appropriate water temperature control on the system to ensure the water temperature does not exceed 70°C as stated in our guidelines.
 
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Why is it that some of these pipe brands can be used for heating systems, circulating at the same or higher temperatures and not be a problem.

As for Uponor pipe stating that the temperatures should not exceed 70 C, well that's barely above the temperature requirements for prevention of Legionella.

Not sure what your regs state, but ours state, the circulation temperature should be a minimum of 65 C.

I wouldn't use a product that gives the supplier a 'get out of gaol card' over a 5 C clause.
 
Why is it that some of these pipe brands can be used for heating systems, circulating at the same or higher temperatures and not be a problem.

As for Uponor pipe stating that the temperatures should not exceed 70 C, well that's barely above the temperature requirements for prevention of Legionella.

Heating systems cycle On /Off so the pipe isn't constantly at high temperatures, even in the UK

Uponor;

Heating systems and fan coil installations where the water temperature does not continuously exceed 80oC, or momentarily exceed 95oC (no more than 100 hours a year), and maximum operating pressure of 10 bar. Also, the system must be installed with room and water temperature controls in accordance with the current Building Regulations Parts L1 (Energy – Dwellings) and L2 (Energy – Non Dwellings) for England and Wales, or an equivalent national standard for Scotland or Republic of Ireland.
 Hot water services installations where the water temperature
does not continuously exceed 70oC, or momentarily exceed 95oC (no more than 100 hours a year), and maximum operating pressure of 10 bar.
 
Heating systems cycle On /Off so the pipe isn't constantly at high temperatures, even in the UK

Plus CH primary water will eventually de-aerate. It's oxygenated water that creates problems for plastic pipe...
 
Having seen what small mice can do to plastic pipe I wouldn`t risk it.
 
Cos copper doesnt come in 50metre coils at 28mm diameter that's why!
 
O God get a plumber in unless it's a swimming centre or a small hospital you won't need a src that big
 
I've been led to believe that plastic is ok for a return loop provided the system isn't running continuously , ie it's on a timer so it's only running at intermittent times.
 
I've been led to believe that plastic is ok for a return loop provided the system isn't running continuously , ie it's on a timer so it's only running at intermittent times.

No no only copper, q and e or mlcp
 
Abandoned secondary return, now going with straight delivery. Mice shouldn't pose a problem as the pipes will be in a dedicated insulated structure buried in the ground /concrete floors of the main building. I have never experience mice damage on any of the electrics/pipework i have dealt with over the last 30 years. I would think there would be less likelyhood in the countryside than an urban environment as field mice tend to be smaller than the normal domestic variety and don't struggle to find natural foods etc. With older town properties having timber joist floors I could imagine this might be an issue. Rats might be more of an issue in urban areas as it has been found that you are never more than 5 metre from one!

This barn conversion is a total rebuild internally with solid floors and modern fully insulated structures above with attention being given to voids and cavities. so not envisaging a problem!
 
Depending on run / run off times of hot water you may need one
 
Thing is you've asked for help and gone with what you want anyway even when we're telling you from Our experience it's not a good idea, but you obviously know better
 
Sorry don't understand the point you are trying to make here, as because you have all advised that loop was not a good idea, i have reverted to a straight feed of the hot water to the bathrooms and not looping it back though for the life of me i cannot see that the effect on the pipework will be any greater in a direct feed than it would be in a controlled loop!
 
I was really making reference to the insistence on using plastic when you would be susceptible to wildlife. I have seen it loads of times in rural areas
 
Sorry don't understand the point you are trying to make here, as because you have all advised that loop was not a good idea, i have reverted to a straight feed of the hot water to the bathrooms and not looping it back though for the life of me i cannot see that the effect on the pipework will be any greater in a direct feed than it would be in a controlled loop!

The reason we said no is the size doesn't need to be the same size as your main hot circuit

And s lot once that length has cooled down you need to draw all the cold water off before you can get hot with a src this is minimal
 
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