Hep2o in DHW recirculating system

[Bonner]

Plumber point this out to me, said he will need to run hot water in copper. Doesn’t make sense to me, anyone know why?

[Radian]

As you can see, the stated reason appears to be because Hep2O hasn't been tested for that use. Litigation protection I guess. Seems stupid.

[dpmiller]

they may be talking about commercial ringmains, that often run at far higher temperatures.

[Bonner]

3 hours ago, Radian said:

As you can see, the stated reason appears to be because Hep2O hasn't been tested for that use. Litigation protection I guess. Seems stupid.

Further research indicates something to do with the standard not covering this application. No practical reason it can’t be used but I am not going against manufacturers recommendations (they are the same)

[JohnMo]

May be worth reading the specification.  Look at the intermittent and long term max temperatures.  Our circulation pump lets us set times and temperature of the hot water circulation, we only have it on for an hour or so morning and evening at around 40 degrees.  So would see any issue with any pipe material suitable for domestic plumbing.

[joth]

My plumber said the same (about my DIY JG speedfit secondary return pipework) explaining it's because it can't survive being at a permanent 24/7 high temperature, the plastic breaks down much faster. Take it or leave it but that was his explanation

 

Doesn't worry me much as my secondary return (if I ever get around to commissioning it) will be time and motion controlled so the pipework generally spend most the time at/near room temperature. Just the same as a heating pipe run, which it is rated for. 

[cherryfountain]

 I have used Pegler Tectite MLCP for all my H+C. pipework no joints under the screed .

[PeterW]

We’ve discussed this before and I quoted what Wavin told me back then. You also need to remember that your central heating will be running at a higher temperature for longer, a circulation system will be fine. 

 

1 hour ago, joth said:

being at a permanent 24/7 high temperature, the plastic breaks down much faster. Take it or leave it but that was his explanation

he’s guessing ..! PEX and the likes are guaranteed for a minimum 50 years, mostly it’s lifetime. 

[PeterW]

@Bonner here you go. 
 

 

I quoted Wavins own technical note. You basically run the UVC blended temp (~45°C) and you don’t have a problem. As @dpmiller says, this is about commercial ring systems that use local TMVs and circulate hot at 70-75°C

 

 

[Nickfromwales]

I’m doing all my client installs with Hep2O and hot returns. Zero issues when installed robustly and deployed correctly. I did one install where just the HRC was in copper, but not done one in copper since…..just no need to in a domestic setting tbh.

Continuous operation doesn’t occur as they’re typically timed or ‘pulsed’ on/off with suitable means of control ( eg a system designed specifically which provides the required mitigation ).

[joth]

4 hours ago, PeterW said:

he’s guessing ..! PEX and the likes are guaranteed for a minimum 50 years, mostly it’s lifetime. 

Yeah I think more likely passing on other people's guessed explanation than coming up with his own, but certainly JG Speedfit is not guaranteed for use in secondary return applications, like hep2o, it's excluded by the MIs.

Our plumber was an absolute stickler for keeping within MIs.

 

https://www.johnguest.com/sites/jg/files/2022-01/RWC11339_JG-Speedfit-Technical-Specs-Guide_v11.pdf

 

"Speedfit products must not be used on any continuously operated re-circulating systems as they are not approved

under the current version of these standards."

 

[Bonner]

12 hours ago, cherryfountain said:

 I have used Pegler Tectite MLCP for all my H+C. pipework no joints under the screed .

Looks interesting. What do the manufacturers instructions say about recirculating systems?

[Bonner]

12 hours ago, PeterW said:

@Bonner here you go. 
 

 

I quoted Wavins own technical note. You basically run the UVC blended temp (~45°C) and you don’t have a problem. As @dpmiller says, this is about commercial ring systems that use local TMVs and circulate hot at 70-75°C

 

 

Thanks @PeterW just what I was looking for! It didn’t come up in my search for ‘recirculating’ DHW 🙄

[PeterW]

8 hours ago, joth said:

Our plumber was an absolute stickler for keeping within MIs.

 

https://www.johnguest.com/sites/jg/files/2022-01/RWC11339_JG-Speedfit-Technical-Specs-Guide_v11.pdf

 

"Speedfit products must not be used on any continuously operated re-circulating systems as they are not approved

under the current version of these standards."

But again this is down to BS7291 Class S and the use of the 3 factors as quoted previously - keep the temperature lower than 60°C and ideally use occupancy / time based circulation and you don’t have an issue regardless. 

[joth]

1 hour ago, PeterW said:

But again this is down to BS7291 Class S and the use of the 3 factors as quoted previously - keep the temperature lower than 60°C and ideally use occupancy / time based circulation and you don’t have an issue regardless. 

 

Absolutely, that's what I said in my first post in the thread:

 

15 hours ago, joth said:

Doesn't worry me much as my secondary return (if I ever get around to commissioning it) will be time and motion controlled so the pipework generally spend most the time at/near room temperature. Just the same as a heating pipe run, which it is rated for.