I (think I) blew up my HEP2O DHW flow !!

[ShaunCorbs]

No sorry to say no plastic pipe can be used for a return circuit

And you might need the pump

With the pump off and a valve shut on the pump / return circuit

Leave it for a day / over night with no one running hot water

Go to the furthest outlet away from the cylinder and time the time it takes to get hot

If more than 30 seconds it needs one

 

[townfanjon]

aslong as you use the hep inserts its fine / you can use anyfitting town

Nah , not in jonnys world its not lol

 

[Chuck]

Of course this also means a short-duration run of the hot tap may well have the pump running after the tap is closed but as the 22mm loop would/should not be restricted by closing the kitchen tap – WHY DID THE HEP SPLIT? J Maybe it’s nothing to do with my control setup and pressure but the pipe was quite happy until the pump was recently put into service.

I don't like plastic pipe for permanent installations.

A possible explanation for your failure is that if the kitchen tap shuts rapidly (e.g. a 1/4-turn design) a hydraulic shock wave will propagate back up the pipe and the transient rise in presssure leads to failure of the pipe.

The size of this effect depends on the pipe diameter and flow rate before the tap is shut, but according to

Filtration Water Hammer Calculator

a 3/4" pipe supplying water at 1 gal/min will experience a 19psi transient rise in presure due to hydraulic shock when the tap is suddenly stopped. So, this could plausibly have been the straw that broke the camel's back.

 

[ShaunCorbs]

Nah , not in jonnys world its not lol

 

[townfanjon]

Think about this , you mix some plastic fittings and pipe and flood a house , do you think the insurance will pay out ?? “ I rest my case “ lol

 

[ShaunCorbs]

Think about this , you mix some plastic fittings and pipe and flood a house , do you think the insurance will pay out ?? “ I rest my case “ lol

Speedfit and hep will warrenty there fittings / pipe if on used other manufacturer pipe aslong as the same manufacturer inserts are used

Same could be said for compression fittings

 

[townfanjon]

Speedfit and hep will warrenty there fittings / pipe if on used other manufacturer pipe aslong as the same manufacturer inserts are used

Same could be said for compression fittings

So if there is a leak , which manufacturer does you or the insurance company claim off lol . 50 % each maybe , nah . Never mix them . Its the law !!

 

[johnduffell]

Are people saying they think the non matching fitting is at fault? I feel like the issue was a combination of pressure and temperature over time. Remember at high temperatures the rated pressure of plastic pipe drops off rapidly.
In our install I didn't trust plastic pipe completely as our water meter has a check valve, so I installed one of those mini expansion vessels in the feed. This avoids any overpressure due to quick closing of taps and water warming up ambient temperature.

 

[townfanjon]

Are people saying they think the non matching fitting is at fault? I feel like the issue was a combination of pressure and temperature over time. Remember at high temperatures the rated pressure of plastic pipe drops off rapidly.
In our install I didn't trust plastic pipe completely as our water meter has a check valve, so I installed one of those mini expansion vessels in the feed. This avoids any overpressure due to quick closing of taps and water warming up ambient temperature.

No John , I am not blaming the odd fittings I just commented on them . I never mix fittings .

 

[SimonG]

The fault was caused by incorrect materials on a secondary return.