Hot water return

[billy_smith]

Can Hep2o be used for a secondary return in a domestic property, I had to first fix a rather large property today and all pipe work is Hep with copper on show.

I had a look over the drawings but nothing said about copper for the return circuit, I thought plastic wasn't allowed on the H/W return ?

Grundfos bronze circulator going on 15mm return at cylinder.

 

[Dan Robinson]

Not according to the destructions.

Uponor is apparently going to publish that they can.



So your home owner is stuck with no warranty. No insurance.

 

[billy_smith]

The answer here is a complete re-pipe of the hot water service then or removal of the secondary return.

At what point would a property require a hot return, I thought it was a bit overkill for domestic use myself.

 

[Dan Robinson]

Depends on the length of the pipe runs. Domestic covers a lot.

Remember it is the whole loop. From cylinder to cylinder.

No good going up the house in plastic then back down in copper.

 

[billy_smith]

Longest hot water run is approx 20m from cylinder.

I wonder how many other new builds/renovations are completely plastic installs.

 

[Dan Robinson]

Thousands, and it will probably only be a couple that ever experience the a problem.

Would you want that on your public liability though?

I sure as hell wouldn't especially in some of the 7 figure places I have been working on in the last couple of years.

Fork that. No amount of PTFE is gonna get you out of that ****storm.

 

[Agile]

The purpose of that hot water system is so you get virtually immediate hot water at the tap.

But since plastic CAN be used for hot water feeds, can anybody guess why it should NOT be used for a return?

 

[locosaki1978]

If you can get hot water at the outlet within 1min then I'm sure no return would be required.

 

[Dan Robinson]

Think you should check your terminology Tony.

Plastic can't be used on secondary hot water circulation systems.

Also known as Continuously Operated Re-circulating Systems

It can be used for feeds off the loop. But not the loops itself.

If you have the system already there at least make it non-continuous by building in time and temperature control to give the pipe a rest.

It is the continuous heat of the system AND chemicals in domestic tap water that can make the pipe go brittle.

 

[Biggles..]

The purpose of that hot water system is so you get virtually immediate hot water at the tap.

But since plastic CAN be used for hot water feeds, can anybody guess why it should NOT be used for a return?

that'll be because the manufacturer says so.

Continuous circulation of oxygenated hot water at the upper end of the temp range of the plastic causes failure with the tube.

 

[billy_smith]

So if the pump is on a timer and is off for say 8 hours through the night would this suffice.

The spec is for a pump with timer, I did notice that.

 

[Dan Robinson]

You'd have to ask the manufacturer.

I asked JG a year or two ago and they were very non committal. Although I was regaled with tales of floods, pestilence, death and destruction.

Polypipe said no, but better than nothing.