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speed fit on secondary return

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It's got nowt to do with whether it will fail or not. The pipe hasn't been tested for use on secondary hot water circulation systems because it isn't a common enough application to warrant the expense. It is therefore not approved for use for this application.
 
Mike Jackson said:
It's got nowt to do with whether it will fail or not. The pipe hasn't been tested for use on secondary hot water circulation systems because it isn't a common enough application to warrant the expense. It is therefore not approved for use for this application.
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Decided to bite the bullet,ripped out all the plastic,repiped in copper,would have been ok in plastic,still got short stabs connecting the sanitary,but none on the ring main,felt an air of superiority,until I felt the pain of buying copper at todays prices.
 
The hotter the pipe gets the less pressure it could take so If you were really unlucky and your pressure reducing valve failed and your thermostat failed I think you could very easily blow the pipe like you see has happened on some heating systems.
 
markfxy said:
its not continuously operated with a timer and a stat you would never run a secondary return 24/7 it'll run at a lower temperature than central heating and probably for the same length of time in the winter
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Why not?
 
The whole point of having a HWSR is so hot water is instant with no deadleg and waiting, also negates legionella.
 
Howsie said:
Really depends on the customers requirements. If they have a 24/7 requirement and the pipes are lagged properly then I can't see the problem.
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We are talking about a domestic setting
Not commercial or industrial
There won't be a 24/7 requirement so it would be inefficient to have running all the time
 
Perhaps but perhaps not.

The point being that as an installer you have to cater for the potential use and its not unreasonable to assume that a HH may want instant hot water on some occasions 24/7.
 
Howsie said:
Perhaps but perhaps not.

The point being that as an installer you have to cater for the potential use and its not unreasonable to assume that a HH may want instant hot water on some occasions 24/7.
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You do it your way and ill do it my way
Simple
The way fuel is going the least amount that can be used the better and more cost effective
 
Right I will just tell you why not to use plastic on secondary returns.....

This came from a big chief at Hep20 owned by Wavin......we kept going to water leaks in a nursing home when the pipe had failed, so lads on call just banged a meter with a couple of sockets job done, but sadly, it kept happening, I got called out and noticed it was only the secondary return, every other pipe installed in the same place and the same time, same materials etc was ok......

i made a call, and it basically comes down to the pipes composition, it is not continually rated for heat 24/7 like Mike pointed out, why? Because of the memory effect it needs to cool down, he quoted for every hour on, it should be off an hour, obviously not intermittently, but if on 12 hours it should be off 12 hours in total......as the plastic heats it changes state, and only relaxes and goes back to the state when cool, if it does not get back to its original state, it becomes more brittle and will fail eventually.....just like bending a shatter proof ruler, it won't break straight away, bit it will turn white, where the stress is, then fail at that point, if it is subjected to more stress over time.

As some have pointed out, in domestic applications where the pump is timed it should not be a problem, unless its left on constant......be warned insurance companies are getting wise to water damaged claims, we had the one in a new build, loss adjuster with the aid of his plumber, pointed out it was not fit for purpose, they refused to pay out!
 
Vern has it spot on. If you use pushfit on a secondary return, and get a problem, the manufacturer immediately has a get-out from their warranty. Your insurance company will also refuse to pay out, because, as the manufacturer has expressly forbidden its use, you have used materials that are not fit for purpose.

No amount of arguing about timers and stats and duty cycles will change the fact that the manufacturer clearly states not to use their product in this way. Whatever the underlying reason for that statement, its existence means that you would be 100% liable for any claim.
 
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I should make a point too said new build was a 6 bed, oak doors, floors etc, very nice only around 3 year old, they guy left everything on constant and used the room stats etc, hot water and secondary return was on 24/7! Hence the failure, luckily we did not do the install, we got involved with the WB 40 CDi which was under gassed and no ABV.....Anyhow it failed when they were at a party, it brought down ceilings, poured everywhere, remember this is mains pressure hot water fed via a 300 l Megaflo, it just kept leaking out!

This job is still going on legally, but the twist the owner supplied ALL the materials, the installer just used what he was given, but I feel this is no excuse, after all maybe it is not as well known about using plastic on seconday returns but using plastic on gas because the owner supplied the materials would be no defence either!

Regards the nursing home, it was always the 15 mm secondary return that failed, not the draw offs, which is essentially the same pipe run, only thing I put it down to was when we ripped it all out, all the runs were 22 mm with just 15 mm stabbings for sentinel points in copper, I assume the 22 mm was slightly tougher or different wall thickness?
 
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