Secondary Return On Plastic Pipe - Oops?

[Spikey101]

Hi guys, first post on here! Been reading it on and off for years though about people's problems, and now I have one!

I'm a Plumber/Gas Engineer (Domestic and Commercial) and I bought a house (A real fixer upper, only left two walls standing) about a year ago. Well i've finally got round to the first fix stage, and as the builder put down a load of that horrible chipboard flooring and glued it upstairs I decided to put all the services in in Hep2o. I don't use plastic very often at all (The guy who trained me would be in tears if he knew) but know a few guys who swear by it and decided to give it a go as i'd rather drill the joists than gouge great big chunks out of the top.

Anyway, the point. It's not a big house at all but the water is all over the place and the cylinder is right at the front (Large 3 bed semi, with ensuite and downstairs loo and utility) so being a tart I wanted to put in a secondary return. I have to admit I did see in the Hep2o literature that they don't recommend use of their pipe for a hot water return but the way it's worded is as if it's purely because it hasn't been specifically approved for that purpose, not that it's detrimental. Well anyway I finished putting it all in today and then decided after the fact to have a read about why...

There's lots of conflicted opinions as always, some people say it's because if it's always hot the pipe can go oval which isn't a problem as it'll be on a timer to work in the mornings for maybe an hour and the evenings for 3-5 hours so the pipe will have a chance to recover. But there's also people saying it could promote legionaries? Well i've done my course a few years back on legionnaires treatment and safety and although I don't remember all that much I don't remember hearing about that. The return probably comprises about 7-8 lengths of 15mm so it isn't a lot of water volume to sit at a bad temperature either, certainly less than a large 5 bed system in just the hot flow anyway.

I'd appreciate anyone's thoughts because if it really could be a legionnaires risk I need to know as me and the fiance will probably be having kids within a few years and if anything happened I couldn't forgive myself!

Thanks for any help!

 

[muggles]

Plumber using plastic...you should hang your head in shame!

I don't think you're any more likely to get legionella forming in a plastic pipe than you are in a copper one. Keep it above 60 degrees and you'll be fine. The main concern is the continuous heat I think. The installation manual says "Continuously operated re-circulating systems are very different
from conventional hot water supply and central heating
systems found in domestic properties, for which our products
have been tested to, under either BS 7291 2010 Class S
or WRAS approval standards, and for this reason Hep2O
products must NOT be used on any continuously operated
re-circulating systems as they are not approved under the
current version of these standards."

I'd suggest that if you use it on your secondary circulation system it'll invalidate the warranty...not that the warranty amounts to a bag of beans anyway

 

[Dan Robinson]

Continuous high temperature fresh water will wear the pipe.

You'll, at the very least need a timer and thermostat.


Kiss good by to your home insurance if the pipe fails, let alone the warranty

 

[Spikey101]

Eek, i'll never hear the end of using this plastic from anyone it seems!

I'm not fussed about losing the warranty on the pipe and fittings, i'd probably not bother claiming anyway, although if you have a serious leak and you installed it correctly do they cover the damages to property also?

Hmm, good point about the home insurance though. I guess that would depend how sh**hot the insurance guy is and what my small print says.

I'm installing a complete Vailant system with their VRC470 controller which has a secondary pump module (At an extra charge of course!) to bring the pump on and off on another timezone. Would you also put a stat in line with that? The pipe will stay just as hot regardless surely?

Also the oxygen in the fresh water shouldn't make a difference to plastic? How do you think it would wear it? It's no different to heating surely? And i'd be running it no more often, probably a lot less.

 

[muggles]

Eek, i'll never hear the end of using this plastic from anyone it seems!

I'm not fussed about losing the warranty on the pipe and fittings, i'd probably not bother claiming anyway, although if you have a serious leak and you installed it correctly do they cover the damages to property also?

No, they don't, hence my comment about the warranty not amounting to a bag of beans. If a fitting blows off, or an o-ring fails, they'll just give you a new one. It's quite unlikely they'd even bother to argue the point. You'll still have thousands of pounds worth of damage to pay for out of your own pocket, but at least you'll have a shiny new fitting to put on once the mess is all cleaned up.

Better hope you don't have mice as well - they LOVE to chew plastic pipes, especially the elbows

 

[Spikey101]

Heh, like you say then it's not worth anything anyway. I can understand why they don't pay out for damages to property but at the same time who is going to quibble over the cost of an elbow when you came home to see the 50" plasma swimming down the drive??

If I hear any mice rustling i'll just hole saw a bunch of 6" holes in the floor everywhere and let the cat at em!

We have had a spate lately of Rats eating through plastic in a school science room, it's ridiculous, we're on the third leak now and this time we've said it'll have to be changed to copper if it happens again as the pest people's poison doesn't seem to be working either... It likes speedfit! The house will be well sealed though so i'm not worried about vermin. It was more the issue of dying due to nasty diseases!