Plastic heating pipe buried in concrete.

[Agile]

This is just an aside for the professionals!

A friend was called last Wednesday to fix a burst plastic pipe buried in concrete. He found it by luck and fixed it.

Next day he was called to the same problem at a different point and fixed that as well. He became suspicious and started asking the owner about the heating system. The owner admitted the rads got VERY hot but he had not bothered to call anyone to see it.

I was called in and discovered the min gas rate was set too high AND there was a PCB fault that prevented the gas valve being released when the boiler was up to temperature on CH. The wrong gas valve setting was a result of a lack of proper servicing and the owner had been aware the boiler had a problem but had ignored it.

His lack of care cost him dearly in repairing two leaking pipes set in concrete.

Tony

 

[Soggy_weetabix]

Tony,

Veering off a bit here, but what are your views on burying plastic pipe if fittings will be screeded over (compression or speedfit).

Had a mail shot from IDEAL about a certain gas valve 'unregulating' itself recently, which made for worrying reading. Would like to know how this is possible. Yes, Im an engineer but I am beginning to think a very good electronic knowledge is a must for boiler engineers in the market we are moving into.

 

[Agile]

The problem above was caused because the plastic pipe softened beyond the bursting point. It is rated at about 130*C at 1.5 Bar typically.

The boiler was perhaps up to 100*C and could have been up to 3 bar. This caused it to fail EVEN though it was to a large extent constrained by the surrounding screed.

I have never considered plastic as safe for sealed heating systems. I even point out the risks to any clients if I find it anywhere.

Your question, what do I think about FITTINGS on buried plastic pipe. I suppose my answer is that if a pipe HAS to be buried then if its not for heating then its better with no fittings buried at all. If its for heating then I would not want to have any buried fittings and would prefer not to have any plastic used at all!

I come from an electronics background and I find that very useful. Just today, I was working on an Isar which had leaked water on the display module. To try to get it working, I soldered the lead directly on to the PCB only to find the PCB had failed due to overheating the transformer.

Fitting a stock "new" PCB I found it was not giving the 325 vdc to the fan. I will try another tomorrow, first on a new fan just in case the boiler fan is faulty too.

Whils dealing with that I was thinking how difficult anyone would find all that boiler without electronics knowledge.

Tony

 

[ChrisR]

Plastic pipes need to be able to move - a lot - when they get hot. I've now lost count of how many leaks I've seen where joints were encased in concrete, due to restrictions on movement. Some copper some plastic. I wouldn't dream of using pushfit anywhere inaccessible; if plastic pipes must be joined say under laminate flooring then a cover is still needed and I suppose I'd tolerate a compression fitting.

Electronics - I wouldn't say you NEED any electronics knowledge beyond what I covered at school. Watts = Volts x Amps, and Volts = Amps x Ohms (resistance) would be about it. If you can recognise which components are resistors or semiconductors (transistors, diodes) that tells you which ones are likely to get hot. It's worth learning the fairly simple skill of soldering electronic components - had to redo a couple of hundred joints today!

 

[Paul Barker]

I agree with Tony, at least when learning about all this the term flame rectification is simple to comprehend if you are dealing with turning ac into dc in other areas of your life. So the whole learning process about boiler behaviour is simplified to you.

I design and build valve amplifiers, my knowledge of solid state is very limited but it all eminates from first wound components secondly valves. A strong uderstanding of these underpins any electronic knowledge. My focus of knowledge is back in the '30's. Electronics hasn't improved since then in terms of sound quality it is worse. The amplifiers of today however are smaller lighter cheaper and more reliable.

In a boiler I just have to remember that solid state voltage references replace VR tubes, resistors are tiny little things and they are held far too close to the board, instead of stood off where they should be so they can cool. rectification is solid state.

Dry joints of course proliferate in boilers. I don't think many manufacturers take into account the flame temperature of the nearby burner when rating the components on the pcb and as for the manufactrurers who don'
t encapsulate them but let them sit right under the pump bead point? 'nuff said.

OOPS, I've been using a hybrid copper plastic installation practice. Should I go back to copper then?

 

[Softus]

This is just an aside for the professionals!

Should this not be in Trade Talk, then?

I have never considered plastic as safe for sealed heating systems.

Really? Have you ever installed a boiler that contains plastic parts?

And could you remind everyone of the official stance of the IPHE? You know the organisation - the one that promotes the use of Hep2o, on its web site.

 

[gas4you]

I always install plastic pipes within the plastic conduit that the manufacturers supply and use continuous lengths under the screed.

 

[Softus]

Me too.

I can't help wondering why would anyone would do it differently.

 

[cowboyplumber]

This post is obviously fraudualent.
Agile cannot possibly hae any friends...

 

[gas4you]

 

[Agile]

This is just an aside for the professionals!

Should this not be in Trade Talk, then?

I dont think this site had a Trade Talk in 2005 when those postings were made.

Unusual for Softus to reply to a two year old posting!

It must be the recession!

Tony

 

[Softus]

I dont think this site had a Trade Talk in 2005 when those postings were made.

Unusual for Softus to reply to a two year old posting!

Fair point. You got me.

It must be the recession!

Kindly leave my hair line out of this.

 

[Kev F]

we have fitted many plastic pipes in screed but if using speedfit, hep etc always try and put it in a trunking in the floor, never had a problem with any under floor heating systems