Insulated dual pipe "shrinking"

sas

Hello,

I have an oil boiler in my garage. It is connected to the house by one of those preinsulated district heating type pipes.

I'm not naming a specific product for the moment. It has a blue plastic outershell, inner insulation is white foam and the pipes are a sort of yellow plastic. It is rated to 95 degrees. We've the boiler set very low (temp stat reads 40 degrees when system at full tile) and it isn't used very often. We've a low energy build and our need for heat is minimal. The system was installed in July and only came into use Oct last year.

I've been monitoring the pressure gauge on the tank and noted that it was dropping and there was air to be released from the top of the tank. I don't have an automatic filling loop because I need to find leaks when they are there. The tank would be destroyed I'm told if there was a constant flow of fresh water into the sytem. My system is a combined buffer\dhw tank. The water in the tank only leaves the tank to flow to the oil boiler. All hot water is extracted from the tank by heat exchanger.

My plumber visited this morning to investigate and noted that the copper pipes leaving the top of the boiler are being pulled down approx 2.5 inches below the level that they set it at.

The insulated pipe appears to be shrinking and pulling on the fittings. This is approx. a 10 metre run.

The natural assumption at this point would be that traffic over the area of the pipe is driving it into the ground. The pipe is still exposed outside (the outer shell of it is) and there is slack on it. If the pipe was being pushed further into the ground, the slack would be used up first.

Also, my carpenter has exactly the same product in his house. The flow on this run has been shrinking for 2 + years. They keep adding in additional pipe above ground in the hope that the shrinkage stops. At this stage they believe the flow has shrunk by more than 2 feet. I am not aware of the length of the overall run. This system is used more regularly than mine and at hotter temps which could explain the more dramatic shrinkage.

I am awaiting a return call from my supplier. My carpenter is already dealing with them however and he got what I would suggest is nonsense about the need to physically fix the pipes themselves ( i.e. the yellow plastic pipe that carries the water in the insulated pipe) to a rigid point using special brackets. I've reviewed the documentation on the manufacturers website and found no mention of shrinkage. I also reviewed all the accessories recommended for the system and there is no such bracket for fixing the pipe itself.

If anyone has encountered similar, I'd really appreciate any thoughts and feedback.

Thanks,

SAS

Dtp79

I've seen it too on that same pipe. Get back onto your supplier. Pipes shouldn't shrink

oikster

I've heard of underfloor pipes pulling out of manifolds:eek::eek::eek:

corkgsxr

thats mad. something messed up there.

what brand is it. even pm me.

im bet its not qual

Dtp79

corkgsxr wrote: »

thats mad. something messed up there.

what brand is it. even pm me.

im bet its not qual

It's not qual no. If I'm thinkin same as OP it's outer shell is blue and pipe is yellow and insulation is white

corkgsxr

Dtp79 wrote: »

It's not qual no. If I'm thinkin same as OP it's outer shell is blue and pipe is yellow and insulation is white

the insulation in a few diff pieces?

Dtp79

corkgsxr wrote: »

the insulation in a few diff pieces?

Ye I think it's in layers

pache

Dtp79 wrote: »

Ye I think it's in layers

If it were a shrinkage problem what would the best course of action be??.

corkgsxr

pache wrote: »

If it were a shrinkage problem what would the best course of action be??.

Whip it out.

Or what about pulling out the pipe and replacing with qualplex and use there insulation and ducting

pache

corkgsxr wrote: »

Whip it out.

Or what about pulling out the pipe and replacing with qualplex and use there insulation and ducting

whip it out....

jeeezzzzeeussss !!!!

sas

Thank you all for your responses.

It would appear I've hit a common problem. We all appear to be talking about the same product. As suggested, it isn't a qualpex product.

I spoke with the Irish agents on friday. What I was told is that they've never had any problems with the pipes "once the ends are fixed to a fixed point" e.g. bracketed to the wall. While this may be true, the pipe didn't come with any instructions at all. The builders providers weren't aware of the issue. I wouldn't have purchased it if I was aware of a shrink issue.

I've requested details in writing of the expected shrinkage of the pipe. If it's expected to stop shrinking now then what's happened can be dealt with.

I would share the opinion that a pipe designed to carry hot water shouldn't shrink when it encounters hot water. I'm expecting furter correspondence tomorrow.

I'm not sure how to proceed. The other job I referred to is 2 years older than mine i.e. it appears to be a fundamental failure of this product, it's unlikely to be a single bad batch 2 years apart. I can't fix 1 end of the pipe because it terminates approx 2 foot short of the house perimeter in the ground i.e. I've nothing to fix it too. There is a reason for this which is logical but not relevant for here I believe.

This is now holding up footpaths and other additional ground works so I'd prefer not to adopt a wait and see approach as regards the shrinkage.

I'll let you know how I get on. I'll pm those that asked.

Dtp79

sas wrote: »

Thank you all for your responses.

It would appear I've hit a common problem. We all appear to be talking about the same product.

I spoke with the Irish agents on friday. What I was told is that they've never had any problems with the pipes "once the ends are fixed to a fixed point" e.g. bracketed to the wall. While this may be true, the pipe didn't come with any instructions at all. The builders providers weren't aware of the issue. I wouldn't have purchased it if I was aware of a shrink issue.

I've requested details in writing of the expected shrinkage of the pipe. If it's expected to stop shrinking now then what's happened can be dealt with.

I would share the opinion that a pipe designed to carry hot water shouldn't shrink when it encounters hot water. I'm expecting furter correspondence tomorrow.

I'm not sure how to proceed. The other job I referred to is 2 years older than mine i.e. it appears to be a fundamental failure of this product, it's unlikely to be a single bad batch 2 years apart. I can't fix 1 end of the pipe because it terminates approx 2 foot short of the house perimeter in the ground i.e. I've nothing to fix it too. There is a reason for this which is logical but not relevant for here I believe.

This is now holding up footpaths and other additional ground works so I'd prefer not to adopt a wait and see approach as regards the shrinkage.

I'll let you know how I get on. I'll pm those that asked.

That pipe is slightly larger than 1" qual. Could you pull it out and at the same time from the opposite end push qual through?

sas

Dtp79 wrote: »

That pipe is slightly larger than 1" qual. Could you pull it out and at the same time from the opposite end push qual through?

If I hit issues wth the supplier I'll try anything. I'd imagine that it wouldn't be terribly easy to attempt your suggestion, we're talking 15 metres. The insulation is packed tight enough. If it did work it would be an easy out.

Wearb

sas wrote: »

If I hit issues wth the supplier I'll try anything. I'd imagine that it wouldn't be terribly easy to attempt your suggestion, we're talking 15 metres. The insulation is packed tight enough. If it did work it would be an easy out.

Perhaps to pull it through, you could insert and glue something like a piece of brush handle inside both pipes and that might make it easier, because it wouldn't be increasing the overall diameter and giving it nothing to snag on. Perhaps use some inert lubricant too.

Dtp79

Wearb wrote: »

Perhaps to pull it through, you could insert and glue something like a piece of brush handle inside both pipes and that might make it easier, because it wouldn't be increasing the overall diameter and giving it nothing to snag on. Perhaps use some inert lubricant too.

good idea but drive in some short screws for security

Outkast_IRE

Isnt this thread jumping ahead of itself. With the whole replacing the pipe situation,

Ok pulling out the old pipe is going to be tough bloody work, your talking about 15 meters of 360 degree frictional resistance and lets say you do get it out and replace with 1 inch qual, as we all know one inch qual although easy to bend temporarily tends to spring back and i would forsee fierce trouble with regards to stopping into digging into the insulation on the way back through.

The first thing that jumps into my head is i wonder is it possible to purchase two 1 inch braided flexible hoses and put them in with some slack. Taking photographic evidence of the slack etc.

If the pipe has shrunk it has probably shrunk as much as its going to, i think putting in two 1 inch braided hoses with slack it a good simple soloution which allows you to keep an eye on the expansion/contraction.

sas

Are you suggesting that I install the braided flexible hoses between the copper of my burner and the insulated pipe sticking out of the ground?

If so it makes sense here. My problem is that the other end is under 3 foot of gravel and I can't leave it exposed for monitoring because it's already been the entrance for vermin.

Outkast_IRE wrote: »

Isnt this thread jumping ahead of itself. With the whole replacing the pipe situation,

Ok pulling out the old pipe is going to be tough bloody work, your talking about 15 meters of 360 degree frictional resistance and lets say you do get it out and replace with 1 inch qual, as we all know one inch qual although easy to bend temporarily tends to spring back and i would forsee fierce trouble with regards to stopping into digging into the insulation on the way back through.

The first thing that jumps into my head is i wonder is it possible to purchase two 1 inch braided flexible hoses and put them in with some slack. Taking photographic evidence of the slack etc.

If the pipe has shrunk it has probably shrunk as much as its going to, i think putting in two 1 inch braided hoses with slack it a good simple soloution which allows you to keep an eye on the expansion/contraction.

Outkast_IRE

sas wrote: »

Are you suggesting that I install the braided flexible hoses between the copper of my burner and the insulated pipe sticking out of the ground?

If so it makes sense here. My problem is that the other end is under 3 foot of gravel and I can't leave it exposed for monitoring because it's already been the entrance for vermin.

Yes that it what im suggesting and then monitoring it.

Then stick the braided hose on the pipework above ground, you are only using it really to give you some flexibility with regards to monitoring expansion/contraction, as i said i would install it slighltly slack, at this stage you would hope any shrinkage has occured, i dont see why it would happen again.

As for the other end being under gravel dont worry about it for now, if there was a leak it would show up as a pressure drop already so just concentrate on the side by the burner for now

sas

Update:

The response I've gotten is that under ISO 2505:2005 (which covers thermoplastic piping) shrinkage of up to 3% is acceptable at 80 degrees.

If we fix the ends of the pipe in place it won't happen we're told.
3% for us is 450mm. So far on the end we can see we've lost approx 50mm.

I'm going to talk to suppliers of alternatives and see if they too have acceptable shrinkage numbers i.e. are they all the same.

I'm bemused at this point.

corkgsxr

never heard the likes of that.

ill only be using qual from now on

gctest50

Stainless ? might be $$$ though

http://www.pipesystems.com/site/index.cfm?id_art=24956&vsprache=EN

http://www.origen.ie/products.php?id=5&id2=164

Needs username and password:

http://polytherm.ie/Our_Products/Insulated_Piping_Systems/index.asp?id=2&pid=8