Using Insulated Pipe Supports for PEX Pipe

[WorldPeace]

I notice that people strap their PEX pipe to floor joists first and then install pipe insulation. I'm thinking about doing it in reverse order. I wanted to install the pipe insulation and then fix the insulated PEX pipe. Not only would it maintain the seal of the insulation but overall installation would be easier.

1. Is there a reason why people usually clamp the pipe first before installing pipe insulation?

Is it because you would have to use bigger and more expensive clamps?

2. Can anyone recommend an insulated-pipe support/hanger?

I'm assuming that for a 1/2'' PEX line, I would need a pipe restraint with an inner diameter that's 1-1/2''. (1/2'' for the pipe plus two 1/2'' walls of insulation.) So, I guess I would need something like this. Is there something better that anyone can suggest?

 

[JohnCT]

Amateur's take on this.. I would think you would get a more complete insulation if you insulate first, but if this pipe will be exposed to sub freezing conditions, then there's no insulation you can install that will prevent a freeze if the water doesn't move for some time.

It's probably easier to strap the pipe first since the clamps are available (make sure to leave some slack for dimensional changes). I don't know how much insulation is lost to the joists if the insulation is cut to fit.

John

 

[Sponsor]

 

[Helper Dave]

We use 1 1/4" 2-hole straps on 1/2" with the foam tube insulation; 1 1/2" straps for 3/4" insulated.

 

[Tuttles Revenge]

We use 1 1/4" 2-hole straps on 1/2" with the foam tube insulation; 1 1/2" straps for 3/4" insulated.

Its a much better system and method which takes 3x as long to install. Most plumbers are probably needing to hustle on spec homes or certain lower budget remodel projects and spending extra time making 5% more efficient insulation just isn't worth the effort.

 

[Jeff H Young]

Its not clear to me that it saves time strapping pipe tight to joists and then fighting putting insulation on. I guess sending a flunky back to insulate might save some labor cost .
A journeyman piping it wanting to get water turned on quicker or just lazy . much better to slip long pieces of insulation on and use a bigger strap over the outside .

 

[John Gayewski]

Fittings fittings fittings. If your installing a straight run with no penetrations insulating first would be easier.

Even cheaper have an insulator insulate the pipe.

 

[Jeff H Young]

Fittings fittings fittings. If your installing a straight run with no penetrations insulating first would be easier.

Even cheaper have an insulator insulate the pipe.

never had a insulator come out on houses . and on a good job they leave insulation for us to slip over pipe. and it would be concidered shoddy to strapp without space for insulation.

 

[WorldPeace]

This is really helpful! This allows me to order the correct sized pipe hangers!

1/2'' inch pipe + insulation => 1 1/4'' pipe hangers

3/4'' inch pipe + insulation => 1 1/2'' pipe hangers

Thanks!

We use 1 1/4" 2-hole straps on 1/2" with the foam tube insulation; 1 1/2" straps for 3/4" insulated.

 

[WorldPeace]

I'm guessing that it would take longer overall if you insulate after you install the straps. You just install the insulation and then install larger hangers. But, if you insulate afterward, you would have to constantly cut around each hanger.

I am assuming it wouldn't be a huge difference in time though. But, it would definitely look better like below:

Is there a reason why it would take 3x longer if you insulate before you install straps or hangers?

Its a much better system and method which takes 3x as long to install. Most plumbers are probably needing to hustle on spec homes or certain lower budget remodel projects and spending extra time making 5% more efficient insulation just isn't worth the effort.

 

[wwhitney]

PEX and copper pipe are CTS (copper tube size), OD = nominal + 1/8".

Schedule 40 ODs:

1/2" = 0.84"
3/4" = 1.05"
1" = 1.315"
1-1/4" = 1.66"
1-1/2" = 1.9".

So, for 1/2" CTS pipe, with 1/2" thick insulation, the OD is 1-5/8", which mean uses a pipe strap for 1-1/4" Schedule 40 or 1-1/2" CTS.

For 3/4" CTS pipe with 1/2" thick insulation the OD is 1-7/8", which means use a pipe strap of 1-1/2" Schedule 40.

But if the insulation is different thickness you would need different straps. And the straps may tend to compress the insulation; if you can get a thin square of sheet metal to roll into a half pipe, or rigid piece that is already formed into a half pipe, using it between the insulation and the strap will reduce compression.

Cheers, Wayne

 

[Tuttles Revenge]

Is there a reason why it would take 3x longer if you insulate before you install straps or hangers?

Installing 2 hole straps vs installing a single nail plastic isolator. There are multiple parts to installing 2 hole straps and a power tool if you're using screws like most people would. A "snail" already has its nail ready to go and uses just a hammer to install. Just saying in fast construction jobs such as spec homes time is money.

The projects I bid have time built into the proposal for all sorts of extras... like putting insulation on nice and neat. But that costs.

 

[John Gayewski]

I think you should try to do a lot of piping with insulation on it and find out for yourself. The only viable way of doing this is like ac guys who buy rolls of copper with insulation on it. It ends up torn even when they try hard not to, and it's only one long piece, and there are no fittings. They have to come back and fix where the fittings go, and it also looks like dog #$&@ a lot of the time. There are exceptions. I think the picture you posted was not pre insulated pipes.

 

[Jeff H Young]

it totally depends on what im doing if im running on the bottom of a bunch of floor joists 16 inch on center I wouildnt want to strap tight to joists. If Im hanging 3/4 or 1 inch copper with 1 inch isulation Id run (off the top of my head) I guess 3 inch hangars and allow for iy on the ends to put insulation later. If Im on my back under a house and im insulating ill get the insulation , and try to get the important areas while im running the copper. everyone has got thier ways and it just depends on a few factors but good to have insulation on hand to get certain areas as you go i think

 

[Reach4]

Nobody mentioned pre-insulated pex, such as this 1/2 inch.
https://www.supplyhouse.com/Wirsbo-Uponor-F6040500-1-2-Pre-Insulated-AquaPEX-Tubing-100-ft-coil

I expect it costs more than threading insulated tubing over the pex, but maybe the time saving could make it worthwhile for some.

 

[WorldPeace]

I agree it would save time but as you said, it's more expensive. At about 3 times the cost of regular Pex-A plus the insulation, I don't know if it's worth it. Although I do wonder why they don't sell pre-insulated pipe as the standard.

Nobody mentioned pre-insulated pex, such as this 1/2 inch.
https://www.supplyhouse.com/Wirsbo-Uponor-F6040500-1-2-Pre-Insulated-AquaPEX-Tubing-100-ft-coil

I expect it costs more than threading insulated tubing over the pex, but maybe the time saving could make it worthwhile for some.

 

[John Gayewski]

I agree it would save time but as you said, it's more expensive. At about 3 times the cost of regular Pex-A plus the insulation, I don't know if it's worth it. Although I do wonder why they don't sell pre-insulated pipe as the standard.

Pex is sold more for radiant tubing. When compared to domestic water uses, the radiant market is way bigger. You don't want insulation on that. Plus they are in a competing market. If it was better they would do it.

 

[Reach4]

Pex is sold more for radiant tubing. When compared to domestic water uses, the radiant market is way bigger.

The radiant tubing would be oxygen barrier type.

 

[John Gayewski]

The radiant tubing would be oxygen barrier type.

In the last few years that's been something that has grown. There are people who don't subscribe to it being a thing. Or if they do they say the boiler water water should be treated and must monitored anyway. But yes hepex is becoming the standard.

 

[WorldPeace]

I don't know why but 1-1/4'' pipe strap fits 1/2'' CTS pipe insulation. I confirmed this today. This is consistent with Helper Dave's post.

PEX and copper pipe are CTS (copper tube size), OD = nominal + 1/8".

Schedule 40 ODs:

1/2" = 0.84"
3/4" = 1.05"
1" = 1.315"
1-1/4" = 1.66"
1-1/2" = 1.9".

So, for 1/2" CTS pipe, with 1/2" thick insulation, the OD is 1-5/8", which mean uses a pipe strap for 1-1/4" Schedule 40 or 1-1/2" CTS.

For 3/4" CTS pipe with 1/2" thick insulation the OD is 1-7/8", which means use a pipe strap of 1-1/2" Schedule 40.

But if the insulation is different thickness you would need different straps. And the straps may tend to compress the insulation; if you can get a thin square of sheet metal to roll into a half pipe, or rigid piece that is already formed into a half pipe, using it between the insulation and the strap will reduce compression.

Cheers, Wayne

 

[wwhitney]

I don't know why but 1-1/4'' pipe strap fits 1/2'' CTS pipe insulation. I confirmed this today. This is consistent with Helper Dave's post.

My info was an elaboration on Helper Dave's post to allow you to calculate the strap sizes for different thicknesses of insulation; his info is based on 1/2" thick insulation, I believe. But apparently you used 1/2" thick insulation:

1/2" CTS = 5/8" OD, and 5/8" + 1/2" + 1/2" = 1.625", very close to the 1.66" OD for 1-1/4" Schedule 40.

Cheers, Wayne