PEX question

[northmaine]

I am hooking up my OWB and instead of running the isulated pipe all the way could i run pex through my unheated harage wrapped with isulation? Would the cost savings be worth it? If I run the themopex all the way it would be about 110' if I go through the garage It would be 50' of thermopex and 75' of pex.

 

[Chris S]

You could use any type of pipe in your garage. My reccomendation would be to use fiberglass pipe insulation, not the foam type.
The fiberglass has an actual R value.
A little more costly but " you get what you pay for"

 

[northmaine]

What type of PEX should I use? I looked online and there is a few differnt types and I have no Idea what to use. I think this option would be alot cheaper. The thermopex is $13 a foot from the dealer and I get 25' for free. thanks for you help

 

[Huskurdu]

I am hooking up my OWB and instead of running the isulated pipe all the way could i run pex through my unheated harage wrapped with isulation? Would the cost savings be worth it? If I run the themopex all the way it would be about 110' if I go through the garage It would be 50' of thermopex and 75' of pex.

I am not versed on the OWB installations, but past experience has taught me to be careful that you maintain enough flow for your application. Your pex size needs to be sufficient for your heat load/output. I ran 1" pex for my application and it's a bit small. Also, when you create joints in your run it will create more head also. I know that on OWB installations they push the 1" stuff but upsize if you can afford it. Pay-me-now or Pay-me-later kind of scenario. Hope this helps.

 

[Tony H]

I would probably go with the run thru the garage that way you can insulate much better you can use any of the pex with air barrier and could consider pex-al with the aluminum shield in it as it's much more rigid and wouldn't need as much support but it also is harder to bend .

 

[Gooserider]

Before going with Thermopex, I'd do some real careful figuring of head loads and pumping resistance - IIRC Thermopex doesn't come bigger than 1" - and we see LOTS of people that report problems with not getting enough flow, or having pump cavitation issues due to needing a high head (and energy wasting) pump to get the needed flow. Going to larger sizes, or several parallel runs can give you a system that will work much better and consume less electricity while operating... Crunch your numbers before spending money... Another option that I've seen some people use is to do plain O2 barrier pex and spray it with foam - there are arguments that it can cost less than Thermopex, and / or do a better job of insulating.

Gooserider

 

[northmaine]

any more tips on this? best way to insulate etc.... i ordered a 300' roll so i will have enough to run in the house....

 

[Gooserider]

any more tips on this? best way to insulate etc.... i ordered a 300' roll so i will have enough to run in the house....

It might be worth doing a search on the subject, but from what I've seen, several folks have had very good results with laying the pipe out in the trench, then hiring one of the spray foam outfits to come out and put 3-4" of closed cell foam around the tubes. I think I've seen a cost of $7-8 / foot for the foam, plus the cost of the tube itself, so it isn't a LOT cheaper than Thermopex, if at all, but it allows the use of larger tube sizes. Before putting any tubing in the ground, I would really be careful to do a full heat load calculation, and look at how many BTU/hr you need to deliver to the loads, and what sort of water volume (gpm) you will need to move to do that, then choose a pipe and pump combo that will supply the needed volume at a flow velocity of 2-4 feet per second...

Be conservative on your numbers - it is difficult / expensive to add more capacity to your piping if it turns out to be smaller than you should have chosen, while there is no harm in being over-size, and possibly a benefit in terms of being able to use a smaller lower power demand pump to circulate your water.

I can't emphasize this enough - it is probably the number one problem we get with people doing remote boiler setups (after the issues everyone has, like green wood and such) An undersized pipe can cause all sorts of problems including inadequate design day heating, and frequent pump failures.

Gooserider

 

[flyingcow]

Before going with Thermopex, I'd do some real careful figuring of head loads and pumping resistance - IIRC Thermopex doesn't come bigger than 1" - and we see LOTS of people that report problems with not getting enough flow, or having pump cavitation issues due to needing a high head (and energy wasting) pump to get the needed flow. Going to larger sizes, or several parallel runs can give you a system that will work much better and consume less electricity while operating... Crunch your numbers before spending money... Another option that I've seen some people use is to do plain O2 barrier pex and spray it with foam - there are arguments that it can cost less than Thermopex, and / or do a better job of insulating.

Gooserider

I don't know what IIRC means, but I bought inch and a quarter thermopex. It's a true ID also. Chances are i bought from the same dealer "northernmaine" is getting his price from.

 

[yknotcarpentry]

Don't know to much about the pex, but I was doing some work last winter at a house where we finished a bonus room above a garage. There was a bar in the room so it needed plumbing and the only way there was throught the garage. THe plumber used normal pex and when insulation the ceiling of the garage we did a skim and pack technique (3" of foam under the floor sheathing then fiber). Anyway I told the spray foam guy about the pipes and asked if he could spray them well. He said that a greater r value would be achieved by "building a card board box around the pipes creating an air gap and then spraying that. He also added that if anything where to happen to the pipes they wouldn't be wasted due to being covered directly with foam. (ie you could rip open the box and the tube will be there as is , where if they had foam all over them they would be junk) I know my local ace hardware, Ricci lumber in portsmouth NH sells a self spray foam kit, it says it covers 100 linear feet, doesnt say how thick etc kinda vague but its about $300..... thats all I have

 

[rowerwet]

I would wrap each pipe in foam spray or snap on type and then find a way to wrap both insulated pipes inside another layer, foil bubble wrap, felt, closed cell foam (foam camping mattress wrapped and secured with tywraps?) and then possibly a plywood box over the whole thing to protect and support.

 

[Gooserider]

Don't know to much about the pex, but I was doing some work last winter at a house where we finished a bonus room above a garage. There was a bar in the room so it needed plumbing and the only way there was throught the garage. THe plumber used normal pex and when insulation the ceiling of the garage we did a skim and pack technique (3" of foam under the floor sheathing then fiber). Anyway I told the spray foam guy about the pipes and asked if he could spray them well. He said that a greater r value would be achieved by "building a card board box around the pipes creating an air gap and then spraying that. He also added that if anything where to happen to the pipes they wouldn't be wasted due to being covered directly with foam. (ie you could rip open the box and the tube will be there as is , where if they had foam all over them they would be junk) I know my local ace hardware, Ricci lumber in portsmouth NH sells a self spray foam kit, it says it covers 100 linear feet, doesnt say how thick etc kinda vague but its about $300..... thats all I have

I don't think you would gain any R-value from building a box around the pipe, but one advantage of doing it that way is that if one ever DID need to service the pipes (which isn't very likely, but...) if they are in a box then it should be possible to pull them out and replace them if needed. If the pipes get foamed in, then the only way to ever get to them would be to rip out all the foam along the entire pipe run...

Gooserider

 

[MNBobcat]

I ran 1 1/4 thermopex along the back wall of the garage and into my house. No matter what you run you will have to insulate it. So I figured I'd run insulated thermopex and save messing around trying to insulate bare pex.

Besides that, I got a deal on buying a 300 foot roll. Since I had about 50 feet left over from my outside and garage runs, I decided I'll use it inside, too. I'm going to try and run the thermopex all the way to my furnace.

 

[flyingcow]

I've got about 60ft from the outside of the house foundation to the garage foundation, all under ground. Then from there I got about 15ft above grade, exposed on the back wall of garage in to boiler room. The 15ft section i did in the Thermopex also. For me it was a simple( a little pricey) way to complete the run. Works well. The exposed piece is in an unheated section of garage, in the coldest times of the winter I put my hand on the thermopex and no noticeable heat loss. I'm happy.
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If I was to insulate bare/exposed pex I'd lean towards the foam that snaps right on to it. Than wrap it with a foil/vinyl backed fiberglass(like a waterheater wrap) Gives you a little vapor barrier on the outside. Spray foam would work well too. If it's a solid run you won't need to be taking it apart. Not to step on toes, but bubble wrap or any kind of an air barrier is not productive. Waste of money if you think you're gaining btu's. Might be asking for heat loos or freezing problems.

 

[ken999]

Another vote for spray foam of you are going to run PEX through the garage.