Insulating Pex

fourustircom · Feb 18, 2008

Hi, Folks!

Instead of buying Microflex or other pre insulated Pex, has anyone tried insulating the Pex and placing in corrigated drain pipe themselves? What kind of insulation did you use?

The stuff I think my dealer wants to sell me looks like PVC wrapped with foam. It appears that both the Pex lines are run through the PVC which means the 2 lines are touching. I understand that is a bad thing. Or is this not the plan.

Thanks!

HUSKYMAN · Feb 18, 2008

The two lines touching is not a problem. You have to be careful with the PVC stuff because it does not bend so you have to use and purchase elbows for every turn which makes installation a much bigger PIA and makes pushing the pex lines through more difficult

I prefer the pex line already insulated and inside a 4 or 5 inch tile. It comes in big rolls and installs much faster. It also costs about half as much and works very well.

Husky137 · Feb 18, 2008

In my thermpopex, the 2 lines are insulated from each other, no touching.

iCreek · Feb 18, 2008

PEX insulation

fourustircom said:
Hi, Folks!

Instead of buying Microflex or other pre insulated Pex, has anyone tried insulating the Pex and placing in corrigated drain pipe themselves? What kind of insulation did you use?

Thanks!

I have seen the pre-insulated PEX, looks nice but was way out of my budget. We used 4" schedule 40 pipe buried below frost line to the stove, $1.40 a foot, and insulated the PEX inside that pipe with some 5/8" pipe insulation I got at Lowes, $2.00 per 6' section. I think it would depend on your location and climate, we are in the midwest and our frost line here is shallow 30" - 32".

Here is a past post on my project.

http://www.arboristsite.com/showthread.php?p=826913#post826913

Here is a look at my inside run to my utility room, on an inside wall, using the insulation, the blue line is cold water going out to stove for filling.

I am sure we have some heat loss, more than if I spent $ 11-17 a foot for the better insulated pipe, but when the snow and ice was on the ground I could not see the pipe path to the stove. I bought my PEX for .45 a foot at Lowes also, so my install was kind of 'do it yourself'.

Here is a pic after about 5 minutes running, I still need to insulate all the way to the exchanger. I have gotten 170 before, just got to IR the right spot.

The below pic is what I am getting out of my heat registers, I guess this is alright, seems to heat our house pretty quick.

HUSKYMAN · Feb 18, 2008

I didnt bother insulating all the way to the exchanger, as long as the pipe is in the house the heat is not being wasted.

Also there is no net heat loss by not insulating each pipe in the PVC. So what if the temp at the heat exchanger is a few degrees less, the water will be hotter when it gets back to the boiler so the heat is not wasted. Seems like extra work with no benefit to me.

iCreek · Feb 18, 2008

HUSKYMAN said:
I didnt bother insulating all the way to the exchanger, as long as the pipe is in the house the heat is not being wasted.

Also there is no net heat loss by not insulating each pipe in the PVC. So what if the temp at the heat exchanger is a few degrees less, the water will be hotter when it gets back to the boiler so the heat is not wasted. Seems like extra work with no benefit to me.

Hmmm, OK, maybe I don't need to insulate all the way to the utility room

I was thinking out loud I should, but my basement is heated and I don't appear to have a problem heating the house the way it is.... I could save a few bucks, thanks for the tip, learning here everyday

Does anyone else here have some temps at exchanger and at registers?

Geez · Feb 18, 2008

I installed my OWB last fall but never insulated the pex for the 35 feet (each way) from the foundation where it comes in to the heat exchanger. My crawl space and cellar are not heated except for residual heat from the house and off the furnace, so I figured the heat would not go to waste.
Anyway, a couple weeks ago I finally got around to insulating the lines and my inline thermometers jumped 6 degrees at the exchanger. I don't really notice any drop in air temp in the cellar either.
Under the circumstances, I wish I had done it earlier. Who knows how much less wood I would have used.:bang:

iCreek · Feb 18, 2008

Geez said:
Anyway, a couple weeks ago I finally got around to insulating the lines and my inline thermometers jumped 6 degrees at the exchanger. I don't really notice any drop in air temp in the cellar either.

What was that temp reading, at your exchanger? Just curious.

fourustircom · Feb 18, 2008

Insulation?

So, Geez, what did you use/do to insulate and surround your PEX? I read somewhere that one should add sawdust(?)over the pipe before filling in the trench.

Lot's of great info!

Thanks!

fourustircom · Feb 18, 2008

Thermal expansion

Maybe this is why PEX should be loose fitting in the conduit of choice...

PEX will install a bit differently than normal PVC or copper tubing. Allowances must be made for ever 10 degrees of change in temperature. PEX will contract one inch every 100 feet of pipe with every 10° of temperature change. Offset this by making a loop in the PEX that is no more than 8 times the diameter of the tubing.

This was from a DIY site. Maybe that foam filled, corragated, Pex pipe is not such a "hot" idea!

MS-310 · Feb 18, 2008

The key to a good underground pex line is....To keep it dry. I mean that it has to be in a sealed tile, wraps dont work (tear easy). Microflex is alsome stuff used it for 3 or 4 years now and love it, it can really flex comepared to logstar and other types....Remember closed cell foam and keeping the water away from the pex lines....Also sawdust holds water. We sell it and other types also.

crowbuster · Feb 18, 2008

I thought the same as you icreek, leaving the heat in the basement, had to insulate after all, it was way to hot in kitchen and loading room. Utility room was also way to hot. Much better after I put the foam pipe wrap around the lines and exchanger, has to save on wood as well.:greenchainsaw:

abohac · Feb 18, 2008

Pex

I agree MS310. Before I put mine in I asked tons of questions and the best advice I got was keep it dry. I thought the cost for that premanufactured stuff was way to high but then again it is the most important aspect of your stove. You simply have to have this part right or things just won't work right. I don't know who told you that the lines shouldn't touch but I have 4 1" lines in the PVC you are talking about (they are jammed in there and it was a real #####). I went with some stuff made in Canada that was over a $1 per foot. It was foam over PVC wrapped in a rubber sleeve. I glued it then the manufacturer gave me what resembled rubber bandaids for each seam. I dug my trench on grade with fall to the house so that the water could get out of the pipe if I ever srpung a leak. If I were you I wouldn't skimp on this portion of you installation.

ericjeeper · Feb 18, 2008

I will give my feelings.

I am trying to heat the house. Not the boiler. So I insulated each line individually. I slid armorflex over the pipe.(is a lot like trying to put socks on a rooster)
paired the two insulated lines up then took the foil faced bubble wrap insulation used the 16 inch wide roll then paired the two lines together in this. Then I wrapped it all in shrink wrap.. Lots of roundie rounds.Then I shoved it into a 5 inch non perforated corrugated tile..My run is only 40 feet or so and I had to be above the slab on the house end and just below grade on my storage tank end. So no need to bury it below frost.It is no deeper than one foot. Where my lineset entered my storage tank I Peeled back shrinkwrap and insulation and filled the pipe with that expanding spray foam. (you know the stuff that sticks to everything within a mile of where you squirted it) As I do not want steam to go into the lineset from the storage tank. The other end enters the sidewall of my garage well above grade.. The ground freezes tight over my lineset so I figure I have done my job in preventing heat loss to the earth.

Geez · Feb 18, 2008

iCreek said:
What was that temp reading, at your exchanger? Just curious.

After insulating, I'm running at 162°

Geez · Feb 18, 2008

fourustircom said:
So, Geez, what did you use/do to insulate and surround your PEX? I read somewhere that one should add sawdust(?)over the pipe before filling in the trench.

Lot's of great info!

Thanks!

In the crawl space and cellar I used the foam pipe insulation you find in most hardware stores. The buried lines are the pex wrapped with closed cell foam in drainage pipe. They are buried about 4' deep and I covered them with 3" of foam sheathing insulation about 18" wide before burying, with strips alongside the pipe as well.
I didn't use the high tech piping but it's working well. At leat there is no sign of snow melt or winter grass growing over them. :laugh:

fourustircom · Feb 19, 2008

Insulating

I had not planned on scrimping/cutting corners on that part, but if I can get the same result and save a buck, I could but that to better use elsewhere. Cool ideas!

I've heard the thing about tubing not touching from several places, here and elswhere. I'm not sure of the reasoning, folks preheat the water coming into a waterheater. It seems like the same kind of thing.

I think having the underground and inside tubing well insulated and having the furnace in the wood shed out of the wind should help reduce heat loss and hopefully the amount of wood I'll be burning.

Thanks!

tanker · Feb 19, 2008

I spent the money and used the good stuff(logstor) 2-1'' lines in polyurethane then a foil wrap then what looks like about a 5'' waterline. Temp of 195 at boiler 160' from house,temp of 195 at basement. I guess I don't understand the extra waterline out to the boiler that I see most people put in,on my waterheater sidearm,2 water spigots,1 on the cold fill on the water heater,1 on thehot in from the boiler. A washing machine hose( hose with 2 female ends is all you need to fill the boiler. This is my 3rd year with my boiler(35% no-burst boiler antifreeze mix) and I have not had to add any water, the level is the same now as when I first fired it up and the nitrite level is still good and haven't had to add any extra chemicals

Geez · Feb 20, 2008

tanker said:
. I guess I don't understand the extra waterline out to the boiler that I see most people put in,on my waterheater sidearm,2 water spigots,1 on the cold fill on the water heater,1 on thehot in from the boiler. A washing machine hose( hose with 2 female ends is all you need to fill the boiler.

This is the method I use as well. The downside you must be aware of though, is the potential for boiler water and chemicals possibly backflowing under certain conditions into your water source (well) and contaminating it. At the least you should have a check valve or backflow preventer.

tanker · Feb 20, 2008

Geez said:
This is the method I use as well. The downside you must be aware of though, is the potential for boiler water and chemicals possibly backflowing under certain conditions into your water source (well) and contaminating it. At the least you should have a check valve or backflow preventer.

actualy have 1 in the line that feeds the original boiler in the basement along with a ball valve(has been shut off since o.b. went on line) When using hose to fill o.b., with hose,just make sure what valve you turn off and on first.

Insulating Pex

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