Any one use Microflex insulated pex

[hedge wood]

The dealer I am getting the Garn threw is recommending the Microflex pipe. I have not priced it yet. I like the idea of the spray foam pex in trench but there is two problems with it. The last time I had some spray foam insulation done which by the way we like it took a act of Congress to get a contractor out here to do it. The other problem may be or not is the water table is high around here and we might get water in the trench when we dig down under the normal frost level around here.

 

[heaterman]

The dealer I am getting the Garn threw is recommending the Microflex pipe. I have not priced it yet. I like the idea of the spray foam pex in trench but there is two problems with it. The last time I had some spray foam insulation done which by the way we like it took a act of Congress to get a contractor out here to do it. The other problem may be or not is the water table is high around here and we might get water in the trench when we dig down under the normal frost level around here.

We use the sprayed method about exclusively and have had excellent results with it. The company I use up here has been doing this type of application for over 15 years and has a track record of nearly zero failures. They say that as long as the trench is dry during the application the water table really doesn't make any difference and I have seen several jobs that prove their point. The product they use is impervious to water within about 10 minutes of application. What I'm saying is that it wouldn't be a deterrent to me. I like the sprayed foam because you get a full dimension of foam all the way around the tube whereas on any "packaged" product you will see an inch or less on the sides.

The part about requiring an act of congress to get them out I really can't speak to. Your local conditions and circumstances will prevail.

 

[hedge wood]

Heaterman
That is what I am worried about if we can keep the trench dry at all some times when we dig 4 or 5 feet deep on this farm we get water in the trench as we dig. that was the only reason I was looking a premake pipe at all. I am asumeing you always try to bury the lines under the froze line when you do these installs.

 

[heaterman]

Heaterman
That is what I am worried about if we can keep the trench dry at all some times when we dig 4 or 5 feet deep on this farm we get water in the trench as we dig. that was the only reason I was looking a premake pipe at all. I am asumeing you always try to bury the lines under the froze line when you do these installs.

Typically we don't get them below frost. Some of our installs run directly beneath plowed driveways that I know push the frost level down to 6-7' in this neck of the woods. Many are on farms with very heavy (as in tons) traffic on them all winter. The reasons for getting below frost as far as heat loss is concerned are pretty marginal when you can encase the tubing in 4" of foam all the way around it. Staying above the water table would far far outweigh that consideration in my book. When dealing with a remotely located open system type boiler, as is often the case, I like to place the HX by the wood burner enabling the underground line to be filled with antifreeze and also be pressurized along with the house system which helps a lot for air elimination. You also avoid any issues that can be encountered when dealing with elevation changes between the wood boiler and the house because the static pressure of the sealed system will take care of raising the water where it needs to be. In nearly every case you will be able to use a smaller circ to move the same water along with avoiding cavitation issues in a long unpressurized length of tube. Few of our trenches are more than 30-36" deep.
You want to make sure that the insulating contractor uses closed cell urethane based foam of at least 1 pound density, a pound and a half or even two is better for crush resistance but the heavier foams do lose a bit of R-value.

 

[Piker]

This year we are going to begin using the microflex exclusively in our outdoor installations. There are just too many horror stories about people losing massive amounts of Btu's into the ground all winter because they wanted to save a few dollars on underground pipe. Heaterman has spoken many times about some installers trying to get 150k Btu's through 1" pex... and it's these same guys who are shoving a supply and a return wrapped in bubble wrap inside a 4" schedule 20 drain pipe which fills with water. I have even seen people use their own bubble wrap that's not meant to take the heat of direct contact with a hot water line, and all the bubbles pop. There's not really any part of an installation that's worth skimping out on, but if there's one thing that I would say is paramount, it's getting a good line in the ground.

At any rate, this will be my first season using the microflex, so I don't really have any useful input on the product i suppose, but it looks to be about the best stuff around... and the easiest to work with as it is actually much more flexible than some of the alternatives. I think it's a nice system, even at the premium price.

cheers

 

[hedge wood]

Heaterman
Thanks for the input. I have lots more questions. Its good to know we only need to go 30 to 36 inches deep. Now I need to find out what size pex I need to run. I have 200 ft to go from where the garn will be to my house. At this point we heat the main floor which is 1472 sq feet with a 70,000 btu furnace second floor that is 1152 sq feet with a 46,000 btu furnace and we have a third floor which is 1152 also with no heat. We also have a full basement 1152 sq feet that we currently don't heat. Currently we keep the first floor at 70 degrees and the second floor at 55 degrees and burn about 1500 gallons of propane a year which also includes the hot water for two people. I want to make sure we size the pex so we will have plenty of heat and extra so I can install heat in the basement and third floor if needed later. I plan on putting heat exchangers in the furnaces and maybe some type radiant heat on the first floor. To run the antifreeze from the heatexchanger by the garn to the house what will I need for a expansion tank or resevoir and where would you place the pump.

 

[Jim K in PA]

Hedge - I, too, have heard horror stories of cheap underground pipe installs. My neighbor is living with one where when it rains a lot he has steaming hot water running out of the schedule 20 pipe that he shoved bubble wrapped pex through.

However, my personal experience is the same as Steve's (Heaterman). I used closed cell sprayed polyurethane foam and my pipes are 30" down (I live in NE PA). I have zero (0) heat loss underground. Pics are on my web site (link in sig).

I have no doubt the ecoflex will certainly do the job, and I harbor no criticisms toward it . . . other than the price. At nearly 5 times the cost per linear foot for the ecoflex, I think properly applied spray foam is a worthy consideration if price is a concern.

If you have spray-foam contractor access issues, then the ecoflex may make more sense for your installation.

 

[heaterman]

Heaterman
Thanks for the input. I have lots more questions. Its good to know we only need to go 30 to 36 inches deep. Now I need to find out what size pex I need to run. I have 200 ft to go from where the garn will be to my house. At this point we heat the main floor which is 1472 sq feet with a 70,000 btu furnace second floor that is 1152 sq feet with a 46,000 btu furnace and we have a third floor which is 1152 also with no heat. We also have a full basement 1152 sq feet that we currently don't heat. Currently we keep the first floor at 70 degrees and the second floor at 55 degrees and burn about 1500 gallons of propane a year which also includes the hot water for two people. I want to make sure we size the pex so we will have plenty of heat and extra so I can install heat in the basement and third floor if needed later. I plan on putting heat exchangers in the furnaces and maybe some type radiant heat on the first floor. To run the antifreeze from the heatexchanger by the garn to the house what will I need for a expansion tank or resevoir and where would you place the pump.

I'm going to say that you'll need 12-15gpm to meet your load at design temps (-2* @ Beatrice) based on sq footage of 4,928 and a WAG heat loss of 30btu/sq ft.

You really should do a heat loss calc to determine what your load actually is. Don't take my estimates on the heat loss to the bank but you will wind up with 1.5" tube for a 400 foot run and those flow rates. Especially if you consider additional demand for DHW.

If you are using a hx and pressurizing side B you can put the main loop circ anywhere. I would install the air scoop and expansion tank directly "upstream" of the circ where ever you place it. It will get ride of air in the system like a dream. Use isolation flanges with purge valves from Webstone and your initial fill will go very smooth.

 

[Piker]

Heaterman,

I just wanted to thank you for the time you spent with me today in regards to spray foaming underground lines. I have heard of people doing this before, but never really put much thought into doing it myself for any of my customers. Having never seen a professional do that around here before, I was apprehensive. After talking to you, I now feel pretty confident in the process. I have a local spray foam contractor that I am working with to get my thermal storage tanks insulated, I am sure they would be happy to do a couple lines for me this year.

thanks again.

cheers

 

[heaterman]

Heaterman,

I just wanted to thank you for the time you spent with me today in regards to spray foaming underground lines. I have heard of people doing this before, but never really put much thought into doing it myself for any of my customers. Having never seen a professional do that around here before, I was apprehensive. After talking to you, I now feel pretty confident in the process. I have a local spray foam contractor that I am working with to get my thermal storage tanks insulated, I am sure they would be happy to do a couple lines for me this year.

thanks again.

cheers

Not a problem my good man. Any time you need a brain to pick, mine is available. (Picking is kind of slim in some topics though)
I think Mark has my cell # if you don't catch me in the office.

Regarding the water table issue. We did one last fall that water literally ran into the trench at a depth of about 12". Since it was a low spot next to a drive we simply laid the tube on top of the ground and covered it with about 12-18" of dirt. Couldn't see a trace of it this winter.

All the best in your new endeavor.

 

[hedge wood]

Heaterman
I appreciate your input.Iwill do a manual J I just wanted to know what size pipe I needed to be priceing. Just wanted to make sure I have a large enough pipe so if we decide to heat the whole house we can. Is there a certain type of pex I need also how large of plate type heat exchager should I be looking at and where is the best place to buy one at.

Heaterman
Thanks for the input. I have lots more questions. Its good to know we only need to go 30 to 36 inches deep. Now I need to find out what size pex I need to run. I have 200 ft to go from where the garn will be to my house. At this point we heat the main floor which is 1472 sq feet with a 70,000 btu furnace second floor that is 1152 sq feet with a 46,000 btu furnace and we have a third floor which is 1152 also with no heat. We also have a full basement 1152 sq feet that we currently don't heat. Currently we keep the first floor at 70 degrees and the second floor at 55 degrees and burn about 1500 gallons of propane a year which also includes the hot water for two people. I want to make sure we size the pex so we will have plenty of heat and extra so I can install heat in the basement and third floor if needed later. I plan on putting heat exchangers in the furnaces and maybe some type radiant heat on the first floor. To run the antifreeze from the heatexchanger by the garn to the house what will I need for a expansion tank or resevoir and where would you place the pump.

I'm going to say that you'll need 12-15gpm to meet your load at design temps (-2* @ Beatrice) based on sq footage of 4,928 and a WAG heat loss of 30btu/sq ft.

You really should do a heat loss calc to determine what your load actually is. Don't take my estimates on the heat loss to the bank but you will wind up with 1.5" tube for a 400 foot run and those flow rates. Especially if you consider additional demand for DHW.

If you are using a hx and pressurizing side B you can put the main loop circ anywhere. I would install the air scoop and expansion tank directly "upstream" of the circ where ever you place it. It will get ride of air in the system like a dream. Use isolation flanges with purge valves from Webstone and your initial fill will go very smooth.