Re-pipe or modify? also ?underground storage tanks

[vermonter]

I am nearing the end of my 1st year with an Eko 40. I followed bad advise from my installer and did not insulate the pex pipe (which is in a water tight conduit 157 ft from my house in and insulated room/woodshed). It was his belief that with as big a circulator as we were using the heat loss would be minimal. He was wrong. The rest of the install was excellent and he feels terrible. He usually installs Tarms and usually indoors. I am running my system with non- toxic glycol and consider my self a novice in terms of this stuff but want to do it right. I am getting about 15 degree drop in temp when I compare the gauges on the wood furnace to the one on my oil furnace that the pipe enters before being dispersed to the house. The question is whether to dig it up and build a simple blueboard or similar box filled with spray foam along the outside of the conduit or dig it up and re do the whole thing with the Thermopex product (I would need 400 feet I think as it only comes in 300 and 100 ft rolls and I will be about 20-30 feet short with just a 300 ft roll) Thermopex sounds like a great product though expensive however cheaping out probably got me in this mess to begin with right? Any help is appreciated. Thanks to No-Fossil for the viewing at his house. I did buy the Eko after all! The other question I had was whether anyone has thought of burying a storage tank with an exposed cap and super insulating it during install (obviously for those of us doing outdoor storage) I am going to add storage this fall and have plans for adding on to my insulated furnace room but wondered if this was possible.
Peace
Loving it in Vermont,
Eko 40
Husqvarna 350

 

[WoodNotOil]

If your wood heated water passes through your fossil boiler before going to zones, you may have a different issue. I don't doubt that you are losing heat between the boilers with uninsulated lines. However, if your zone return water mixes with the the wood heated water before going into the fossil boiler, that would also cause a difference in boiler temp. That is how my Tarm was piped following one of Tarms own piping schemes. Double check with your installer that this is not the/an issue with your current setup. It could be causing or at least contributing to the problem. Best to rule it out. I am correcting this piping problem on my own system this summer.

 

[vermonter]

I checked the piping and it seems like it does not mix as you were worried about
The conduit is a 4" interior which holds the 2 1" pex
I have access on both ends and have stuffed insulation in at each end
the pex is pretty tight inside. I wondered if foam could be shot in from the ends but I can't believe it would get by the pex?

 

[in hot water]

to move 136,000 BTU of a 40% PG fluid at 170F average temperature, that distance you really need 1-1/2" pex.
It calculates to

14.5 GPM, 4.6 feet of head per 100' of tube and 3.7 FPS. Design around a 4 FPS velocity for troublefree service.

1-1/4" copper would do it.

I have tried a couple underground, insulated concrete tanks for solar storage. I would go underground only as a last resort. A large delta T to deal with and the potential of water around the tank is a concern.


hr

 

[Nofossil]

The other probelm you have is that with the two pex lines touching each other, you have a long buried counterflow heat exchanger. I'll bet that the return water picks up heat on its way from the house back to the boiler. It's probably impossible to overinsulate - any loss will happen every hour that the boiler is running, year after year. Another problem is that some foam insulation materials get waterlogged over a long period of time. I think blueboard does OK, but I'm not sure that all spray-in foams are waterproof over the long haul.

I'd echo the concerns about burying a storage tank - really hard to insulate well and keep the insulation dry.

 

[vermonter]

I value your input no fossil especially since I met you in person
Am I to infer from your post that you would favor the Thermopex solution?
Do you also have an opinion on the recent post that recommended I switch out to 1 1/2 inch?
Thanks

 

[Nofossil]

I value your input no fossil especially since I met you in person
Am I to infer from your post that you would favor the Thermopex solution?
Do you also have an opinion on the recent post that recommended I switch out to 1 1/2 inch?
Thanks

I have to be careful here - I have no experience at all with Thermopex, so all I can do is repeat what I heard someone else say. With that disclaimer, I've heard positive comments.

The post about 1 1/2" is dead on. That's really expensive in Thermopex, though. Being the cheapskate that I am, I'd think long and hard about whether I could come up with a less expensive solution. Then I'd probably do it, be unhappy with the results, and do Thermopex anyway. YMMV.

 

[leaddog]

An other way is to make a blue foam vee lay in two 1in supply and two 1in returns seperating the supply and returns with some blue foam spacers. You could then use closed cell foam spray and foam it. Or as I did use closed cell foam in a pourable mix. The pourable mix is what they make surfboards out of. It is alittle less exspensive as you don't have to pay a hasmet charge. About $500 for 50cu ft. It's a two part mix and you would need to do it in two pours. You pour it in and in about two minutes it starts to foam and rise. Then you would go back and do the second pour on top.
The easiest way would be to lay your pipe and have a foam contractor come and foam it with closed cell foam. Make sure it is closed cell as it won't absorb water where open cell will.

with that much You should be able to find a contractor to do it for about the same money.
leaddog

 

[hoth2oguy]

Between the need to increase pipe diameter AND add insulation, it would seem that the best solution is to replace your existing piping with pre-insulated 1 1/2" pex (although off the top of my head I would have thought 1 1/4" would do it). Also the most expensive option I am sure.....

 

[jebatty]

1" copper is rated at 8 gpm x 2 = 16 gpm. 1-1/4" copper is rate at 14 gpm and 1-1/2 copper is rated at 22 gpm. 14 gpm at delta-T=20 is 140,000 btuh; 22 gpm at delta-T=20 is 220,000 btuh. Plastic is rated a little lower.

 

[DaveBP]

Vermonter,

Your dilemma makes me wince thinking about all the times I've burned myself with the combination of ignorant advice and my own skinflint tendencies.

Any hope you have of making things better is going to involve a backhoe.

There's no way to insulate your pipes in place. They are laying on the bottom of your duct so most of the insulation is not going to be around the pipes and as Nofossil implies, having the pipes adjacent to each other is very wasteful even if they are well insulated from the surrounding earth.

Big pipes cost a lot of money. Big circulators pumping against high head can cost even more over years of service. "in hot water" gave some example numbers. And be careful about comparing pipe sizes between PEX and metal pipes. Metal pipe is named by inside diameter. PEX IDs vary. I've heard of PEX called 1 1/2" that measured 1 1/4" on the inside. Huge difference when designing a system and trying to save long term money.

It's always the teeter-totter of saving money now or saving more money over the long term. How much money can you afford to save?

Good luck.

 

[vermonter]

seems the general advice here is to bite the bullet and tear it out, put in new insulated pipes (either prefab or homespun). The cost of the Thermopex (157ft to the wood shed) makes my head spin. The system works as it is I just know it can work better. My next investment was going to be water storage but now should it be re-pipe before water? Water storage was going to give me duration of heat in the warmer months for domestic hot water but heat loss also is very wasteful.
Confused and regretful in Vermont.

 

[in hot water]

seems the general advice here is to bite the bullet and tear it out, put in new insulated pipes (either prefab or homespun). The cost of the Thermopex (157ft to the wood shed) makes my head spin. The system works as it is I just know it can work better. My next investment was going to be water storage but now should it be re-pipe before water? Water storage was going to give me duration of heat in the warmer months for domestic hot water but heat loss also is very wasteful.
Confused and regretful in Vermont.

Or you could move the stove Then the cost of underground piping for?? feet goes down proportiantly. That extra 57 feet is throwing a wrench in the works for off the shelf pipe sizes, and pressure drop.

hr

 

[vermonter]

I am not sure if anyone is still on this post but what about this for an idea:
I could leave the existing 4 inch conduit with the 2 uninsulated 1" pex in place and they could become the new return
Then I could buy a slightly less expensive 1" insulated dual pex and use it strictly as a supply
This should match things up but I don't know if 2" as an effective supply/return is too big or if it is a case of the bigger the better
I also wonder if anyone knows of other suppliers of long section 100+ insulated pex that can compete with Thermopex?
I tried to get a quote from "Insulpipe" but they told me they were not competitive.
Thanks
Vermonter

 

[Floydian]

(broken link removed to http://www.pexflex.net/html/techinfo_index.htm)

http://www.rovanco.com/flexible_pipe.html

You might contact these folks and find out your closest dealers.

Using your existing lines as 2 returns is still going to equal huge heat loss.
From everything I have read on this site, it sounds like its time to bite the bullet and do things right.

Good luck,
Noah

 

[Floydian]

I'll add that the closed cell polyurethane sprayfoam option seems to be a good one. If you search this site a bit you can find some good info. Also, garn.com's forum has some discussion on this subject.

Noah

 

[easternbob]

I used the dual pexflex and I was happy with the quality and it's easy to install. Not the cheapest thing out there but the place I bought it from sold it by the foot and therefore I did not have to worry about left-over.

 

[gorbull]

Vermonter,

Here are some options.

http://www.flexsulseal.com/
(broken link removed)
http://www.insulseal.com/photos.html
(broken link removed)
(broken link removed to http://www.urecon.com/english/english.html)
(broken link removed to http://www.uponor.ca/Header/Service/For-Professionals/Products/Pre-insulated-pipe.aspx)

Variations of the same thing. Sorry I have not done my homework with the prices so I don't know if substantial savings are possible.