CVPV or Black Pipe

[Mushroom Man]

I have officially given up on HVAC installation contractors. My experience thus far is that either the pricing is out of this world, ($13,000. quotation for part of the job) or the service is bad. I waited 2 months for a return visit after one contractor spent one day stringing the wrong pex. We exchanged phone calls at least every few days and there were frequent made and missed appointments. until I finally reached the end of my patience. At least he did not charge me because he knew how bad he screwed me over.

So I'm now my own installation guy. Yes, in the depth of winter. I figure, well... I built a 1500 gallon masory insulated tank and it holds water, so I can do this too. My learning curve is going to be very steep.

Most people seem to use black pipe to plumb the boiler loop and the primary loop (where a primary is used). I just called a plumbing supply place to ask about Chlorinated Polyvinyl chloride (CPVC) as an alternative. They have used it for such applications. They even have fittings for adapting from the 2" boiler outlets to the CPVC via brass then copper.

According to one supplier it can be up to 60% cheaper than metal, though I doubt this.

The schedule 80 CPVC is rated as follows: Heat Deflection Temperature,°F at 66 psi = 217* (D 648 according to ASTM Test method). I don't know what the heat deflection temperature is, but I could guess that it would melt there.

Has anyone here used CPVC instead of black pipe. It appears easier to carry. Will it work?

I'll use PEX for the narrower pipes but there is a hefty length of 1.5" pipe with multiple turns and I'd like to simplify that part of the install if possible.

 

[Dave T]

ShroomMan,
I am no plumber but yes black is heavier and more combersome to work with than CPVC and CPVC will handle a lot of heat..I would question a lot of heat for prolonged periods days,months,years bite the bullet and use the black pipe and do it once and sleep better at night knowing your pipe will handle even an overheat situation, and last as long as the boiler..I would also question the shutoffs and other plastic components..Plumb in black and use teflon tape and tighten the crap out of them thats my 2 cents..Dave

 

[twitch]

Mushroom Man,
Everything I've heard and read says that any piping that boiler water will run through needs to have an oxygen barrier. I'm not sure if CPVC has that or not, just a thought. Here's a thread with a similar question:

https://www.hearth.com/talk/threads/22116/

 

[WoodNotOil]

I used some CPVC on the unpressurized side of my flat plate hx. It works, but I would not trust it personally on the boiler side. The CPVC shut offs are crap by the way. The whole piping ends up being really floppy and I can't imagine it would last a long time. I will eventually replace most of my CPVC with copper. I only used it because I was running out of money on my storage tank project and needed to just get it working. IMHO - definitely use either black pipe or copper. They manufacture black pipe manifolds which can save a lot of time. If you are doing a P/S piping, look at the hydro separators as they replace the need for a primary loop and simplify things greatly.

 

[Mushroom Man]

Thank you for the help so far. I realize that black pipe is the undisputed standard. I am just trying to ascertain whether other materials have been tried by users of this forum

I have been able to find 2 manufacturers who have higher temperature rated CPVC. Max 110*C (that's 230 F*) at 264 PSI. If these are correct, I wouldn't be concerned about overheating

(broken link removed to http://www.polyone.com/en-us/docs/Documents/Vinyl) CPVC Product Bulletin.pdf
and
(broken link removed)

I don't know about oxygen barriers but these might be able to handle that too. More research required.

 

[markpee]

We had a discussion here a while ago about CPVC, and I believe the outcome was that the CPVC cracked as it became brittle after a short time. I too had found good supporting evidence that it would handle the heat, but I think it gets weak when it goes from hot to cold, etc.

 

[Tony H]

The question you need to ask is .. Would I trust my 6000.00 boiler to a plastic pipe ? Black pipe is not that hard to work with it kind of like building a puzzle just connect with teflon tape + dope and use at least a 24' wrench on the 1" and over pipes and you will be fine

 

[Steaming Pile]

Thank you for the help so far. I realize that black pipe is the undisputed standard. I am just trying to ascertain whether other materials have been tried by users of this forum

I have been able to find 2 manufacturers who have higher temperature rated CPVC. Max 110*C (that's 230 F*) at 264 PSI. If these are correct, I wouldn't be concerned about overheating

(broken link removed to http://www.polyone.com/en-us/docs/Documents/Vinyl) CPVC Product Bulletin.pdf
and
(broken link removed)

I don't know about oxygen barriers but these might be able to handle that too. More research required.

Trust me if you have ever seen a boiler in a overheat situation you would say black pipe is the only safe way. It can cause extreme pressure and is scary as hell!! No exageration! Even soldered joints can and will come apart if your boiler becomes hot enough to make steam.

 

[Steaming Pile]

One other thing the pipe can be rated for a certian pressure but the joints won't nesecarily withstand that same pressure.

 

[chuck172]

You'll be O.K with copper. Especially if you use 95-5 solder.
http://www.engineeringtoolbox.com/pressure-ratings-solder-joints-d_1162.html

 

[jebatty]

Over a 9 year period I had two CVPC joint failures/cracks with boiler water at 180F. The failures started with just a drip, not catastrophic, and I was able to replace. The first failure I considered an anomaly, but the second failure made me realize that CVPC is suspect in this application.

 

[Steaming Pile]

You'll be O.K with copper. Especially if you use 95-5 solder.
http://www.engineeringtoolbox.com/pressure-ratings-solder-joints-d_1162.html

I'm not saying copper isn't adequate I'm just saying when things get hairy I'd like to have something more substantial than PVC. The joints in PVC would be my concern. Even Pex sounds like a better alternative

 

[Mushroom Man]

Black pipe is certainly coming up the favorite.

I wonder if some contributors to the thread are confusing CPVC with PVC. They are similar in appearance and ease of handling but that is where the comparison ends. CPVC has a 40-50* C higher heat rating than PVC. A few specialty suppliers of CPVC appear to have even higher heat ratings. It's those specialty guys I want to check out. I would want the chosen product to support 230*F and not become brittle with hot/cold cycling

I suspect the cost is much higher than PVC too, but I'm not there yet.

I agree with the idea of black pipe for the boiler loop but this specialty CPVC stuff (referenced earlier) might be suitable for the primary and storage loop. I think those loops could be isolated in such a way that in the event of failure, the boiler would be safe.

I definitely will go with Pex or Pex-al-pex for the other secondaries (barn, greenhouse and sand filter)

Thanks for the contributions so far

 

[Dave T]

When you go for it keep us updated on your results, maybe your on to something..Dave

 

[BrownianHeatingTech]

I'm not aware of any oxygen-barrier CPVC out there.

And, as some have noted, it's not just the pipe strength, but the joint strength. In most cases, pipe joints are far weaker than the pipe itself. Just because the CPVC is rated to withstand a given temperature/pressure combination does not mean that the joints will withstand that. The fittings (cast, rather than extruded like the pipe) are also a failure point. I used to do plumbing as well as heating, and CPVC is a very popular piping material in the “manufactured housing” market. Skimping on insulation is also popular with some of those manufacturers, so freeze-ups were common. Burst pipes were rare, but burst joints/fittings were very common.

Black iron and copper are both reasonably easy to work with, and have a proven record of longevity.

Joe

 

[Mushroom Man]

The weight of boiler room opinion has spoken. Black iron pipe is the best solution. Copper is a second choice. CPVC is in distant third place.

Has anyone here used a larger diameter primary than their boiler loop. It was suggested by one contractor. For example, a 1.25" steel boiler loop, followed by a 1.5" primary loop of steel.

The logic, as I remember it, was to enable greater flow in the primary with less pump. I remember him saying that he has seen examples with a 20gpm flow from the boiler circuit and 100 gpm in the primary.

In my case, I am only looking for 20-25 gpm in the primary and I could do that with 1.5" steel and an inexpensive (to operate) pump. Using 1.25" in the primary requires more pump and more power. The incremental cost of 1.5" (versus 1.25") pipe in the primary is small due to to the short distances involved.