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Rav 01-04-2012 06:56 PM

Armaflex vs. Kflex
I want to purchase insulation for my hot water heating pipes (old black pipe, hot water boiler). I was planning on getting AP Armaflex self-sealing elastomeric tubes. Home Depot carries Armaflex but not in the size I need (2-3/8). I live in the Maryland suburbs of Washington DC and am having trouble finding a local place that I can get Armaflex. I tried Googling HVAC supply houses but couldn't find ones that say they carry Armaflex. I do have Grainger just a few miles away, but they carry Nomaco Kflex (and K-Flex USA, which I assume is the same thing?). I'd rather work with a local company, such as Grainger, than purchase online. The question is, how does Kflex compare to Armaflex? Thanks.

Baldrick 01-04-2012 07:05 PM

How are you going to apply Armaflex to the piping? It is sealed and has to be slid over the piping. You need something that is split with self sealing adhesive on it. Why do you feel you need to insulate the pipe? Is it running thourgh unconditioned space?

Marty S. 01-04-2012 07:39 PM

For a boiler you want fiberglass like this instead of armaflex

Rav 01-04-2012 07:51 PM

Thanks for the responses so far.

Baldrick: The Armaflex/Kflex is pre-split and pre-glued. So you put it around the pipe, remove the celophane-like-material that protects the adhesive, and pinch the two halves together. And this is unconditioned space, the basement. I don't need the basement to be so warm, I'd rather have the heat preserved for the conditioned space upstairs.

Marty S: I know I would need fiberglass if it was steam pipes, but this is hot water (heating) pipes. The maximum they would get is about 160 degrees. Given that, do you still think fiberglass is a better way to go, and why?

Marty S. 01-04-2012 08:01 PM

Fiberglass on boiler pipes is what I was taught. Never questioned why but have seen armaflex melt on heat pump discharge lines which is less then 160 degrees.Guessing that's the reason why

Baldrick 01-04-2012 08:08 PM

All the armaflex we use (soft rubber) is not split but must be slid over the pipe. Foam style insulation (kflex) I assume is split with peel off tapes on each side. I would tend to agree that hot water heating is too hot for Armaflex but should be ok for foam type.

yuri 01-05-2012 06:57 AM

I would use fibreglass. The other 2 types will tend to dry out in time and crumble. Fibreglass will last forever and probably has a higher R value.

bobinphx 01-05-2012 07:31 AM

Question about fiberglass.
how is it applied to the pipe? are we talking about a spiral wrap? or is there a split solid fiberglass sleeve type? what about sealing up the fiberglass. The reason I ask, is that I have seen spiral wrap, but it appears that its has to be wrapped fairly tight, thus compressing the insulation and in my mind losing the efficiency of the fiberglass. I have also seen a round ridged type of fiberglass pipe insulation. The ridged looks like it also gets a coating of mastic and or pain. so again, which are we talking about???
thanks in advance.

yuri 01-05-2012 08:00 AM


Originally Posted by Marty S. (Post 812705)
For a boiler you want fiberglass like this instead of armaflex

Read up about it in this link. Some have an aluminum foil outer backing which this does and you use silver foil tape from HDepot to seal it. They also have preformed insulated elbows so you don't have to carve them out of the insulation yourself.

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