When the concrete is setting up push some 12 penny nails into the concrete - every few inches - about an inch in from the 2 by 6 frame.  

I had the same problem ,  I broke out the shovel and dug the crawl space 12 inches deeper where the heater went .

Valves designed for this have what's called a 1/2 inch FIP Inlet on them.Here's a photo of one:The other way of attaching the valve to the tubing (if the end of the tubing is not threaded but is instead smooth) is via a type of valve inlet called a 1/2 inch NOM Comp Inlet.

A 21 inch cabinet instead of a 12 inch wall.

Normal pressure is 3 or 4 ounces per square inch. 

Buy a decent light-duty chainsaw (I suggest a Husquevarna 455, with a 18 inch bar).

In the kitchen and the front entry, there is old-style oak hardwood, about 2 inches wide and probably 3/4 of an inch thick.

I buy contractor packs at box stores, unless they're the 2-inch thick ones that only Ace carries (not Lowe's or HD).  

The commercial carpets are much better about absorbing carpets.There is also a type of cement that is poured over the floor about an inch think that is used for that purpose and works very nicely.

I use a 12 inch broad knife as a shield to keep it OFF THE TRIM.