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Okay, now that the primary loop is established, there are a few exceptions to go over.

1. I show most of my zoning of secondary circuits as zoning with valves, but you can also zone with pumps which can be a great way to do it, but pumps are expensive and this is usually only cost effective if you are doing fewer but larger zones.
2. The water fill usually occurs at the air-compression tank, but on my last drawing I showed it as filling at the return side. This is usually seen on older boilers, on new installs or modulating boilers it is best done at the tank.
3. On this post, I am showing the concept behind secondary circuits, not the exact science. So don’t run off and install per this drawing as the balance will be off!

The primary circuit just cycles hot water like a rotary circles cars in traffic. The secondary circuits are like the side streets that draw as the demand requires. With this setup, you can mix higher temp radiators in a system with lower temp hydronic floors and not starve the one or overheat the other…

Basically you are zoning the different types from one another.

This is how the secondary loops connect to the primary

If you feel lost or overwhelmed, this should help. If your house is old and has an original radiator-heat boiler system, then the radiators are probably the primary circuit. The pipe leaves the boiler and goes on a loop with each radiator having a branch supply and branch return. It is unlikely that the system has any connections between supply and return that are not a radiator of some sort. This was a simple way to pipe the system and required only one pump (albeit a relatively big one) to circulate the water.

The bummer of it is that room-by-room temp control is more difficult and is a bit of a fumbling science. Also, air problems are shared by every component in the system. And if all that was not enough, one thermostat controls the whole thing! Simple, but not very accurate and a waste of energy.

So, we decided to trace and build them in-house. That is how we did the majority of the fabricating on this project although we had help from Burkart’s Millworks and a few others.

Making the corbel templates

First we made a cutout sample of a corbel still in place and used that to trace our templates. Second, we cut the two outer pieces for all 32 corbels from 1×16 Miratec trim boards. To achieve matched pieces, we clamped two pcs of the Miratec together, this method yielded book-end pairs.

A rescued original corbel with the bookend templates

Once all the outer pieces were cut, we began cutting the centerpieces. We  made a template for the centers because the centerpiece of each corbel was recessed 5/8″  on the lower face of the corbel. To make this piece we used treated 2×12.

The three pieces were then sanded using an oscillating spindle sander and a table sander to clean the profiles for assembly. They were then adhered together using OSI polyurethane adhesive and galvanized finish nails. The adhesive was over-applied at the seams and the pieces were tightly clamped with vise clamps to press some of the glue out. The excess was wiped away and acts as a sealant to prevent water from getting between the pieces.

Finally, the assembled corbels were given a fine-grit sanding and pocket holes – with plugs (drilled from like materials using a plug-cutter) were drilled for screws to attach the corbels. The pieces were the primed twice and painted twice. I do not recall the primer used but the paint was Sherwin-Williams Duration exterior paint. The paint has a lifetime warranty and does not require priming (although we usually do). Also, this paint is bombproof! I do not often tout painting products ( due to the risk of backing a product that turns out not to work 15 years later) but this is fantastic paint (and at fifty bucks a gallon it should be).

The pieces were then transported to the site and installed using DeckMate 3.5″ screws and the plugs were inserted. Then came the touch-up painting and standing back to admire…

The final product installed - a weather-resistant French Corbel

And the project result was…

The completed porch - Custom from top to bottom

With that in mind and venting aside, lets talk about what works. Lets say you have a brick home that is over 60 years old. Then lets say that the walls you have on the inside are plaster-on-brick (with exception to most interior walls). You have an insulation value in that wall of less than 1 (remember, neither plaster or drywall, not even brick, are good insulators and you should always rate them at an R-value of less than 1). I know what you are thinking. You are thinking “this guy is full of it, my house has 15″ thick brick walls – that has gotta be insulating”, and/or  “less than 1 R-value, but my house is ;ike 3 feet from my neighbors and I couldn’t hear them running a jackhammer through my brick walls”, which is insulation – but not the heat/cold (thermal) kind – that is sound (acoustical) insulation.

You might think to say that 3-wythes of brick (in masonry, courses are vertical stacks and wythes are the measure of horizontal rows) thick, how much air can get through? Well, a lot is the answer. Imagine that brick is like a very hard cotton ball. Air still gets through it (called air infiltration) whether you realize it or not. Now, with good tuckpointing, and with a good interior plaster coat with a painted surface, that air leakage can be reduced but still exists.

Brick or masonry walls  do not insulate for temperature much better than – say – siding. Or even better…stone. Brick is of course man-made, but it shares several properties similar to that of stone. And when it comes to stone, have you ever been to Cold-Stone Creamery? They take a large slab of stone and set it on top of cooling tubes (refrigeration lines) because it transmits the cold so well and is great for slowing the melting of ice-cream as it is violently forced to coexist with various toppings. (It really is a beautiful process if you like ice cream). So stone is great for creamerying (??? what do they actually call that- toppinging?), but not so great as an insulator.

So you want insulation on those masonry walls? There are two common ways to achieve it. 1 is to use furring strips (1/2″ to 1″ thick strips of lumber that are on average 1.5″ wide) and try to use pieces of rigid (board insulation) to insulate. The insulation board is expensive but also it is on average R6 per inch. That is 2x better R-per-inch than fiberglass or cellulose can offer (see building insulation types post).

This method has its place but is not my preference if the situation allows me to do full-furring. Full furring is basically framing a 2×4 wall on the interior side and up against the brick wall. You can get at least R13 insulation in the cavities, there is plenty of room for electrical and plumbing lines to be installed, and you can even buy yourself some structural earthquake safety. See part 3 for that revelation….