Add a heating loop to an existing wood boiler

[Draven8795]

Going to help a buddy out with some radiant heating. Right now he has a wood burner which runs 1" line into a small garage 20x9. The previous owner just tacked the 3/4" pex from the 1" to the wall and ran the rest to the heat exchanger in the furnace in the basement. Needless to say that doesn't heat the garage and is probably loosing a bunch of efficiency before it gets to the furance.

Is it possible to add a 1/2" manifold loop in between the boiler and the forced air furnace exchanger to now heat the slab he's going to pour in the garage? No pump or zone control at this point. If they are running the furnace the garage is also just included in the loop.

 

[finn]

You need to replumb it as a primary /secondary system, with a pair of close coupled tees for each zone, each zone having its own circulator pump, with a third pup for the primary loop, and appropriate relays to turn on the primary and zone pump as the thermostat calls for heat.

That’s how I did both of mine, and it works well.

 

[nadogail]

You might want to increase the size of the heating coil in the boiler fire box, more surface area on the tubes will make for better heat transfer.

An additional coil of type K tubing in the firebox will make a big difference.

 

[Draven8795]

You need to replumb it as a primary /secondary system, with a pair of close coupled tees for each zone, each zone having its own circulator pump, with a third pup for the primary loop, and appropriate relays to turn on the primary and zone pump as the thermostat calls for heat.

That’s how I did both of mine, and it works well.

I installed my system at my house and that's how i did it as well. I am going to price out making that a zone. But out of curiosity, if we just do a 3/4" x 3x4" x 1/2" Tee will the water flow through everything or is the secondary pump required to make the offshoot zone work correctly?

I assume he's not going to want his garage the same temp as the house which is why i'm going to lean towards setting up a pump with a thermostat.

 

[Draven8795]

So honestly i think what i'm going to do is just get either a 2 or 3 way zone valve depending how i decided to do the piping and a 24v transfomer and hook a thermostat in between then then just let the boiler pump do it's thing if that space needs some heat.

 

[Jackfre]

While I know these types of systems can be controlled but I am very careful with the wood boilers. You are potentially building a bomb. I built a wood boiler for my father about 50 years ago and just put the circulator on all the time. I also lined up the relief valves for redundancy. You say the coil is just laid up the wall. Is it just tubing or is there hw baseboard element on the wall?

 

[Draven8795]

They laid the supply line from the boiler once it comes out of the ground and to the house and on to the furnace basically on the garage floor and then into a crawl space to so i assume that was losing a lot of heat to an unoccupied space. So he's ripped out the garage floor now (which is 20x9) so we are going to put the main supply line in the concrete now and add a small zone off that same supply. At this point i think i'll use a 24v transformer to thermostat to a 3 way zone valve. The pump in the boiler itself does run 24/7 so if the garage needs some heat it'll just pump through with the wood burner pump once the third leg of the valve is opened.