Heat for my garage

I am trying something new this year to heat my garage. I have a KA-6 in my garage, 1 1/4 pex running underground to my oil boiler to heat my house and domestic hot water. When I built my garage, 28x32, I put 600' of pex in the floor and never hooked it up to anything. This year I decided to put what I call a sidearm heater into the boiler. I drilled a couple of holes and run a few feet of iron pipe in the fire box, connected it an old gas hot water tank for storage with an an expansion tank, circulator and on to the radiant in the floor. Only had the boiler running a few days, seem to have gotten all the air out now we wait and see. Not looking to heat her to 70 degrees just keep it a little warmer than freezing.

There are different ways
between the boiler and the hydraulic collector has a natural circulation.
A pump pushes in floors

Why didn't you just connect the radiant slab as another zone?

One 600 ft loop i dont think is going to cut it is the slab insulated? Typically a radiant system is designed with multiple 200 ft loops to keep the return temp within 10 deg you may want to look into a modine unit and plumb that into your header the boiler in the garage should keep it pretty warm

there are 2 300' loops in the floor - the slab has 2" styrofoam under and all around the outside, the "side arm" won't take BTU's away from my house heat as it's in the fire box by itself. I do suppose, it is taking a few btu's away from the house at some scientific level, but not from the BTU's stored for the house. if I get 50% performance, thats better than 0%. I'm not looking to keep it WARM just a little above freezing.

could work, i tookthe return loop off the house, and fed my radiant manifold with that your floor only needs 120* max, keeps your house priority. little more expensive to hook it up, couple pumps mixing valve and a means to control it

Too much work for me when the water is already there. I would have just made a second zone with the house as priority. It doesn't seem like you would garner enough extra heat but let us know how it goes.

I did a simular set-up in my house, installed a zone in the cellar on its own thermostat. Then installed cast iron radiator with ball valves on the return in the cellar of the garage where the boiler is located. this way if my cellar is too cold , tweak the valves for heat in cellar of garage to get about 50 degrees in cellar, closed when not needed. there are as many ways as there are people, what ever works for you. thanks dan

well so far so good.
just looked at the return water temp.... 54.7 temp dropped below 35 for most of the night and around 3am headed south below freezing. it hasn't gotten to cold yet either so i'll have to see where she goes during a cold snap.

Whoa, I admire your effort but I really don't think a side arm water coil is going to have a noticeable heating impact on a slab of concrete with 600 feet of pex in it.. I hope it works though Thats just my opinion.

You are liable to get condensation on the "cold" pipe inside the boiler.

Well, I am happy to report that (so far), the experiment is performing as expected. The garage floor is hanging in the vicinity of 50 degrees. today has been cold and the door was open for about an hour and as I write this the return temp is 52.5 degrees.

Well now that the heating season is all but over I want to report that over the course of the winter the return water temp was in the 40's and low 50's. only once I saw the return temp 31.4 I say I am pleased with the results. Think I may increase the size of the iron pipe to 3/4 and see what happens.

any sign of condensation? thats cool it worked out for ya, pretty much free heat right?

There is very little water in the exhaust from burning anthracite, there is very little water in coal.
Burning oil, NG and propane does create water, but not burning anthracite..
Anthracite is breaking carbon bonds and joining the carbon it with oxygen in the air, creating CO and CO2.

Burning oil, NG and propane which are Hydrocarbons, you also are breaking Hydrogen to carbon bonds and joining the hydrogen with oxygen, which makes water: H2O..

So you can safely run cooler temps with burning anthracite.. there is a little water in the coal itself, but a very small percentage, unlike Bit and sub-Bit coals which have a lot of water in the coal, depending the the mine and vein of coal..

Condensing of exhaust on less than 140* surfaces is a carryover from burning hydrocarbons, it is really not an issue with burning anthracite.

Correct me if I'm wrong, but this was explained to me many years ago. It make sense to me..

Greg L