iDRY Vacuum Kilns

Sponsors:

Need help with radiant configuration for garage heat

Started by Engineer, November 28, 2015, 02:10:14 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Engineer

I'm going to be heating my garage the same way I heat my house - with radiant PEX tubing in the slab.  I have several zones in the house so the PEX from the OWB circulates through a fairly large plate-style heat exchanger, which in turn connects to a primary manifold (or loop) that has all the zone piping branching off from that loop.  Each zone has a mixing valve and circulator pump.  The primary loop has an air purge valve and expansion tank.  This system also heats domestic hot water for the house.

Now, for the garage, it will be a single zone.  Just a three-port manifold for the in-slab tubing.  The mixing valve and circulator pump should be the same concept as the zones in the house, correct?  I am wondering if I even need the heat exchanger and primary loop because I will be only running a single zone.  The other dilemma is that I have no water supply to the garage, although I can plumb in a hose connection and check valve to add water from the house-mounted hose bib which is less than 100 feet away.  Do I still need an air purge and expansion tank?

I am concerned that I will overheat the space, as I am only using the radiant heat to "take the edge off" - trying to maintain the garage at a consistent 62-64 degrees year-round.  I don't really have "cold" water to run through the mixing valve to temper the 175-185 degree water coming from the OWB. 


I guess I need help visualizing this.  It should be simple but I'm not getting it.  Any help for plumbing a single radiant zone with an OWB as the heat source and no water supply?

beenthere

Unless I am missing something, just put in a circulator pump that only pumps hot water when the thermostat is below the set point in your garage. If there is hot water to pump, all the better. If no hot water, then no heat.

I heat three zones in my house that way.

What am I missing?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Holmes

OWB feed { with a circulator }and return to the heat exchanger.  Heat exchanger for radiant with circulator, relay, thermostat to control heat.  That relay could also control the other OWB circulator and turn it on when there  is a heat call, and off when heat is satisified[ simple method].  After the plate heat exchanger you need  # 30 expansion tank a 3 way mixing valve then the circulator, and you should have a 30psi relief valve, temp. and pressure gauge air scoop and a draw off on both the feed and return line to purge. filling with a hose will work when needed.  The cold water you are looking for is the return water coming back after going thru the slab it enters the 3 way mixing valve and a lot of it gets sent back out under the slab again.  Hope this helps.  Dana
Think like a farmer.

garret

Garage area?  A single zone may not be a good idea.  Remember that there is an optimal flow rate for a given size PEX in terms of heat transfer and bubble elimination.  Example:  1/2 " PEX rule of thumb; maximum circuit length ~ 250 ft.  Also, good drainage, and insulation under slab (>= 2in high extruded foam) is a must.  I've seen some good CAD-based software online for designing radiant under slab projects.  The app I used was a free 30 day version.  The results were excellent and I am very satisfied.  Radiant is the way to go.  Whether you go forward with the project or not, put in the tubing.
E-Classic 2400 comfortably heating 4,200 sq.ft. and unlimited DHW, Off-grid, Photovoltaic-powered pumps in gloomy SW PA , 34 t splitter, numerous Husky chainsaws

Thank You Sponsors!