Super-Simple Radiant V 3.0

hr

3/8 PAP would be an excellent choice of tube. At that spacing, and with that many bends, the PAP will be easier to keep.

This may be a application where plates are not desieable, if 135°F is the only choice for supply temperature. You may knock that temperature with some flow control if temperature control is not possible. A slab sensor might be a good overheat protection, somehow :)

Get a 4-1/2 angle grinder with a masonary wheel. Maybe rig up some sort of vacumn cleaner for dust control. You might gang two wheels on the grinder to get the correct width cut in one pass.

hot rod

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=144&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Mike T., Swampeast MO

Connected to CONSTANTLY circulating, reset converted gravity mains. Single circulator (B&G 100) in system thus the really short loops. Spacing will probably be around 6". There will actually be more branch loops but I left them out for some form of clarity.

Supply temp tops at about 135° @ design (8°).

The Danfoss FHV will modulate on air temp, so surface temp of the floor is essentially "unlimited". I can't let the system have too much conduction or the floor surface will overheat. I believe that plates underneath the cement board would be overkill in this application.

Yes, I can deal with the nighmarish cutting of the cement board to fit around the tube--it won't be fun but I'm patient.

Heat loss of space is about 14,000 btu/hr. Gross square footage about 525 for loss of about 26 btu/hr/sqft. BUT, it's a kitchen/laundry so heated square footage of floor is about 300 sq.ft.

Three iron TRVd rads (two standing, one old-fashioned panel built into island) in the space. They can easily carry the complete heat loss themselves at my supply temps. BUT, it won't bother me if they only begin to heat in really cold weather. Something tells me though that the FHV would "win" in a battle with the TRVs and the floor would overheat during cold weather.

Questions:

1) Can I possibly do this with PEX without damaging the tube/oxygen barrrier? Pex-Al-Pex?

2) Any suggestions regarding air elimination in this clusterf$*k? Remember--it's a converted gravity system and this is just tapped into the mains. The supply "manifolds" (in dark red) will be below floor level in the basement. The FHV has a built-in air purge.

3) Any guess as to surface temp when running at full circulation (meaning if I left out the FHV) and only added it if absolutely necessary? (3/8" pex in approx 1" of cement/tile @ 135° supply).

Weezbo

Nice drawing:)

not that this will help a group however,I am In Alaska,recently ,i laid 3 125' lines of 5/16ths one weezbo two mm stadler lashed them up to 1/2 sweat by 3/8ths pro pex connectors ,with a three way manifold used for distribution of hoses for a compressor used to run nail guns on a construction site. it has a sparky low temp porportional fixed mixer the current temp is like 40 ish out side (4a.m.) and 70 in the daytime. the water temp is like within 1 or 2 degrees of room comming and going from these loops,i have cranked it up.and it will go at least 90:).the tubes are covered in about 3/8ths cement now concrete,so in essence it is a 3/4(+/-1/8th")slab on an existing insulated slab.each loop has a 3/8"full port valve on the return so i can purge any given line or isolate any given line..were i going for top of the line right now id probably go the route of constant circulation with a spiro air vent above the floor to eliminate the air as in your drawing(on the 1" line) i like the idea of a buderas panel somewhere in the equasion for extreme cold weather .right now other than a sparko 60 100 mixer for gardening apps and a 15 series grunfos ss recirc on continiously and a t stat controlling the boiler i have not much in the way of control over it. i am buzy...lotsa new homes.never tryed this in a new home:)

Mike T., Swampeast MO

Thanks for ideas Hotrod. The Danfoss FHV is a flow-controlling valve (uses a standard TRV actuator) but it modulates on air temperature. They do have a "floor temp" modulating valve as well, but it's not really floor temp as it actually modulates on return temp and they say that panel is limited to around 130 square feet. Perhaps this arrangement with the FHV supplying a manifold and VERY short loops with [presumed] low delta-t would allow a significantly larger panel. Any commment from someone at Danfoss?

I'd kind of planned on cutting the cement board into pieces and installing the tube between pieces. Your angle grinder idea (done after the cement board is fully installed) sounds good IF I can find a way to handle the dust Cutting cement board with a masonary blade results in LOTS of extremely fine dust that tends to rise and hang in the air for a LONG time--it also seems to stick to everything.

Mike T., Swampeast MO

Thanks Weezbo. Yes, that does give me some idea of what to expect. The full-port ball valve on every loop (plus a valve and air vent) on the return manifold was in my head even though I was hoping that someone might have an idea that didn't involve so many valves and fittings.

Of course the kitchen would be above the two basement rooms (a slop kitchen for fish/game/projects & room for my old Nautalis--maybe it'll get used more) that I intend to semi-finish (REMOVABLE CEILING OF COURSE). I haven't had any air problems in my existing radiant loops after initial purge but that first purge is a pain on one in particular.

There is 162 sqft EDR of iron radiation in the space so "not enough heat" won't be a problem. My other radiant experiments here were intended to be "floor warming" but wound up being "floor heat". Kind of hoping to do similar here.