djk,
Why two boilers in your setup?
For my system, I got a design manual from a government quango, then designed the system on the following parameters;
Diesel burner; boiler/furnace, 36kw, ( 115,000 bthu) - also runs rads in 'new' house.
15mm pex-polythene underfloor pipe, all loops = 100m (328'), 10 loops total = 1 km ; 6 on ground floor, spaced at 225mm (9") centers. 22mm (7/8") od copper feeds to manifolds, as the longhouse is 40 meters (130') long including the boiler room.
Floor water temperature 40C (104F), and boiler temp 75C (167F), planned settings.
Thermostatic mix/return valves provide floor water- 2 zones only.
100W/m2 output under insulated cement floor.
70W/m2, 1st floor under wood floor.
Ground floor will be ceramic tiles.
Total area 90m2 per floor.
Est output 15kw (9+6) max.
(When we move next door, the new house will just be on frost stats in winter.)
3 circ pumps, 1 per zone , 1 x boiler circulation.
Programmable controllers, 1 each zone.
Thermostats, 1 per zone.
Insulation is 2" extruded ps under the concrete, and 8" of rockwooll, 13mm drywall lined ( 1/2" sheetrock) walls/roof, + double glazing. Under the 24mm wood floor, it's alum foil reflectors on 25mm insulated board, these zones are also air 'sealed'.
Water pressure regulated at 1.5 bar, 20psi, by a diaphragm gas/water bottle. I assume yours is in the boiler?
We heat all our water by electricity, as cheap rate tariff is about the same price per kwh (gross) as diesel oil in France.
I have run up the ground floor system, still building first floor.
I put 30% glycol antifreeze + inhibitor in the system. I can go to England in the winter and not worry about power outs, ( our 500ma poco trip does not reset itself after a power cut.)
Her indoors also wants reversible aircon and VMC (mech venting), and (apparently) were getting a unit similar to the one you posted, where I'm going to put it is my problem!
Plus we have a woodstove in new house, and I'll be fitting one in the renovation, but I still have some issues to solve for that, namely a remote air supply.
Hope to post pics on completion.
Alan
