Hello all,
I posted many moons ago about a outdoor reset question I had. I'm a bit further along now as my system is "complete". Ill minimally describe my system but can answer any questions necessary:
I installed in ceiling radiant in each room of my house. 1/2" PEX in AL plates with insulation above. Two zones, first and second floor. I have not yet applied 5/8 gypsum over the plates. The system is fed by a Versa-Hydro mod con boiler. This unit uses a heat exchanger to transfer tank energy (119 gal DHW) to the space heating circuit with a variable speed PID controlled pump. I have two Tekmar Tstats 552 (first & second floor). I thought i could use the programming feature but now i understand/appreciate more radiant systems should be set at a constant temp. I understand Tekmar makes very nice ODR controls which work with there Tstat's but again the Versa-Hydro has it's own ODR internal so the fancy Tekmar's are probably wasted (live and learn).
Perhaps the 5/8 gypsum will help (that's why i chose it) but here is my question/problem. I want my system on more often. I want a warm ceiling to radiate to all the objects in the room. Right now the system cycles too much, warms the air when it's on, satisfies the Tstat for long periods but leaves surfaces in the house cool which suck my energy. When the tubes are warm all is well and it feels wonderful. I've been tweaking the ODR curve to try and get it right. I think the theory is to get the system to the point where it Doesn't need a Tstat but just above so it can recoup from random large heat losses (extended door open, wind chill etc). I think i have the low outdoor temp/high water temp close but the high outdoor temp/low water temp seems to keep coming down. Right now the curve is 125@5, 85@69 (system temp@outdoor temp). When I get home the house is 69 but the zones are off (have been off for a while) and stay off for a long time (let's say outdoor is 45-60 right now). This feels chilly. I'm motivated to keep lowering the 85 temp and bring the curve down more to force the zones on more.
Does this seem reasonable? I can't say I've read about anybody lowering the system temp this low. I understand i'ts tough to control when the outdoor temp is close to the indoor. I'm hoping the added thermal mass (albeit modest) of the drywall will help store energy. Any suggestions? I guess this is a big question, any help is appreciated.
AMAC
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