Paul, you've pretty much got it figured out: A too-high soil pH combined with chronic dryness are the likely culprits. I have turned these things around with a combination of soil sulfur, wide mulch rings under the trees, and supplemental watering. Where I happen to live, there's plenty of iron in the soil but for species like RB, it is unavailable due to high soil pH. If that is also true of your location, the sulfur alone will, in time, correct that issue. +oM

I'm no rose expert, but my roses have never been bothered by high temperatures. If they were container-grown, a good soaking the day before a heat wave should do it, and then water again in about three days as long as you're not seeing droopy branch tips before that. If they were bare root they might need more water since the roots aren't as extensive during their first year. I've never been able to overwater my roses, so err on the side of a good watering this week.

If you are comfortable in using software to help with your decision...download a free copy of the "Indoor Air Quality Emission Simulation Tool (IA-QUEST) -- Version 1.1" http://www.nrc-cnrc.gc.ca/eng/projects/irc/simulation.html If this is not your cup of teaÂthe consolation prize is Âif you did the architecture right and the radiant floor heating load is less than 10 Btu/hr/sf the surface temperatures will be less than 75 deg F and using something like (or equivalent to) the Uponor quiktrac, the fluid temperatures would be controlled to less than 90 deg F. (assuming youÂve had a professional design the system). These are very low temperatures (less than your nominal skin and body core temperatures)Âand will have minimal effects on emissionsÂi.e.: the short wave solar radiation through windows will have a greater influence on emissions from furniture, finishingÂs and flooring than the floor heating system. Additionally, the floor finish (as well as other finishes) will have a significant impact on TVOC emissionsÂwater based (moderate) vs. oil based (very high) vs. natural  unfinished (very low)Âalso influential on the IAQ will be your ventilation strategy...a separate dedicated ventilation system with constant flow and ducted with supply and returns to each room will assist in mitigating concerns (assumes outdoor air is also of good quality). [see: http://www.arb.ca.gov/research/apr/past/indoor.htm] The Canadian Mortgage and Housing Corporation have wonderful resources for environmentally sensitive peopleÂsee this link to get you going in the right direction: http://www.cmhc-schl.gc.ca/en/inpr/bude/heho/upload/Research-House-for-the-Environmentally-Hypersensitive.pdf If you are inclined to read academic papers this document is very useful: The Medical Perspective on Environmental Sensitivities http://www.chrc-ccdp.ca/research_program_recherche/esensitivities_hypersensibilitee/toc_tdm-en.asp Last words: there are in some jurisdictions requirements for professional engineering or certified designers in hydronic systems ( http://www.municipalaffairs.alberta.ca/documents/ss/STANDATA/building/bci/06BCI012.pdf) ...at the very least make sure your radiant designer and installer has been certified through either the Radiant Panel Association, or The Canadian Institute of Plumbing and Heating or the Heating Refrigeration Air Conditioning Institute of Canada. Regards, rb

Here's how a triple aquastat works, assuming you have a boiler that maintains a minimum temperature. Even on a new boiler, if there is a distance between the aquastat and the gauge, you can have 20 or more degrees difference between the two. It sounds like temperature override because of distance or corrosion on the bulbs, as paulbm noted. Sit there and watch the gauge. The burner should shut off at the high limit on the auqastat. You can calibrate the aquastat and gauge to get them closer. When the temp gauge shows 180, turn the hi limit on the aquastat down until it clicks and the burner goes off. That should about even out the temp difference. Set the low limit 20 degrees below the high limit. You can always adjust if your needs aren't being met. But, first, rule out any problems. Low Limit Controls and the Differential With NO call for heat: On a temperature rise (water temperature is below the low limit) the burner circuit breaks at the low limit setpoint. The burner will maintain the low limit setting if the domestic hot water use requires it to do so. With a call for heat and differential setting of 10: Below, or at the low limit, the burner will start immediately and continue to run until the thermostat is. The circulator will run if the boiler water temperature is at, or above the low limit. The circulator will when the water temperature reaches 10 degrees below the low limit setpoint to preserve hot water for the domestic water coil. The circulator will resume operation when the water temperature is again at the low limit setpoint. With a call for heat and differential setting above 10" At any differential setting greater than 10 degrees, the circulator will start when the temperature rises to the difference between the differential setting and 10 degrees. Example: With the differential set at 25 degrees and the low limit set at 160 degrees, on a temperature rise, the circulator will begin again at 175 degrees. 160 degrees plus (25-10 = 15 degrees). Temperature goes above High Limit: If the boiler temperature should go above the high limit, the burner will shut off and the circulator will continue to run until the boiler temperature is 10 degrees below the high limit setting, at which point the burner will restart. Honeywell 8124A Literature: On a temperature rise, with the adjustable differential at the minimum setting of 10 degrees F, the burner circuit (R-B) breaks and the circulator circuit (R-W) makes at the control setpoint. On a temperature drop of 10 degrees F below the setpoint, the R-B circuit makes and the R-W circuit breaks. At any differential setting greater than 10 degrees F, the R-B make temperature and the R-W break temperature remain the same (control setting minus 10 degrees F). The R-B break and R-W make temperature are the setpoint temperature plus the difference between the differential setting and 10 degrees F.