My system has been running well for 2 months.  I am wondering if anyone can advise me on set points.  I have two 4 ton GeoComfort units working together to power 10 MultiAqua fan coils and the existing baseboard.  Currently i have the baseboard set 3 degrees below the fan coils and the bb does not kick on even when it has been in the single digits.  I currently have my system set to cycle when the water temp falls to 113 and run until it is 127.  I have been averaging between 75 and 80 kwh per day.  I am currently paying .104 per KwH.  Just curious if anyone thinks changing the set points would be advantageous.

If I understand this correctly you have spare heating capacity at the present setpoints. That certainly suggests you could bring them down some, and doing so will increase COP and efficiency. Power consumption doesn't appear out of line for tonnage and climate.

Didn't we once discuss an outdoor temp reset control for your system? I've never set one up but it sounds like this would be a good fit for you. Tank temp setpoints could be adjusted for outdoor temperatures - the cooler the water the more efficient your units will run. Cooler water means lower head pressures, which will help unit compressors live longer. If 120 water is good for single digit weather, 100 might suffice when it is 30 outside.

Upper limit for water temp is unit's rated ability. Go too low and the Multiaquas will blow uncomfortably cool air.

It looks like your air side can keep your house warm.  If you want the bb to do some or most of the work,  you might want to set them at or above the fan coils.


Glad yours is is keeping your house warm.

THanks for the quick response.  We did in fact discuss this before, but at the time i was just figuring things out and had no historical data to compare.  I think the multiaquas are rated down to 110 degrees and the bb running below that drops BTUs rather drastically from what i understand.  I will keep playing with it.

Jim,

which model of MultiAqua do you use? Is there much fan noise?

Reflecting on this a bit I wonder if it would be better (quieter, more even heat, no fan power use) the let the baseboards lead and the Multiaquas act as '2nd stage'

GeoDean:  I would have to pull out the books to reference model numbers.  They have no aux heating elements in them, they are a simple fan coil.  Noise is noticible, but by no means intrusive.  The unit in our bedroom cycles on and off about every hour throughout the night and it hasn't woken me up yet.   Let me know if you want specifics and i will pull out the books.

Engineer:  I have had the system running that way for the past two months.  I just wanted to try using the MultiAquas as primary to see if there were any differences.  I have not noticed any change in the average daily usage, but overall the house seems warmer as the air is circulating more.  On a downside I have noticed that the loft area adjacent to the great room does get very warm but until we find the remote for the ceiling fan it is something we will deal with. 

Thanks for the help everyone, it is nice to have a place you can blindly cast to and get answers from knowledgable people!