Replies

1. 
   Jim_Pappas | Mar 16, 2002 05:28am | #1

   *
   I am building a vacation house in snow country. We do not have a heat pump, but instead will have radiant floor heating. We do have gas fireplaces in the house which will be on millivolt thermostats. If we lose power while we are gone, the fireplaces will continue to work with no power.

   /Jim Pappas

1. 
   David_Thomas | Mar 16, 2002 07:32am | #2

   *Since my radiant runs off of a HWH (no electric use there), the only thing I'd need to power are low wattage circular pumps. Which I'd do off of a invertor from the car battery. But I haven't had a power failure long enough (more than 18 hours) to need that. Not the automatic back-up that Jim's gas fireplace is, but easier than splitting and hauling wood. -David

1. 
   Jim_Pappas | Mar 16, 2002 05:46pm | #3

   *Since this is a vacation house, I want it to be automatic. If the heat goes out for any reason (electric outage, boiler failuer, etc) then the fireplaces will automatically light when the temperature drops to the temp I have those units set to. I will have 5 fireplaces in this house, one large 58K BTU fireplace in the great room, and one smaller one in each of the 4 bedrooms. Each bedroom has an attached bathroom, so that will be a good place for the backup heat. All the fireplaces will have millivolt thermostats so no electricity is needed for them.I also plan to set up my thermostats for communication/control with the security system. This will allow me to use the security systems' telephone interface to change the main thermostats remotely (ie: warm up the house from 60 to 70 before I leave home). The particular security system I have in mind (HAI) will call a series of numbers with messages and/or pages if the temperature was to drop below some predetermined value. So for example, I might set up my system as follows:Normal temp - 70Away from home setting - 60Trip point for alarm - 55Milivolt fireplace settings - 50Unless I am missing something, this should be a good system for my use (unless the gas main fails).I do have one question. Are milivolt thermostats somehow different than normal thermostats? The reason I ask, is that I do not know of any milivolt thermostats that can be remotely set by home automation equipment. The only ones that I have seen in fireplace catalogs are manual. This is not really a big deal, but it would be nice to hve them change automatically to my preset values when I set the alarm system rather than run around the house making sure that they are all turned down to the lower setting. It would also avoid finding out that we missed one, resulting in an inefficient fireplace providing the primary heating for the entire house while we were gone.

1. 
   Bill_Hartmann | Mar 16, 2002 05:59pm | #4

   *JimThe millivolt system has to work with very low voltages and currents so that they need contacts that are self cleaning and they can't have an anticipating resistor that some have.I believe that Honeywell has an electronic setback that will work on millivolt, but that is not what you are looking for.The other option is to use a conventional 24 volt thermostate system with a relay. But then it need external power. You could parallel the millivolt units set at 50 with the relay from controllable ones.

1. 
   Jim_Pappas | Mar 16, 2002 06:53pm | #5

   *Bill,Thanks for the quick reply. I had assumed that there was something like the low impedance contacts that you described.As far as installing 2 thermostats in parallel, that is an interesting thought. However, this isn't really that important to me. I think I will just make sure all of the fireplace thermostats are manually set correctly before leaving the house.It would have been a nice feature to just set all of the thermostats (normal, and fireplace) automatically to their setback positions when arming the security system to "vacation" mode. I will still get this feature with the normal heating thermostats. Later, when returning to the house, I can use the telephone interface of the alarm system to remotely change the setting from "vacation" to "Away", and the alarm system will remain set, but the house will start heating up to normal temperatures, ready for our arrival./Jim Pappas

2. 
   Dave_Richeson | Mar 17, 2002 12:39am | #6

   *Jim,Check with a Trane or Carrier regional representative. Both have system controls, monitors and communication packages that you will find very good for what you want to achieve. I work with the Trane system (Tracer Summit) daily and it is pretty good. Carrier has a similar system but I have not used it. Another is Barber-Coleman, but I don't recommend them because of product support and compatability issues.Tim, I am putting two wood burners in my home. They are not just backup to the geothermal, but part of the over all heating system design. If the system is built and works as designed I'll have an annualized HVAC cost of less than $500. Not bad for a 4800 sq.ft. all electric home.Dave

3. 
   Tim_Mooney | Mar 18, 2002 06:42am | #7

   *That would be darn cheap Dave.