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Infloor Radiant Heat issue



  • Cogeneration?

    Would this be a place for cogeneration, with the waste heat used for the house?--NBC
  • Steamfitter66
    Steamfitter66 Member Posts: 117
    Good piping practice is

    4X pipe diameter of straight pipe on supply and discharge of pump and control valves. If velocity is over 4 fps then 6x.
  • RCO
    RCO Member Posts: 51
    Update Thus Winter

    Just wanted to post an update on electric usage/cost from December and January this season.  Based on the regular rate of $.1053 per KWH and the dual fuel rate of $.0602 per KWH, we've save approximately $250 over the past 2 months.  We have not used much propane with the Rinnai heater.....but also have had issues with it.  The gas company/installer has not been able to trouble shoot at this point.  We continue to have issues with the exhaust vent icing up which shuts down the system.  The installer was back out earlier this month to adjust the venting as we have an extended vent/intake of about 60 - 70".  He gave the venting more slope to the outside but found it was still icing up this past week.

    We've used more KWH this winter because of the extreme cold.  However, I'm pleased with the savings thus far.  So far this winter, we've been leaving the system at 59 - 60 degrees when we are gone and the heater at around 54 - 55 degrees.  I'm not sure if we'll save by turning the radiant back to 55 and the heater to 50??

    I an considering a couple of things.  One is to install a slab thermostat...possibly a Tekmar 518??  As I've indicated in the past, the temp at the outside wall has been 5 - 6 degrees less than the thermostat temp reads via air sensing. 

    I'm also looking into replacing the existing the existing fireplace doors with a more air tight system with a blower.  I'm not sure if there are some economical ones out there but just want to be able to get more efficiency while burning wood.  Something to keep more of the warm air from inside going out the chimney and a fan to get the warm air out into the living area.  The current fireplace does have an outdoor air intake.  But doors are rather leaky and no blower.

    I've appreciated all the feedback!

    Thank you!
  • Gordy
    Gordy Member Posts: 9,537

    As far as the fireplace goes other than an airtight high efficiency insert not much you can do with it. You have an outside air intake which helps. You won't really find "air tight" doors which may create problems if you could find them. Outside air intakes are not meant to sustain combustion alone, but are meant to reduce air taken away from the interior of the house, and in some cases if wind direction is right can actually suck air out of the fire box.
  • Eastman
    Eastman Member Posts: 927
    edited February 2014

    If I remember correctly, you are hardly at this location, correct? I would lower the temperature to around 50 for the electric, 45 for the space heater. 10 degrees is not a significant setback in that climate. You would save roughly twice as much.

    Ideally the system supply temperature should also be adjusted lower while you are gone.

    Yes on the slab sensor, but you might want to consider a two stage tekmar thermostat. If you are still having temperature control issues, the second stage could kick on something else, perhaps the rinnai, but I kinda doubt that heater can interface with a conventional thermostat.

    Other things to consider: there are thermostats that are controllable by phone (without internet), and a basic landline is usually pretty cheap. They could also probably be configured to call you if the temperature drops to low.

    "As I've indicated in the past, the temp at the outside wall has been 5 - 6 degrees less than the thermostat temp reads via air sensing." -not sure I understand your concern. Are you worried about where to put the stat or are you hoping the slab sensor will eliminate the 5 degree difference?

    Regarding the fireplace: I have a similar setup with outside air. Check the interface between the masonry and metal trim of the doors. For me, that was the biggest spot for air leakage by far. I also have a device on top the chimney that closes the flue when not in use.

    Unfortunately the glass blocks the radiant energy and those blowers don't extract much heat from the fire.
  • RCO
    RCO Member Posts: 51

    Thanks for the advice the setback.  We've typically set the t-stat lower in past winters decided to try 59-60ish this winter.  Will definitely try that the next time up to see how that works for us.  Need to make sure our backup is functioning as it should be for times when electric is controlled. 

    My comment on slab thermostat was touching both of your points.  Mainly wondering if the slab stat would make the outside wall temp more consistent with the existing area where t-stat is located.  However, the current t-stat is located on wall of closet holding boiler so  not sure if that is the place in which you would want to place the probe?? 

    Are you referring to adjusting the water temp on the boiler while we are not there as well?? Also it sounds as though you can get a t-stat controllable by regular phone vs. internet?  We have neither there but lines are to the house for phone which would probably be cheaper than internet.

    Yes...not sure I want to spend a ton of money on fireplace insert.

  • Eastman
    Eastman Member Posts: 927

    The sensors for the stat should be measuring spots that are representative of the living areas you want to control. Tough call in your case, generally an outside wall is considered bad, but I don't think you have too many inside walls. Closet may not be the best location either, but I don't really know where that is in relation to the rest of your home.

    Even if you put the tstat at the outside wall, it will not correct the temperature difference, it would simply increase the temperature of the whole home. You really need to adjust the system's delta T if you wish to affect the floors distribution patterns. This would require a change in the flow rate.

    "Are you referring to adjusting the water temp on the boiler while we are not there as well??"

    Yes, you may gain additional savings by running at a lower temperature. This may reduce thermal losses into the ground and at the perimeter of the slab. However, I don't think there is a way to adjust that setting without taking the cover off the boiler and exposing you to potential electrical hazards.

    I can't recommend any particular phone controlled tstat, I just know they exist. A basic phone line is like 10 to 15 dollars. Call a day ahead and reset the temperature. Forgot to turn the temp down, call and reset it. I'd want one that could call me if the heat goes out.
  • SWEI
    SWEI Member Posts: 7,356
    A basic phone line is like 10 to 15 dollars

    in a few jurisdictions, yes.  But even there, the total monthly bill will probably be closer to $35.00
  • RCO
    RCO Member Posts: 51
    Phone Line Access

    Just checked with one of the phone companies up there.  A basic phone line is $14.50 per month......with taxes and federal excise fees it is roughly $20 - $25 per month. 

    I'm somewhat limited as to where I can access a space to insert probe for slab thermostat.  Maybe it would be worthwhile placing it towards the back side of the closet area closer to the outside wall??  The closet that houses the boiler system and exhaust/intake venting for the gas heater goes under the stairs leading to the loft.  I don't have very easy access to try to place the probe under the landing of the stairway outside the closet unless I would run the line behind baseboard to place probe in from front side (see pictures above of landing where Rinnai heater is sitting).  This would possibly give a more accurate reading than inside the closet??

    Thank you!
  • Eastman
    Eastman Member Posts: 927
    edited February 2014
    something else to look into

    check this out: http://allthingsd.com/20060125/connect-cellphone-home/

    Looks like there is a way to connect a cell into a regular residential phone system. I'm curious if you could get it to work with a phone thermostat. -can't see why not.

    Combine this adapter with a prepaid cell. You can get a pageplus 1 year contract for $80, and there's no taxes. Trackphone and others may have similar plans. This gives you 2000 minutes on verizon's older CDMA network which tends to be the best for rural areas from what I hear. Maybe track phone would be better in your specific area.
  • RCO
    RCO Member Posts: 51
    Surprising Electric Bill

    OK. Our electric costs have been considerably lower this winter due to dual fuel service. Probably heating costs have been better due to the fact that we found out our radio control unit was/is not working properly to control our electric boiler when needed! We've contacted an electrician to check this out our next trip up.

    Anyway, our last month's billing from 1/28 - 2/25 was $175 which included 126 KWH - general electric & 2127 KWH - electric heat. We were there on 2/6 - 2/9 in which heat was turned up from 55 or 59 degrees to 70 and then back down to 59. It was also turned up on 2/14 to 70 and back down on 2/15 in the afternoon to 55 or 59. This was due to the unfortunate issue of quests using our cabin and arriving to find the water line frozen from well to cabin.

    So I was surprised to see this past billing, 2/25 - 3/25, to be $48! This included 102 KWH - general electric and 55 KHW - heat electric. This is the first time in which we have no been up there nor has temperature been changed during a billing cycle during the winter. Could this be possible?? Is the secret in leaving the temp at a constant?? I've attached copies of temperature averages for those 2 billing cycles. PS We are having someone check this weekend to make sure we have heat!!
  • Eastman
    Eastman Member Posts: 927
    edited March 2014
    not possible, floor is not working

    55 kilowatt hours for a month is roughly equivalent to the output of a 75 watt bulb.  At an average temperature of 11 degrees F, it's clear the floor is not working.  Did your guests turn up the thermostat for the rinnia?

    Do you have enough propane to run the system for over a month?

    What is the radio control unit that you spoke of?
  • Gordy
    Gordy Member Posts: 9,537
    Propane usage

    Have you compared that with the low electric bill time frame?

    Agree with Eastman.
  • RCO
    RCO Member Posts: 51
    Thanks for Response

    No, I do not know the settings on the gas heater. I don't believe it was touched as the radiant heat would've been adequate upon arrival. But don't know any details. I will hopefully have someone check it out later today. I'm having this person check the boiler, breakers, heater setting, and propane usage.

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    Get ready for pocket/wallet shock...

    The cost of LP where I am at exceeded the cost per therm for electricity. Polar vortex = demand outstripping LP supply and price went through the ceiling....

    Just warning...

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • RCO
    RCO Member Posts: 51
    Propane Costs

    Thanks Mark! Yes, I know the price has been crazy this winter. I've not added any to our tank since early fall fill up. The last time up in early February the gauge indicated between 60 - 70 so don't know where we are at this point. We had the heater set at about 54 so would kick on when electric boiler was controlled. However, we had received notification in February that for some reason the electric company didn't believe they had been controlling our heat during severe cold periods. They had a technician out to the place to check the wireless control unit and said it wasn't working. So, I'm assuming that situation helped us on propane! We notified our electrician who contacted the company. He said that was all that was needed to be done until we get up there and he would check the connection to control unit.

    I'm not sure of worst case, if we've had no heat?? Our water pump was shut off and lines drained before we left in early February. Our guests using it the next weekend found that we had no water as line between well and cabin was frozen (common problem up there this winter) as frost reports have been in the 10 - 12 foot depth in some areas. So we should have no water leakage issues.

    I've someone checking this afternoon so will know shortly what seems to be the issue.