Thermaray Electric Radiant Ceiling Heating System?
Tiziano
| Posted in Energy Efficiency and Durability on
Anyone have experience using a Thermaray Electric Radiant Ceiling Heating System? The main company seems legit (https://thermaray.com/residential-radiant-ceiling-heaters/), but the nearest distributor to me has no address on their site (https://premierenergyusa.com/) so I’m leery.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
This is an old idea form the 1950s from a time when we thought electricity would be too cheap to meter.
This is pure resistance heat and will be very expensive to operate give todays cost per kWh.
If you install a heat pump instead your bills will be a quarter of what resistance costs to operate.
Walta
Thanks. We can get to -20F during some nights in Jan and Feb, so I'm not sure about heat pumps yet.
Tell me your county or zip code and I'll do an analysis for you.
55331
OK, the analysis I did is here:
https://docs.google.com/spreadsheets/d/14v7VA7I9W6ctAcoPxDZDnEAI4Xvi7JO0g4Rgbe-BHHU/edit?usp=sharing
The performance of a heat pump depends greatly on the location, the equipment and the house, so for the sake of an example I used a Mitsubish P-Series and assumed a house with a heating load of 40,000 BTU/hr. You can see the performance data for the heat pump I used at: https://ashp.neep.org/#!/product/34535/7/25000/95/7500/0///0
From the NEEP.org website I used performance data for that unit to estimate what happens to the output and efficiency as the temperature drops. That website also has climate history data, which I downloaded for your zip code to get the hours per year at each temperature.
According to the climate data from NEEP, the design temperature is -6F and the coldest it typically gets in a year is -24F. Based on those assumptions, that heat pump would meet 96% of the heating load, 4% would have to be provided by a backup heat source. If that backup heat source is resistance electric, the weighted seasonal coefficient of performance (COP) would be 2.4; ie, a pure resistance heating system would use 2.4 times as much electricity. It would use just over 11,500 kWh per year for heating.
The heat pump meets 100% of the heating load at temperatures above -8F. I assumed zero contribution below -13F. There are so few hours below -13F that changing the assumption to some heat pump output changes the annual electricity by less than 100 kWh.
Assuming only backup heat below -13F, it needs to be able to meet the full load at -24F, or 51,000 BTU/hr. That's about 15000 Watts or about 60 Amps.
Thanks. That's pretty cool.
Given the size of the structure (12' x 16' with a mono-slope ceiling 13' high down to 8'), and 54 sq feet of windows on the north wall, I'm not yet sure what BTU to plan for.
Maybe this: https://gotductless.com/products/msz-fs06na-muz-fs06na-mitsubishi-6-000-btu-hyper-heating-single-zone-system
What's more important than the size of the building is the insulation level. If you tell us your insulation in the roof and walls we can estimate the heating load.
My Rheem heat pump heats my house down to +6°F with the strip heat locked out.
I do not feel bad about using the strip heat for the few hours each year they are needed.
There are vapor injected heat pumps that run well at -15°F.
Walta
Thanks!
Tiziano,
I grew up with ceiling radiant panels in one part of the house. The pitch for them was from good ol' Reddy-Kilo-Watt that indeed pushed a future of nuclear power too cheap to meter. Needless to say that part didn't go too well.
Of more interest to you might be the rather poor performance and the mounting problems encountered. The panels were thick and the wiring needs forced us to redo the entire ceiling as well as the electrical panel. Still ugly once done. After activation it became pretty obvious that a standard 8' ceiling left one's head too close and feet too far to be comfortable. New panels may have altered the heat signature compared to the ones I knew, but two things became very clear.
First, the heat pattern from above created a fairly sharp gradient of warm tops and no warmth under tables or desks. (a home office was the original driver of the remodel) This might have been less noticeable in a highly insulated home, but we are talking the 60's. The second thing meant I did enjoy the ceiling location. My reading getaway in the attic was veeeery warm all winter. The panel's heat output seemed to be equal up and down.
As an alternative, I would suggest what I am using now for my entire heating, radiant cove heaters. (Link at bottom, no reward to me) These seem to project the heat as very long wave infrared which has proven quite even and capable of carrying our heat needs which seem similar to yours. We have about 7800HDD and several nights a year that go to -10F or lower. The cove heaters high on wall location means we have freedom of furniture placement and no pet hair to remove like baseboard or the wall panel types. And little hands can't touch them. Visually, they are less obtrusive than wall cassettes for ASHPs and dead silent.
DC has correctly noted the very KWH hungry nature of radiant, but you are only seeking supplemental heating when the ASHP is at its lowest COP. Of course if the ASHP craps out or freezes over than at least you have survival heat. Allowing for panel space will be your biggest concern if mixing the two heat sources with all electric appliances. Separate thermostats would limit their activity as needed.
I fully support the new ASHP tech that provides decent COP levels down to zero and beyond and would have gone a mixed route IF I hadn't been building before such units existed. I am also at a high enough altitude that de-rating of all traditional appliances factored into my final choices. More notes on how things are 10 years on, if you like.
https://www.radiantsystemsinc.com/