Questioning using Radiant vs Alternative
Last Post 06 Oct 2021 04:52 PM by sailawayrb. 2 Replies.
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kenmoremmmUser is Offline
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06 Oct 2021 06:29 AM
I'm building a house in the Canadian Rockies near Kimberley, BC. House will be about 3700SF (too big, I know). 1900 on main, 1800 in basement. Call it roughly a 50'x40' footprint. Ceilings are 9ft for the most part, with more like 11ft for the living room. Basement will have ICF walls and house will be likely built to BC Step Code 4+ level.

All along, I have been thinking of hydronic floor heating for the house as I once lived in a house with that system and loved it. I still need to read these articles (https://www.greenbuildingadvisor.com/collection/radiant-floors), but my understanding, now, is this may not be the best approach. Instead, I have seen many recommendations for a combination of hydronic heating, ATW heat pumps, minisplits, etc. I am totally throughly confused now!

Gas rates are as follows: https://www.fortisbc.com/accounts-billing/billing-rates/natural-gas-rates/residential-rates. Electric rates are as follows (https://app.bchydro.com/accounts-billing/rates-energy-use/electricity-rates/residential-rates.html)

Other variables: We are debating on whether to install solar. Our location is very sunny (for BC) and our house is well positioned to capture a lot of south facing light. A logical size panel grid that would fit on our roof is an 11.88kW system which is estimated to produce 13,044kWh/yr, assuming panels are snow covered during winter months. We are also debating on natural gas fireplace vs EPA certified wood fireplace/stove (secondary heat, not primary).

Obviously, if we go with solar, then we would try to get off natural gas as much as practical. Our builder, who lives nearby and recently built his own house, has 3600+ SF of space (smaller footprint) and he has a 139000 BTU/h 40.7kW condensing natural gas heater. His house was just assessed at Step Code 4 with a rated consumption of 88 GJ/year (61 from NG, 27 from electricity). I expect my house will have slightly better air tightness and windows, but since it's bigger with a larger footprint, will likely have less overall efficiency.

So, the million dollar question: what do I do?

I like the idea of an electric boiler, but to get the same energy output, it seems like we'd be looking at three 14.4 NextGen models. Alternatively, I know I have read that instead of the boiler, we should use a heat pump like Arctic or Nordic. And, we could supplement either system with minisplit units (which I'm not really a fan of). So confusing to know the best choice. Help!
newbostonconstUser is Offline
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06 Oct 2021 10:46 AM
I am from Michigan and the only way to heat is with Natural Gas if it is available. I have done two houses with radiant floor heating throughout. First one was R19 wall R38 ceiling and the floors were toasty warm keeping the house warm. New house is R30 walls and R80 ceiling and the floors don't heat up that much to keep the house warm thus they don't feel warm but aren't cold. I have radian on all floor and have had to turn off in the walkout(50% exposed)basement floors because it gets to warm down there. Radiant floor heat both up and down so the main floor heats everything it was a waste to put it in the basement. I put in 2 inches of foam under the basement floor.

ICF basement is a waste if you don't take it to the roof in my opinion. I have 10k of solar and 30kWh of batteries and haven't' paid and electric bill since install.

We have the option heating with Geo(we use it to air condition) but the cost to heat on natural gas is 80% or the cost to run the geo, I have done extended tests on this running both ways. But may add more solar to also heat more.

Electric boiler is going to be 4 times the cost to run if you have natural gas. Electric is 100% efficient but cost 4 times the money to run. Hope you understand this.

I do think you Canadian peoples....do make better window then US idiots....We bought Inline fiberglass windows out of Toronto.

Wood stove is always better then Gas. We have a Supreme Duet duel sided fire place and love it. It can be ducted to rooms if you want. We heated one season with it and saved $300 in heating but bought $1000 in wood....wasn't worth it.

We are 3700 sqft on main level and same in basement.

Mini splits are nice in you don't mind the look of them but no mater what they say (in your area) they wont be cheaper then Natural Gas on the cold days but can air condition for you. So maybe a combination of heated floors on the main level and mini splits in some rooms.
"Never argue with an idiot. They will only bring you down to their level and beat you with experience." George Carlins
sailawayrbUser is Offline
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06 Oct 2021 04:52 PM
After too many years of getting this same question from many people, I have concluded that there isn’t any one best answer. There are both local economic issues and personal desire issues that must be determined and carefully considered. The economic issues are the easiest to sort out. You will need to run the numbers to determine the annual operational cost of each potential heat source option for your specific locality using calculators like these that fully and properly consider your building heat heat loss, your local heating degree days, your local fuel costs and each potential heat source option COP (Coefficient of Performance):

Heat Loss Analysis Calculator

Integrated Heating System Performance Calculator

Gas boilers have a COP between about 0.85 (non-condensing) and 0.98 (condensing) which equates to 85% to 98% fuel/heat energy conversion efficiency. Electric boilers always have a COP of exactly 1.0 which equates to 100% fuel/heat energy conversion efficiency. Air to water heat pumps have a COP as high as about 3.5, but which can be much lower under cold temp conditions. Ground to water heat pumps (often mistakenly called Geothermal) have a COP as high as about 4.5, but which can be much lower under cold temp conditions too. True Geothermal has a nearly infinite COP and I got to experience this while living in a home adjacent to a hot spring. Gas and electric boilers convert gas and electric fuel energy into heat energy. Instead of converting fuel energy to heat energy, heat pumps use and move existing heat from the outdoor environment to the indoor living space and thus don't perform nearly as when it is cold outside when there isn’t much heat available to be used and moved. You will need to carefully read and understand the performance characteristics of your potential heat source options to accurately ascertain their effective COPs and their associated annual operational costs for your specific locality.

In addition to determining the annual operational cost of each potential heat source option for your locality, you will also need to determine the total acquisition cost of each potential heat source option. Acquisition cost includes the cost of procuring the heat source option equipment, the local labor cost of installing the equipment and the projected maintenance cost over the equipment's expected lifetime. 10 to 15 years is a reasonable lifetime number to use. Longer is wishful thinking. Once you have this total acquisition cost number for each potential heat source option, you then divide it by its expected lifetime number of years and add this to the previously determined annual operational cost number. The heat source option that has the lowest total annual cost is the best choice economically. Heat pump systems often don’t pass muster in many locations when this type of detailed economic ROI (Return on Investment) analysis is done to fully and properly evaluate them.

In addition to the local economic issues, there are also personal desire issues to be considered too. Are you okay with how mini split heads look in your home? Are you okay with hearing the sounds of the heating system cycling on and off? Are you okay with the heating system blowing air around and creating drafts? Do you live in a remote area where having a complex and high maintenance heating system is problematic? Sometimes these personal desire considerations outweigh the economic considerations. Everything in life is a tradeoff, eh?

Having personally lived in homes with every possible heating system option, I feel I can say without any reservations whatsoever that hydronic radiant floor heating and masonry heaters are by far the most comfortable and pleasant heating options. If you don’t know about masonry heaters, you might find this useful:

Masonry Heaters

But there is a caveat about hydronic radiant floor heating that you also need to be mindful of and carefully consider too. In a highly energy efficient home, the floor surface temp will only be a couple degrees at most higher than the room thermostat indoor temp setpoint. So the floors will NOT be toasty warm…but they will never feel cold either. I will also add that if you are already doing new slab-on-grade construction, hydronic radiant floor heating using an electric NextGen boiler is by far the lowest acquisition cost heating system option than anything else.

The other thing that I will offer as a suggestion if you truly want a highly energy efficient home is to first make it one level (so you can totally control wall solar heat exposure with the roof overhang design), minimize the overall square footage, and minimize the window and door area, especially on the East, North and West facing sides of the building. Even the best windows in the world are far far worse in R-value and outdoor air infiltration than the worst walls in the world... Design the roof overhang and windows on the South facing side of the building to generate Winter solar heat gain and to reject Summer solar heat gain...this is called passive solar cooling/heating. Then maximize insulation and sealing to the point of diminishing return for your specific locality. If you don't know about diminishing return, there are people on Green Building Advisor that can explain this to whatever level of detail you desire. Don't bother or waste your time and money with trendy energy certifications. Just save your low cost utility bills which can be directly compared to other homes being sold in your locality. Maybe when you try to sell your home this will get your home sold quicker and for more money, but don't count on this as the majority of population is totally clueless about such things.

When we designed our current retirement home, we made it one level, constructed the walls using ICF, designed the roof overhang and windows for maximum passive solar cooling/heating, placed a masonry heater in the center of the floor plan and used an electric NextGen boiler as the heat source for our hydronic radiant stamped concrete floors. Full disclosure, NextGen Boiler is one of our affiliates:

NextGen Boiler

When you can get the required heat gain of your home down to a small number, the COP of the heating system becomes less important and the acquisition cost of the heating system becomes more important. We can heat both our Southern Oregon 2400 sf home and our separate 1600 sf garage/shop/guest quarters (ACCA Manual J 26F 99% Outdoor Design Temp) for under $30/month using a simple and low acquisition cost electric NextGen boiler which is expressly designed for hydronic radiant floor heating and avoids the additional acquisition expense and installation expense of needing a separate hydronic panel (controller, pumps, expansion tank, pressure differential valve, pressure relief valve, etc.). When we also use our masonry heater (via a 90 minute wood firing every other day), this drops to about $15/month. Given our low humidity, diurnal temp climate and highly energy efficient home, we don't need or have AC (ACCA Manual J 95F Outdoor Design Temp). Interior thermal mass, opening the windows at night and running the whole house fan for a couple hours easily keeps our home under 68F during the hot summer months even when we have a couple continuous weeks of triple digit temps reaching 110F. If we needed AC, a mini split system may have gone into our home too. Construction photos of both buildings may be found here if interested:

Borst Shop Construction Photos

Borst Residence Construction Photos

And having lived in large homes on smallish suburban property previously, I very much prefer a smaller, cozy, well-built home on a large remote rural property, especially as I get up in years and US population civility and IQ continues to keep decreasing.

Gayle
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
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