Trying to save with hydronic: failing spectacularly

9 years ago

I am building a 2-story home with developed basement in Alberta, Canada with fully developed basement (1300 sq ft), main floor 1500sqft, upper floor 1500. It has triple pane windows, R24 insulation. I also have 3 fireplaces (basement, main, and master bdrm).

From a plumbing perspective, it was spec'd with hydronic heating to basement and garage, and a Phoenix PH130-80 gal quick recovery tank.

Heating-wise, calculations came up with 74000 total BTU / 86000 output BTU for the main floor and basement, and upper floor 50000 total BTU / 67000 output BTU, so I was spec'd with two Lennox Elite furnaces, a 90000 BTU and a 70000 BTU.

Since installing in floor heating was $3/linear foot, my plumber estimated doing the whole main floor would cost roughly $5800 for two zones. I said yes, since modeling figured I'd save $$ from utilities within 10 years.

But then my Phoenix tank was borderline, so I needed a boiler upgrade to the Buderus GB142-45 = $10,000.

I called the heating companies to see if I could downgrade my furnaces now that I have added another floor of in floor heating and he recommended that I keep the furnaces the same! He said all the duct work rough-in has to be in anyways for future AC, and even if I downgraded to just an air exchanger (no heating component), I'd save something like $2000 only, so it wasn't really worth it. Plus having a backup is nice in weather like Alberta.

Then he pointed out I needed a steam humidifier to make sure my engineered hardwood does not dry out due to the radiant heating = $1800.

And convinced me on the optional HRV = $3000

And a Lennox XC14 for the upper floor only = $4500

Questions:

1. Do you agree that I can't downgrade my furnace now that I have radiant heat? This doesn't seem right, but will downgrading actually result in significant savings?

2. What is total BTU vs output BTU and which one do I use to select the furnace? I'm guessing the output BTU.

3. Can you find anywhere to save money in this scheme?

It seems like the Buderus is too expensive, but I can't find Canadian prices for the boiler (I can order it in US for $5000).

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Comments (6)

fsq4cw
9 years ago
Is all the radiant installed?

Had you considered radiant in-floor with a geothermal heat pump and gas boiler backup?

SR
jackfre
9 years ago
It is hard to save when you did not start with a firm plan. With the radiant, which you will enjoy, I would not use gas furnaces and ductwork. Mini-splits would have been the ideal compliment to your radiant system. The HRv is a good idea and if I am not mistaken, code in Canada. Canada's ventilation standards are light years ahead of the U.S.' Buderus make excellent boilers. I had one in my last house.
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dprae
Original Author
9 years ago
Thanks for the comments. Actually, the whole I idea of me posting is so that I *can* come up with a firm plan before I sign the contract. Nothing is built yet, sorry if I didn't make that clear.

I looked into geothermal extensively, but decided against it. I read an analysis for my specific area and in the end it did not make economic or environmental sense at this present time. (Briefly, it relates to electricity being generated by coal, and cost of electricity vs gas).

Another issue cropped up while I was researching. We were hoping to have nice carpet in the upper and basement floors, hardwood in the main. Not the idea hydronic flooring I realize.

At this moment, I'm leaning towards the advice of just doing all hydronic heat for the whole house, the HRV, and rough in A/C ducting. I'm counting on the HRV to circulate all the warm air around (in case the carpeted areas are too cool, which I don't think will be likely). Fireplaces as backup.

I'll post some scenarios and cost/benefit analysis for others to consider later on when I run some calculations.
jackfre
9 years ago
You are in Alberta. I'm assuming much of your elec is hydro, correct? I know that BC Hydro is looking at a 30% increase in rates over the next two years. Check out the projections in your area.

I would suggest that you evaluate the mini-splits over your ducted system. They are much more efficient and you have absolute zone control. IF you go with ducting make sure you watch the pressure test being done on that new duct system.
dprae
Original Author
9 years ago
I looked up the ductless mini splits - looks awesome! Using this plus zones radiant in floor heat, I can pretty much have separate zoned heating and cooling, and the option to add more cooling units if needed.

I wasn't quoted on the ductwork, but do you estimate the extra cost of 3-4 mini splits would offset the rough-in plus AC of the central system?

Do you recommend going completely ductless and furnace free then? The hydronic heating plus fireplace backup (and mini split back up to a lesser extent) will take care of heating?

What are the options regarding humidity then? Can a humidifier be tied in to HRV?
ionized_gw
9 years ago
I just want to pass on the thought that I understand that if you have pets, you need to make provision for them to find a resting place off the radiant floor.