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Thread: Inefficient radiant heat setup?
02-01-2005, 03:43 PM #1Regular Guest
- Join Date
- Feb 2005
Hopefully you guys can figure out my problem...
I built a new 2-story home last fall. I have an electric furnace coil which I use as my primary heating source for all 3 levels of the house. I also have an 84% efficient gas boiler which is used for my domestic hot water and for 4 radiant heat zones:
upper garage ~900 sq ft
lower garage ~900 sq ft
basement ~1600 sq ft
exercise room ~150 sq ft
I also have a gas fireplace, gas cooktop, and Aprilaire humidifier on the furnace air return with is tapped into the hot water.
My problem is that my gas bills this winter have been higher than what I was expecting. My first 2 gas bills were:
121 CCF from 10/13/04 to 12/14/04 (1.95 CCF/day)
176 CCF from 12/14/04 to 1/17/05 (5.18 CCF/day)
I have been using the electric furnace coil since we moved in so I wasn't expecting this kind of usage during the winter. I thought the in-floor heat would be fairly efficient/inexpensive but it doesn't appear so. The thermostats on all 4 radiant heat zones are set low enough so they only kick-in when the outside temps are below zero which has only been about 10 days this winter. We have been using the fireplace maybe about 10 hours a week and the gas range for maybe 5 hours a week.
The humidifer is hooked up to the hot water and it has
been running a lot this winter, but I wouldn't think that make the boiler kick-in too much for the hot water supply, would it?
I called the plumber who installed everything and he couldn't really think of anything except for possibly trying to hook the humidifier up to cold water.
Since the radiat heat hasn't been used much since its been a relitively normal winter I'm leaning towards the humidifier as being the source of the problem but I don't know, are there any boiler setting or other configurations I could try?
Thought it would include my location, but anyway, I live in Rochester, MN
[Edited by nixima on 02-01-2005 at 03:45 PM]
02-01-2005, 07:54 PM #2
How warm do you have it set up in both garage? I am sure that's where your higher useage is going to.. That's alot of floor space to heat.
Also, Why are you use electric heat for your main heat, and not the hot water radiant heat? Or Does RPU give you a "break".
02-01-2005, 09:20 PM #3
I would defintiely connect the humidifier to cold water, because it makes more sense to do that, but I doubt that is your high usage point.
I'm thinking the garage, too, like mayguy.
Also, is your domestic hot water coming from the boiler? Doing a lot of laundry? Taking a lot of showers? Filling the jacuzzi, etc????
What was the average outdoor temp in the first bill, compared to the second bill? You're in Minnesota. I'm thinking that it wasn't that cold during the first bill...
02-01-2005, 09:25 PM #4Regular Guest
- Join Date
- Feb 2003
I hope those concrete slabs are insulated, or the earth is gonna be sucking the BTU's out of your radiant system faster then what's going into the living space. Garages are not the most well insulated parts of a home with that big garage door. What temp to you keep the garage at?
02-01-2005, 09:31 PM #5
I looked closer on my Aquila bill, it don't say temp avg.. I know when I was w/ NSP, they printed temp avg.
I have feeling the garage is what costing you the most for gas usage.
BTW, I am in Rochester as well.
02-02-2005, 09:24 AM #6Regular Guest
- Join Date
- Feb 2005
Hi, thank you for the responses!!
It is true that the temperatures have been colder during the second bill but I was thinking since I have been using the electric coil (20KW Electromate with WarmFlo controller) that my gas usage shouldn't change very much. I am trying to use the electric for the furnace as much as possible because I think it is cheaper than using gas since the power company gives me a deal on the electricity through the dual fuel program.
I have the lower garage set to 58F and the upper garage set to 50F. Both garages are fully insulated and the in-floor lines were installed on top of about 2" of pink styrafoam insulation. I check the thermostats regulary and they are usually always at about 3 degrees higher than the set point. So I don't think the in-floor is running very much.
My plumber is stopping over today to change the humidifier over to cold water and he is going to check the boiler and mixer valve settings.
My boiler is used for my hot water but it is only me and my wife in the house and we haven't been using an excessive amount of hot water besides the humidifier.
One thing I noticed last night was that the WarmFlo controller on the Electromate has an Efficiency adjustment on it with ranges from A to G. "A" is labled as most efficient and G is labled as least efficient. There is also a setting below G with says "Full Electric." I have been running at setting "E." I'm not exactly sure how this works. I'm thinking that setting A uses mostly gas and setting G uses mostly electric. Can anyone verify that this is true?
I'm thinking I will have to keep messing with these Warmflo settings over the years in order to figure out which setting is the most cost effective. I'm thinking even if I use the most efficient setting "A" that it might not be the most cost effective because it uses less electric which is probably the most cost effective.
02-02-2005, 04:15 PM #7
For the other part of the house that don't have radiant heat and uses the air handler for heat, is it an air handler with electric strip heater, and a hydro coil?
What kind of rate is RPU giving you or are you on People?
02-02-2005, 04:21 PM #8Regular Guest
- Join Date
- Feb 2005
mayguy- I have an electric coil in the furnace plenum (sp?) I believe it is called Electromate or something. I'm not sure if you would call this a strip or not but there is noting hydro (water?) about it.
My power company is Peoples. I think the normal electricity rate is something like 0.74 and the duel fuel rate is like 0.34. I know it more than half the normal rate. I can get the exact numbers if you want them?
02-02-2005, 07:39 PM #9
Most radiant systems use a considerble amount of fuel to get the mass to temp, but once at temp they don't use much fuel to maintain the temp.
It sounds like your using the radiant as second stage heat.
We have a couple in, where the radiant system can't handle the load at design temp, we have hydro coils in the air handlers as second stage heat, they love it.
Radiant heat should be set and left to do its job, not turned up and down.Contractor locator map
How many times must one fix something before it is fixed?