I recently constructed a 900 sq ft garage attached to my house with an additional 900 sq ft addition above it. I installed 3 300 ft loops in the garage floor for radiant heat. The ceiling of the garage has 20 inches of cellulose and the 2x6 walls are filled with cellulose. The addition above was spray foamed and its ceiling has cellulose with an R60 value. The upstairs is heated with the house's HVAC system. Because of the great insulation and the fact that the heat from the house is transferring somewhat to the garage, the garage stays pretty warm. Coldest temps in the garage have been 44 but it was during a week long cold spell where temps were below zero for several days. All that said I am now trying to figure out what to do for heating the floor. My house is all electric so if I want to go gas it will have to be propane. I know gas will be cheaper but I would really like to stay electric. My original intent was a 10 kw electric boiler but since the addition was completed and the new heat pump with 12 kw of back up heat was installed, our electric bills have risen to over 300 bucks a month. I can only imagine what a 10kw boiler is going to do. I have considered a 10 gal electric water heater with a 4.5 kw 220 element in it. Anyone have any thoughts on this as to if it would work or not. I have also considered a point of use electric water heater of about the same KW rating. I guess in my mind a watt is a watt so why does it matter if it is a boiler or a water heater. Also I am only looking to keep the garage about 55 so that is only a 15 degree temp rise at most. My 3rd option is to install propane, something like the takegi jr. I have access to 100 lb propane bottles for basically free. I like this option the most but I believe they only contain 20 gallons of propane. I fear that I will constantly be swapping bottles. Any insight is greatly appreciated especially from those that are running electric systems.
Radiant floor heat options
- Thread starter burhead
- Start date
My garage is larger and well-insulated, with six loops totaling approx. 1300 ft. on one zone. After much study, I decided to use a system from Radiant Floor Company (www.radiantcompany.com) that uses an Electro Industries boiler. It's a straightforward installation and has been trouble-free. The boiler can be adjusted for different water output temperatures as well and the folks there were helpful relative to sizing and component selection.
Their site provides a good overview and discusses various available heat source options. I'm not affiliated with them and am a customer- just pointing you to one source with information that might help with your decision.
Good luck with your choice.
Their site provides a good overview and discusses various available heat source options. I'm not affiliated with them and am a customer- just pointing you to one source with information that might help with your decision.
Good luck with your choice.
It helps to know where you are located.
I have a heat pump in my 1000 sqft. house and am very happy with it. I am in SWPa and the pump rarely goes to the backup heat. That is when you are really spinning the meter. My electric bills are rarely over $150. When I take my total bill and divide by the KWHs used, it averages about .09 per KWH. What are your electric rates?
How well is the rest of the house insulated?
What temp do you want it to be in the garage? Or a better question is, what is the goal for the garage? Do you want it warmer all the time or just a few times a week when you are in there? If it is staying in the 40s why heat it at all? If you just need heat a few times a week, maybe just a hanging electric heater. That's all I have in my detached garage right now and it doesn't really affect my bill that much. I only use it when I'm going to be in there a few hours a couple times a week.
Any heat you put in the garage is going to reduce the load on your main heater a bit, but if you are heating the floor with resistance heating and that causes your heat pump to run less, it is going to actually cost you more.
I have pex in my detached garage floor and am currently adding solar panels as an experiment to try and raise the temp in there when the sun is shining. I am plumbing it so I can add an electric boiler in the future if I want it warm all the time.
Do you have a south facing wall where you could add solar? Again this all depends on what your goal is.
I have a heat pump in my 1000 sqft. house and am very happy with it. I am in SWPa and the pump rarely goes to the backup heat. That is when you are really spinning the meter. My electric bills are rarely over $150. When I take my total bill and divide by the KWHs used, it averages about .09 per KWH. What are your electric rates?
How well is the rest of the house insulated?
What temp do you want it to be in the garage? Or a better question is, what is the goal for the garage? Do you want it warmer all the time or just a few times a week when you are in there? If it is staying in the 40s why heat it at all? If you just need heat a few times a week, maybe just a hanging electric heater. That's all I have in my detached garage right now and it doesn't really affect my bill that much. I only use it when I'm going to be in there a few hours a couple times a week.
Any heat you put in the garage is going to reduce the load on your main heater a bit, but if you are heating the floor with resistance heating and that causes your heat pump to run less, it is going to actually cost you more.
I have pex in my detached garage floor and am currently adding solar panels as an experiment to try and raise the temp in there when the sun is shining. I am plumbing it so I can add an electric boiler in the future if I want it warm all the time.
Do you have a south facing wall where you could add solar? Again this all depends on what your goal is.
rburke65
Well-known member
We just keep asking the same question.....why would we need to know where he lived.......
Ok I am going to give you more info than you ever wanted. We are located in NW Iowa. Temps range from -teens to triple digits. The original house is an earth home and did not have a central HVAC system, heating was done in the past with baseboard heaters in 3 of the south facing bedrooms and a PTAC unit in the living room. All other rooms were unconditioned and stayed quite comfortable. I added on the garage in front of the old garage. This allowed me to turn the old garage area into living space, gain 3 stalls out the front of the house and an additional 900 sq ft upstairs. The original house was 1100 sq ft and it is now around 2200. The HVAC was great all summer with just the outside condenser cooling the house. Utility bills were about 15 bucks (about $220) a month more than when we had no AC. Now that winter has hit the heat pump does a great job when the temps are above 15 degrees. When the temp goes below 15 degrees the electric strips engage and we see the extremely high bills. Nothing I can do about it. Our electric rates average around .12 per kw. It is a tiered rate so the more you use the cheaper it is. As for the garage, I use it to work on projects in the winter or to work on the family vehicles. It is actually quite comfortable out there but I would love to lay on a warm floor while working on stuff. I am thinking of trying to keep the ambient temp around 50-55. Today it is 45 even though temp outside is 9. I know that heating the garage floor is going to help with heating the attached house, just trying to figure out the best way to do it.
anthony666
Well-known member
I only ask because he said he doesn't believe heat pumps work well in his area, then didn't say where that was, or what temps he is dealing with. Mine works great and if he said he lived next door to me then I would have told him there is something wrong with his system. Maybe someone who lives in Iowa with all electric heat will chime in and agree with him that heat pumps don't work well there. I don't see how it hurts to know where he is. It is just more info for us to try and help the guy.
Thanks for the input so far. I will see if I can find some info on doing a load calc. I had the local wholesale house size a boiler for me but it was done basically on the sq ft of the garage and didn't take into account the insulation or the fact that it was attached to the house. I was mainly hoping to hear from some with electric boilers or water heaters to see if their systems operate efficiently or if someone had figured out what had been added to their monthly bill. Also kind of curious how much propane the guys with gas water heaters are using. I wasn't bashing the heat pump, everyone is putting them in here but most have gas backup or like me, electric backup to supplement them when the temps get too low.