Electric Radiant Floor Heating Under Brick Floor?

bluestore123

Hello all,

I am converting a street facing garage into a storefront and am in the proccess of taking out the current gravel ‘floor’ and replacing it with a hand laid brick floor made out of old reclaimed bricks. I already converted the first about 1/4 of the floor into bricks some months ago, and getting ready to finish the rest of the floor, am thinking about different heating solutions for the space. The house that sits atop the garage is heated by a gas powered water radiant floor heat system which works very well and is very efficient $$$ wise. The space is in NYC (cold east coast winters, expensive electricity).

I thought briefly of laying some pipes in trenches under the bricks and connecting it to the current system but was advised that it would be pretty complicated and potentially quite expensive with a plumber. My next idea, in an effort to find a solution with a relatively cheap initial install cost, but also long term economic efficiency, was electric radiant floor heating matts, or something similar (ditra?), under the bricks. I would only be doing this on the remaining 3/4 of the floor as I do not want to dig up the bricks that are already down.

The space is about 300 square feet total, and not that well insulated currently, but I am also going to be working on that. I laid the last section of bricks with sand over some fine gravel/dust, and then filled it in with a sand heavy concrete mix. My main concern is if the heat will permeat the brick and heat up the space and to what degree. And I wonder if I would be able to do this myself with some internet guidance or would need to hire someone (which I am not opposed to).

I am mostly looking at radiant heating solutions because I am under the impression that they are more efficient. The easiest would probably be some kind of electric baseboard heaters, but I have been told they are very inefficient and the space is in NYC which seems to have some of the highest electricity costs in the country. I also read about radiant wall heating but I think that is supposed to go behind the drywall from what I can tell, and is a little less feasible. I even thought about a wood burning stove but I’m not sure thats the most practical (or legal)- maybe as an add-on later if it’s actually possible.

You can probably already tell but I am not technically versed regarding any of this stuff and am pretty much learning everything as I go along, although I get some help from the landlord/family member who built the house which the garage is a part of. Any kind of input/advice/ideas are much appreciated! Thank you!

Hot_water_fan

I am mostly looking at radiant heating solutions because I am under the impression that they are more efficient. 

This isn’t true. 

Electric baseboard is the easy answer here: yes, it’ll be expensive to run, but the initial cost is so low and if the space is small enough, who cares. A solution that gets you cooling too, like a ductless mini split, would be more efficient than resistance heat. 

jesmed1

For retail space in NYC you are definitely going to need AC in the summer, or you will be out of business in a hurry. Take @Hot_water_fan's advice and install a ductless mini-split that will give you heat in the winter and AC in the summer. Yes it's more expensive up front, but without AC you will be regretting it next August.

EdTheHeaterMan

You will need to place 2” hard foam insulation below the radiant heat mats, otherwise you will be sending a lot of that heat into the ground. Radiant heat goes in all directions (Think the rays of the sun coming DOWN from the sky). If you don't insulate, and just place the radiant heat mats on the base material, you can expect to pay 3 times as much to heat the floor thru that 2.5" of brick. I like the Mini Split idea, along with some electric radiators if you need auxiliary or supplementary heat.

bluestore123

Thank you everyone for the responses, I really appreciate it! I had not thought of it, but a mini-split system does sound quite appealing because it can provide both heat and cooling and I do plan on being in business through a few seasons haha. I also have a friend that is a newly minted HVAC technician so I am going to ask him for advice and see if I can possibly get a deal on installation. My advisor/landlord/family member who built the house still thinks that an electric radiant system would be the way to go for efficiency and ease of installation, and I kind of am inclined to agree, also because it is a 'nice' form of heating. Except that we really are not that knowledgeable about it and if I actually did need to install foam insulation below the heating wires I would definitely not go in that direction. He was suggesting just stapling(?) heating wires down into the ground instead of using a mat, but I have no idea if that is feasible. And I will probably go with an electric baseboard for supplementary heat if needed but they seem be very inefficient/expensive in NYC (just last winter using a small electric space heater pretty sparingly in my room the electricity bill supposedly was hundreds of dollars more than usual. I wonder if there is some kind of professional I could contact/consult with all the specifics of the situation and space to get some peace of mind because I would like to get started on finishing the brick floor as soon as possible. @Hot_water_fan @jesmed1 @EdTheHeaterMan

Hot_water_fan

My advisor/landlord/family member who built the house still thinks that an electric radiant system would be the way to go for efficiency 

They’re wrong!!! An electric radiant floor would use 3x the electricity of a ductless minisplit. Especially one that’s not insulated underneath! 

And I will probably go with an electric baseboard for supplementary heat if needed but they seem be very inefficient/expensive in NYC

Electric baseboard would be the same operating cost as electric resistance floor heating. 

bluestore123

@Hot_water_fan
If that is the case then I will definitely go with the ductless mini-split! I guess his rational was that it would take a long time but once the bricks were heated up they would hold/release the heat for a long time. And that it would be so efficient that any heat loss down into the un-insulated ground would not matter (also that heat always rises? lol). But I think these assumptions were based on the hydronic radiant heating he installed in the house which I guess is simply cheap because gas is cheaper than electricity. And it appears neither of us seem to know anything about the efficiency of different types of electric heating. Thank you!

Hot_water_fan

Ha yeah every part of that reasoning is wrong. But problem solved. Good luck! 

Ironman

 “I wonder if there is some kind of professional I could contact/consult with all the specifics of the situation and space to get some peace of mind because I would like to get started on finishing the brick floor as soon as possible“


You just had two very good ones give professional advice.

EdTheHeaterMan

And I will probably go with an electric baseboard for supplementary heat if needed but they seem be very inefficient/expensive in NYC

Electric baseboard would be the same operating cost as electric resistance floor heating.

It would be the same cost to generate the electric heat BUT, and this is a big

BUT

The electric resistance heater would be touching the ground below the brick floor. So the bricks will need to be heater by conduction. That is one of the three ways that heat moves from one place to another, and while it is conducted to the bricks above it , it will also be conducted to the dirt below it. See, heat that travels by conduction will heat anything it is in contact with. Think of an iron frying pan on the stove. The heat from the stove hits the bottom of the pan, that pan conducts the heat to stuff your are cooking inside the pan. It is also conducted to the handle of the frying pan. You don't want it there but you can't stop it from going there. So you use a pot holder to pick up the frying pan.

That heat also goes down the the splash guard below the electric element, and even further down to the top of the oven (if it is that type of stove) below it. So you will be paying for heating the dirt if you do not insulate then attach the electric element then place the brick on top of the insulation.

But you can check with the experts, like the landlord/advisor/family member who will not have to pay that electric bill. I'm sure they will offer the best advise. You know, since they are not paying for it.

bluestore123

@Ironman I guess I'm just realizing that you guys with thousands of posts on here might know a thing or two haha. I really do appreciate the advice!

@Hot_water_fan At the risk of beating a dead horse- If I go forward with a DIY Mr. Cool 9k or 12k btu mini-split system as I now plan to (is there any point in going slightly overkill with the btu's for a store with hopefully more than a handful of people in it at a time?), do you think throwing a few hundred dollars worth of electric heating line under the remaining bricks to use an auxiliary heat source might be worth it at all? As in stapled to the ground and covered with a sand concrete dusting then bricks. Or not really, given as you said it would probably just be the same electric cost as a baseboard heater (which is also easier and cheaper).

bluestore123

@EdTheHeaterMan Well I guess that pretty much answers the question I just posted without refreshing the page first, oops. It makes sense that there would be a lot of wasted heat/electricity if I do not insulate the ground. And I definitely want the cheapest and most efficient option because of course I will be paying for it. I guess I was just giving the radiant much more than its fair consideration because I am getting an extremely good deal on the space from the landlord/advisor/family member and they were, now I see misguidedly, very in favor of that type of solution at least in some part. Cheers and thanks for your time/insight!