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Old 01-09-2020, 07:08 AM   #1
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Radiant Floor Heating: Electric vs Water Retrofit


Which do you think is better on the matrix of efficiency, comfort, and ease of install?

My husband has recently gotten it into his head to install Ditra-Heat electric in the kitchen, dining room, and office because he thinks it'll be easier (and maybe cheaper since we can install it ourselves,) than installing the water radiant conversion we've been planning forever.

I think it's going to be massively expensive on the electric bill, plus I don't think it's that much more work to do the "real" water installation given the stuff we're already planning to do[listed below for those interested.]

My husband says I'm biased and being "unfair" to just doing electric in the kitchen/dining room and leaving the rest baseboard... He might be right, I complain about the baseboards a lot when I'm decorating; they take up valuable [floor] wall space and end up covered by furniture so they don't seem like they are very efficient.

I say my husband's biased, because he's making excuses to do "less work" and because he feels that the retro-fit between the joists (aka "not embedded in cement") version isn't nearly as efficient as I think it is.

HALP!!



-----

Various factors: Years ago we put in a new [NatG] boiler, intending to convert the house from baseboard to radiant floor heating (via water.) We have 4 zones set up at the boiler to do hard flooring and soft flooring down, hard and soft up, and there's "capability" to put in zones for the garage floor and/or driveway area / walkway (we hadn't decided so the installer just left room.) We do not have the manifold thingy yet.

Currently, we have no baseboard's in the entire back half of the house (removed baseboards in the kitchen for a remodel, removed 90% of the baseboard in the dining room, and there's a single strip of baseboard in the office that'll be removed when we install a french door this summer or next.)

We haven't removed any upstairs baseboard. However, the only downstairs ceiling we weren't really planning on taking down anyway is the game room, but I've already got my husband doing a bunch of wiring in the ceiling for a pool table light and some other stuff in there (via removing the upstairs room's sub-flooring ATM.) I'm even making my husband completely redo the stairs because the risers are uncomfortably high.
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Old 01-09-2020, 07:24 AM   #2
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Friends had a house, 5000 sf all done like this with insulation below it, they never complained about anything to do with it.



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Old 01-09-2020, 10:54 AM   #3
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Efficiency – Based on the Internet resources that I just referenced, Alaska has the fourth highest residential electric rate in the US, but if you’re only debating doing a few rooms, the extra operating cost for electric underfloor might not be significant. You could calculate what percentage of the house those three rooms make up and estimate what the extra electric heating cost would be. Something to consider is that if you go down this route and find that your electric bill spikes up there might be some “thermostat conflict” in the household. If it’s more of an “open concept” house with fewer walls, the more dollar conscious person might want to turn down the electric heat and let natural gas generated heat flow into the kitchen, dining room and office at the expense of it not being as comfortable in those rooms as the other person might want.

Comfort – I can’t think of a reason why electric or hydronic underfloor heat would be different, except if one cycles on/off more than the other. Something that provides more constant heat to the floor would provide a more comfortable heat to the occupants.

Ease of install – there are a few different ways to do hydronic underfloor heat, but I suspect that they are all going to be more work than electric. We’ve recently completed expanding (ourselves) the hydronic heating system in our house to the main floor, under tile and floating engineered hardwood. It was a lot of work. Photo below. We didn’t do the “between the joists” method that you mentioned, opting for this method that puts the tubes closer to the space intended to get the heat.

The one factor that you haven’t mentioned that would be a big one for me is reliability. I’m very confident that the tubes that we just installed in the floor will last for decades (barring me doing something silly with a drill or nail gun). I wouldn’t have that same confidence in electric resistance heating mats, but I’ll admit that I have not researched that at all, since we excluded that option based on operating cost. It would be good to do some research on their reliability.

We switched from baseboard heat to underfloor heating and the difference in comfort in the house is significant, especially in the lower story with a concrete floor. Everywhere is comfortable now, instead of it being nice by the baseboard heaters and colder further away.

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Old 01-09-2020, 12:53 PM   #4
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Stay away from electric resistance heat!

Once the power plant losses are taken into consideration it's the least efficient way to heat out there and the cost of operation reflects that. Unless you're near 100% hydro.

Only acceptable way to heat with electric is to run a heatpump and alaska is probably too cold for even cold climate units.

Burn gas.

If your baseboards are electric now, at a minimum put in hydronic instead. Cheaper than in floor but not as nice looking.
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Old 01-09-2020, 01:47 PM   #5
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Even though I ask a bunch of questions about my system, I would never go back. I have installed electric and modified/re-routed/added to hydronic.

Unless I absolutely have to, I will probably never have any other heating system than radiant in my house. And radiant will always be in my house even with GFA. Even if it is retro-fitted in.

And, I won't go into efficiencies, costs, etc... others will be along to do that. And to tell you not to do it. F-Em. (I get REAL feisty when I am sick and I still on the tail end of it)

Mystriss. Hold your guns. As @user_12345a stated, and unless you and hubbie are both independently wealthy or have your own source of unlimited electricity, you will be better off with going with NG hydronic.

I love electric radiant. When used properly. When you aren't already set up for NG Hydronic. When you want spot heating. When you can't reach the area easily....

On another project, I did a 10x14 room with radiant wire and it turned out great. I did a bathroom room with radiant mats. Another with radiant wire. And I will be doing the bathroom in my current home with a radiant mat as it will be too hard to do with hydronic tubing.

But, in the front hall/ laundry room, I will be retro-fitting with the tubing.

It is all staple up.
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Old 01-09-2020, 04:19 PM   #6
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Re: Radiant Floor Heating: Electric vs Water Retrofit


I will pass all this onto my husband and hopefully he'll come around.

We happen to be near Anchorage, which has a hydro electric plant (plus natural gas power plant and a wind farm,) so we run about $0.14/kwh I hear that's about 13% or so higher than the national average. None-the-less we already spend over $500/m on electric just for the appliances, computers, and lights. The NG bill is $188/m level pay (roughly $20-50/m in the summer and $250-300/m in the winter)

@user _2345a ick electric baseboards gotta be the worst thing ever... Ours are water baseboards. The "copperpus" as I call her [pic attached so that name makes sense], is absolutely brilliant and we've never once regretted the huge price tag for installing it.

@Nealtw I sure wish we had those Ibeams... looks to be what 16" tall? Unfortunately, we're gonna have to fit our radiant tubes, baffles, and insulation into traditional 2x10 16OC lumber joist spaces >.<

@Chris616 so what did you do over the tubes there? Cement? That's the part my husband /really/ doesn't want to do. I hear it holds the heat so your waters not constantly running, but I'm not sure we wanna put a bunch of thin cement floors in the house with the earthquakes - both the 4-6" thick slabs in the garage & shop have cracked pretty bad (not thick enough). The one in the shop actually split in half during the big 2019 quake so we're probs going to have to practically demo the shop to fix it >.<

@ktownskier I can't wait for radiant! I've been looking forward to it since right after we bought the place in '02, back when the tech was still new heh. Alas, my husband was working 3, sometimes 4 jobs, up until just last summer and we've had to do a bunch of other [often unexpected] remodel/improvement projects first. We're finally almost there though \o/
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Old 01-09-2020, 04:22 PM   #7
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Baseboards are radiant as is.

Anyhow, 14 cents per kwh is way too much to consider using electric resistance heat. I would say 5 cents, absolute max.

What kind of heat does the kitchen have now? To me, extending the hot water system be it rads or in floor sounds like the only reasonable option.

Doesn't necessarily need to be in-floor.
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Old 01-09-2020, 04:45 PM   #8
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Re: Radiant Floor Heating: Electric vs Water Retrofit


@Mystriss

The house I spoke of was all 2x10 and the pipe was about 1 1/2" below the sub floor.

When they did the hardwood they were afraid of damage to the pipe so they glued the floor down.
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Old 01-09-2020, 05:02 PM   #9
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Quote:
Originally Posted by Mystriss View Post
I will pass all this onto my husband and hopefully he'll come around.

We happen to be near Anchorage, which has a hydro electric plant (plus natural gas power plant and a wind farm,) so we run about $0.14/kwh I hear that's about 13% or so higher than the national average. None-the-less we already spend over $500/m on electric just for the appliances, computers, and lights. The NG bill is $188/m level pay (roughly $20-50/m in the summer and $250-300/m in the winter)

@user _2345a ick electric baseboards gotta be the worst thing ever... Ours are water baseboards. The "copperpus" as I call her [pic attached so that name makes sense], is absolutely brilliant and we've never once regretted the huge price tag for installing it.

@Nealtw I sure wish we had those Ibeams... looks to be what 16" tall? Unfortunately, we're gonna have to fit our radiant tubes, baffles, and insulation into traditional 2x10 16OC lumber joist spaces >.<

@Chris616 so what did you do over the tubes there? Cement? That's the part my husband /really/ doesn't want to do. I hear it holds the heat so your waters not constantly running, but I'm not sure we wanna put a bunch of thin cement floors in the house with the earthquakes - both the 4-6" thick slabs in the garage & shop have cracked pretty bad (not thick enough). The one in the shop actually split in half during the big 2019 quake so we're probs going to have to practically demo the shop to fix it >.<

@ktownskier I can't wait for radiant! I've been looking forward to it since right after we bought the place in '02, back when the tech was still new heh. Alas, my husband was working 3, sometimes 4 jobs, up until just last summer and we've had to do a bunch of other [often unexpected] remodel/improvement projects first. We're finally almost there though \o/
Thanks for this picture post. It answers a cost question I've long had about that type of heating system that shunned being answered. I can now see the copper is of more value than our complete heating and cooling system with in floor PVC ducts. In this instance a pic is worth way more than a 1,000 words.
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Old 01-09-2020, 06:41 PM   #10
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Quote:
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@Chris616 so what did you do over the tubes there? Cement? That's the part my husband /really/ doesn't want to do. I hear it holds the heat so your waters not constantly running, but I'm not sure we wanna put a bunch of thin cement floors in the house with the earthquakes - both the 4-6" thick slabs in the garage & shop have cracked pretty bad (not thick enough). The one in the shop actually split in half during the big 2019 quake so we're probs going to have to practically demo the shop to fix it
“Gypsum concrete” is the thing that you’re referring to. It’s applied like a thick soup over the tubes and is supposed to float out to a flat surface. The floor structure and other things in the house really needs to be planned for that beforehand because of the thickness (1.5”) and weight (15 lbs/ft2).

We got a quote from a contractor for designing the tubing layout and installing this product.
https://www.rehau.com/download/87257...pport-tool.pdf
The price was a lot more than we were wanting to spend, for some plywood with aluminum adhered to the back side (which to my thinking puts the aluminum on the wrong side of the plywood).

In the end, what we did was:
- Used some software to design the tubing layout.
- Took up the old hardwood flooring and (fortunately) poorly adhered tile down to the original plywood subfloor.
- Laid new 5/8” plywood on top of the subfloor.
- Used various jigs and straightedges to router 2300 feet of groove sized for ½” PEX (and it didn’t kill my router).
- Installed the tubing into the grooves.
- For the bathrooms/mudroom/pantry we laid Schluter Ditra and tile.
- For all other spaces we first laid a layer of aluminum to help pull the heat from the tubes (picture below during installation), then installed a floating engineered hardwood (each piece is glued to its neighbour, but nothing is glued or nailed to the floor).

Chris
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Old 01-09-2020, 11:41 PM   #11
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Quote:
Originally Posted by SeniorSitizen View Post
Thanks for this picture post. It answers a cost question I've long had about that type of heating system that shunned being answered. I can now see the copper is of more value than our complete heating and cooling system with in floor PVC ducts. In this instance a pic is worth way more than a 1,000 words.
Yeah, we paid $10-12k for that setup back in 2004. That said, we don't regret a penny of it and I'm fairly certain it's paid for itself by now on energy savings, more so given the comfort levels (like we don't run out of hot water - and I like my showers on max hot for an hour)
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Old 01-09-2020, 11:43 PM   #12
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Re: Radiant Floor Heating: Electric vs Water Retrofit


@Chris616 I like it a lot, way better than the push up baffles, and I think it'll fit into our plans perfectly; I'm replacing all the 1/2" sub-flooring anyway. Time to go find a 1/2 router bit
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Old 01-10-2020, 12:01 AM   #13
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Re: Radiant Floor Heating: Electric vs Water Retrofit


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Baseboards are radiant as is.

Anyhow, 14 cents per kwh is way too much to consider using electric resistance heat. I would say 5 cents, absolute max.

What kind of heat does the kitchen have now? To me, extending the hot water system be it rads or in floor sounds like the only reasonable option.

Doesn't necessarily need to be in-floor.
There's no heat sources at all in the kitchen or dining room - we removed the baseboard's (two shown in the first pic there) during remodeling probably 10 years ago:

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Radiant Floor Heating: Electric vs Water Retrofit-img_1191.jpg Radiant Floor Heating: Electric vs Water Retrofit-img_1190.jpg
This is the remodel the 7.0 quake did last winter - all my rice on the floor
Radiant Floor Heating: Electric vs Water Retrofit-20181130_105534.jpg
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Old 01-10-2020, 04:50 AM   #14
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Re: Radiant Floor Heating: Electric vs Water Retrofit


Electric is easier and cheaper to install.

Gas will provide the same or better comfort, and not require a loan to pay for its operating cost.

Electric resistance heat is just too expensive to use.
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Old 01-10-2020, 09:57 AM   #15
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Re: Radiant Floor Heating: Electric vs Water Retrofit


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@Chris616 I like it a lot, way better than the push up baffles, and I think it'll fit into our plans perfectly; I'm replacing all the 1/2" sub-flooring anyway. Time to go find a 1/2 router bit
Before you launch into anything, something to consider is the water temperatures required for different types of heating. Your existing baseboard heaters, because of their small surface area, need fairly hot water supply. The type of loop layout that we did has a high surface area so doesn’t need high temperature water (and hardwood flooring doesn’t want that anyway). If you maintain both types of heat emitters you’ll need a way to produce two different water temperatures. Here’s an article from the guru of hydronic heating on that subject.

Chris

https://www.pmengineer.com/articles/...eating-systems
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