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Heated Battle

February 7, 2013 |

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posted by Ana White

There's a heated battle going on up at the Momplex.

Or maybe I should say a battle over what type of heat system we should put upstairs in the Momplex.

Downstairs, in the bonus areas and the garages, we've got water tubing poured inside the concrete slab.  All we have to do to heat the downstairs is run hot water from a boiler through those pipes, and it will warm the floor, radiating heat throughout the lower floor.

But upstairs is where we are having the heated battle.

Originally, we had decided on baseboard heat because it's simple and cheaper.

image from Home Depot

I know, I know, not the prettiest option, but we liked the idea of baseboard because they would be quick and easy to install, and the heat system would react faster to temperature changes.  We have radiant heat in our garage, and it seems to be lethargic when adjusting to a heat change.  Coupling the downstairs radiant heat slab with the baseboards upstairs could give us the best of both, right?

Well, no.  What happens when you run baseboard heat is you have to run your boiler at a higher temperature.  This makes the system less efficient in the long run - meaning it will cost Mom more money to heat the Momplex than full radiant heat would.  

So we started thinking about installing radiant heat in the upstairs as well.  Then we would be able to run the entire boiler system at a lower temperature.

I know, I know, those of you who build professionally, you can say it .... you really want to plan for and install radiant heat BEFORE any other utilities, or at least plan for it to be placed over your subfloor.  It really is not ideal to decide to change your heat system this late in the game.

But here's reality.  Changing a heat system after finishing the Momplex, say a few years down the road when heating fuel is $6 or $8 a gallon, well, that's more than just not ideal.  It a full blown remodeling job involving ripping down drywall and running tubing.  The old saying "it's better late than never" is definitely true here.

So, we are doing tons of research, and it seems the options for radiant heat have really expanded in the last few years.  And our options for installing radiant heat upstairs have grown considerably.

Image from Comftemp

We could install the tubing under the subfloor between the rafters, and use aluminum heat transfer plates to transfer the heat from the water lines to the floor.  

Would the heat rise?  What plates would work best?

image from Healthy Heating

Or we could place the tubing on top of the subfloor in the aluminum transfer plates, and fill in the gaps with plywood.  The benefit here is the heat is directly under your flooring - not separated by subflooring - so the heat transfers more effectively to your warm cozy toes.

Is this better than below the floor?

Image from Glockzin Heating

On some installations, a thin layer of concrete is actually poured on the upstairs floors with the tubing, to create an effective means of transferring the heat out of the hot water in the tubes into the floor. 

And then there's the FlexPlate - which is graphite instead of aluminum, which is supposed to aid heat transfer even more.  Does it work?  Is it worth the extra $$$?

Image from Ultra-Fin

And then there's the Ultra-Fin, which works kinda like a hybrid between the baseboard heater and the radiant.  You snap the ultra-fins on your tubing, suspended below the floor, and it works like a baseboard, drawing the heat out of the pipe and heating the air space between the joists.  You then insulate the bottom of the joists and count on heat rising to warm your floors.  We love the Ultra-Fins because you'll need about half the tubing, which is half the work installing, and it will recover quicker (in theory) when we have dramatic temperature changes, but we can still run the boiler at a lower temperature.

Question is, will it work as advertised?

And that's the biggest question of all - will it work?  What system is better?  How will you know?  

We've been reading tons of reviews and doing research online, but at the end of the day, I just want to hear from real people what works in their homes for radiant heat.  

Lucky for me, I know you!  Do you have a radiant heat system?  What kind is it?  Do you love it or hate it?  Would you have done something different?  Do you have the Ultra-Fin system?  Does it work?  

Thank you so much for taking the time to comment and help us with this really big, and hopefully hot, decision!

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Comments on systems

Been through this with the engineer-SO while designing our house witn in-floor hydronic ... he does heat transfer equations in his sleep! We're collecting the heat from solar collectors, which is not possible for you, but once you have a tank of hot water it doesn't matter where it comes from.

In-floor heating, by its nature, is slow to react. You really have to "set it and forget it" for maximum efficiency, and use spot heaters as needed, electric blankets, or add and remove clothing to stay comfortable. For example, we're planning to have a separate loop control and lots of coils for the bathrooms so we can have toastier temps in there, and lower temps in the areas where we will be expected to not be naked in. And heat lamps in the dressing areas because I'm a wimp.

"Will the heat rise"? It's like gravity - it's physics. You CAN rely on the physics of heat transfer to work, no matter what in-floor system you use. Even a slightly warmer floor will warm up the air next to it, and it rises, taking the heat with it and more heat replaces it.

The only difference between having the coils under the sub floor (providing you insulate them against the lower temps in the garage and don't try to have it at living room temperatures) versus under the finish floor is that it will take longer for the heat to get to the surface through the thermal mass of the subfloor and finish floor. That means that if you are using a set-back thermostat you have to make the morning start time a bit earlier than you would. The flip side is that the floor cools off more slowly - thermal mass again - so you can have the evening set-back time earlier.

IMPORTANT: You aren't losing the heat in the floor - that violates the laws of physics - it's in there and will come out.

SYSTEMS: Unless you built the subfloor for the weight, you can't do the embedded in concrete stuff. Any of the other systems would work for you - so it's down to what is locally available, easy to install and cheapest.

We're looking at the PEX systems:
http://www.pexheat.com/

posted by Tsu Dho Nimh | on Thu, 2013-02-07 14:15

Heat rise

One more thought. Although the heat will rise, not so much as you would expect. Most houses are not air tight, most houses that fall into the super insulated category are. Most houses have convective air flow in the winter; cold air enters low, through the floor and void spaces like electrical outlets are connected to. This makes air flow inevitable as the hot air (more of an issue in forced air heating) rise. This warm air then seeks a way out via can lights, lighting fixtures and poor ceiling insulation details. Most authorities having jurisdiction mandate a vented ceiling insulation detail which encourages this convective air flow.
There is much less in a well insulated house. Some poorly designed houses seeking to remove these convective currents end up being a little stale inside and can suffer from moisture in the air.
An ERV or Energy Recovery Vent removes air from the house and moves the heat into incoming fresh air.
The super insulated house I built has a little air flow because of a Neanderthal approach the building department considered safe but I did what I could to minimize it. The heat was not on much on the second floor above 30 due to convective heat rising from the second floor.

posted by Gizmoredtoot | on Fri, 2013-02-08 08:44

Radiant plus radiators

We have radiant heat stapled to the underside of our first floor (no transfer plates, but we did insulate below the tubing- enough heat leaks out to keep the basement warm, but most of the heat is directed up), and we use European, flat radiators in the bedrooms upstairs. The radiators run at lower boiler temps- right now we have the water at 140 degrees (on the high end, but we found the system couldn't keep up on very cold days without the boost).

I love the radiant- we keep the thermostat around 65 and it feels just fine (we're in Maine).

The radiators in the bedrooms are on a separate zone and they really react quickly- we can keep the room at 62 for most of the day with the door closed, then before bed get the temp up to 68 in about 15-20 minutes. We let the room cool off overnight and the heat kicks back up to 68 before we wake up.

Buderus is one brand, but I know there are others. They're not especially expensive, they look pretty good and are compact. Here's a link: http://www.buderus.us/products/radiant-heat-products.html

posted by AdrienneB | on Thu, 2013-02-07 14:17

Heat

We have all three types, in concrete, under sub-floor, and between sub-floor & flooring, heating in our house in Wyoming. Since we are plumbing contractors, we wanted to see which gave off the most even, efficient heat. Under the sub floor is the least efficient in our house. There is often a 10 deg difference between the room it is used in and the other rooms of the house. We are planning to tear it up and re-install it with a layer of foam-board insulation, tin, then the piping. The foam insulation fits between the joists and keeps the heat transfer from going down, tin reflects up. Tubing here, will lay on top of the tin, since there is no way to attach it to the bottom of the sub-floor ( crawl space is not big enough to get into) We did not use baseboard since it would of meant running pipe on an outside wall.

posted by jinsin1 | on Thu, 2013-02-07 14:24
clips

More

This tubing claims "no special tools" - unlike PEX, and also claims no radiator plates needed. Staples up, with special staples, and has connectors that look like drip system barbs.

www.wattsradiant.com/products/onix/

posted by Tsu Dho Nimh | on Thu, 2013-02-07 14:27
clips

radiant heat

we have it throughout our house and i would definitely do it again. the floor doesn't "feel" warm (its just put right under our old wood flooring, with bubble insulation under) unless there's something on top the floor- like a peice of clothing or something- but its very even. you don't have cold spots like you do with baseboard. we use a programmable thermostat to turn it down at night and come back up in the morning. Love it.

posted by jlbarahona | on Thu, 2013-02-07 15:58
clips
jvos's picture

radiant heat in super insulated homes

I have been considering building a super-insulated home and was looking forward to having radiant floor heat. Through my research I found out that that type of heating system does not perform well in a super-insulated house (such as yours). I was greatly disappointed to say the least! Unless it is different due to the extreme cold in Alaska, I would do some more serious research before making the investment.
http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/radiant-...

posted by jvos | on Thu, 2013-02-07 17:04

Heat

Oh so many different ways to approach heat and insulating. If your house is well insulated you need very little heat to create a comfortable living space. Installing radiant heat in an existing space is costly and a pain the butt. It is only worth the effort in very few applications and I would look at wall mounted radiant heaters instead. These things are extremely efficient and much less costly than installing in floor heat. Also please don't listen to people who give advice based solely on research, or name drop a company rather than actual life experience. Every home is different and no one, without seeing your space and asking questions about your life style will be able to give you advice on how you should spend this kind of money. Have fun.

posted by RobRoy | on Thu, 2013-02-07 17:25
clips

Inapplicable advice

http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/radiant-...

Good article, however ... the author's concern about solar gain in the winter causing overheating doesn't apply in an Alaskan winter. It probably doesn't apply in Alaskan spring or fall either.

If you had been keeping up with Ana's project, the "existing space" is not a finished space - it's under construction. It's wide open to anything except a concrete embedded system.

The author's advice to spend more on insulation and better windows also doesn't apply: it's already insulated, sealed, caulked, etc.

posted by Tsu Dho Nimh | on Fri, 2013-02-08 11:37
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annalea's picture

Two options I've used.

We put radiant heat beneath the subfloor (just tubing, no fins or other metal) and laminate flooring, in the house we built in 2003-2004. It was a big house, with a huge vaulted living area (24' at the peak) and open floor plan. And really, the heat recovered really quickly. It wasn't as efficient as we'd been told, but I chalk that up to not having more thermal mass in the floor. It was lovely to have warm floors, though. I really miss that in our current space. (Hardwood floors get cold! lol)

Right now we've got Cadet's Soft Heat radiant baseboards. If you can work around the fact that they take up a lot of wall space, I really really like them. They're pretty darn efficient, provide gentle & effective heat, and no noise. With a good setback thermostat, I nearly never have to touch the settings (unless I'm pulling a late night, and want to keep the room warm, for instance). We're not heating much space--we've got one 6' SoftHeat in the bedroom (12'x16'), and one will go in the living/kitchen area (about twice the size of the bedroom).

If I had it to do again, though, (and money was no object) I'd beef up the floors and put a good radiant heat system above the subfloor. Not concrete (that just gives me the heebie jeebies--the thought of jackhammers being involved in any repair job, because our second story floor just isn't stiff enough to not crack the concrete over time) . . . but something like the Healthy Heat option that's installed above the subfloor. I've seen other options like that one, as well.

Hope that helps!

It is not necessary to change. Survival is not mandatory. -- W. Edwards Deming

posted by annalea | on Thu, 2013-02-07 20:52
clips

radiant heat

Yes Yes and Yes.
Radiant heat is just that, it radiants up from the source creating the most efficient way to heat. My mother had a kitchen added to an old farm house and she debated about the radiant heat. My husband who manages a plumbing and electric supply house convinced her it was the way to go. She loves it and the fact that it heats from the bottom up just makes complete sense.

As for the method of heating the water that passes through, that is truly up to you. We have a wood furnace in our garage. Unlike a wood stove or fireplace it lacks beauty and elegance but puts out massive heat that we have tied into our existing hot water baseboard throughout our home. We also have a oil burner in our basement. Oil is very expensive so we burn wood. I'm trying to convince hubs to change out our hot water baseboard to radiant but it is a massive job that he is slowing considering it as it is just the best way to heat hands down. It also eliminates the issue of drapes near baseboard heat, as well as the issue of not being able to place furniture to the wall.

So yes, I promise you will not be disappointed. Just as the up flush toilets, there is a better way.

posted by opalm | on Thu, 2013-02-07 20:56
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Jasi's picture

heat

I grew up with radiant heat and it was wonderful. So delightful to get out of bed in the morning. The sensation is like a seat warmer in a car, as long as there's no cold wind, you feel warm because your body is in contact with warmth. It does indeed radiate upwards and made the rooms very comfortable. I have noo idea how much it cost my parents to run, it came with our large, then-modern ranch built on slab. It really helped my allergies too.

posted by Jasi | on Thu, 2013-02-07 21:00
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radiant heat

We have radiant heat as the only heating source in our home. My husband does cement work so we have the styrofoam poured walls and all our floors are cement with pex tubing (our house is a single story with a full basement). We have never had a problem with the house being cold. We live in Minnesota, so we have some pretty cold weather. Honestly, most of the time our house is almost too hot - right now it is 76. Our family members complain that it is too warm. The only downside is when it's in the 30's and we may have a one or two day warm up, the house doesn't cool down as quickly as a typical forced air system. But that's not a big deal, just open a window. The one great thing - we go thru 1 propane tank of LP a YEAR - and all our appliances are gas. It costs us around $700 to heat our house the entire winter. Again, living in Minnesota where the heat is on from October - April (or May) that is very impressive. We purchased our system from Radiantec. One of the reasons was we could use a hot water heater rather than a boiler for our house. Good luck! http://www.radiantec.com/index.php

posted by rhulshizer | on Thu, 2013-02-07 21:38

Hydronic choices

A book by John seganthaller might be in order. He is the Sam maloof of hydruanic heating. A couple easy choices first. Use Runtal radiators. They are designed for low temp systems and make great towel warmers. Second modify your boiler loop to use the warmer water upstairs and then use it downstairs. Most high efficiency boilers actually work more efficiently as the difference in temp goes up. Retrofitting a tube system into a upstairs is a little tricky. The below floor systems are best installed from the underside. As long as you keep the loops under 300' and more pipe near the exterior walls joy should be fine. Mostly the better and best heat transfer attachment systems will be noticed as more (or less) rapid response to the thermostat. Note to self, you may run into troubles with a building code if you use surface mount floor systems. Stair risers are a problem.
Last easy choice is forced air. Install a heating coil (or several, one for each thermostat area) in the old duct work. You can even use an ERV to bring in fresh air, flow over a coil and heat the rooms. Any shop that sells coils can size them for your needs.
I heated the 1930 portion of my last house this way. No easy way to retrofit hydraunic heating there.

posted by Gizmoredtoot | on Thu, 2013-02-07 22:45

I installed an under subfloor

I installed an under subfloor system when we built our house 5 years ago, and we have been largely disappointed with the efficiency and slow response times. As mentioned previously, you really need to set it and forget it, but even then I found that if we had a cold snap for a couple days, the system would run non-stop for a day or two trying to catch up.

We've since gone to heating with wood pellets, leaving the radiant as a backup, and have cut our heating bill in half. If I had it to do again, I might try an over the subfloor system combined with the lower temperature radiators.

posted by sblanc | on Fri, 2013-02-08 10:58

Hi Ana, Love your blog! My

Hi Ana,
Love your blog! My husband and I built our home here in the mountains of Colorado in 2004. We have in-floor radiant heat with a 1-1/2" layer of lightweight concrete on top. We also had the option for a "gypcrete" layer, which is even lighter, and may be an option if your floors are already installed. You would have to check with an engineer. We have been thrilled with our system for 8 years now and so glad we spent the extra money. We don't have any hot or cold spots and when we lose power the floors stay warm for quite a while. Having our tubing above the subfloor allowed us to fine tune where we wanted heat. i.e. more tubing by the windows, in front of bathroom vanities, none in the pantry ect.... Also we have multiple zones and sub zones that allow us to fine tune even further. On the flip side our neighbor who also built at the same time as us, stapled his tubing under the sub flooring with no concrete. He has not been a happy camper. When it gets super cold here, he has cold spots that he just can't get warm. For us, it has made a difference having the thermal mass of the concrete that slowly and consistently lets off heat. One down side - when we leave for any length of time and turn down our heat, it takes a good five hours to bring the heat back to a normal temp. For us, it's a small price to pay and the benefits, for us, greatly outweigh that negative. We made mistakes building our house, but radiant heat was one of the things we did right.
Good luck with the Momplex!
K.

posted by pincky | on Fri, 2013-02-08 11:15
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Ana White's picture

A huge thank you to everyone

A huge thank you to everyone who took their time to comment - I can't tell you how thankful we are for your input!!! We've review a few times each and every one of your comments and have looked into your advice - even ordering the Modern Hydronics book and calling Radiantec! You are so awesome - I know this Momplex will have the best possible heat system because of your help!

posted by Ana White | on Fri, 2013-02-08 14:59

Didn't you have to use thicker beams anyway...?

There was one comment-er who expressed concern about the addition weight of the possible concrete. Am I remembering correctly that you wound up getting beams that were a few inches thicker than you actually needed? I would discuss that with the engineer obviously, but would that account for the additional weight of the concrete?

The only upside I can think of of doing under floor heating is that it would allow you could potentially delay the decision a little longer as long as you aren't planning on closing up the first floor ceiling any time soon.

posted by loudsilence99 | on Fri, 2013-02-08 17:11

Love our simple system! Our

Love our simple system! Our Canadian house was well insulated, to the R2000 standard and at first our hating system would overheat us. A few adjustments were made after the first year and it is now the most comfortable heat we have ever had. On top of that we used 30% less power than identical houses in the neighborhood heated with electric baseboards.

As for the install it was 3/4" PEX clipped up to the bottom of the subfloor and R-12 bat insulation under the tubes. Since there was finished space below there was no reflective material used. Four zones of 300' loops with a single pump and a four way flow regulating manifold for each zone, (Rehau pre-build manifold). We use electrically heated water with return water temperature control; Not room thermostats! A combination of bamboo and tile was put on top.

The general idea was for the pump to run 24/7 for the heating season and the heater would sense the return water coming back from the floor. If the water was too cold the heater would turn on and inject heat into the loops, once the return water made it up to the setpoint the heater would turn off but the pump would continue to circulate. The "always on" pump distributes and evens out the floor temperature as there are "variable" heat loads due to sunlight, kitchen cooking, propane insert use, entry and exit doors etc.

During the first week or so we got the flow rates dialed so all rooms were the same temperature. The farthest zone on the north side had the highest flow and the living-room/kitchen directly above the heater unit only needed 1/2 the flow rate but everywhere was the same temperature.

The heater had a low power element for maintenance, (2250W) and a high power element for start-up and peak loads, (4500W). The 4500W would be used to heat the water upto 85 DegF while the 2250W would heat it upto 87 DegF, (return temperatures). Each of them would let the water drop 5 deg from their setpoint before turning on again. We turn the system on in the fall and off in the spring, otherwise no fuss and perfect temperature all over the house.

posted by erinn.richardson | on Sun, 2013-02-10 15:27

The radiator business is busy

The radiator business is busy coming up with alternatives to the hulking white radiators that hiss in the corners of rooms. Once you take note of how boring the old-fashioned white panel radiators look, it's certainly hard to live with them.

Radiators

posted by Sam Lucas | on Sat, 2013-04-20 02:43

Heating quotes

Heated floors are amazing and I think a real luxury. Ten years ago it was not as common and I remember going to a friends house who had them in the winter and thinking how awesome it was. This post is also a great step by step on how to install the heated floors. Thanks so much.
devis installateur chauffage

posted by michel | on Thu, 2013-07-25 04:12

Heating quotes

Heated floors are amazing and I think a real luxury. Ten years ago it was not as common and I remember going to a friends house who had them in the winter and thinking how awesome it was. This post is also a great step by step on how to install the heated floors. Thanks so much.
devis installateur chauffage

posted by michel | on Thu, 2013-07-25 04:14

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